Peopling of the New World remains contentious

New genetic studies reach differing conclusions

It is generally accepted that the humans first reached the New World by crossing the land bridge between Siberia and Alaska during the last Ice Age. However, the number of migrations and their timing has been debated for many decades.

The Paleoamerican model states that the earliest Americans or Paleoamericans were replaced by a second, separate wave of migrants from which today’s Native Americans are descended. The model is based on apparent differences in craniofacial morphology between some early fossil remains and more recent Native American. Note that this hypothetical second migration is distinct from the much later migrations responsible for around half of Aleut-Eskimo ancestry, and a tenth of Na-Dene ancestry.

Two new studies, published respectively in the journals Science and Nature, have reached opposing conclusions. Publishing in Science, Raghavan and colleagues analysed whole genomes of 31 present-day people from the New World, Siberia and Oceania, 23 ancient New World genomes and single nucleotide polymorphism genotypes from 79 present-day people from the New World and Siberia. The ancient DNA included samples from a 4,000 year-old Saqqaq individual from Greenland and the 12,600 year-old Anzick-1 (Clovis culture) individual from Montana.

They found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the New World in a single migration from Siberia no earlier than 23,000 years ago and after no more than 8,000 years of isolation in Beringia. Around 13,000 years ago, these ancestral Native Americans diversified into two basal genetic branches: one that is now dispersed across North and South America and another restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians, including Siberians and, more distantly, Australo-Melanesians. But populations believed to be relict Paleoamericans including the Pericúes from Mexico and the Fuego-Patagonians, are not directly related to modern Australo-Melanesians, contrary to the predictions of the Paleoamerican Model.

The second study, published by Skoglund and his colleagues in Nature, featured genomic data from 63 Native Americans, who belonged to 21 diferent populations, and showed no discernable evidence of European or African ancestry. Results showed that some Amazonian Native Americans descend partly from a founding population with an ancestry more closely related to Aboriginal Australians, New Guineans and Andaman Islanders than to any present-day Eurasians or Native Americans. This genetic signature is not seen in present-day Northern and Central Native Americans, or in the Anzick-1 genome. The source population for this Australasian-related ancestry was named ‘Population Y’ after Ypykue´ra, which means ‘ancestor’ in the Tupi language family spoken by the Suruı´ and Karitiana.

The researchers suggested that Population Y had already admixed with a lineage related to First Americans by the time it reached Amazonia, and that it was the explanation for the differing craniofacial morphology noted above. However, no ancient DNA directly extracted from remains with this morphology, so the results did not prove that these people were Population Y. The absence of linkage disequilibrium in Population Y suggests that it arrived in the New World a long time ago. Furthermore, while it shows a distant genetic affinity to Andamanese, Australian and New Guinean populations, it is not particularly closely related to any of them, suggesting that its ultimate source in Eurasia no longer exists.

It is to be hoped that future ancient DNA studies provide further insight into the results of the Skoglund study.

References:

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Skoglund, P. et al., Genetic evidence for two founding populations of the Americas. Nature 525, 104-108 (2015).

Raghavan, M. et al., Genomic evidence for the Pleistocene and recent population history of Native Americans. Science 349 (6250), 841, aab3884-1-10 (2015).x

Ohalo II ‘proto-weeds’ indicate attempts to cultivate wild cereals 23,000 years ago

Evidence of low-level food production at Epipaleolithic site

Ohalo II is a well-studied sedentary hunter-gatherer settlement on the shores of the Sea of Galilee. Associated with the Kebaran culture, the site dates to the Early Epipaleolithic period and was occupied around 23,000 years ago. The partially-excavated site is believed to cover an area of around 2,000 sq. m. (21,500 sq. ft.), and excavations have revealed the remains of six huts. Faunal remains suggest that the Ohalo II people hunted gazelle and deer, trapped hare and birds, and caught fish. From preserved botanical remains, no fewer than 142 different plant species have been identified, including emmer wheat, barley, brome and other small-grained grasses, acorns, almonds, pistachios, olives, legumes, raspberries, figs and grapes. These were collected from a range of habitats, including the nearby Mount Tabor.

In a newly-published report, archaeologists report the identification of 13 plant species now classified as weeds, mixed with large quantities of wild cereal seeds, including emmer, barley and oats. The presence of such species among cereals is considered to be one of the key archaeological indications of food production – in this case some 11,000 years before the onset of full-blown agriculture in the region.

That the Ohalo II people were harvesting wild cereal stands is supported by a study of glossed flint blades found at the site. The pattern of use-wear ‘sickle gloss’ polish observed on the sharp edges of these blades is consistent with their use to harvest wild cereals before they fully ripen and scatter their grain. Such a practice known from the later Natufian culture, but has not previously been documented for the Kebaran.  The blade also bears traces of hafting on the opposite side to the cutting edge, indicating that it was possibly a part of a sickle. Again, such tools are very rare in a pre-Natufian context.

However, the report suggests that these techniques were not carried on in later times, and they evidently represent a failed attempt at low-level food production. Sickle-harvesting did not come into widespread use until the Early Natufian around 8,000 years later, or 15,000 years before the present.

Reference:
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Snir, A. et al., The Origin of Cultivation and Proto-Weeds, Long Before Neolithic Farming. PLoS One 10 (7), e0131422 (2015).

