Introduction:
Homo heidelbergensis, or “archaic Homo sapiens”, is the name given to the large-brained hominins that appeared in Africa 600,000 years ago and migrated into Europe and possibly Asia. It is conventionally regarded as having given rise to modern humans in Africa and the Neanderthals in Europe.
The type specimen is the Mauer Mandible (Mauer 1), a virtually-complete lower jaw recovered from fluvial beds near the village of Mauer, in south-west Germany. The find was made on 21 October 1907 by a gravel-pit worker named Daniel Hartmann and described the following year by Professor Otto Schoetensack of the University of Heidelberg. The Mauer Mandible has been dated to 500,000 years old.
Until about ten years ago, the rather unsatisfactory term “archaic Homo sapiens” was used to describe any mid-Pleistocene hominin that wasn’t Homo erectus, Homo sapiens, or a Neanderthal. The latter was usually classified as a subspecies of Homo sapiens, i.e. H. s. neanderthalensis, but they are now generally regarded as a separate species. Consequently “archaic Homo sapiens” is itself regarded as a separate species, with the 1907 name Homo heidelbergensis having seniority under the rules of taxonomy.
As Manzi (2004) notes however this is no more than a revision of the old paradigm, with the substitution of a grade “archaic Homo sapiens” with a clade, Homo heidelbergensis, accompanied by the recognition of three distinct species, i.e. H. heidelbergensis, H. neanderthalensis and H. sapiens, with corresponding speciation events between the Middle and Late Pleistocene in Africa and Eurasia.
Whether or not Homo heidelbergensis is a genuine species or simply a grade of “Version 3.0 human" containing several species remains controversial.
Key Fossils:
Kabwe (Broken Hill), Zambia: Skull and several postcranial bones including a femur and a tibia (Broken Hill 1). It was found in an iron and zinc mine in Broken Hill, Northern Rhodesia (now Kabwe, Zambia) in 1921 by a Swiss miner named Tom Zwiglaar. Dating is uncertain, but probably between 700,000 and 400,000 years old. It has a cranial capacity of around 1100cc and was originally described as Homo rhodesiensis.
Lake Ndutu, Tanzania: a 400,000 year old cranium, found in 1973, with an estimated cranial capacity of 1100cc.
Bodo, Middle Awash, Ethiopia: a 670,000-600,000 year old cranium found in 1976 by a survey headed by Jon Kalb. Cranial capacity is 1300cc.
Sima de los Huesos, Atapuerca, Spain: 350,000 year old remains representing 28 individuals, including three nearly complete skulls, SH4 (cranial capacity 1390cc), SH5 (cranial capacity 1125cc) and SH6 (cranial capacity 1220cc).
Petralona, northern Greece: Skull discovered in cave system in 1960, dated 250,000 – 150,000 years old, with a cranial capacity of 1200cc.
La Caune de Arago, Tautavel in southern France: isolated teeth, cranial, mandibular and fragmentary postcranial remains belonging to at least four adults and three children, dated to approximately 450,000 years old. The distorted Arago 21 cranium has an estimated capacity of 1150cc.
Mauer, Germany: the Mauer Mandible, as mentioned above.
Steinheim, Germany: a distorted but nearly complete cranium found in a gravel pit 1933 by Karl Sigrist. It is believed to be 350,000-250,000 years old. The cranial capacity is 1100cc.
Boxgrove, England: a partial tibia discovered in 1994 dated to 423,000-362,000 years old, associated with Acheulian tools.
Swanscombe, England: three skull fragments belonging to the same individual recovered between 1935 and 1955; believed to be 300,000-200,000 years old and popularly known as Swanscombe Man, though now thought to be female. The cranial capacity has been estimated at 1325cc.
Dali, Shaanxi Province, China: a 250,000 year old cranium discovered by Shuntang Liu in 1978, with a cranial capacity of 1120cc.
Jinniu Shan: cranium, vertebrae, ribs, pelvis, patella and limb bones discovered in 1984. The cranial capacity is 1300cc and the remains are believed to be 250,000 years old.
Description:
Manzi (2004) selects the Middle Pliocene fossils from Kabwe, Petralona and Dali fossils as being typical of Homo heidelbergensis. They have a “transitional aspect” between earlier and more recent hominins which include both primitive and derived traits. Primitive or “archaic” features include a heavily-built cranial structure with massive brow ridges; crests in the temporo-occipital region, including erectus-like occipital and angular tori; a low and antero-posteriorly elongated cranial vault; a protruding and large facial skeleton; and the absence of a modern chin. These traits are however reduced in comparison to Homo ergaster/erectus.
The main derived feature is that the general shape of the cranial vault is consistent with increased brain-size. The frontal is less receding than it is in earlier hominins; the parietal profile is more convex along the mid-sagittal plane and less angled in coronal sections; and the occipital squama is more vertical and arched.
The cranial capacity is typically between 1100-1300cc, around 90% of that of modern humans, a considerable increase on that of Homo erectus/ergaster.
Affinities to other hominins:
The view that this species evolved in Africa about 600,000 years ago, then migrated into Europe, and that the two lineages led to respectively Homo sapiens and the Neanderthals, is probably as convincing as any of the alternatives.
Homo antecessor (known only from Spain) has recently been touted as ancestral to Homo heidelbergensis, suggesting that either the latter was a European species that later migrated back into Africa, or that Homo antecessor evolved in Africa.
Another possibility is that African and European Homo heidelbergensis are different species, with the Bodo Cranium an early example of the former. On this view, the African species would take the name originally assigned to the Bodo Cranium, Homo rhodesiensis. However the sudden increase in brain size to 90% of the modern average seen in the fossil record at around 600,000 years ago, after remaining more or less static at 65% during the previous 1.2 million years, does suggest a punctuated event which in turn suggests a single species.
Just about all that can be safely said at the present time is that our understanding is very incomplete!
Technology:
Homo heidelbergensis is associated with the same Acheulian (Mode II) technology as that originated by Homo ergaster 1.65 million years ago; however later Acheulian hand-axes are thinner, more symmetric and more extensively trimmed. Some authorities describe this technology as “Late Acheulian”. It is possible that its appearance is connected with the emergence of Homo heidelbergensis and is a product of this species greater cognitive abilities.
References:
J. M. Bermudez de Castro, J. L. Arsuaga, E. Carbonell, A. Rosas, I. Martınez, M. Mosquera (1997): A Hominid from the Lower Pleistocene of Atapuerca, Spain: Possible Ancestor to Neandertals and Modern Humans, Science Vol. 276 30 May 1997.
Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.
Conroy G (1997): “Reconstructing Human Origins: A Modern Synthesis”, W.W. Norton & Co. Inc, New York, NY & London.
Klein, R. (1999): The Human Career (2nd Edition), University of Chicago Press.
Klein R & Edgar B (2002): “The Dawn of Human Culture”, John Wiley & Sons Inc., New York.
Lewin, R and Foley, R 2004: Principles of Human Evolution (2nd edition), Blackwell Science Ltd.
Manzi G (2004): Human Evolution at the Matuyama-Brunhes
Boundary, Evolutionary Anthropology 13:11–24 (2004).
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
Stringer C & Andrews P (2005): “The Complete World of Human Evolution”, Thames & Hudson.
© Christopher Seddon 2009
Wednesday 21 January 2009
Saturday 17 January 2009
Homo ergaster
Introduction:
Homo ergaster ("working man") is an extinct human species that is known in the fossil record in Africa from possibly > 1.9 million years ago (KNM-ER 2598) and more securely 1.7-18 million years ago (KNM-ER 3733). By 600,000 years ago, it had been supplanted by the more advanced Homo heidelbergensis (“archaic Homo sapiens”).
Homo ergaster is usually assumed to have evolved from Homo habilis and to be the first human species to have left Africa. It is widely recognised as the stem species for later humans, including ourselves. It is now thought to be distinct from Homo erectus, which persisted in Asia until as recently as 50,000 to 30,000 years ago.
Homo ergaster was described in 1975 by Colin Groves and Vratislav Mazak. The type specimen is KNM-ER 992, a mandible discovered in 1971 at Koobi Fora, East Turkana, in Kenya.
Fossil record:
Homo ergaster is known from fossils recovered in East and West Turkana, Kenya; Swartkrans, South Africa; Olduvai Gorge, Tanzania; Bouri, Ethiopia; Buia, Eritrea and possibly from Dmanisi, Georgia. Key fossils include from these locations include:
From Koobi Fora, East Turkana: KNM-ER 3733, a cranium discovered in 1975 by Bernard Ngeneo, believed to be 1.8-1.7 million years old.
KNM-ER 3883, a cranium discovered in 1976 by Richard Leakey, 1.4-1.6 million years old.
KNM-ER 1808, cranial and post-cranial remains, discovered in 1973 by Kamoya Kimeu, believed to be 1.5 million years old. These remains are thought to be from a female and show coarse bone growths suggesting hypervitaminosis A, a lethal condition arising from excessive Vitamin A consumption. This could have arisen from consumption of carnivore liver or possibly bee brood. That KNM-ER 1808 survived long enough for the pathology to show up in her bones implies that she was cared for by others of her own kind.
KNM-ER 2958, a partial occipital bone is possibly > 1.9m years old. If so, it is the earliest fossil evidence for Homo ergaster.
From West Turkana: The “Turkana Boy” (KNM-WT 15000), an almost-complete adolescent male skull and skeleton discovered in August 1984 by Kamoya Kimeu on the banks of the Nariokotome River, dated to 1.33-1.64 millon years old. One of the most important fossil finds ever made, the Turkana Boy is even more complete than “Lucy”. Based on dental irruption, he was 11-12 years old at death.
From Swartkrans: SK 847, a partial cranium noted in 1969 at the Transvaal Museum, Pretoria by Ronald Clarke, though discovered twenty years earlier by museum palaeontologists Robert Broom and John Robinson, 1.0-1.5 million years old.
The “Daka Cranium” (BOU-VP 2/66), from Bouri, Middle Awash, Ethiopia, a 1.0 million year old calvaria with a cranial capacity of 995cc, discovered 1997 by W. H. Gilbert, may belong to Homo ergaster but both it and a similar cranium from Buia, Eritrea may represent a migration from Asia back into Africa by Homo erectus.
OH9 and OH 12 from Olduvai Gorge, Tanzania. OH9, discovered by Louis Leakey in 1960 is a 1.2 million year old cranium provisionally designated Homo leakeyi. It has a cranial capacity of 1067cc. OH 12, discovered by Margaret Cropper in 1962 is an 830,000-620,000 year old fragmentary cranium.
D2700 from Dmanisi, Georgia, is a skull dated at 1.95-1.77 million years old. The brain-case is very small, just 600cc, more consistent with Homo habilis, but postcranial remains from the same site suggest Homo ergaster affinities. These hominins have been described as a separate species, Homo georgicus.
Description:
Much of our knowledge of Homo ergaster comes from study of the Turkana Boy, who stood 1.62m (5ft3) at death and would have attained at least 1.82m (6ft) had he reached adulthood.
But his brain, which was almost fully-grown, had a volume of just 880cc, only 2/3rds that of a modern human. Mature Homo ergaster had a cranial capacity of around 900cc (Klein, 1999) though it ranged from as little as 600cc (D2700) to as much as 1100cc (OH 9). Although the average is rather more than that of Homo habilis, the effective difference is only small given H. ergaster’s greater stature.
H. ergaster possessed the characteristic long, low brain-case of pre-sapiens human species; a flat and receding forehead; a bony brow-ridge over the eyes. The nose projected forward, with downward-orientated nostrils, similar to a modern human, again unlike the more ape-like H. habilis. But the jaws were massive and prognathic (jutting) and the teeth were intermediate in size between H. habilis and modern humans. They were completely chinless.
The rib-cage is barrel-shaped rather than conical, the pelvis is narrower and in body proportions, very much like modern humans, with lower limbs indicating a full striding gait. Homo ergaster was a fully-committed terrestrial biped, unlike Homo habilis, which retained relatively longer arms, shorter legs and a conical ribcage: remnants of an arboreal past now finally abandoned.
The narrower pelvis increases the energy efficiency of muscles involved in bipedal movement, but this forced the lower part of the ribcage to narrow. To retain the same lung capacity, the upper part of the ribcage expanded to give it its modern barrel shape. The down side is that the female birth canal narrowed. This in turn would have restricted antenatal brain growth. The very long postnatal dependency of modern humans might have had its origins with Homo ergaster.
