Saturday, 25 April 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.

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).

Tuesday, 7 April 2015

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 HuĂ  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.

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