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Earliest evidence of dentistry in Late Upper Palaeolithic

Stone tools used to treat dental caries 14,000 years ago

Humans have been practicing dentistry for a surprisingly long time. The earliest dental filling, made from beeswax and dating to 6,500 years ago, was reported from Slovenia in 2012 and a bow drill was apparently used to remove decay from molar teeth recovered from a 9,000-year-old Neolithic graveyard in Pakistan. The increase in carbohydrate consumption in the Neolithic was accompanied by an increase in dental caries, and a need for dentistry. The drilling, cleaning and filling dental cavities is documented in ancient Egyptian texts, which confirm that the practice was established by at least the fifth millennium BC.

Evidence of a much earlier origin for the treatment of dental caries has now emerged from Epigravettian site of Riparo Villabruna in northern Italy. Researchers studied a lower right third molar from a 25-year-old male, originally recovered in 1988 and radiocarbon dated to around 14,000 years ago. They noticed a dental cavity that had apparently been cleaned and on investigating with an electron microscope they found V-shaped striations that appeared to have been caused by scraping.

The researchers then attempted to replicate the striations on recently-extracted third molars, using pointed tools made from wood, bone and microlith. The use of such tools as toothpicks is well documented from the Palaeolithic. It was found that the microlith tool produced grooves and ridges matching those found on the Villabruna tooth, which thus provides the earliest known example of dental surgery. The cavity had been dug with a flint microlith to remove the dental decay and presumably relieve toothache.

The Villabruna specimen suggests that there was at least some knowledge of dental disease treatment well before the Neolithic. This study suggests that early forms of carious treatment entailed an adaptation of a toothpick to lever and scratch out decay rather than the drilling practices of later times.

Reference:

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Oxilia, G. et al., Earliest evidence of dental caries manipulation in the Late Upper Palaeolithic. Scientific Reports (2015).

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Early modern human from Romania had recent Neanderthal ancestor

Ancient DNA from Peştera cu Oase demonstrates inbreeding no more than four to six generations previously

The cave site of Peştera cu Oase (‘Cave with Bones’) in Romania has yielded some of the earliest fossil remains of modern humans in Europe. The remains of three individuals recovered from the site include a largely-complete lower jawbone (Oase 1), the near-complete skull of a 15-year-old adolescent, and a left temporal bone. The remains are around 40,000 years old and exhibit a mosaic of modern and archaic features. Modern features include the absence of browridges, a narrow nasal aperture, and a prominent chin; but there are also archaic features such as a wide dental arcade and very large molars. There is little doubt that they are modern humans and not Neanderthals, but some aspects of the morphology are consistent with Neanderthal ancestry.

Researchers have now recovered ancient DNA from the Oase 1 jawbone and sequenced the genome. They report that between 6 to 9 percent of the genome is of Neanderthal origin, a higher percentage than for any other modern human genome sequenced to date. Three chromosomal segments of Neanderthal DNA are of considerable length, suggesting that the Neanderthal contribution to the Oase 1 individual occurred so recently in their past that the chromosomal segments of Neanderthal origin had little time to break up due to recombination. The researchers turned their attention to seven segments of the genome that appeared to be of recent Neanderthal origin and from the genetic lengths of these, implied that Oase 1’s Neanderthal ancestor had lived no more than four to six generations earlier, or less than two hundred years.

The existence of such a recent Neanderthal ancestor casts doubts on theories that suggest that interbreeding occurred only very occasionally, or was confined to an early episode soon after modern humans first left Africa. However, the researchers failed to establish a clear relationship between the Oase 1 individual and later modern humans in Europe, suggests that they may have been a member of an early modern human population in Europe that eventually died out without contributing much to later European populations.

Reference:

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Fu, Q. et al., An early modern human from Romania with a recent Neanderthal ancestor. Nature 524, 216-219 (2015).

Kennewick dispute set to reignite

Ancient DNA confirms Native American affinities

Kennewick Man died about 8,600 years ago and was between 40 to 55 years old at the time of his death. In 1996, his skull and some other skeletal parts were discovered in the Columbia River, Kennewick, Washington State. The find was of interest not just to anthropologists but also to Native Americans, who refer to him as the Ancient One. The Plateau people of the Pacific Northwest claimed an ancestral relationship and requested repatriation of the remains as provided for under US federal law (Native American Graves Protection and Repatriation Act or NAGPRA). The land where the remains were found is managed by the US Army Corps of Engineers, who announced that they were willing to hand over the remains. This in turn precipitated a lawsuit from scientists wishing to study the remains.

The plaintiffs’ claim was based on the morphology of the skull, which is long and narrow, with a narrow face, and a jutting chin. It is quite unlike the broad-headed, broad-faced appearance typical of Native Americans and resembles that of certain Pacific populations, in particular the Ainu and Polynesians. It was argued that Kennewick Man belonged to a population that reached America before the ancestors of the present-day Native Americans, and that the request for repatriation of the remains must therefore be rejected. In 2004, the plaintiffs’ claim was upheld by a judicial ruling.

However, subsequent discoveries have cast doubt on the claim that Native Americans are descended from migrants that replaced an earlier American population. Remains have been found that are even older than those of Kennewick Man, yet fall comfortably within the morphological range of present-day Native Americans. Other remains have yielded mitochondrial DNA belonging to haplogroups only found in Native American populations. Genetic studies have failed to find any evidence for a replacement of early Paleoindians by ancestors of today’s Native Americans.

It has been suggested that skull data has simply been misinterpreted. In one study, researchers applied statistical methods to skulls from all over the world, dating from around 15,000 years ago to the present day. They found that when shape variation was considered over a wide geographical range or over a long period of time, the skulls formed a continuum rather than discrete categories. The same pattern was also seen when New World skulls were considered on their own. The supposed Paleoindian and Native American forms were no more than extremes at opposite ends of a continuum, and most of the New World skulls fell well between the two extremes.

