Modern humans share a common ancestor with Neanderthals, the extinct species that were our closest prehistoric relatives. However, the details on when and how they diverged are a matter of intense debate within the anthropological community.
Ancient DNA analyses have generally indicated that both lineages diverged around 300,000 to 500,000 years ago, which has strongly influenced the interpretation of the hominin fossil record.
This divergence time, however, is not compatible with the anatomical and genetic Neanderthal similarities observed in the hominins from Sima de los Huesos. The Sima fossils are considered likely Neanderthal ancestors based on both anatomical features and DNA analysis.
Dr Gomez-Robles said: “Sima de los Huesos hominins are characterised by very small posterior teeth (premolars and molars) that show multiple similarities with classic Neanderthals. It is likely that the small and Neanderthal-looking teeth of these hominins evolved from the larger and more primitive teeth present in the last common ancestor of Neanderthals and modern humans.”
Dental shape has evolved at very similar rates across all hominin species, including those with very expanded and very reduced teeth. This new study examined the time at which Neanderthals and modern humans should have diverged to make the evolutionary rate of the early Neanderthals from Sima de los Huesos similar to those observed in other hominins. Paper. (open access) – Aida Gómez-Robles. Dental evolutionary rates and its implications for the Neanderthal–modern human divergence. Science Advances, 2019; 5 (5): eaaw1268 DOI: 10.1126/sciadv.aaw1268 More.
Well, this paper is likely to add fuel to the “intense debate”:
Although this study presents compelling evidence, experts may disagree. “I just don’t see the argument that dental rates of evolution are absolutely known to the point where we can then say that for certain the Neanderthal-modern human divergence must have been earlier than 800,000 years ago,” says Rick Potts of the Smithsonian Institution to Smithsonian.Chia-Yi Hou, “Neanderthals and Modern Humans Diverged Earlier than Thought: Study” at The Scientist
If Neanderthals “diverged” from “modern humans” 800,000 years ago but many of us have Neanderthal genes (yeah, 23andMe stuff, for sure), what chance is there that much of the contention is based on the fact that we don’t really know enough to be sure of very many things?
What, really, do claims about speciation contribute?
See also: Researchers: Sediba is not a human ancestor after all. Back to Lucy, but… The anthropologist is right, the fossil record IS full of surprises. But the news that Lucy is only “the best candidate” is worth some reflection. It sounds like we have little to go on and Lucy is at best plausible.
A physicist looks at biology’s problem of “speciation” in humans
Follow UD News at Twitter!