Human history according to pop science mags, is a history in which stronger groups made weaker groups extinct. That is the reason a gulf appears gulf between humans and other primates. Darwin said it would be so, which not only made the idea canonical, it set off a search for missing links, sometimes with tragic consequences.
Recent evidence that early human groups intermingled/married has meant that Neanderthal man can’t really play that role with anything like the gusto he formerly displayed.* Recent stories from The Scientist and Nature give the sense of it:
From The Scientist
Modern humans of European descent have a lot in common with their Neanderthal ancestors when it comes to genes related to fat breakdown in the brain. A team led by investigators from the Chinese Academy of Sciences in Shanghai has found that people of European descent have three times the number of Neanderthal-like sequences in such genes compared to other modern human populations examined. The results, published today (April 1) in Nature Communications, point to how studying ancestral sequences could help researchers better understand modern humans.
So now it is just accepted that Neanderthals are some of our ancestors.
The rest of the story is, of course, uncertain; “the biogeography is fuzzy,” and we don’t know for sure that the sequences are exclusively and explicitly from Neanderthals, nor do we even know why certain gene sequences are conserved, despite the title claim that they confer an evolutionary advantage. It is circular reasoning to claim that certain gene sequences “must have conferred” an evolutionary advantage if they were conserved. They could in fact have been conserved, like old coins found in a wall, without conferring any advantage.
Similarly, a Nature News feature informs us, complete with portrait, about the Neanderthal in the family,* thanks to a boom in “ancient genomics.”
One would wish that ancient genomics were not so dependent on ghosts:
Ghost populations also lurk in ancient DNA. While analysing high-quality genomes of a Neanderthal and a Denisovan, a team led by Reich and Montgomery Slatkin at the University of California, Berkeley, noticed a peculiar pattern: present-day sub-Saharan Africans are more closely related to Neanderthals than they are to Denisovans4. But evidence from other ancient genomes suggested that the two archaic groups were equally related to present-day Africans. After weighing the possibilities, the scientists realized that they might have uncovered another ghost population.
The puzzle could be solved, they theorized, if Denisovans had interbred with a species that had left Africa perhaps more than 1 million years ago and branched off from the common ancestor of humans, Neanderthals and Denisovans. Subsequent Denisovans would have inherited DNA sequences that present-day Africans lack, explaining why Neanderthals seem to be closer kin to Africans.
Reich’s team is analysing genetic signatures in humans with Denisovan DNA to establish when the Denisovans mated with this mystery population — information that could narrow the range of fossils to which it might belong. Genomes studied by Pääbo’s lab, principally the Sima de los Huesos remains, may also reveal clues.
We are warned that ghost populations should be “handled with care.” A more traditional approach to science did not address ghosts at all.
While we are here, I’ll shortly be starting a series on human evolution over at Evolution News & Views on human evolution, including Neanderthals. I’ll be examining the evidence (real and imagined) gathered over the last decade, for a fully natural origin of the human race. Stay tuned. – O’Leary for News
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