Following the 2004 ruling, study of Kennewick Man continued, but only now have researchers obtained ancient DNA from the remains. A team led by Morten Rasmussen has published its results in the journal Nature and they show that Kennewick Man is more closely related to present-day Native Americans than to any other population worldwide. Based on a comparison with Native American groups for whom genome-wide data is available, several groups are apparently descended from population closely related to that of Kennewick Man, including the Confederated Tribes of the Colville Reservation (Colville), which is one of the five groups claiming Kennewick Man.

A renewed claim for repatriation now seems inevitable.

References:

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1.	Rasmussen, M., Sikora, M., Albrechtsen, A., Korneliussen, T. & Moreno-Mayar, J., The ancestry and affiliations of Kennewick Man. Nature 523, 455-458 (2015).
2.	Jantz, R. & Owsley, D., Variation Among Early North American Crania. American Journal of Physical Anthropology 114, 144-156 (2001).

Did Aboriginal Australians rediscover boats after over 20,000 years?

Evidence for human activity on island in ancient mega-lake

Lake Mungo is the largest of a series of 19 now dried up lakes making up the Willandra Lakes system. The region is a World Heritage Site covering 2,400 sq. km (925 sq. miles) in southwest New South Wales, about 1,000 km (620 miles) west of Sydney. The water levels in the lakes remained high until 45,000 years ago and then began to decline. They dried up completely 22,000 years ago, and have remained dry ever since. However, a recent survey has shown that 24,000 years ago, Lake Mungo underwent a sudden massive filling episode, increasing its depth by 5 m (16 ft.) and its volume by 250 percent. Lake Mungo became linked to its neighbour, Lake Leaghur, at two overflow points, so creating an island in between.

Humans arrived in the Lake Mungo region at least 20,000 years before the mega-lake phase. The expansion of Lake Mungo would have substantially affected mobility, forcing people to skirt the mega-lake. However, the presence of hearths and stone artefacts on the island suggests that they repeatedly crossed the inflow channel, taking stone tools and hunting equipment with them. While they could have swum, using bags to carry tools, it is likelier that they used boats.

This implies a highly flexible response to the sudden change in conditions, and possibly a re-discovery of boat technology. While Aboriginal Australians must have used boats to reach Australia in the first place, there is a lack of evidence for pelagic fishing and navigation to offshore islands around the Australian coast until a few thousand years ago. It has accordingly been assumed that watercraft technologies were abandoned after initial arrival and dispersal across Australia. If boats were used to cross Lake Mungo during its expanded phase 24,000 years ago, then this represents the revival of a technology which had apparently been abandoned over 20,000 years earlier, and at a location well inland and far from any major navigable rivers.

Reference:

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Fitzsimmons, K., Stern, N., Murray-Wallace, C., Truscott, W. & Pop, C., The Mungo Mega-Lake Event, Semi-Arid Australia: Non-Linear Descent into the Last Ice Age, Implications for Human Behaviour. PLoS One 10 (6), e0127008 (2015).x

Stop hiding behind dangerous drivers

I won’t mince my words: cyclists who ride on the pavement are an urban blight, at least in North London. I would like to be able to walk to the shops and back without having to be aware that at any second I will be confronted by a cyclist barrelling towards me on the pavement at high speed. Every few minutes I will see a cyclist on the pavement somewhere. Every few weeks I experience what would be described in aviation circles as a ‘near miss’. I’ve given up remonstrating with them: I’ll be sixty later this year and the torrent of foul-mouthed abuse that invariably follows is surely not good for my blood pressure.

Yet what is the response when I complain about this on a ‘Comments’ thread where cycling issues are being discussed on the Guardian website? I’m told I’m having a “petty rant about a problem that does not exist”. I’m accused of making it up because I have an “anti-cycling agenda”. If the problem does not exist, why would I have an anti-cycling agenda? You don’t need to be Mr Spock to see that that is completely illogical.

There have been two high-profile incidents recently involving injury caused to pedestrians by idiots cycling at speed on the pavement. In the first incident, a 44-year-old woman in Bermondsey, South London, was scarred for life. In the second incident, a three-year-old girl was hit and dragged along the pavement in Blackpool. Only by extreme good fortune did she escape serious injury. The response of what I would term ‘cycling activists’ to these incidents is, frankly, disgraceful. See some of the comments under the two reports, but also see this response from the supposedly-responsible London Cycling Campaign. The paranoid, self-pitying headline “Pavement cycling incident sparks anti-cycling commentary in media” sets the tone for the rubbish that dismisses the Blackpool incident as ‘rare’ (which, I’m sure, will be of great comfort to the little girl) and then bangs on about how 98 percent of serious or fatal injuries to pedestrians are due to collisions with motor vehicles.

So that’s all right, then?

Another frequent comment is that you are better off being hit by a bicycle than you are by a car. Maybe it’s just me, but I don’t particularly want to be hit by either. This Youtube video sums up the apparent contempt ‘cycling activists’ have for people who complain about pavement cycling. The video ends with an appeal to tackle the ‘real problem’ of bad drivers.