These changes would have also forced a reduction in the size of the digestive tract, which could only have happened in conjunction with higher quality food. This suggests consumption of more meat, tubers, bulbs, etc and the possible use of fire for cooking, but there is no hard evidence for either.
Homo ergaster colonised dryer, more seasonal African environments, where there was relatively little surface water or shade. Its physique is not unlike that of present-day humans living in equatorial East Africa, who have slim bodies and long limbs; a body-shape that gives a higher surface area to volume ratio than the stockier build of, say, an Eskimo and is more efficient at dissipating (as opposed to conserving) heat.
Under hot conditions, the projecting, human-like nose would act as a condenser, preventing moisture from being exhaled and so wasted. It is likely that Homo ergaster was almost naked, like a modern human, but unlike any previously-existing hominin. This would have greatly aided heat dissipation. Like modern Africans, Homo ergaster was almost certainly dark-skinned, to protect against skin cancer. (Scarre, 2005; Cameron & Groves, 2004).
Because the natal brain size was less than that of modern humans, the birth canal, though still problematic, was smaller than that of modern humans. Consequently Homo ergaster may have been a more efficient biped than ourselves, and was probably a superb all-round runner that would have left our best athletes trailing in its wake. Enhanced middle and long-distance running abilities would have given them an edge when hunting; conversely when the tables were turned, sprinting abilities would have helped them to escape predators.
Origins:
As noted above, the widely-accepted view is that Homo ergaster evolved from Homo habilis. Although Homo rudolfensis is also a possible ancestor, it seems likely that this taxon is off the line of human evolution and should be removed from Homo altogether (Cameron & Groves, 2004).
Another possibility is that both Homo habilis and H. ergaster both evolved from a common ancestor around 2.3 million years ago. Spoor et al (2007) note that both species were sympatric in the Turkana Basin for approximately 400,000 years. They believe that this is a more likely explanation than the alternative, which is a Homo ergaster split from an earlier population of Homo habilis, with the Turkana Basin being a region of secondary contact between the two species. Cameron and Groves (2004) take the opposite view, pointing out that Homo ergaster does not appear in the fossil record until much later than Homo habilis.
If the second scenario is correct, and Homo ergaster split in a sudden “punctuated” evolutionary event, a possible cause would be the increase in seasonal rainfall and aridity that occurred across Africa with the onset of the Pleistocene, 1.8 million years ago.
On the other hand it is possible that from 3 to 2 million years ago in Africa there existed a “bush” or complex of closely-related but distinct hominin species, and that Homo habilis and H. ergaster could have emerged from totally separate branches. If this is correct, then there are still many species of hominin remaining undiscovered.
Relationship to Homo erectus:
It used to be the general view that the “Version 2.0 humans” living in Africa and Europe until 600,000 years ago and Asia until possibly 50,000-30,000 years ago belonged to a single species, Homo erectus. But this view has fallen out of fashion. On average, the African skulls tend to be higher-domed and thinner-walled than those from East Asia, and they have less massive faces and brow-ridges. Accordingly the African hominins are usually now classified as Homo ergaster, with the designation H. erectus reserved for Asian fossils. Many sources do still lump both together as Homo erectus or use the term “African Homo erectus” in preference to H. ergaster.
The view that Homo ergaster left Africa and evolved into Homo erectus, while Africa remained exclusively populated by stay-at-home H. ergaster, is almost certainly an oversimplification.
The presence of the 1.95-1.77 million years old ergaster-like skulls at Dmanisi show that humans had left Africa by then, but whether or not these hominins can be included in Homo ergaster or were ancestral the Homo erectus in Asia remains a matter for debate.
The discovery of an erectus-like hominin at Ceprano, Italy, in 1994 and its similarity to the Olduvai hominin OH 9 (Clarke, 2000) has led to the view that there was a migration back into Africa by Homo erectus. In addition to OH 9, the more recent OH 12, the “Daka Cranium” (BOU-VP 2/66), from Bouri and the similar cranium from Buia have been proposed as examples of “Into Africa” Homo erectus rather than Homo ergaster (Cameron & Groves, 2004). The partial skullcap OH 9 has massive brow-ridges, thick walls and angular rear profile typical of East Asian Homo erectus, but in other characteristics it is like Homo ergaster. The Buia and Daka skulls show only minor differences from earlier Homo ergaster (Scarre, 2005).
Berhane Asfaw argues that “the Daka cranium confirms previous suggestions that geographic subdivision of early H. erectus into separate species lineages is biologically misleading, artificially inflating early Pleistocene species diversity. Rather, the Daka calvaria is consistent with the hypothesis of a widespread, moderately polymorphic and polytypic species [i.e. Homo erectus] at 1.0Myr” Asfaw et al (2002).
Subsequent evolutionary career:
The traditional view is that around 600,000 years ago, Homo ergaster (or African Homo erectus) evolved into the larger-brained “archaic Homo sapiens” from which two distinct subspecies, the Neanderthals and modern Homo sapiens (us), eventually arose. The currently popular view represents only a slight updating of this paradigm in that “archaic Homo sapiens” is now seen as a distinct species, Homo heidelbergensis. This species migrated into Europe, where it evolved into Homo neanderthalensis (the Neanderthals). Meanwhile, H. heidelbergensis in Africa evolved into Homo sapiens about 200,000 years ago. While it does seem likely that African Homo erectus (whatever this may be) did evolve into larger-brained hominins it is problematic as to whether there was just one successor species or several; from which of these Homo sapiens eventually arose; of if indeed the progenitor species for Homo sapiens was African or a European species that migrated back into Africa.
Technology:
The earliest Homo ergaster remains, including the Dmanisi hominins, are associated with the Oldowan (Mode I) tool tradition. At about 1.65 million years ago these primitive tools give way to the teardrop shaped “hand-axes” of the Acheulian (Mode II) tradition, named for Saint-Acheul in Northern France, where the first examples were found at in the mid-19th Century. The oldest known Acheulian tools are dated to 1.65 million years ago from West Turkana, Kenya and 1.5-1.4 million years ago from Konso, Ethiopia, East Turkana, Kenya and Peninj, near Olduvai Gorge, Tanzania (Scarre, 2005).
The Acheulian hand-axe tradition endured with little change until it was finally abandoned 250,000 years ago. It has been described as displaying a “variable sameness” that strikes “even enthusiasts as monotonous”. The tradition does however represent a considerable advance on its predecessor as it is necessary for the maker to preconceive the form of the finished tool from a block of raw material. The 3D symmetry often shown by the axes indicate their makers were intent on imposing form on the artefact rather than just creating a sharp edge as in the Oldowan tradition. This is very difficult and requires forward planning (Mithen, 1996).
Despite the name, the function of these often beautifully-crafted hand-axes remains conjectural. At some sites such as Melka Kunture in Ethiopia, Olorgesailie in Kenya, Isimila in Tanzania and Kalambo Falls, hand-axes occur in large numbers and appear to have been discarded soon after manufacture, with no sign of wear, suggesting that they were never used. Another major puzzle is that they are often too large to be useful (see, for example, the fine example in the Natural History Museum in Kensington).
One theory (Kohn & Mithen, 1999) proposes that the axes were made to impress prospective mates. When a female saw a large, symmetrical axe, she might conclude that its maker possessed the right attributes to father successful offspring. The axe, having served its purpose (or not) would then be discarded. This – like the elaborate bower of the male bower bird – would be an example of the extended phenotype of a species playing a role in sexual selection (Dawkins, 1982).
Regardless of whether or not the mate selection hypothesis is true, the hand-axes almost certainly were used as tools. Experiments have shown them to be effective for butchery purposes; some may have been used as a discus for bringing down prey; others could have been used for chopping and scraping wood. Klein and Edgar (2002) liken the Acheulian hand-axe to a Swiss army knife.
Another issue with the hand-axes is that while they are ubiquitous in Africa and western Eurasia, they are not found east of Northern India. This was first noted by American archaeologist Hallam Movius in 1948. The “Movius Line” has stood the test of time and two theories have been proposed to explain it. One is that the ancestors of those living east of the Movius Line left Africa before the hand-axes were invented. The other possibility is that the migrants from Africa passed through a region lacking suitable materials to make the axes, and by the time they emerged from it, the tradition had been forgotten.
Recent discoveries support the first possibility. Hominin remains such as the Mojokarta Child [Homo erectus] from Java have now been dated to 1.81 million years ago and the Dmanisi hominins are at least 1.77 million years old, predating the earliest-known Acheulian hand-axes.
References:
Berhane Asfaw, W. Henry Gilbert, Yonas Beyene, William K. Hart,
Paul R. Rennek, Giday WoldeGabriel, Elisabeth S. Vrba & Tim D. White (2002): Remains of Homo erectus from Bouri, Middle Awash, Ethiopia, Nature Vol. 416, 21 March 2002.
A. Ascenzi, F. Mallegni, G. Manzi, A. G. Segre & E. Segre Naldini (2000): A re-appraisal of Ceprano calvaria affinities with Homo erectus, after the new reconstruction, Journal of Human Evolution (2000) 39, 443–450.
Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.
Clarke R.J (2000): A corrected reconstruction and interpretation of the Homo erectus calvaria from Ceprano, Italy, Journal of Human Evolution, Volume 39, Number 4, October 2000, pp. 433-442.
Conroy G (1997): “Reconstructing Human Origins: A Modern Synthesis”, W.W. Norton & Co. Inc, New York, NY & London.
Dawkins R (1982): “The Extended Phenotype”, Oxford University Press.
Klein, R. (1999): The Human Career (2nd Edition), University of Chicago Press.
Klein R & Edgar B (2002): “The Dawn of Human Culture”, John Wiley & Sons Inc., New York.
Kohn M & Mithen S (1999): “Handaxes: products of sexual selection?” Antiquity 73: 518-526.
Lewin, R and Foley, R 2004: Principles of Human Evolution (2nd edition), Blackwell Science Ltd.
Manzi G (2004): Human Evolution at the Matuyama-Brunhes
Boundary, Evolutionary Anthropology 13:11–24 (2004)
G. Manzi, F. Mallegni, and A. Ascenzi (2001): A cranium for the earliest Europeans: Phylogenetic position of the hominid from Ceprano, Italy, PNAS August 14, 2001 vol. 98 no. 17 10013.
Mithen S (1996): “The Prehistory of the Mind”, Thames & Hudson.
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
F. Spoor, M. G. Leakey, P. N. Gathogo, F. H. Brown, S. C. Anton, I. McDougall, C. Kiarie, F. K. Manthi & L. N. Leakey (2007): Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya, Nature Vol 448 9 August 2007.
Gen Suwa, Berhane Asfaw, Yohannes Haile-Selassie, Tim White, Shigehiro Katoh, Giday WoldeGabriel, William K. Hart, Hideo Nakaya, Yonas Beyene (2007): Early Pleistocene Homo erectus fossils from Konso, southern Ethiopia, Anthropological Science, Vol. 115, 133–151, 2007.
© Christopher Seddon 2009
Homo ergaster ("working man") is an extinct human species that is known in the fossil record in Africa from possibly > 1.9 million years ago (KNM-ER 2598) and more securely 1.7-18 million years ago (KNM-ER 3733). By 600,000 years ago, it had been supplanted by the more advanced Homo heidelbergensis (“archaic Homo sapiens”).
Homo ergaster is usually assumed to have evolved from Homo habilis and to be the first human species to have left Africa. It is widely recognised as the stem species for later humans, including ourselves. It is now thought to be distinct from Homo erectus, which persisted in Asia until as recently as 50,000 to 30,000 years ago.
Homo ergaster was described in 1975 by Colin Groves and Vratislav Mazak. The type specimen is KNM-ER 992, a mandible discovered in 1971 at Koobi Fora, East Turkana, in Kenya.
Fossil record:
Homo ergaster is known from fossils recovered in East and West Turkana, Kenya; Swartkrans, South Africa; Olduvai Gorge, Tanzania; Bouri, Ethiopia; Buia, Eritrea and possibly from Dmanisi, Georgia. Key fossils include from these locations include:
From Koobi Fora, East Turkana: KNM-ER 3733, a cranium discovered in 1975 by Bernard Ngeneo, believed to be 1.8-1.7 million years old.
