Fossil evidence for interbreeding between Neanderthals and modern humans

Lower jawbone discovered in 1957 could be from Neanderthal/modern human hybrid.

Although interbreeding between Neanderthals and modern humans has been inferred from genetic data, convincing fossil evidence for hybridisation has hitherto been lacking. Claims that the 24,500-year-old skeleton of a 4-year-old child found at Abrigo do Lagar Velho, Portugal in 1998 is an example of a hybrid (Duarte, et al., 1999) have not been widely accepted. Notably, the burial was typical of the Gravettian, a culture that is firmly associated with modern humans. It is possible that the infant was simply an unusually stocky modern human juvenile, or a ‘chunky child’ as one critic put it (Tattersall & Schwartz, 1999).

A newly-published report has claimed that a better case may be made for a lower jawbone from the Riparo Mezzena rocks helter, northern Italy. The jawbone was found in 1957, along with stone artefacts of the Mousterian tradition. As this tradition is firmly associated with Neanderthals in Europe, the 34,500-year-old jawbone was assumed to be Neanderthal. Mitochondrial DNA extracted from the jawbone confirms it to be Neanderthal. However, the Mezzena lower jawbone shows a number of modern features, including an incipient chin, which contrasts with the chinless jaws of ‘classic’ Neanderthals. The authors of the report claim that these features demonstrate hybridisation between Neanderthals and modern humans (Condemi, et al., 2013).

It is possible that the interbreeding occurred with a modern population thought to have been living at the nearby site of Grotta di Fumane (Longo, et al., 2012).

References:

1. Duarte, C. et al., The Early Upper Paleolithic Human Skeleton from the Abrigo do Lagar Velho (Portugal) and Modern Human Emergence in Iberia. PNAS 96, 7604–7609 (1999).

2. Tattersall, I. & Schwartz, J., Hominids and hybrids: The place of Neanderthals in human evolution. PNAS 96, 7117–7119 (1999).

3. Condemi, S. et al., Possible Interbreeding in Late Italian Neanderthals? New Data from the Mezzena Jaw (Monti Lessini, Verona, Italy). PLoS One 8 (3) (2013).

4. Longo, L. et al., Did Neandertals and anatomically modern humans coexist in northern Italy during the late MIS 3? Quaternary International 259, 102–112 (2012).