Time and time again, the same fallacious attitude crops up: ‘whataboutery’. Complain about dangerous cycling and the stock response is to complain about cars. It’s a very strange moral perspective to dismiss the problem of dangerous cycling because motorists cause more death and injury than do cyclists. By the same logic, we should dismiss the problem of dangerous drivers because they are responsible for fewer deaths than wars, global warming, ISIS, etc. A more sinister interpretation is that it represents a collective ultimatum: until dangerous driving are tackled, we will continue to cycle on the pavement, ignore red lights, pedestrian crossings, and indeed any rules that don’t suit us. The injuries to the woman in London and the little girl in Blackpool should be seen as collateral damage in a perceived war between cyclists and motorists. This attitude will not advance the cause of cycling one iota. For as long as it persists, it will only enhance the non-cycling world’s perception of cyclists as anti-social nuisances with a massively over-inflated sense of entitlement. In my view, it is an attitude that is about as representative of the silent majority of law-abiding cyclists as football hooligans are of the tens of thousands of genuine fans who attend matches each week. I have family and friends who cycle. Not one of them thinks this way. Cycling is a mode of transport and a recreational activity. It is not a religion and cyclists are not an ethnic minority. If ‘cycling activists’ want to be taken seriously, they need to stop trying to defend the indefensible.

Skull surgery used to treat post-traumatic osteomyelitis 4,900 years ago

Did Chalcolithic surgeons possess medical knowledge which remains poorly-understood to this day?

It sounds counter-intuitive, but there is some evidence to suppose that long-bone fractures heal faster if patients have also sustained traumatic skull injuries. The exact mechanism is not fully-understood, but may involve the cytokine interleukin-6, bone morphogenic proteins, and prolactin, all of which are released in response to a brain injury. What is remarkable is this might have been known in Chalcolithic times – and used as a treatment.

In 1992, archaeologists discovered the Early Chalcolithic cemetery of Pontecagnano in southern Italy, associated with the Gaudo Culture and dating to around 4,900 to 4,500 years ago. PC 6589.1 is a 25-year-old male, whose skull shows two lesions. The right thigh bone shows a poorly healed mid-shaft fracture, which had resulted in a chronic infection of the bone marrow known as osteomyelitis affecting both thigh bones.

The condition would have been disabling and was probably the ultimate cause of death, but an evidently-skilled prehistoric surgeon had attempted a cure. The skull lesions were the result of surgical trepanations of the skull cap, where holes had been made in the skull to expose the dura mater. One hole was apparently produced by scraping; the other by drilling with a stone point. There is evidence of significant bone regrowth, suggesting lengthy postoperative survival of the patient.

While the procedure was undoubtedly carried out with the intention of freeing the patient from his painful and disabling condition, the exact reason is not clear. The traditional explanation is that trepanning releases evil spirits associated with the symptoms affecting the patient, but it is possible that healers were aware of a strange curative phenomenon which modern medical science is only now rediscovering.

References:

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Petrone, P. et al., Early Medical Skull Surgery for Treatment of Post-Traumatic Osteomyelitis 5,000 Years Ago. PLoS One 10 (5), e0124790 (2015).x

New hominin species reported from Ethiopia

Australopithecus deyiremeda was a contemporary of ‘Lucy’

Hominin remains comprising a complete lower jawbone, a partial lower jawbone and two partial upper jawbones, together with some accompanying teeth have been described as a new species, Australopithecus deyiremeda. The fossils were excavated in 2011 in the Woranso–Mille study area, central Afar, Ethiopia. They were found in deposits dated from 3.3 to 3.5 million years old, making Australopithecus deyiremeda a contemporary of Australopithecus afarensis (the species to which the well-known fossil ‘Lucy’ belongs) and the controversial hominin species Kenyanthropus platyops. The specific name deyiremeda means ‘close relative’ in the local Afar language and follows a now-established tradition of using local languages to name hominin species.

Australopithecus deyiremeda is distinguished from Ardipithecus ramidus by its thicker dental enamel and more robust lower jawbone. It is distinguished from Australopithecus afarensis by a number of features of its lower jawbone, by the positioning of its cheekbones in relation to the upper jawbone, and by its smaller back teeth.

What are the implications of this discovery? For a long time, it was believed that there was just the one hominin species, Australopithecus afarensis, living in the period from four to three million years ago, in East Africa. It was possible to argue that the earlier Australopithecus anamensis (4.2 to 3.9 million years ago) and the later Australopithecus garhi (2.5 million years ago) were simply early and late forms of the same species and that Australopithecus bahrelghazali from Chad (known from a single 3.5-million-year-old specimen) represented a Central African extension of its range. On this view, Australopithecus afarensis was a single, long-lived, geographically widespread species, capable of occupying a wide range of habitats. Not until 2.8 million years ago did other hominin species start to appear: Australopithecus africanus and later Australopithecus sediba in South Africa and the so-called robust australopithecines (Paranthropus) in both South Africa and East Africa.

Even if Kenyanthropus platyops is rejected, this view is no longer tenable. There is now incontrovertible evidence that multiple australopithecine species were living in East Africa during the Middle Pliocene. It is also notable that Australopithecus afarensis has been recorded at Hadar, only 35 km (20 miles) north of Woranso–Mille. Not only did these species overlap in time, they were close in geographical terms, probably occupying differing feeding niches.

 Early hominin evolution has been described as more of a tangled bush than a family tree. In addition to Australopithecus afarensis, Australopithecus deyiremeda and possibly Kenyanthropus platyops, it is likely that the Ardipithecus line was still in existence at this time. The Woranso–Mille site has also yielded a 3.4-million-year-old partial hominin foot with an opposable big toe. Though it has not been assigned to a particular species, the toe suggests Ardipithecus or something very similar.

With the LD-50-1 lower jawbone pushing back the origins of Homo to 2.8 million years ago, later australopithecines such as Australopithecus sediba have been bumped from the list of possible human ancestors. However, the Woranso–Mille discovery means that we are no nearer identifying from just which part of the ‘tangled bush’ the first humans emerged.