KNM-ER 3883, a cranium discovered in 1976 by Richard Leakey, 1.4-1.6 million years old.
KNM-ER 1808, cranial and post-cranial remains, discovered in 1973 by Kamoya Kimeu, believed to be 1.5 million years old. These remains are thought to be from a female and show coarse bone growths suggesting hypervitaminosis A, a lethal condition arising from excessive Vitamin A consumption. This could have arisen from consumption of carnivore liver or possibly bee brood. That KNM-ER 1808 survived long enough for the pathology to show up in her bones implies that she was cared for by others of her own kind.
KNM-ER 2958, a partial occipital bone is possibly > 1.9m years old. If so, it is the earliest fossil evidence for Homo ergaster.
From West Turkana: The “Turkana Boy” (KNM-WT 15000), an almost-complete adolescent male skull and skeleton discovered in August 1984 by Kamoya Kimeu on the banks of the Nariokotome River, dated to 1.33-1.64 millon years old. One of the most important fossil finds ever made, the Turkana Boy is even more complete than “Lucy”. Based on dental irruption, he was 11-12 years old at death.
From Swartkrans: SK 847, a partial cranium noted in 1969 at the Transvaal Museum, Pretoria by Ronald Clarke, though discovered twenty years earlier by museum palaeontologists Robert Broom and John Robinson, 1.0-1.5 million years old.
The “Daka Cranium” (BOU-VP 2/66), from Bouri, Middle Awash, Ethiopia, a 1.0 million year old calvaria with a cranial capacity of 995cc, discovered 1997 by W. H. Gilbert, may belong to Homo ergaster but both it and a similar cranium from Buia, Eritrea may represent a migration from Asia back into Africa by Homo erectus.
OH9 and OH 12 from Olduvai Gorge, Tanzania. OH9, discovered by Louis Leakey in 1960 is a 1.2 million year old cranium provisionally designated Homo leakeyi. It has a cranial capacity of 1067cc. OH 12, discovered by Margaret Cropper in 1962 is an 830,000-620,000 year old fragmentary cranium.
D2700 from Dmanisi, Georgia, is a skull dated at 1.95-1.77 million years old. The brain-case is very small, just 600cc, more consistent with Homo habilis, but postcranial remains from the same site suggest Homo ergaster affinities. These hominins have been described as a separate species, Homo georgicus.
Description:
Much of our knowledge of Homo ergaster comes from study of the Turkana Boy, who stood 1.62m (5ft3) at death and would have attained at least 1.82m (6ft) had he reached adulthood.
But his brain, which was almost fully-grown, had a volume of just 880cc, only 2/3rds that of a modern human. Mature Homo ergaster had a cranial capacity of around 900cc (Klein, 1999) though it ranged from as little as 600cc (D2700) to as much as 1100cc (OH 9). Although the average is rather more than that of Homo habilis, the effective difference is only small given H. ergaster’s greater stature.
H. ergaster possessed the characteristic long, low brain-case of pre-sapiens human species; a flat and receding forehead; a bony brow-ridge over the eyes. The nose projected forward, with downward-orientated nostrils, similar to a modern human, again unlike the more ape-like H. habilis. But the jaws were massive and prognathic (jutting) and the teeth were intermediate in size between H. habilis and modern humans. They were completely chinless.
The rib-cage is barrel-shaped rather than conical, the pelvis is narrower and in body proportions, very much like modern humans, with lower limbs indicating a full striding gait. Homo ergaster was a fully-committed terrestrial biped, unlike Homo habilis, which retained relatively longer arms, shorter legs and a conical ribcage: remnants of an arboreal past now finally abandoned.
The narrower pelvis increases the energy efficiency of muscles involved in bipedal movement, but this forced the lower part of the ribcage to narrow. To retain the same lung capacity, the upper part of the ribcage expanded to give it its modern barrel shape. The down side is that the female birth canal narrowed. This in turn would have restricted antenatal brain growth. The very long postnatal dependency of modern humans might have had its origins with Homo ergaster.
These changes would have also forced a reduction in the size of the digestive tract, which could only have happened in conjunction with higher quality food. This suggests consumption of more meat, tubers, bulbs, etc and the possible use of fire for cooking, but there is no hard evidence for either.
Homo ergaster colonised dryer, more seasonal African environments, where there was relatively little surface water or shade. Its physique is not unlike that of present-day humans living in equatorial East Africa, who have slim bodies and long limbs; a body-shape that gives a higher surface area to volume ratio than the stockier build of, say, an Eskimo and is more efficient at dissipating (as opposed to conserving) heat.
Under hot conditions, the projecting, human-like nose would act as a condenser, preventing moisture from being exhaled and so wasted. It is likely that Homo ergaster was almost naked, like a modern human, but unlike any previously-existing hominin. This would have greatly aided heat dissipation. Like modern Africans, Homo ergaster was almost certainly dark-skinned, to protect against skin cancer. (Scarre, 2005; Cameron & Groves, 2004).
Because the natal brain size was less than that of modern humans, the birth canal, though still problematic, was smaller than that of modern humans. Consequently Homo ergaster may have been a more efficient biped than ourselves, and was probably a superb all-round runner that would have left our best athletes trailing in its wake. Enhanced middle and long-distance running abilities would have given them an edge when hunting; conversely when the tables were turned, sprinting abilities would have helped them to escape predators.
Origins:
As noted above, the widely-accepted view is that Homo ergaster evolved from Homo habilis. Although Homo rudolfensis is also a possible ancestor, it seems likely that this taxon is off the line of human evolution and should be removed from Homo altogether (Cameron & Groves, 2004).
Another possibility is that both Homo habilis and H. ergaster both evolved from a common ancestor around 2.3 million years ago. Spoor et al (2007) note that both species were sympatric in the Turkana Basin for approximately 400,000 years. They believe that this is a more likely explanation than the alternative, which is a Homo ergaster split from an earlier population of Homo habilis, with the Turkana Basin being a region of secondary contact between the two species. Cameron and Groves (2004) take the opposite view, pointing out that Homo ergaster does not appear in the fossil record until much later than Homo habilis.
If the second scenario is correct, and Homo ergaster split in a sudden “punctuated” evolutionary event, a possible cause would be the increase in seasonal rainfall and aridity that occurred across Africa with the onset of the Pleistocene, 1.8 million years ago.
On the other hand it is possible that from 3 to 2 million years ago in Africa there existed a “bush” or complex of closely-related but distinct hominin species, and that Homo habilis and H. ergaster could have emerged from totally separate branches. If this is correct, then there are still many species of hominin remaining undiscovered.
Relationship to Homo erectus:
It used to be the general view that the “Version 2.0 humans” living in Africa and Europe until 600,000 years ago and Asia until possibly 50,000-30,000 years ago belonged to a single species, Homo erectus. But this view has fallen out of fashion. On average, the African skulls tend to be higher-domed and thinner-walled than those from East Asia, and they have less massive faces and brow-ridges. Accordingly the African hominins are usually now classified as Homo ergaster, with the designation H. erectus reserved for Asian fossils. Many sources do still lump both together as Homo erectus or use the term “African Homo erectus” in preference to H. ergaster.
The view that Homo ergaster left Africa and evolved into Homo erectus, while Africa remained exclusively populated by stay-at-home H. ergaster, is almost certainly an oversimplification.
The presence of the 1.95-1.77 million years old ergaster-like skulls at Dmanisi show that humans had left Africa by then, but whether or not these hominins can be included in Homo ergaster or were ancestral the Homo erectus in Asia remains a matter for debate.
The discovery of an erectus-like hominin at Ceprano, Italy, in 1994 and its similarity to the Olduvai hominin OH 9 (Clarke, 2000) has led to the view that there was a migration back into Africa by Homo erectus. In addition to OH 9, the more recent OH 12, the “Daka Cranium” (BOU-VP 2/66), from Bouri and the similar cranium from Buia have been proposed as examples of “Into Africa” Homo erectus rather than Homo ergaster (Cameron & Groves, 2004). The partial skullcap OH 9 has massive brow-ridges, thick walls and angular rear profile typical of East Asian Homo erectus, but in other characteristics it is like Homo ergaster. The Buia and Daka skulls show only minor differences from earlier Homo ergaster (Scarre, 2005).
Berhane Asfaw argues that “the Daka cranium confirms previous suggestions that geographic subdivision of early H. erectus into separate species lineages is biologically misleading, artificially inflating early Pleistocene species diversity. Rather, the Daka calvaria is consistent with the hypothesis of a widespread, moderately polymorphic and polytypic species [i.e. Homo erectus] at 1.0Myr” Asfaw et al (2002).
Subsequent evolutionary career:
The traditional view is that around 600,000 years ago, Homo ergaster (or African Homo erectus) evolved into the larger-brained “archaic Homo sapiens” from which two distinct subspecies, the Neanderthals and modern Homo sapiens (us), eventually arose. The currently popular view represents only a slight updating of this paradigm in that “archaic Homo sapiens” is now seen as a distinct species, Homo heidelbergensis. This species migrated into Europe, where it evolved into Homo neanderthalensis (the Neanderthals). Meanwhile, H. heidelbergensis in Africa evolved into Homo sapiens about 200,000 years ago. While it does seem likely that African Homo erectus (whatever this may be) did evolve into larger-brained hominins it is problematic as to whether there was just one successor species or several; from which of these Homo sapiens eventually arose; of if indeed the progenitor species for Homo sapiens was African or a European species that migrated back into Africa.
Technology:
The earliest Homo ergaster remains, including the Dmanisi hominins, are associated with the Oldowan (Mode I) tool tradition. At about 1.65 million years ago these primitive tools give way to the teardrop shaped “hand-axes” of the Acheulian (Mode II) tradition, named for Saint-Acheul in Northern France, where the first examples were found at in the mid-19th Century. The oldest known Acheulian tools are dated to 1.65 million years ago from West Turkana, Kenya and 1.5-1.4 million years ago from Konso, Ethiopia, East Turkana, Kenya and Peninj, near Olduvai Gorge, Tanzania (Scarre, 2005).
The Acheulian hand-axe tradition endured with little change until it was finally abandoned 250,000 years ago. It has been described as displaying a “variable sameness” that strikes “even enthusiasts as monotonous”. The tradition does however represent a considerable advance on its predecessor as it is necessary for the maker to preconceive the form of the finished tool from a block of raw material. The 3D symmetry often shown by the axes indicate their makers were intent on imposing form on the artefact rather than just creating a sharp edge as in the Oldowan tradition. This is very difficult and requires forward planning (Mithen, 1996).
Despite the name, the function of these often beautifully-crafted hand-axes remains conjectural. At some sites such as Melka Kunture in Ethiopia, Olorgesailie in Kenya, Isimila in Tanzania and Kalambo Falls, hand-axes occur in large numbers and appear to have been discarded soon after manufacture, with no sign of wear, suggesting that they were never used. Another major puzzle is that they are often too large to be useful (see, for example, the fine example in the Natural History Museum in Kensington).
One theory (Kohn & Mithen, 1999) proposes that the axes were made to impress prospective mates. When a female saw a large, symmetrical axe, she might conclude that its maker possessed the right attributes to father successful offspring. The axe, having served its purpose (or not) would then be discarded. This – like the elaborate bower of the male bower bird – would be an example of the extended phenotype of a species playing a role in sexual selection (Dawkins, 1982).
Regardless of whether or not the mate selection hypothesis is true, the hand-axes almost certainly were used as tools. Experiments have shown them to be effective for butchery purposes; some may have been used as a discus for bringing down prey; others could have been used for chopping and scraping wood. Klein and Edgar (2002) liken the Acheulian hand-axe to a Swiss army knife.
Another issue with the hand-axes is that while they are ubiquitous in Africa and western Eurasia, they are not found east of Northern India. This was first noted by American archaeologist Hallam Movius in 1948. The “Movius Line” has stood the test of time and two theories have been proposed to explain it. One is that the ancestors of those living east of the Movius Line left Africa before the hand-axes were invented. The other possibility is that the migrants from Africa passed through a region lacking suitable materials to make the axes, and by the time they emerged from it, the tradition had been forgotten.
