November 12, 2012

Dynamics of genetic and morphological variability within Neandertals (Hawks 2012)

A useful quote:
A problematic aspect of the idea of Levantine  Neandertals is that the very features that distinguish them from European Neandertals tend to  align them with modern humans. For example,  the Amud skeleton has stature and limb proportions that set it apart from European Neandertals,  but that fall within the range of variability of the  Skhul and Qafzeh skeletal remains. Trinkaus  (1995) considered the Near East, including  Shanidar and the Levantine samples, to include  two forms of hominins: “late archaic” and “modern” forms. He argued that the late archaic forms  in the Near East have no close connection to  European Neandertals, and that similar features  reflect mosaicism or generalized archaic morphology in both evolving populations 

Journal of Anthropological Sciences Vol. 90 (2012), pp. 1-17

Dynamics of genetic and morphological variability within Neandertals

John Hawks

Summary - Paleogenomics may suggest changes to the way anthropologists have discussed the dynamics and morphological diversity among Neandertals. Genetic comparisons show that later Neandertals had relatively low autosomal genetic variation compared to recent humans. The known mitochondrial sample from Neandertals covers a broader geographic and temporal range, and shows greater diversity. This review addresses how genetic data compare to morphological and archaeological evidence about Neandertal variation and dynamics. Traditional views emphasized the morphological differences between western and eastern Neandertal populations, and between early and later Neandertals. Genomes broadly support these groupings, without resolving the outstanding question of the affinities of specimens from southwest Asia. However, the pattern of genetic variation appears to reject a long, in situ transformation of Neandertal groups over time, suggesting instead a more rapid process of regional dispersal and partial population replacement. Archaeological indicators sample dynamics on a much finer timescale than morphological or genetic evidence, and point to dispersal and turnover among Neandertals on a regional scale. In this way, genetic evidence may provide a bridge between the timescales relevant to morphological and archaeological comparisons. New ways of looking at the morphology of Neandertals may yield a better picture of their interactions and movements.

Link (pdf)

2 comments:

terryt said...

"A problematic aspect of the idea of Levantine Neandertals is that the very features that distinguish them from European Neandertals tend to align them with modern humans".

To me that has always screamed out 'hybrids'. However I'm pleased to see that it is finally becoming widely accepted.

"Traditional views emphasized the morphological differences between western and eastern Neandertal populations, and between early and later Neandertals. Genomes broadly support these groupings"

I would be absolutely stunned if it had been shown that Neanderthals did not vary through space and time. Virtually every other species does so. However inbreeding can eliminate variation to a great extent so that if an inbred population is able to survive for any great length of time it will not vary very much over time or space.

eurologist said...

A problematic aspect of the idea of Levantine Neandertals is that the very features that distinguish them from European Neandertals tend to align them with modern humans.

Hawks, for whatever reason, pretty much denies the existence of a heidelbergensis grouping - despite decades of research validating it, in the 800,000 to 300,000 ya time frame in Europe, the Levant, and Africa, and with later non-Neanderthal descendants in Africa and West Asia.

Early eastern (Levantine and surroundings) humans were decidedly more heidelbergensis-like for much longer than Europeans, who started transforming into Neanderthals starting some time <300,000ya with completion ~150,000ya. That is, towards the east, the original and less specialized heidelbergensis features were preserved until a very late expansion of more typical Neanderthals just 10,000 years or so before culturally (not just anatomically) modern humans swept the region.

In other words, any similarities between (perhaps wrongly categorized) "Neanderthals" and modern humans in the Levant should first be grounded on the fact that for ~500,000 this region saw heidelbergensis-like people of European, SW Asian, and African descent intermingling while forming AMHs. Admixture with later arriving Neanderthals is a secondary, and lesser aspect.