References:

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1.       Haile-Selassie, Y. et al., New species from Ethiopia further expands Middle Pliocene hominin diversity. Nature 521, 483-488 (2015).

Killed with a blunt instrument

Evidence for lethal interpersonal violence in the Middle Pleistocene

Evidence of interpersonal violence between humans resulting is (perhaps surprisingly) rare in the Pleistocene. Examples include the Shanidar 3 and St. Césaire 1 Neanderthals, from Iraq and southwestern France respectively. Shanidar 3 suffered a penetrating injury from a projectile weapon, and St. Césaire 1 suffered a fractured skull consistent with a deliberate blow from a sharp object. It cannot be ruled out that the injuries were the result of accidents: a hunting injury in the case of Shanidar 3 and a fall in the case of St. Césaire 1 (though the location of the injury at the apex rather than side of the cranial vault makes this unlikely). Neither incident was fatal, at least not immediately so, as both lived long enough thereafter for healing to begin. There are also cases where bones have been de-fleshed and broken open to extract marrow, suggesting cannibalism – although it is unclear whether individuals were attacked and killed, or whether they were already dead and possibly eaten by their companions.

The 430,000-year-old site of Sima de los Huesos (‘Cave of Bones’) in northern Spain has yielded a large number of human remains described as either Homo heidelbergensis or as proto-Neanderthals. The remains were found in a deep pit into which they were intentionally dropped, either as part of a mortuary ritual or more likely as a means of hygienically disposing of dead bodies.

Cranium 17 is a very complete cranium recovered in 52 pieces. It comprises the entire face, including much of the upper dentition (upper right C to M3 and upper left C to M2), the frontal bone, most of the sphenoid bone, the left parietal bone, the left temporal bone minus the mastoid process, and most of the occipital bone. The slight dental wear suggests that Cranium 17 belonged to a young adult.

Most of the fragmentation of the cranium involved dry bone breakage occurring long after death. 

However, there were two unhealed depressed fractures consistent with blunt force trauma from the same weapon (or ‘tool’ as the paper euphemistically describes it), resulting in penetration of the bone-brain barrier. Either injury would probably have been fatal: two suggests an intention to kill. Furthermore, the presence of two injuries caused by impact with the same object more or less rules out post-mortem damage to the cranium caused by it landing on a hard object when it was dropped into the pit, or by subsequent rock-falls.

Cranium 17 represent the earliest reasonably clear-cut case of interpersonal violence between humans leading to death. It demonstrates that this rather depressing aspect of human behaviour has an ancient origin.

References:

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1.	Sala, N. et al., Lethal Interpersonal Violence in the Middle Pleistocene. PLoS One (2015).

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Sorry seems to be the hardest word

Which do you think is the better response to the appalling incident where a little girl was hit and dragged along the pavement by a cyclist?

THIS:
“We at London Cycling Campaign were shocked to hear that a child had been hit by a cyclist on a pavement in Blackpool. Pavement cycling is both dangerous and illegal. We unreservedly condemn the thoughtless and selfish actions of the individual responsible. We wish the child a full and speedy recovery and our thoughts are with her and our family. We feel that it would be inappropriate to make any further comment at this time.”

OR the actual response to the incident?
Just read it and make up your own mind as to which response is more likely to gain the support of the non-cycling public.

Earliest stone tools found in Kenya

3.3-million-year-old tool tradition significantly predates first humans

In recent years, a growing body of evidence has suggested that the making of stone tools predates the emergence of the earliest humans. In the 1990s, Oldowan-type tools dating to around 2.6 million years ago were found at the Gona River study area in Ethiopia. The tools slightly predated the then-earliest known humans, but as they were not associated with hominin remains there was no way of telling who the toolmakers had been. Towards the end of the decade, evidence of carcass butchery dating to around 2.5 million years ago was found at the nearby Bouri Formation. Bones of large mammals with cut-marks thought to be made by stone tools in the process of de-fleshing the carcasses were associated with australopithecine remains. Unfortunately, on this occasion, no actual stone tools were found.

Similarly, in 2010, it was claimed that animal bones from Dikika, Ethiopia, show cut-marks resulting from de-fleshing, and signs of having been struck with hammerstones to extract bone marrow. The remains are 3.39 million years old, early enough to preclude human involvement – but again no actual tools were found. It could not be ruled out that naturally-occurring sharp pieces of stone had been used. It is also possible that as the bones were buried in coarse-grained, sandy deposits, trampling by animals could have produced the marks. Taken as a whole, these finds made a good case for australopithecine tool making, but did not settle matters beyond reasonable doubt. Conclusive evidence was still lacking.

Such evidence has now been reported from the Kenya site of Lomekwi 3, just west of Lake Turkana. More than one hundred stone artefacts have been recovered, and at 3.3 million years old they predate even the recently-reported LD 350-1 human jawbone by half a million years. The artefacts include flakes and the cores from which they were struck. It has been shown that the cores were rotated as successive flakes were struck off, confirming that the flaking was intentional and not the result of accidental fracturing. Researchers have also managed to ‘refit’ one of the flakes back to the core from which it was struck. The tools are larger and heavier than typical Oldowan artefacts, and methods by which flakes were struck from cores was less effective. It is suggested that they represent a technology intermediate between the use of stone tools for pounding and hammering and the more flake-orientated Oldowan.

This pre-Oldowan technology has been named Lomekwian and is the final proof that hominins contemporary with Australopithecus afarensis (‘Lucy’s’ people) were making stone tools.

Reference:
Harmand, S. et al., 3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya. Nature 521, 310-315 (2015).