Recent discoveries support the first possibility. Hominin remains such as the Mojokarta Child [Homo erectus] from Java have now been dated to 1.81 million years ago and the Dmanisi hominins are at least 1.77 million years old, predating the earliest-known Acheulian hand-axes.
References:
Berhane Asfaw, W. Henry Gilbert, Yonas Beyene, William K. Hart,
Paul R. Rennek, Giday WoldeGabriel, Elisabeth S. Vrba & Tim D. White (2002): Remains of Homo erectus from Bouri, Middle Awash, Ethiopia, Nature Vol. 416, 21 March 2002.
A. Ascenzi, F. Mallegni, G. Manzi, A. G. Segre & E. Segre Naldini (2000): A re-appraisal of Ceprano calvaria affinities with Homo erectus, after the new reconstruction, Journal of Human Evolution (2000) 39, 443–450.
Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.
Clarke R.J (2000): A corrected reconstruction and interpretation of the Homo erectus calvaria from Ceprano, Italy, Journal of Human Evolution, Volume 39, Number 4, October 2000, pp. 433-442.
Conroy G (1997): “Reconstructing Human Origins: A Modern Synthesis”, W.W. Norton & Co. Inc, New York, NY & London.
Dawkins R (1982): “The Extended Phenotype”, Oxford University Press.
Klein, R. (1999): The Human Career (2nd Edition), University of Chicago Press.
Klein R & Edgar B (2002): “The Dawn of Human Culture”, John Wiley & Sons Inc., New York.
Kohn M & Mithen S (1999): “Handaxes: products of sexual selection?” Antiquity 73: 518-526.
Lewin, R and Foley, R 2004: Principles of Human Evolution (2nd edition), Blackwell Science Ltd.
Manzi G (2004): Human Evolution at the Matuyama-Brunhes
Boundary, Evolutionary Anthropology 13:11–24 (2004)
G. Manzi, F. Mallegni, and A. Ascenzi (2001): A cranium for the earliest Europeans: Phylogenetic position of the hominid from Ceprano, Italy, PNAS August 14, 2001 vol. 98 no. 17 10013.
Mithen S (1996): “The Prehistory of the Mind”, Thames & Hudson.
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
F. Spoor, M. G. Leakey, P. N. Gathogo, F. H. Brown, S. C. Anton, I. McDougall, C. Kiarie, F. K. Manthi & L. N. Leakey (2007): Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya, Nature Vol 448 9 August 2007.
Gen Suwa, Berhane Asfaw, Yohannes Haile-Selassie, Tim White, Shigehiro Katoh, Giday WoldeGabriel, William K. Hart, Hideo Nakaya, Yonas Beyene (2007): Early Pleistocene Homo erectus fossils from Konso, southern Ethiopia, Anthropological Science, Vol. 115, 133–151, 2007.
© Christopher Seddon 2009
Sunday 11 January 2009
Java Man and Peking Man (Homo erectus)
Java Man is the popular name given to the fossil hominin discovered in 1891 by Eugene Dubois at the village of Trinil, on the banks of the Solo River in eastern Java. The find consisted of a skullcap and a femur. It is uncertain if are from the same individual and the femur is believed by some to be from a modern human. Dubois initially named his find Anthropithecus erectus (“Upright man-ape”, suggesting it was more ape-like than human) then he renamed it Pithecanthropus erectus (“Upright ape-man”, suggesting closer human affinities).
Peking Man is the popular name given to the fossil hominins discovered in the 1920s and 1930s at Zhoukoudian, near Beijing and described as Sinanthropus pekinensis by Davidson Black.
In 1944 both species were reclassified as Homo erectus by the late Ernst Mayr as part of a general tidying-up exercise of the bewildering plethora of hominin genera and species then recognised.
Eugene Dubois (1858-1940) was a Dutch anatomist who became fascinated with the subject of human origins. He had been an avid fossil-collector from childhood and believed that fossils provided the best way of elucidating evolutionary history, an approach which was not universally accepted at the time.
Dubois became convinced that the best place to search for the fossil origins of mankind would be the tropics, and to this end he joined the Dutch army as a doctor and had himself posted to the Dutch East Indies, arriving in Sumatra in December 1887. The demands of his day job meant it was quite a while before he could begin his search of the many caves in Sumatra, where he believed the fossil evidence would be found. Eventually, though, he was able to investigate the caves at Lida Adjer and duly began to unearth the bones of various mammals. Armed with this evidence, he managed to persuade the Dutch government to relieve him of his medical duties and allow him work full time on his fossil-hunting. He was also assigned the services of fifty convicts to help him with his excavations.
After failing to discover any human fossils in Sumatra, Dubois received permission in April 1890 to transfer his work to neighbouring Java. He began searching cave sites, but again without success, so he began investigating open sites as well. Finally he was rewarded with success and in October 1891, at Trinil, he recovered a low-domed angular thick-walled human skullcap with a large shelf-like brow ridge. In August 1892 he recovered a humanlike femur from what he believed to be the same site.
Convinced he had found the “missing link” – a transitional form between humans and apes, Dubois at first proposed the name Anthropithecus erectus based on what he believed were the ape-like proportions of its brain - which he estimated at 700cc - and the modernity of the femur. However in November 1892 he revised the cranial capacity upwards to 900cc, closer to that of a modern human than an ape. Accordingly he renamed the fossil Pithecanthropus erectus.
In 1895 Dubois returned to Europe and embarked on a tour to promote his claim to have found the missing link. Although the scientific community were intrigued by his discoveries, his conclusions were generally rejected. Disappointed, he eventually accepted a position as professor of geology at the University of Amsterdam and refused to allow any examination of his fossils until, under increasing pressure to grant access, he finally relented in 1923. His motives have been questioned: the popular view is that he was acting out of spite, like an angry schoolboy taking his ball and going home. However it is more likely that he was protecting his intellectual property. In 1897 he had permitted Gustav Schwalbe of the University of Strasburg to make a cast of the skullcap: Schwalbe had then produced a monograph that had been far more sympathetically received than any of Dubois’ own work.
By the 1920s and 1930s further hominin fossils were coming to light. In 1927 the Canadian anthropologist Davidson Black described Sinanthropus pekinensis (“Chinese man of Peking” [Beijing]), based on an examination of two teeth recovered from the cave site of Zhoukoudian in Dragon Bone Hill, near Beijing. The find became popularly known as Peking Man. Several skullcaps were recovered from the same site in subsequent years. Both Black and anatomist Franz Weidenreich noted similarities between the Zhoukoudian finds and Pithanthropus, but Dubois rejected the similarities.
Unfortunately the Zhoukoudian fossils were lost during World War II. Work at the site was halted by the Japanese invasion in 1937, but the fossils remained at the Cenozoic Research Laboratory of the Peking Union Medical College until 1941, when an attempt was made to transfer them to the United States for safekeeping. They were never seen again. It is thought that they were in possession of a group of US marines, who were captured when war broke out between Japan and the USA. Fortunately Weidenreich had made plaster casts, now in the American Museum of Natural History, New York. After the war, excavation resumed at Zhoukoudian and a number of discoveries have been made since, including two skull fragments. Zhoukoudian became a World Heritage site in 1987.
In 1936 palaeontologist Ralph von Koenigswald made a further discovery on Java itself. Excavating near Mojokerto, eastern Java, in 1936, von Koenigswald recovered a juvenile skull now known as the Mojokerto Child, who was anything from 2 to 6 years old at death, but again Dubois rejected any affinities to Pithecanthropus. The following year, von Koenigswald made further discoveries at Sangiran, East-Central Java with the aid of local people, who he promised to pay 10 cents for each find. The finds included fragments making up an almost-complete skull, though von Koenigswald’s delight at this discovery was somewhat tempered when he learned his helpers were breaking larger finds into smaller pieces to maximise their bounty!
Dubois argued his find was more ape-like than the later discoveries, leading to the popular misconception that he had repudiated his claim that it was an intermediate form. Eugene Dubois died in December 1940, having done himself few favours in the last four decades of his life. British anthropologist Sir Arthur Keith, writing in an obituary notice, observed that Dubois was “an idealist who held his ideas so firmly that he tended to bend the facts rather than alter his ideas to fit them.”
It is now generally accepted that the Javanese and Chinese hominins belong to the same or closely-related species, usually classed as Homo erectus. Some authorities recognise a separate species, Homo pekinensis, for the Chinese hominins.
Dating the Javanese fossils using modern argon-40/argon-39 and potassium/argon dating techniques of volcanic material recovered from the same context as the fossils has been problematic. This is due to deformation and distortion by earth movements of the stratigraphic beds with which the fossils are associated. Another problem has been uncertainty regarding the exact discovery sites, which were less scrupulously recorded than would now be the case. Dates ranging from as recent as 1.0 million to as long ago as 1.65 million have been proposed. Dates of 1.81 million years for the Mojokarto Child and 1.66 million years for the Sangiran fossil were reported in 1994 (Swisher et al, 1994).
Homo erectus (or pekinensis) fossils from Zhoukoudian and elsewhere in China have been dated to between 800,000 and 400,000 years old by palaeomagnetic and biostratigraphic techniques. However stone tools from the Nihewan Basin, 150km (90 miles) west of Beijing have been dated to as far back as 1.6 million years old, implying a much earlier arrival.
References:
Curtis G, Swisher C & Lewin R (2000): Java Man, Scribner, USA.
Klein R (1999): "The Human Career", 2nd edition, University of Chicago Press
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
CC Swisher 3rd, GH Curtis, T Jacob, AG Getty, A Suprijo and Widiasmoro (1994): Age of the earliest known hominids in Java, Indonesia, Science, Vol. 263, Issue 5150, 1118-1121, 25 February 1994.
© Christopher Seddon 2009
Peking Man is the popular name given to the fossil hominins discovered in the 1920s and 1930s at Zhoukoudian, near Beijing and described as Sinanthropus pekinensis by Davidson Black.
In 1944 both species were reclassified as Homo erectus by the late Ernst Mayr as part of a general tidying-up exercise of the bewildering plethora of hominin genera and species then recognised.
Eugene Dubois (1858-1940) was a Dutch anatomist who became fascinated with the subject of human origins. He had been an avid fossil-collector from childhood and believed that fossils provided the best way of elucidating evolutionary history, an approach which was not universally accepted at the time.
Dubois became convinced that the best place to search for the fossil origins of mankind would be the tropics, and to this end he joined the Dutch army as a doctor and had himself posted to the Dutch East Indies, arriving in Sumatra in December 1887. The demands of his day job meant it was quite a while before he could begin his search of the many caves in Sumatra, where he believed the fossil evidence would be found. Eventually, though, he was able to investigate the caves at Lida Adjer and duly began to unearth the bones of various mammals. Armed with this evidence, he managed to persuade the Dutch government to relieve him of his medical duties and allow him work full time on his fossil-hunting. He was also assigned the services of fifty convicts to help him with his excavations.
After failing to discover any human fossils in Sumatra, Dubois received permission in April 1890 to transfer his work to neighbouring Java. He began searching cave sites, but again without success, so he began investigating open sites as well. Finally he was rewarded with success and in October 1891, at Trinil, he recovered a low-domed angular thick-walled human skullcap with a large shelf-like brow ridge. In August 1892 he recovered a humanlike femur from what he believed to be the same site.
Convinced he had found the “missing link” – a transitional form between humans and apes, Dubois at first proposed the name Anthropithecus erectus based on what he believed were the ape-like proportions of its brain - which he estimated at 700cc - and the modernity of the femur. However in November 1892 he revised the cranial capacity upwards to 900cc, closer to that of a modern human than an ape. Accordingly he renamed the fossil Pithecanthropus erectus.
In 1895 Dubois returned to Europe and embarked on a tour to promote his claim to have found the missing link. Although the scientific community were intrigued by his discoveries, his conclusions were generally rejected. Disappointed, he eventually accepted a position as professor of geology at the University of Amsterdam and refused to allow any examination of his fossils until, under increasing pressure to grant access, he finally relented in 1923. His motives have been questioned: the popular view is that he was acting out of spite, like an angry schoolboy taking his ball and going home. However it is more likely that he was protecting his intellectual property. In 1897 he had permitted Gustav Schwalbe of the University of Strasburg to make a cast of the skullcap: Schwalbe had then produced a monograph that had been far more sympathetically received than any of Dubois’ own work.