Did Proto-Aurignacian trigger Neanderthal extinction?

Tooth confirms that Proto-Aurignacian toolmakers were modern humans

A new study has confirmed that a lower deciduous (‘milk tooth’) incisor from Riparo Bombrini is from a modern human, based on its morphology. An upper deciduous incisor from Grotta di Fumane is also modern, based on the extraction of ancient mitochondrial DNA from it. Both sites are associated with the Proto-Aurignacian culture and confirm it to be a modern human rather than Neanderthal culture. The sites are around 41,000 to 39,000 years old.

The Proto-Aurignacian appeared around 42,000 years ago in Southwest and South-Central Europe. It is associated with ornaments, such as perforated shell beads, and it is characterized by bladelets with typical retouched artefacts such as Font-Yves points and Dufour bladelets. This industry has been linked to the Ahmarian tool tradition of the Levant and since the Ahmarian is attributed to modern humans, it has been widely-accepted that the Proto-Aurignacian reflects a westward migration of modern humans from Southwest Asia. However, up until now there has been a lack of supporting fossil evidence for this hypothesis.

The importance of this new confirmatory dental evidence is that they demonstrate that by 41,000 to 39,000 years ago, modern humans were present in Southern Europe. This date range coincides very closely with dates for the disappearance of Neanderthals from the region, with the implication that the spread of the Proto-Aurignacian was responsible for their demise.

References:

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1.  Benazzi, S. et al., The makers of the Protoaurignacian and implications for Neandertal extinction. Science 348 (6236), 793-796 (2015).

2.  Conard, N. & Bolus, M., Chronicling modern human’s arrival in Europe. Science 348 (6236), 754-756 (2015).

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Evidence of interbreeding between archaic and modern humans – or just highly diverse morphology?

50,000-year-old Tam Pa Ling lower jawbone is a mosaic of archaic and modern features

Tam Pa Ling (‘Cave of the Monkeys’) is a cave site in Huà Pan Province, Laos. A fully-modern partial human skull (TPL1) was recovered in December 2009, followed a year later by a complete human lower jawbone (TPL2). The upper jawbone of TPL1 does not match with TPL2, so the two represent different individuals. The fossils are estimated to be from 46,000 to 63,000 years old, establishing an early presence of modern humans in Southeast Asia.

A newly-published study of the more recent discovery suggests that the TPL2 lower jawbone, though essentially modern, possesses a number of archaic attributes. The most obvious sign of modern affinities is the clear presence of a chin. However, viewed from the side, the jawbone is very robust, particularly at the position of the first and second mandibles. In this respect, TPL2 is closer to the archaic than the modern human condition.

While this mosaic could be evidence of modern humans interbreeding with archaic populations – possibly Denisovans or Homo erectus – the authors of the report take the view that early modern humans in the region simply possessed a large range of morphological variation.

Reference:

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Demeter, F. et al., Early Modern Humans and Morphological Variation in Southeast Asia: Fossil Evidence from Tam Pa Ling, Laos. PLoS One 10 (4), e0121193 (2015).x

130,000 year old Neanderthal eagle talon necklace predates H. sapiens influence

Does evidence from Krapina, Croatia refutes ‘bow wave’ theory?

The popular view of the Neanderthals as dimwits has been in trouble for years, as evidence for Neanderthal symbolic behaviour has continued to accumulate. Up until now, however, it is not been possible to unequivocally rule out the influence of modern humans, who reached Europe around 46,000 years ago. The Châtelperronian culture for example, long put forward as evidence of Neanderthal behavioural modernity, has now been shown not to have begun until after the arrival of modern humans. It is assumed that the Neanderthals simply borrowed the trappings of modernity from their new neighbours.

In other regions such as Spain and Italy, the evidence for Neanderthal behavioural modernity has been attributed to what Sir Paul Mellars has described as a ‘bow wave effect’, i.e. long-distance interactions between Neanderthals and modern humans occurring several millennia before the latter become visible in the archaeological record.

This view is now seriously challenged by a new study of eight white-tailed eagle talons that were found at the Neanderthal site of Krapina, Croatia over a century ago. Researchers found 21 cut marks on the talons, and there were areas of high polish consistent with ‘use wear’ as the talons rubbed against each other. The implication is that they were mounted in a necklace or bracelet – clear evidence of symbolic behaviour. Furthermore, it was concluded that the talons come from at least three eagles, suggesting that considerable effort had gone into obtaining them. The white-tailed eagle is fairly rare and it is an aggressive apex predator, far from easy to catch or trap.

Associated faunal remains suggested that Krapina dates to the warm Eemian interglacial period. A direct date of 130,000 years old was obtained in 1995 – which means that it predates any possible influence from modern humans by more than 80,000 years.

References:

1.      Radovčić, D., Sršen, A., Radovčić, J. & Frayer, D., 2015. Evidence for Neandertal Jewelry: Modified White-Tailed Eagle Claws at Krapina. PLoS One, 11 March.

Dmanisi reconsidered

Implications of LD 50-1 jawbone and Spoor H. habilis study for ‘variable single species’ theory

In October 2013, Lordkipanidze and his colleagues reported the discovery of an adult skull from Dmanisi, Georgia. The fifth skull to be discovered at the site, it was complete and undeformed; it is the only known fully-preserved adult hominin skull from the early Pleistocene. They also put forward the radical suggestion that the various species often proposed for early African Homo (Homo habilis, Homo rudolfensis, Homo ergaster and Homo erectus) were all actually variants of the same species, and that early Homo was a single lineage which evolved over time without differentiating into multiple species. This conclusion is based on a claim that shape variation between the five Dmanisi skulls is roughly the same as that seen among the various early Homo skulls from East Africa, even though the former represents a single species and the latter are generally thought to represent several (Lordkipanidze, et al., 2013).

This suggestion must now be reconsidered in the light of last week’s announcement that the LD 50-1 partial lower jawbone places the origins of Homo at least 2.8 million years ago (Villmoare, et al., 2015); and Spoor and colleagues’ (2015) reappraisal of the OH 7 Homo habilis type specimen. The latter report that:

1.       The cranial capacity of OH 7 is estimated at between 729 and 824 cc, which is substantially larger than 500 to 700 cc typically cited and within the range of early Homo erectus;

2.       OH 7 is more primitive than the 2.33-million-year-old AL 666-1 upper jawbone provisionally assigned to Homo habilis, despite being 500,000 years younger.

Spoor and colleagues suggest that AL 666-1 cannot be placed within either Homo habilis or Homo rudolfensis. They do not investigate its true affinities further but suggest that their data is consistent with it belonging to Homo erectus. That it is more derived than Homo habilis implies that the origins of the latter must be sought even further back in time than 2.33 million years ago. The reporting that LD 50-1 is transitional between Australopithecus and Homo places the origin of the latter at around 2.8 million years ago. Putting the two reports together, the implication is that Homo was already diverse lineage by 2.33 million years ago, and that early human types were distinguished by facial morphology rather than by brain size.

Lordkipanidze and his colleagues noted that the morphological diversity within the five skulls recovered at Dmanisi is greater than that recorded for specimens recovered in Africa and assigned to different species. On the basis that the Dmanisi hominins all belong to the same species, they suggest that the morphological diversity in African fossil record of Homo 1.8 million years ago is better interpreted as demes of a single evolving lineage of Homo erectus rather than multiple species.

Given that Homo habilis, Homo rudolfensis and Homo erectus might all have emerged by 2.33 million years ago, an ancestor/descendant relationship between these species seems unlikely. It could be argued that the deme interpretation is more parsimonious than the traditional multiple species view.

Against this view, it has been suggested that the limb proportions of Homo habilis are more apelike (longer arms, shorter legs) than those of Homo erectus (Richmond, et al., 2002). The main problem is that in comparison to classic fossils such as ‘Lucy’ (Australopithecus afarensis) and the Turkana Boy (Homo erectus), we do not have a well-preserved example of Homo habilis. The evidence for the apelike limb proportions of Homo habilis largely rests on the two fragmentary skeletons KNM-ER 3735 and OH 62.

In the case of OH 62, the leg is represented by an upper section of the femur, the true length of which is uncertain. KNM-ER 3735 preserves even less limb detail. A re-evaluation of these specimens in comparison to fossil limb parts OH 34 and OH 35 suggests that the upper-to-lower limb ratio of OH 62 lies within the upper range of modern humans and lower range of chimpanzees; and that KNM-ER 3735 lies in the middle of the modern range, entirely outside the chimpanzee range. Based on these results, the limb proportions of Homo habilis were modern rather than apelike (Haeusler & McHenry, 2004).

Overall, these results appear to refute suggestions that Homo habilis should be reclassified as an australopithecine (Wood & Collard, 1999) and are consistent with the conclusions of Lordkipanidze and his colleagues.

References:

1.      Haeusler, M. & McHenry, H., 2004. Body proportions of Homo habilis reviewed. Journal of Human Evolution, Volume 46, pp. 433-465.

2.       Lordkipanidze, D. et al., 2013. A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology of Early Homo. Science, 18 October, Volume 342, pp. 326-331.

3.       Richmond, B., Aiello, L. & Wood, B., 2002. Early hominin limb proportions. Journal of Human Evolution, Volume 43, pp. 529-548.

4.       Spoor, F. et al., 2015. Reconstructed Homo habilis type OH 7 suggests deep-rooted species diversity in early Homo. Nature, 5 March, 7541(519), pp. 83-86.

5.       Villmoare, B. et al., 2015. Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia. Science, 5 March.

6.       Wood, B. & Collard, M., 1999. The Human Genus. Science, 2 April, Volume 284, pp. 65-71.

The LD 350-1 jawbone

Introduction:

A partial lower jawbone and a number of teeth have been recovered from a surface outcrop of fossil-bearing sedimentary rock in the Ledi-Geraru research area, in the Afar region of Ethiopia. This region has long been associated with the fossils of early hominins. The jawbone has been assigned to Homo (species indeterminate) (Villmoare, et al., 2015). The age of the jawbone is constrained by stratigraphic and palaeomagnetic considerations to between 2.80 and 2.75 million years old (DiMaggio, et al., 2015). This means that LD 350-1 is at least 400,000 years older than the earliest previously-known fossil assigned to Homo. The findings are published as two articles in the journal Science.

What was our previous understanding of human origins?

The conventional view is that the first human species was Homo habilis (‘Handy man’). Discovered in 1960 and announced as a new species four years later, it is believed to have evolved from an australopithecine ancestor though which is disputed. Possibilities include the South African Australopithecus africanus and Australopithecus afarensis from East Africa (or its probable descendant species Australopithecus garhi). The famous ‘Lucy’ belongs to Australopithecus afarensis. In comparison to a modern human, Homo habilis was small brained and its limb proportions (short legs, long arms) were still very apelike. However, the skull was less massively-built than an australopithecine; the upper and lower jawbones were within the human size range; and the feet and thumb joints were humanlike (Conroy, 1997). Homo habilis is known in the fossil record from 2.33 to 1.44 million years ago (Kimbel, et al., 1997; Spoor, et al., 2007). It is then presumed to have given rise to Homo erectus. Although still small-brained in comparison to a modern human, the limb proportions of Homo erectus are similar to those of later humans. Homo erectus first appears in the fossil record 1.8 to 1.9 million years ago (Wood, 2011).