By the 1920s and 1930s further hominin fossils were coming to light. In 1927 the Canadian anthropologist Davidson Black described Sinanthropus pekinensis (“Chinese man of Peking” [Beijing]), based on an examination of two teeth recovered from the cave site of Zhoukoudian in Dragon Bone Hill, near Beijing. The find became popularly known as Peking Man. Several skullcaps were recovered from the same site in subsequent years. Both Black and anatomist Franz Weidenreich noted similarities between the Zhoukoudian finds and Pithanthropus, but Dubois rejected the similarities.
Unfortunately the Zhoukoudian fossils were lost during World War II. Work at the site was halted by the Japanese invasion in 1937, but the fossils remained at the Cenozoic Research Laboratory of the Peking Union Medical College until 1941, when an attempt was made to transfer them to the United States for safekeeping. They were never seen again. It is thought that they were in possession of a group of US marines, who were captured when war broke out between Japan and the USA. Fortunately Weidenreich had made plaster casts, now in the American Museum of Natural History, New York. After the war, excavation resumed at Zhoukoudian and a number of discoveries have been made since, including two skull fragments. Zhoukoudian became a World Heritage site in 1987.
In 1936 palaeontologist Ralph von Koenigswald made a further discovery on Java itself. Excavating near Mojokerto, eastern Java, in 1936, von Koenigswald recovered a juvenile skull now known as the Mojokerto Child, who was anything from 2 to 6 years old at death, but again Dubois rejected any affinities to Pithecanthropus. The following year, von Koenigswald made further discoveries at Sangiran, East-Central Java with the aid of local people, who he promised to pay 10 cents for each find. The finds included fragments making up an almost-complete skull, though von Koenigswald’s delight at this discovery was somewhat tempered when he learned his helpers were breaking larger finds into smaller pieces to maximise their bounty!
Dubois argued his find was more ape-like than the later discoveries, leading to the popular misconception that he had repudiated his claim that it was an intermediate form. Eugene Dubois died in December 1940, having done himself few favours in the last four decades of his life. British anthropologist Sir Arthur Keith, writing in an obituary notice, observed that Dubois was “an idealist who held his ideas so firmly that he tended to bend the facts rather than alter his ideas to fit them.”
It is now generally accepted that the Javanese and Chinese hominins belong to the same or closely-related species, usually classed as Homo erectus. Some authorities recognise a separate species, Homo pekinensis, for the Chinese hominins.
Dating the Javanese fossils using modern argon-40/argon-39 and potassium/argon dating techniques of volcanic material recovered from the same context as the fossils has been problematic. This is due to deformation and distortion by earth movements of the stratigraphic beds with which the fossils are associated. Another problem has been uncertainty regarding the exact discovery sites, which were less scrupulously recorded than would now be the case. Dates ranging from as recent as 1.0 million to as long ago as 1.65 million have been proposed. Dates of 1.81 million years for the Mojokarto Child and 1.66 million years for the Sangiran fossil were reported in 1994 (Swisher et al, 1994).
Homo erectus (or pekinensis) fossils from Zhoukoudian and elsewhere in China have been dated to between 800,000 and 400,000 years old by palaeomagnetic and biostratigraphic techniques. However stone tools from the Nihewan Basin, 150km (90 miles) west of Beijing have been dated to as far back as 1.6 million years old, implying a much earlier arrival.
References:
Curtis G, Swisher C & Lewin R (2000): Java Man, Scribner, USA.
Klein R (1999): "The Human Career", 2nd edition, University of Chicago Press
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
CC Swisher 3rd, GH Curtis, T Jacob, AG Getty, A Suprijo and Widiasmoro (1994): Age of the earliest known hominids in Java, Indonesia, Science, Vol. 263, Issue 5150, 1118-1121, 25 February 1994.
© Christopher Seddon 2009
Saturday 10 January 2009
Homo floresiensis
Homo floresiensis is the name given to a possible human species that lived on the Indonesian island of Flores. One largely complete skeleton (LB1) and a complete mandible (LB2) were found in sediment in the Liang Bua Cave in eastern Flores, in 2003 (Brown et al, 2004). The material, dated at 18,000 years old, was not fossilised or covered with calcium carbonate, but was extremely fragile. The discoverers, a team led by anthropologists Peter Brown and Michael Morwood, recovered further material including a second mandible and postcranial material from other individuals, in 2004. In total, the finds represented at least nine individuals. Stone tools were also found, dating to 95,000-75000 years old and 12,000 years old. These comprised high densities of stone cores, flaking debris, retouched tools and anvils, evidencing a flaking technology comparable to that found at African Oldowan and other Lower Palaeolithic sites. The tools were accompanied by faunal remains, indicating that the area was a focus for a range of hominin activities (Morwood et al, 2005; Tocheri et al, 2007).
LB1 was claimed to have been a 30-year-old female. The cranial capacity of LB1 is 380cc and its stature is no more than 3ft6 (106cm), both of which are comparable to or smaller than Australopithecus afarensis (“Lucy”). The discoverers argued, however, that it possessed a variety of both primitive and derived features, and should be placed in genus Homo:
“When considered as a whole, the cranial and postcranial skeleton of LB1 combines a mosaic of primitive, unique and derived features not recorded for any other hominin. Although LB1 has the small endocranial volume and stature evident in early australopithecines, it does not have the great postcanine tooth size, deep and prognathic facial skeleton, and masticatory adaptations common to members of this genus. Instead, the facial and dental proportions, postcranial anatomy consistent with human-like obligate bipedalism and a masticatory apparatus most similar in relative size and function to modern humans all support assignment to the genus Homo—as does the inferred phylogenetic history, which includes endemic dwarfing of H. erectus. For these reasons, we argue that LB1 is best placed in this genus and have named it accordingly.” (Brown et al, 2004).
The diminutive size of Homo floresiensis was, the team claimed, a result of a phenomenon known as insular dwarfism, where animals living on an island where food is relatively scarce and predators are few or absent will “downsize” over many generations in order to reduce calorific requirements. This is of course no more than evolution favouring the smaller offspring in each generation. If predators do not pose a threat, any advantages in being large will be outweighed by poorer fuel-economy. Before Mesolithic humans reached Flores, the island met both conditions in being both relatively faunally-impoverished and lacking any predators other than the Komodo dragon. If early humans such as Homo erectus had reached Flores, then the same thing could have happened, leading to H. floresiensis.
The team claimed that despite its tiny ape-like brain, the encephalization quotient (EQ) or brain to mass ratio was in the range 2.5 to 4.6, compared with 5.8 to 8.1 for modern humans, 3.3 to 4.4 for Homo erectus/ergaster and 3.6 to 4.3 for Homo habilis. The figure was derived from an estimated brain mass of 433.2gm (based on cranial volume) and two estimates of body mass: an estimate based on stature of 106cm gave 16.0-28.7kg; one based on femur cross-sectional area of 525mm2 gave 36kg.
The EQ is a better indication of intelligence than absolute brain size; for example, elephants and whales have larger brains than humans, but are generally considered to be less intelligent than the latter. The team claimed the higher figure of 4.6 was supported by the probability that Homo floresiensis would have the same lean, narrow body shape as a modern Old World tropical-dwelling human. Thus H. floresiensis was capable of complex behaviour and cognition, and was probably the maker of the tools. Oldowan-equivalent technology would be well within its capabilities.
The discovery attracted considerable publicity, and Homo floresiensis was immediately nicknamed the Flores Hobbit, to Brown’s considerable annoyance (quoted in the Observer, 31 October 2004). However doubts as to whether it was genuinely a new human species emerged almost immediately.
The Indonesian anthropologist Prof. Teuku Jacob claimed that LB1 was a modern human suffering from microcephaly, a developmental disorder leading to a smaller brain. Jacob claimed LB1 was a male Homo sapiens aged 25-30 of Australomelanesian extraction.
An unpleasant dispute then followed when, in December 2004, Jacob removed most of the remains from the Jakarta's National Research Centre of Archaeology, where they had been placed for safekeeping, without permission of this institution’s directors. Jacob was widely cited in press reports as having a reputation for preventing access to specimens in his keeping and Brown was quoted in the New Zealand Herald as saying he doubted “if the material will ever be studied again”.
Jacob eventually did return the remains, but the discoverers claimed the bones were extensively damaged in Jacob's lab during attempts to make casts. The alleged damage included long, deep cuts marking the lower edge of the LB1's jaw on both sides, said to be caused by a knife used to cut away the rubber mould. In addition, LB2 was snapped and glued back together. Whoever was responsible misaligned the pieces and put them at an incorrect angle. The pelvis of LB1 was smashed, destroying details that reveal body shape, gait and evolutionary history. Morwood accused Jacob of being greedy and acting irresponsibly. Jacob denied any wrongdoing and published his own findings contra Brown et al in July 2006 (Jacob et al, 2006). Teuku Jacob died in October 2007, aged 77, but his death did not put an end to the controversy.
Although primatologist Robert Martin of the Field Museum, Chicago, IL supported Jacob’s position (Martin et al, 2006), the majority of workers rejected the microcephaly theory and accepted Homo floresiensis as a new human species (e.g. Argue et al, 2006; Falk et al, 2005 & 2007; Lyras et al, 2008 and Tocheri et al, 2007) .
The studies mainly focussed on the cranial and post-cranial metrics of LB1 in comparison to microcephalic humans, pygmies, early human species (Homo erectus, H. ergaster, H. habilis, etc) and australopithecines (A. garhi, A. africanus, P. bosei, etc.). The general conclusion was that H. floresiensis showed a better fit with the various extinct hominins than it did with the microcephalic or normal modern humans, though the studies differed as to its likely phylogeny, with affinities to Homo erectus, Homo habilis and even the later australopithecines all being proposed. LB1’s long low cranial vault is not a feature shared with modern humans, microcephalic or not (Lyras et al, 2008); LB1’s wrist morphology, based on three wrist bones, predates that of modern humans (Tocheri et al, 2007). Other pathological explanations such as Laron syndrome and cretinism were also rejected (Lyras et al, 2008).
Falk et al (2005) noted expansions in the frontal polar region of LB1. This part of the prefrontal cortex in humans and apes consists of Brodmann’s area 10 (BA10), which in humans may be involved in higher cognitive processes such as the undertaking of initiatives and the planning of future activities. The Falk study concluded that LB1’s brain could not have been a miniaturized version of Homo sapiens or H. erectus.
Citing this study, Argue et al (2006) suggested the implication is that LB1 possessed developed cognitive abilities and was able to plan, respond to conditions, use memories, and transfer information between group members.
Brumm et al (2006) considered 880,000 year old artefacts recovered from the Mata Menge site at the Soa Basin, central Flores in comparison to the Liang Bua artefacts and suggested the two show technological continuity. They suggest the hominins responsible for the Liang Bua artefacts were also responsible for those at Mata Menge, though no hominin remains have been recovered from the latter site.
What are we to make of all this? The case for Homo floresiensis being a pathological modern human does not strike me as being very convincing and on the balance of probabilities I would cautiously accept that it is indeed a new species of hominin. Obviously further evidence, in particular evidence that can be tied to the earlier tool finds, would be highly desirable.
Could H. floresiensis be an intermediate between early Homo and late Australopithecus that migrated out of Africa prior to 2 million years ago (Argue et al, 2006)? It’s not impossible that enhanced cognitive function evolved more than once, in Homo habilis and its descendants and in Homo floresiensis (though the latter would have to be transferred to a new genus to avoid paraphyly should this hypothesis become accepted). Nor would it be impossible for such a hominin to diffuse from Africa, given that the ancestors of the orang-utans did millions of years earlier. The main problem is there is absolutely no other evidence supporting dispersal from Africa of any australopithecine species or of Homo habilis, or of anything intermediate between the two. Homo georgicus, the small-brained hominin from Dmanisi, Georgia, has been touted as evidence Homo habilis did migrate from Africa, but it has now been shown to have a derived Homo ergaster (African Homo erectus) body plan.
Early Homo erectus, or something of that grade seems a more plausible ancestor. The tool technology is consistent with that of the first H. erectus dispersal from Africa, which seems to have happened before the invention of the later Mode II Acheulian hand-axe tradition. The cognitive abilities of Homo floresiensis were probably commensurate with such technology, which predates the emergence of modern human behaviour. As such, therefore, H. floresiensis would have lacked the complex language of modern humans, though it probably had language of sorts.
The question of how the forbears of these people reached Flores in the first place has led some to speculate that they must had the ability to build boats, since Flores – unlike many islands in the Indonesian archipelago – was never connected to the mainland, even during the maximum extent of the ices ages, when sea-levels dropped. But they could have been swept out to sea and stranded there by a natural occurrence such as a flash-flood or a tsunami, possibly on a raft of matted vegetation. This is believed to have been the way the ancestors of the New World monkeys reached South America from Africa; nobody is suggesting that they built boats!
Probably the most controversial idea is that Homo floresiensis survived into modern times and is the mythological Ebu Gogo said to have been living on Flores when the Portuguese arrived 400 years ago, and some claim were still being seen as recently as 100 years ago; and that similar people are the basis of similar legends such as the Orang Pendek from Sumatra and even leprechauns in Ireland?
I will admit to being sceptical (decidedly so about leprechauns!), if only because “little people” are so prevalent in world folk traditions that if these were due to actual diminutive hominins, concrete evidence would have emerged by now. However if an endemic dwarf hominin species can arise on Flores, there is certainly no reason to suppose similar species could not arise elsewhere and it is quite possible that evidence from similar genetically-isolated locations might come to light in the future.
References:
Debbie Argue, Denise Donlon, Colin Groves, Richard Wright (2006): Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo? Journal of Human Evolution 51 (2006) 360-374.
P. Brown, T. Sutikna, M. J. Morwood, R. P. Soejono, Jatmiko, E. Wayhu Saptomo & Rokus Awe Due (2004): A new small-bodied hominin from the
Late Pleistocene of Flores, Indonesia, Nature Vol. 431 28 October 2004.
Adam Brumm, Fachroel Aziz, Gert D. van den Bergh, Michael J. Morwood, Mark W. Moore, Iwan Kurniawan, Douglas R. Hobbs & Richard Fullagar (2006): Early stone technology on Flores and its implications for Homo floresiensis, Nature Vol. 441 1 June 2006.
Dean Falk, Charles Hildebolt, Kirk Smith, M. J. Morwood, Thomas Sutikna, Peter Brown, Jatmiko, E. Wayhu Saptomo, Barry Brunsden, Fred Prior (2005): The Brain of LB1, Homo floresiensis, Science Vol. 308 8 April 2005.
Dean Falk, Charles Hildebolt, Kirk Smith, M. J. Morwood, Thomas Sutikna, Jatmiko, E. Wayhu Saptomo, Herwig Imhof, Horst Seidler and Fred Prior (2007): Brain shape in human microcephalics and Homo floresiensis, PNAS February 13, 2007 vol. 104 no. 7 2513–2518.
T. Jacob, E. Indriati, R. P. Soejono, K. Hsu, D. W. Frayer, R. B. Eckhardt, A. J. Kuperavage, A. Thorne and M. Henneberg (2006): Pygmoid Australomelanesian Homo sapiens skeletal remains from Liang Bua, Flores: Population affinities and pathological abnormalities, PNAS September 5, 2006 vol. 103 no. 36 13421–13426.
G.A. Lyras, M.D. Dermitzakis, A.A.E. Van der Geer, S.B. Van der Geer, J. De Vos (2008): The origin of Homo floresiensis and its relation to evolutionary
processes under isolation, Anthropological Science, 1 August 2008.
R. D. Martin, A. M. MacLarnon, J. L. Phillips, L. Dussubieux,
P. R. Williams, W. B. Dobyns (2006): Comment on ‘‘The Brain of LB1,
Homo floresiensis’’, Science 19 May 2006 Vol. 312.
M. J. Morwood, P. Brown, Jatmiko, T. Sutikna, E. Wahyu Saptomo, K. E. Westaway, Rokus Awe Due, R. G. Roberts, T. Maeda, S. Wasisto & T. Djubiantono (2005): Further evidence for small-bodied hominins from
the Late Pleistocene of Flores, Indonesia, Nature Vol. 437 13 October 2005.
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
Matthew W. Tocheri, Caley M. Orr, Susan G. Larson, Thomas Sutikna,
Jatmiko, E. Wahyu Saptomo, Rokus Awe Due, Tony Djubiantono,
Michael J. Morwood, William L. Jungers (2007): The Primitive Wrist of Homo floresiensis and Its Implications for Hominin Evolution, Science Vol. 317 21 September 2007.
© Christopher Seddon 2009
LB1 was claimed to have been a 30-year-old female. The cranial capacity of LB1 is 380cc and its stature is no more than 3ft6 (106cm), both of which are comparable to or smaller than Australopithecus afarensis (“Lucy”). The discoverers argued, however, that it possessed a variety of both primitive and derived features, and should be placed in genus Homo:
“When considered as a whole, the cranial and postcranial skeleton of LB1 combines a mosaic of primitive, unique and derived features not recorded for any other hominin. Although LB1 has the small endocranial volume and stature evident in early australopithecines, it does not have the great postcanine tooth size, deep and prognathic facial skeleton, and masticatory adaptations common to members of this genus. Instead, the facial and dental proportions, postcranial anatomy consistent with human-like obligate bipedalism and a masticatory apparatus most similar in relative size and function to modern humans all support assignment to the genus Homo—as does the inferred phylogenetic history, which includes endemic dwarfing of H. erectus. For these reasons, we argue that LB1 is best placed in this genus and have named it accordingly.” (Brown et al, 2004).
The diminutive size of Homo floresiensis was, the team claimed, a result of a phenomenon known as insular dwarfism, where animals living on an island where food is relatively scarce and predators are few or absent will “downsize” over many generations in order to reduce calorific requirements. This is of course no more than evolution favouring the smaller offspring in each generation. If predators do not pose a threat, any advantages in being large will be outweighed by poorer fuel-economy. Before Mesolithic humans reached Flores, the island met both conditions in being both relatively faunally-impoverished and lacking any predators other than the Komodo dragon. If early humans such as Homo erectus had reached Flores, then the same thing could have happened, leading to H. floresiensis.
The team claimed that despite its tiny ape-like brain, the encephalization quotient (EQ) or brain to mass ratio was in the range 2.5 to 4.6, compared with 5.8 to 8.1 for modern humans, 3.3 to 4.4 for Homo erectus/ergaster and 3.6 to 4.3 for Homo habilis. The figure was derived from an estimated brain mass of 433.2gm (based on cranial volume) and two estimates of body mass: an estimate based on stature of 106cm gave 16.0-28.7kg; one based on femur cross-sectional area of 525mm2 gave 36kg.
The EQ is a better indication of intelligence than absolute brain size; for example, elephants and whales have larger brains than humans, but are generally considered to be less intelligent than the latter. The team claimed the higher figure of 4.6 was supported by the probability that Homo floresiensis would have the same lean, narrow body shape as a modern Old World tropical-dwelling human. Thus H. floresiensis was capable of complex behaviour and cognition, and was probably the maker of the tools. Oldowan-equivalent technology would be well within its capabilities.
The discovery attracted considerable publicity, and Homo floresiensis was immediately nicknamed the Flores Hobbit, to Brown’s considerable annoyance (quoted in the Observer, 31 October 2004). However doubts as to whether it was genuinely a new human species emerged almost immediately.
The Indonesian anthropologist Prof. Teuku Jacob claimed that LB1 was a modern human suffering from microcephaly, a developmental disorder leading to a smaller brain. Jacob claimed LB1 was a male Homo sapiens aged 25-30 of Australomelanesian extraction.
An unpleasant dispute then followed when, in December 2004, Jacob removed most of the remains from the Jakarta's National Research Centre of Archaeology, where they had been placed for safekeeping, without permission of this institution’s directors. Jacob was widely cited in press reports as having a reputation for preventing access to specimens in his keeping and Brown was quoted in the New Zealand Herald as saying he doubted “if the material will ever be studied again”.
Jacob eventually did return the remains, but the discoverers claimed the bones were extensively damaged in Jacob's lab during attempts to make casts. The alleged damage included long, deep cuts marking the lower edge of the LB1's jaw on both sides, said to be caused by a knife used to cut away the rubber mould. In addition, LB2 was snapped and glued back together. Whoever was responsible misaligned the pieces and put them at an incorrect angle. The pelvis of LB1 was smashed, destroying details that reveal body shape, gait and evolutionary history. Morwood accused Jacob of being greedy and acting irresponsibly. Jacob denied any wrongdoing and published his own findings contra Brown et al in July 2006 (Jacob et al, 2006). Teuku Jacob died in October 2007, aged 77, but his death did not put an end to the controversy.
Although primatologist Robert Martin of the Field Museum, Chicago, IL supported Jacob’s position (Martin et al, 2006), the majority of workers rejected the microcephaly theory and accepted Homo floresiensis as a new human species (e.g. Argue et al, 2006; Falk et al, 2005 & 2007; Lyras et al, 2008 and Tocheri et al, 2007) .
The studies mainly focussed on the cranial and post-cranial metrics of LB1 in comparison to microcephalic humans, pygmies, early human species (Homo erectus, H. ergaster, H. habilis, etc) and australopithecines (A. garhi, A. africanus, P. bosei, etc.). The general conclusion was that H. floresiensis showed a better fit with the various extinct hominins than it did with the microcephalic or normal modern humans, though the studies differed as to its likely phylogeny, with affinities to Homo erectus, Homo habilis and even the later australopithecines all being proposed. LB1’s long low cranial vault is not a feature shared with modern humans, microcephalic or not (Lyras et al, 2008); LB1’s wrist morphology, based on three wrist bones, predates that of modern humans (Tocheri et al, 2007). Other pathological explanations such as Laron syndrome and cretinism were also rejected (Lyras et al, 2008).
Falk et al (2005) noted expansions in the frontal polar region of LB1. This part of the prefrontal cortex in humans and apes consists of Brodmann’s area 10 (BA10), which in humans may be involved in higher cognitive processes such as the undertaking of initiatives and the planning of future activities. The Falk study concluded that LB1’s brain could not have been a miniaturized version of Homo sapiens or H. erectus.
Citing this study, Argue et al (2006) suggested the implication is that LB1 possessed developed cognitive abilities and was able to plan, respond to conditions, use memories, and transfer information between group members.
Brumm et al (2006) considered 880,000 year old artefacts recovered from the Mata Menge site at the Soa Basin, central Flores in comparison to the Liang Bua artefacts and suggested the two show technological continuity. They suggest the hominins responsible for the Liang Bua artefacts were also responsible for those at Mata Menge, though no hominin remains have been recovered from the latter site.
What are we to make of all this? The case for Homo floresiensis being a pathological modern human does not strike me as being very convincing and on the balance of probabilities I would cautiously accept that it is indeed a new species of hominin. Obviously further evidence, in particular evidence that can be tied to the earlier tool finds, would be highly desirable.
Could H. floresiensis be an intermediate between early Homo and late Australopithecus that migrated out of Africa prior to 2 million years ago (Argue et al, 2006)? It’s not impossible that enhanced cognitive function evolved more than once, in Homo habilis and its descendants and in Homo floresiensis (though the latter would have to be transferred to a new genus to avoid paraphyly should this hypothesis become accepted). Nor would it be impossible for such a hominin to diffuse from Africa, given that the ancestors of the orang-utans did millions of years earlier. The main problem is there is absolutely no other evidence supporting dispersal from Africa of any australopithecine species or of Homo habilis, or of anything intermediate between the two. Homo georgicus, the small-brained hominin from Dmanisi, Georgia, has been touted as evidence Homo habilis did migrate from Africa, but it has now been shown to have a derived Homo ergaster (African Homo erectus) body plan.
Early Homo erectus, or something of that grade seems a more plausible ancestor. The tool technology is consistent with that of the first H. erectus dispersal from Africa, which seems to have happened before the invention of the later Mode II Acheulian hand-axe tradition. The cognitive abilities of Homo floresiensis were probably commensurate with such technology, which predates the emergence of modern human behaviour. As such, therefore, H. floresiensis would have lacked the complex language of modern humans, though it probably had language of sorts.
The question of how the forbears of these people reached Flores in the first place has led some to speculate that they must had the ability to build boats, since Flores – unlike many islands in the Indonesian archipelago – was never connected to the mainland, even during the maximum extent of the ices ages, when sea-levels dropped. But they could have been swept out to sea and stranded there by a natural occurrence such as a flash-flood or a tsunami, possibly on a raft of matted vegetation. This is believed to have been the way the ancestors of the New World monkeys reached South America from Africa; nobody is suggesting that they built boats!