This conventional view has a number of problems. Firstly, a second species, Homo rudolfensis is now known to have been contemporary with Homo habilis. First proposed in 1972, it was confirmed as a separate species in 2012 (Leakey, et al., 2012). How Homo rudolfensis fits into the bigger picture is far from clear: some have noted similarities to an earlier hominin, Kenyanthropus platyops (‘Flat-faced man of Kenya’) and it is possible that Homo rudolfensis belongs in Kenyanthropus rather than Homo.

Another problem is that the earliest example of Homo habilis, a 2.33 million year old upper jawbone known as AL 666-1 from Hadar, Ethiopia might in fact be something other than Homo habilis. The oldest uncontested example of Homo habilis is only 1.9 million years old (Lieberman, 2007) and given that the species also persisted well after the appearance of Homo erectus an ancestor/descendant relationship seems unlikely. Instead, it has been suggested that the two species shared a common ancestor (Spoor, et al., 2007).

Finally, it has been suggested that the late australopithecine species Australopithecus sediba from South Africa, which dates to around 2 million years old (Pickering, et al., 2011) is a more plausible ancestor for Homo erectus than is Homo habilis (Berger, et al., 2010).

Could LD 530-1 be an australopithecine?

The date of 2.8 million years ago puts it just after the time of Australopithecus afarensis (3.9 to 3.0 million years ago) and before the late australopithecine species Australopithecus garhi (2.5 million years ago).Given that the Australopithecus garhi is thought to descendant of Australopithecus afarensis, LD 350-1 is in the right place at the right time to be a part of that lineage. In terms of size, both the jawbone and the teeth are within the Australopithecus afarensis range, albeit towards the lower end. However, most other respects, the mandibular and dental characteristics of LD 350-1 fall outside the range for Australopithecus afarensis. The dentition is also reduced (and therefore more humanlike) in comparison to Australopithecus garhi, which would appear to bump the latter from the lineage leading to Homo. Overall, LD 350-1 appears to be transitional between Australopithecus and Homo and is likely to represent the earliest-known example of the latter.

What are the implications if LD 350-1 is indeed Homo?

Models that posit an australopithecine ancestor for Homo from the period 2.5 to 2.0 million years ago (e.g. Australopithecus garhi or Australopithecus sediba) would be ruled out. Instead, Homo diverged from Australopithecus much earlier than hitherto believed. Notably, 2.8 million years ago coincides with a shift to a more arid climate in Africa, suggesting a link between climate change and the emergence of Homo. The fossil record of Ledi-Geraru records a shift to a more open habitat of grasses or low shrubs at around this time.

Reboot for Homo habilis

In a separate study, published in the journal Nature, Fred Spoor and colleagues (Spoor, et al., 2015) carried out a reconstruction of the 1.8 million year old Homo habilis holotype specimen OH 7. The results suggest that the species was larger-brained than previously believed, within the range of Homo erectus. It was also found that the dentition of OH 7 is more primitive than the 2.33 million year old AL 666-1, suggesting that the latter cannot be Homo habilis – but implying that the origins of Homo habilis go back even further. The study did not consider the affinities of AL 666-1 any further but speculated that it could be early Homo erectus. By 2.33 million years ago, the Homo lineage was already apparently diverse, with early human species distinguished from one another more by gnathic morphology than by brain size. The reporting of the early Homo jawbone LD 350-1 dovetails neatly with this study.

What species is LD 350-1?

It is more primitive than Homo habilis but nevertheless lies within Homo. Its describers did not assign a species to it, but it is likely that it will be eventually recognised as a new species within Homo; the earliest human species yet. 

References:

1.      Berger, L. et al., 2010. Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa. Science, 9 April, Volume 328, pp. 195-204.

2.       Conroy, G., 1997. Reconstructing Human Origins: A Modern Synthesis. New York, NY: W. W. Norton & Company, Inc..

3.       DiMaggio, E. et al., 2015. Late Pliocene fossiliferous sedimentary record and the environmental context of early Homo from Afar, Ethiopia. Science, 5 March.

4.       Kimbel, W., Johanson, D. & Rak, Y., 1997. Systematic Assessment of a Maxilla of Homo From Hadar, Ethiopia. American Journal of Physical Anthropology, Volume 103, pp. 235-262.

5.       Leakey, M. et al., 2012. New fossils from Koobi Fora in northern Kenya confirm taxonomic diversity in early Homo. Nature, 9 August, Volume 488, pp. 201-204.

6.       Lieberman, D., 2007. Homing in on early Homo. Nature, 20 September, Volume 449, pp. 291-292.

7.       Pickering, R. et al., 2011. Australopithecus sediba at 1.977 Ma and Implications for the Origins of the Genus Homo. Science, 9 September, Volume 333, pp. 1421-1423.

8.       Spoor, F. et al., 2015. Reconstructed Homo habilis type OH 7 suggests deep-rooted species diversity in early Homo. Nature, 5 March, 7541(519), pp. 83-86.

9.       Spoor, F. et al., 2007. Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya. Nature, 9 August, Volume 448, pp. 688-691.

10.    Villmoare, B. et al., 2015. Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia. Science, 5 March.

11.    Wood, B., 2011. Did early Homo migrate “out of ” or “in to” Africa?. PNAS, 28 June, 108(26), p. 10375–10376.