Probably the most controversial idea is that Homo floresiensis survived into modern times and is the mythological Ebu Gogo said to have been living on Flores when the Portuguese arrived 400 years ago, and some claim were still being seen as recently as 100 years ago; and that similar people are the basis of similar legends such as the Orang Pendek from Sumatra and even leprechauns in Ireland?
I will admit to being sceptical (decidedly so about leprechauns!), if only because “little people” are so prevalent in world folk traditions that if these were due to actual diminutive hominins, concrete evidence would have emerged by now. However if an endemic dwarf hominin species can arise on Flores, there is certainly no reason to suppose similar species could not arise elsewhere and it is quite possible that evidence from similar genetically-isolated locations might come to light in the future.
References:
Debbie Argue, Denise Donlon, Colin Groves, Richard Wright (2006): Homo floresiensis: Microcephalic, pygmoid, Australopithecus, or Homo? Journal of Human Evolution 51 (2006) 360-374.
P. Brown, T. Sutikna, M. J. Morwood, R. P. Soejono, Jatmiko, E. Wayhu Saptomo & Rokus Awe Due (2004): A new small-bodied hominin from the
Late Pleistocene of Flores, Indonesia, Nature Vol. 431 28 October 2004.
Adam Brumm, Fachroel Aziz, Gert D. van den Bergh, Michael J. Morwood, Mark W. Moore, Iwan Kurniawan, Douglas R. Hobbs & Richard Fullagar (2006): Early stone technology on Flores and its implications for Homo floresiensis, Nature Vol. 441 1 June 2006.
Dean Falk, Charles Hildebolt, Kirk Smith, M. J. Morwood, Thomas Sutikna, Peter Brown, Jatmiko, E. Wayhu Saptomo, Barry Brunsden, Fred Prior (2005): The Brain of LB1, Homo floresiensis, Science Vol. 308 8 April 2005.
Dean Falk, Charles Hildebolt, Kirk Smith, M. J. Morwood, Thomas Sutikna, Jatmiko, E. Wayhu Saptomo, Herwig Imhof, Horst Seidler and Fred Prior (2007): Brain shape in human microcephalics and Homo floresiensis, PNAS February 13, 2007 vol. 104 no. 7 2513–2518.
T. Jacob, E. Indriati, R. P. Soejono, K. Hsu, D. W. Frayer, R. B. Eckhardt, A. J. Kuperavage, A. Thorne and M. Henneberg (2006): Pygmoid Australomelanesian Homo sapiens skeletal remains from Liang Bua, Flores: Population affinities and pathological abnormalities, PNAS September 5, 2006 vol. 103 no. 36 13421–13426.
G.A. Lyras, M.D. Dermitzakis, A.A.E. Van der Geer, S.B. Van der Geer, J. De Vos (2008): The origin of Homo floresiensis and its relation to evolutionary
processes under isolation, Anthropological Science, 1 August 2008.
R. D. Martin, A. M. MacLarnon, J. L. Phillips, L. Dussubieux,
P. R. Williams, W. B. Dobyns (2006): Comment on ‘‘The Brain of LB1,
Homo floresiensis’’, Science 19 May 2006 Vol. 312.
M. J. Morwood, P. Brown, Jatmiko, T. Sutikna, E. Wahyu Saptomo, K. E. Westaway, Rokus Awe Due, R. G. Roberts, T. Maeda, S. Wasisto & T. Djubiantono (2005): Further evidence for small-bodied hominins from
the Late Pleistocene of Flores, Indonesia, Nature Vol. 437 13 October 2005.
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
Matthew W. Tocheri, Caley M. Orr, Susan G. Larson, Thomas Sutikna,
Jatmiko, E. Wahyu Saptomo, Rokus Awe Due, Tony Djubiantono,
Michael J. Morwood, William L. Jungers (2007): The Primitive Wrist of Homo floresiensis and Its Implications for Hominin Evolution, Science Vol. 317 21 September 2007.
© Christopher Seddon 2009
Monday 5 January 2009
West Kennet Long Barrow
West Kennet Long Barrow is part of the Avebury complex of Neolithic monuments and is located on a chalk ridge 1 ½ miles south of the village (map reference SU105677).
It comprises a trapezoidal mound, 330ft (100m) long, which has a core of sarsen boulders topped out with chalk rubble from two ditches running parallel to the mound. At the eastern end of the mound are two facing pairs of burial chambers opening off from a central passage, which is terminated by a fifth chamber. At the entrance there is a 65ft (20m) semi-circular forecourt with a facade of large sarsen stones. Probably this area was used for ceremonies.
The monument was constructed around 3650 BC and is one of the largest barrows in Britain. It has been estimated that 15,700 man-hours went into its construction. Excavations carried out in 1859 and 1955-56 revealed the burials of 46 individuals of various ages. The barrow remained in use for around 1000 years, after which it was sealed up with massive flat sarcens being placed to block the entrance. The burial chambers were filled with chalk rubble.
Reference:
Pryor, F (2003): Britain BC, HarperCollinsPublishers, London.
© Christopher Seddon 2009
It comprises a trapezoidal mound, 330ft (100m) long, which has a core of sarsen boulders topped out with chalk rubble from two ditches running parallel to the mound. At the eastern end of the mound are two facing pairs of burial chambers opening off from a central passage, which is terminated by a fifth chamber. At the entrance there is a 65ft (20m) semi-circular forecourt with a facade of large sarsen stones. Probably this area was used for ceremonies.
The monument was constructed around 3650 BC and is one of the largest barrows in Britain. It has been estimated that 15,700 man-hours went into its construction. Excavations carried out in 1859 and 1955-56 revealed the burials of 46 individuals of various ages. The barrow remained in use for around 1000 years, after which it was sealed up with massive flat sarcens being placed to block the entrance. The burial chambers were filled with chalk rubble.
Reference:
Pryor, F (2003): Britain BC, HarperCollinsPublishers, London.
© Christopher Seddon 2009
Sunday 4 January 2009
Silbury Hill
Silbury Hill is a conical, flat-topped Neolithic mound located a short distance from Beckhampton, Wilts (map reference SU100685). It is the largest man-made prehistoric mound in Europe and is 130ft (40m) high and 550ft (167m) in diameter, covering 5 acres (2.2 hectares).
Located in a region rich with Neolithic monuments, it is believed to be 4750 years old. Its purpose is unknown.
It is composed principally of chalk excavated locally. Some 8.75 million cubic feet (248,000 cubic metres) of material went into its construction. It has been calculated that it took 18 million man-hours to construct; the equivalent of 500 men working for 15 years. This suggests social complexity had evolved beyond the tribal level as only a powerful ruling elite could have mustered the resources for such a project.
© Christopher Seddon 2009
Wayland's Smithy
Wayland’s Smithy is a Neolithic burial chamber located near the village of Ashbury, Oxfordshire (map reference SU281854). It lies in a plantation of trees on the Ridgeway, not far from the Uffington White Horse and Uffington Castle.
It is named for Wayland (aka Weland, Volund or Volundr), the Saxon god of metalworking, who features in Old English and Norse mythology. Legend has it that a horse requiring a shoe may be left unattended at the site for a short while with a silver coin for payment. On return, the horse will be shod and the coin gone.
The monument does of course predate Saxon times. It was constructed in two phases: a timber chambered oval barrow built around 3700 BC and a trapezoidal stone chambered long barrow built around 3400 BC. The site is thus of particular interest as it illustrates the transition from timber chambered barrows to stone chamber barrows.
The remains of 14 bodies from the first period of construction were located during excavations in the 1960s. Previously, in 1919, the remains of seven adults and one child from the second phase were discovered.
© Christopher Seddon 2009
It is named for Wayland (aka Weland, Volund or Volundr), the Saxon god of metalworking, who features in Old English and Norse mythology. Legend has it that a horse requiring a shoe may be left unattended at the site for a short while with a silver coin for payment. On return, the horse will be shod and the coin gone.
The monument does of course predate Saxon times. It was constructed in two phases: a timber chambered oval barrow built around 3700 BC and a trapezoidal stone chambered long barrow built around 3400 BC. The site is thus of particular interest as it illustrates the transition from timber chambered barrows to stone chamber barrows.
The remains of 14 bodies from the first period of construction were located during excavations in the 1960s. Previously, in 1919, the remains of seven adults and one child from the second phase were discovered.
© Christopher Seddon 2009
Friday 2 January 2009
Homo habilis
Introduction:
Homo habilis ("handy man") is an early human species that lived between 2.33 to 1.44 million years ago and is quite possibly the earliest member of genus Homo, though acceptance of it being an ancestor to modern humans or indeed of it being a human species at all is not universal. The species was first described by Louis Leakey in 1964.
Fossil Record:
Homo habilis is known from fossils recovered from Olduvai Gorge, Tanzania; East Turkana, Kenya; Sterkfontein, South Africa; and Hadar in the Awash Valley of Afar Depression, Ethiopia.
The first specimen to be discovered, now known as OH7, comprising a partial cranium and mandible, was discovered by Jonathon and Mary Leakey at Olduvai Gorge on 4 November 1960 and has been dated to 1.75 million years old. Other findings from Olduvai Gorge include OH 24, a cranium discovered by Peter Nzube in 1968 and believed to be 1.8 million years old; OH 13 (partial cranium, mandible and maxilla, discovered by N. Mbuika in 1963, 1.66 million years old); OH 8 (foot, probably from the same individual as OH 7, discovered 1960) and OH 62 (partial skeleton, including upper and lower limbs, believed to be female, discovered by Donald Johanson and Tim White in 1986, 2.0 million years old).
KNM-ER 1805 and KNM-ER 1813 were both discovered at Koobi Fora, East Turkana. KNM-ER 1805 is a partial cranium, maxilla, and mandible, dated to 1.74 million years old. The finder and the date of discovery are unknown. KNM-ER 1813 is a cranium dated to 1.8 million years old discovered by K. Kimeu in 1973.
KNM-ER 42703, also from Koobi Fora, is a right maxilla with an estimated geological age of 1.44 million years. It was discovered by John E. Kaatho in 2000. This is the youngest specimen assigned to Homo erectus, and is notable for being younger than KNM-ER 42700: a small, well preserved calvaria with an estimated geological age of 1.55 million years that has been assigned to (African) Homo erectus.
The Sterkfontein specimens include the partial cranium STW-53 discovered by A.R. Hughes in 1976 and dated 1.5 – 2.0 million years old.
From Hadar comes the maxilla AL-666-1, discovered by William Kimball and dated to 2.33 million years old, the oldest specimen with affinities to Homo habilis.
Description:
Homo habilis had a cranial capacity of between 509-675cc (Cameron & Groves, 2004), considerably larger than its putative ancestors, the australopithecines (375-500cc); and that of present-day chimpanzees (400cc), but much less than that of modern humans. It had a prognathic face (jutting jaw), moderate brow-ridges; no saggital keeling (a raised area along the centre of the skullcap); reduced dentition relative to australopithecines; and proportionately long arms and short legs relative to modern humans. It had an ape-like conical ribcage and possibly retained the ape-like ability of arboreal locomotion.
There was a degree of sexual dimorphism in the species. OH 62 which, as noted above, is believed to have been female, was about 1m tall and probably weighed 30kg. Males were probably around 1.3m tall and weighed around 36kg.
Technology:
Homo habilis is generally associated with the Oldowan industry (or Mode I), named for Olduvai Gorge by Louis and Mary Leakey because they were first recognised there. The Oldowan is the earliest stone tool industry and examples dating to around 2.5 million years old are known from Gona, Bouri and Hadar in Ethiopia; from Lokalelei, West Turkana, Kenya dating to 2.4 million years old; from Koobi Fora dating to 1.9 million years old and from Olduvai Gorge dating to 1.8 million years old.
The Oldowan is associated with a number of hominin species and is therefore a toll-making tradition rather than a particular culture. In addition to Homo habilis, the tradition may be associated with Parantropus (“robust australopithecines”) and the “late” gracile species Australopithecus garhi. The latter, discovered in 1997, was found in association with large animal bones showing cut-marks from stone tools. Although no actual tools were directly associated with the fossils, it seems likely that A. garhi made and used stone tools. The remains have been dated to 2.5 million years old. In addition, the Oldowan survived Homo habilis and is associated with a number of later human species.
The Oldowan is characterised by very simple stone tools. The main types are choppers made from cobbles or angular blocks of stone; hammer-stones, which are unmodified chunks that show signs of having been used as hammers in tool manufacture; scrapers made from both cores and retouched flakes detached from cores. Although there is a considerable variety and other types such as discoids and polyhedrons are recognised, much of the variation can be explained in terms of differences in the nature of the raw material available. The overall strategy was likely a least-effort strategy to produce either flakes with sharp cutting edges or cores for chopping. It seems unlikely that the Oldowan toolmakers mastered the sophisticated stone reduction strategies seen in later tool-making traditions.
Evolutionary history of Homo habilis:
The accepted view of human evolution has become considerably more complicated over the last twenty years and it is now recognised that the traditional view of progressive evolution from australopithecine to H. habilis to H. erectus and finally to H. sapiens is at best an oversimplification.
The picture for Homo habilis was complicated in the 1980s by the discovery that fossils previously assigned to Homo habilis actually belonged to two species – Homo habilis and Homo rudolfensis, although it does now seem likely that the latter is an australopithecine-type upright ape, off the line of human evolution.
Homo habilis is believed to have evolved from an australopithecine species, but there is no consensus as to which of those currently known, if any. The traditional assumption that Homo ergaster (i.e. African Homo erectus) evolved from Homo habilis has recently been challenged by the discovery that the two species were sympatric (co-existing) in the Lake Turkana basin in Kenya for almost half a million years, implying that they must have occupied different niches and leading some to believe that the two species diverged from a common ancestor 2.3 million years ago rather than one evolving from the other.
On the other hand Homo habilis appears in the fossil record some 300,000 years before Homo ergaster. Unless earlier H. ergaster remains come to light, it seems likely that a proto-ergaster population split away from an earlier population of H. habilis and only later came into contact with a population of the ancestral species.
For now, then, it is still widely accepted that Homo habilis is ancestral to all later human species, including Homo sapiens.
References:
Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.
Leakey LSB, Tobias PV & Napier JR (1964): A New Species of Genus Homo from Olduvai Gorge, Nature No. 4927, 4 April 1964.
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
F. Spoor, M. G. Leakey, P. N. Gathogo, F. H. Brown, S. C. Anton, I. McDougall, C. Kiarie, F. K. Manthi & L. N. Leakey (2007): Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya, Nature Vol 448 9 August 2007.
© Christopher Seddon 2009
Homo habilis ("handy man") is an early human species that lived between 2.33 to 1.44 million years ago and is quite possibly the earliest member of genus Homo, though acceptance of it being an ancestor to modern humans or indeed of it being a human species at all is not universal. The species was first described by Louis Leakey in 1964.
Fossil Record:
Homo habilis is known from fossils recovered from Olduvai Gorge, Tanzania; East Turkana, Kenya; Sterkfontein, South Africa; and Hadar in the Awash Valley of Afar Depression, Ethiopia.
The first specimen to be discovered, now known as OH7, comprising a partial cranium and mandible, was discovered by Jonathon and Mary Leakey at Olduvai Gorge on 4 November 1960 and has been dated to 1.75 million years old. Other findings from Olduvai Gorge include OH 24, a cranium discovered by Peter Nzube in 1968 and believed to be 1.8 million years old; OH 13 (partial cranium, mandible and maxilla, discovered by N. Mbuika in 1963, 1.66 million years old); OH 8 (foot, probably from the same individual as OH 7, discovered 1960) and OH 62 (partial skeleton, including upper and lower limbs, believed to be female, discovered by Donald Johanson and Tim White in 1986, 2.0 million years old).
KNM-ER 1805 and KNM-ER 1813 were both discovered at Koobi Fora, East Turkana. KNM-ER 1805 is a partial cranium, maxilla, and mandible, dated to 1.74 million years old. The finder and the date of discovery are unknown. KNM-ER 1813 is a cranium dated to 1.8 million years old discovered by K. Kimeu in 1973.
KNM-ER 42703, also from Koobi Fora, is a right maxilla with an estimated geological age of 1.44 million years. It was discovered by John E. Kaatho in 2000. This is the youngest specimen assigned to Homo erectus, and is notable for being younger than KNM-ER 42700: a small, well preserved calvaria with an estimated geological age of 1.55 million years that has been assigned to (African) Homo erectus.
The Sterkfontein specimens include the partial cranium STW-53 discovered by A.R. Hughes in 1976 and dated 1.5 – 2.0 million years old.
From Hadar comes the maxilla AL-666-1, discovered by William Kimball and dated to 2.33 million years old, the oldest specimen with affinities to Homo habilis.
Description:
Homo habilis had a cranial capacity of between 509-675cc (Cameron & Groves, 2004), considerably larger than its putative ancestors, the australopithecines (375-500cc); and that of present-day chimpanzees (400cc), but much less than that of modern humans. It had a prognathic face (jutting jaw), moderate brow-ridges; no saggital keeling (a raised area along the centre of the skullcap); reduced dentition relative to australopithecines; and proportionately long arms and short legs relative to modern humans. It had an ape-like conical ribcage and possibly retained the ape-like ability of arboreal locomotion.
There was a degree of sexual dimorphism in the species. OH 62 which, as noted above, is believed to have been female, was about 1m tall and probably weighed 30kg. Males were probably around 1.3m tall and weighed around 36kg.
Technology:
Homo habilis is generally associated with the Oldowan industry (or Mode I), named for Olduvai Gorge by Louis and Mary Leakey because they were first recognised there. The Oldowan is the earliest stone tool industry and examples dating to around 2.5 million years old are known from Gona, Bouri and Hadar in Ethiopia; from Lokalelei, West Turkana, Kenya dating to 2.4 million years old; from Koobi Fora dating to 1.9 million years old and from Olduvai Gorge dating to 1.8 million years old.
The Oldowan is associated with a number of hominin species and is therefore a toll-making tradition rather than a particular culture. In addition to Homo habilis, the tradition may be associated with Parantropus (“robust australopithecines”) and the “late” gracile species Australopithecus garhi. The latter, discovered in 1997, was found in association with large animal bones showing cut-marks from stone tools. Although no actual tools were directly associated with the fossils, it seems likely that A. garhi made and used stone tools. The remains have been dated to 2.5 million years old. In addition, the Oldowan survived Homo habilis and is associated with a number of later human species.
The Oldowan is characterised by very simple stone tools. The main types are choppers made from cobbles or angular blocks of stone; hammer-stones, which are unmodified chunks that show signs of having been used as hammers in tool manufacture; scrapers made from both cores and retouched flakes detached from cores. Although there is a considerable variety and other types such as discoids and polyhedrons are recognised, much of the variation can be explained in terms of differences in the nature of the raw material available. The overall strategy was likely a least-effort strategy to produce either flakes with sharp cutting edges or cores for chopping. It seems unlikely that the Oldowan toolmakers mastered the sophisticated stone reduction strategies seen in later tool-making traditions.
Evolutionary history of Homo habilis:
The accepted view of human evolution has become considerably more complicated over the last twenty years and it is now recognised that the traditional view of progressive evolution from australopithecine to H. habilis to H. erectus and finally to H. sapiens is at best an oversimplification.
The picture for Homo habilis was complicated in the 1980s by the discovery that fossils previously assigned to Homo habilis actually belonged to two species – Homo habilis and Homo rudolfensis, although it does now seem likely that the latter is an australopithecine-type upright ape, off the line of human evolution.
Homo habilis is believed to have evolved from an australopithecine species, but there is no consensus as to which of those currently known, if any. The traditional assumption that Homo ergaster (i.e. African Homo erectus) evolved from Homo habilis has recently been challenged by the discovery that the two species were sympatric (co-existing) in the Lake Turkana basin in Kenya for almost half a million years, implying that they must have occupied different niches and leading some to believe that the two species diverged from a common ancestor 2.3 million years ago rather than one evolving from the other.
On the other hand Homo habilis appears in the fossil record some 300,000 years before Homo ergaster. Unless earlier H. ergaster remains come to light, it seems likely that a proto-ergaster population split away from an earlier population of H. habilis and only later came into contact with a population of the ancestral species.
For now, then, it is still widely accepted that Homo habilis is ancestral to all later human species, including Homo sapiens.
References:
Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.
Leakey LSB, Tobias PV & Napier JR (1964): A New Species of Genus Homo from Olduvai Gorge, Nature No. 4927, 4 April 1964.
Scarre C (2005) (Ed): “The human past”, Thames & Hudson.
F. Spoor, M. G. Leakey, P. N. Gathogo, F. H. Brown, S. C. Anton, I. McDougall, C. Kiarie, F. K. Manthi & L. N. Leakey (2007): Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya, Nature Vol 448 9 August 2007.
© Christopher Seddon 2009
Thursday 1 January 2009
Homo rudolfensis
Homo rudolfensis is a controversial taxon proposed in 1986 by Soviet anthropologist Valery Alekseyev for the old fossil hominin skull KNM-ER 1470. The skull is believed to be 1.9 million years old and was recovered in 1972 at Koobi Fora on the eastern shore of Lake Turkana (then Lake Rudolf), Kenya. The skull had previously been assigned to Homo habilis, but Alekseyev proposed reassigning it to a new species on the basis of morphological differences, most significantly a cranial capacity which, at 750cc, was significantly larger than that of H. habilis (approx 600-680cc). It also had a flatter, broader face and broader post-canine teeth (molars and premolars), with more complex crowns and roots, and thicker enamel. Subsequently other fossils including mandibles and cranial fragments, all located at Lake Turkana, were assigned to the new species and there is a roughly 50/50 split between H. habilis and H. rudolfensis remains at this site.
Cameron & Groves (2004) reject Homo status altogether for KNM-ER 1470. By phylogenetic analyses of hominin craniofacial morphology, they demonstrated that the australopithecine-like species Kenyanthropus platyops (“flat-faced man of Kenya”), a contemporary of Australopithecus afarensis (“Lucy”), was probably ancestral to KNM-ER 1470 and suggested that Homo rudolfensis should be reclassified as Kenyanthropus rudolfensis.
Homo rudolfensis’ claims as a possible ancestor to modern humans received a further blow in 2007 when KNM-ER 1470 was reconstructed by anthropologist Timothy Bromage of the New York University. Bromage noted that the jaw had been positioned incorrectly and actually jutted out further than originally believed. He downsized the cranial capacity to 526cc, below that of Homo habilis. The reconstructed skull more closely resembles those of Australopithecus (gracile australopithecines) or Paranthropus (robust australopithecines) than those of Homo (humans).
Dr. Bromage’s conclusions are not universally accepted, but if correct they would reinforce the outcome of the Cameron & Groves study.
References:
Bromage T (2007): Craniofacial Architectural Constraints Resolve Major Quandry of Human Evolution, presentation to NYUCD, released 26 March 2007.
Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.
© Christopher Seddon 2009
Cameron & Groves (2004) reject Homo status altogether for KNM-ER 1470. By phylogenetic analyses of hominin craniofacial morphology, they demonstrated that the australopithecine-like species Kenyanthropus platyops (“flat-faced man of Kenya”), a contemporary of Australopithecus afarensis (“Lucy”), was probably ancestral to KNM-ER 1470 and suggested that Homo rudolfensis should be reclassified as Kenyanthropus rudolfensis.
Homo rudolfensis’ claims as a possible ancestor to modern humans received a further blow in 2007 when KNM-ER 1470 was reconstructed by anthropologist Timothy Bromage of the New York University. Bromage noted that the jaw had been positioned incorrectly and actually jutted out further than originally believed. He downsized the cranial capacity to 526cc, below that of Homo habilis. The reconstructed skull more closely resembles those of Australopithecus (gracile australopithecines) or Paranthropus (robust australopithecines) than those of Homo (humans).
Dr. Bromage’s conclusions are not universally accepted, but if correct they would reinforce the outcome of the Cameron & Groves study.
References:
Bromage T (2007): Craniofacial Architectural Constraints Resolve Major Quandry of Human Evolution, presentation to NYUCD, released 26 March 2007.
Cameron D & Groves C (2004): Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.
© Christopher Seddon 2009
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