New Data on Neanderthal Genes

The Nobel Prize in Medicine was given to the men who figured out the Neanderthal genome. Not sure what that work had to do with medicine, but it was presumably good scientific work. Now the team has a new paper on the subject:

Modern human ancestors diverged from the ancestors of Neandertals and Denisovans about 600,000 years ago. Until about 40,000 years ago, these three groups existed in parallel, occasionally met, and exchanged genes. A critical question is why modern humans, and not the other two groups, survived, became numerous, and developed complex cultures.

This is very confusing. What are "modern human ancestors"? The ancestors of modern humans? If so, then Neanderthals and Denisovans are also ancestors. All three groups are ancestors to today's non-African humans.

It is not really true that one of those three groups "survived, became numerous, and developed complex cultures." None of the three succeeded. Only hybrids, mixtures of all three groups, succeeded.

There are sub-saharan Africans today without the Neanderthal and Denisovan genes, but they did not spread throughout the Earth or develop complex cultures.

Comparisons of genomes from the three forms of human show that they exchanged genes several times when they met outside of Africa (Figure 1). Neandertals received gene flow from groups related to the ancestors of modern humans more than 100,000 years ago.10,11,12 In addition, Neandertals and Denisovans exchanged genes5; for example, about 80,000–90,000 years ago in southern Siberia, an individual who had a Neandertal mother and a Denisovan father has been identified.13 When modern humans started spreading out of Africa and the Near East less than 100,000 years ago, they mixed with Neandertals14 and Denisovans.9 As a result, all people who have genetic roots outside of Africa south of the Sahara carry genetic variants that come from Neandertals.15 Ancestors of people in Asia also mixed with Denisovans,9,16 and people of Asian ancestry therefore carry Denisovan variants in addition to Neandertal variants. This genetic contribution from Denisovans is particularly large in some populations in Oceania.16,17

They are still trying to figure out the significance of these genes. A speciesization expert says:

Although human paleobiologists, who love to identify new species, call the Denisovans and Neanderthals species different from modern humans (i.e, different from “Homo sapiens“), I’m stubborn and consider all three groups members of the same biological species. That’s because there’s evidence of gene flow among all the groups: from Neanderthals and Denisovans to modern humans, from modern humans to Neanderthals, and even from Denisovans to Neanderthals and vice versa. Because these archaic genes persist in modern humans, the hybrids between the lineages must have been fertile to allow such backcrossing. Since we have populations who lived at least partly in the same area and produced fertile hybrids, they can be considered biological species, though perhaps biological species in statu nascendi.

Okay, so Neanderthals, Denosivams, and sub-saharans hominin existed as three groups of one human species 100,000 years ago. The Neanderthals had brow ridges that no one has today. We do not know what Denisovans looked like. The sub-saharans probably looked like today's sub-saharan Africans, but not much like other racial groups. All three looked strange to today's Caucasians and Orientals.

Some of these interbred to form hybrids that took over the Earth. All three groups should be considered humans, but it is not clear that any one group was more human than the others. Only the hybrids scaled ujp to large and complex cultures. The paper concludes:

We propose that the genetic basis of what constitutes a modern human is best thought of as a combination of genetic features, where perhaps none of them is present in each and every present-day individual.

This seems right to me. The modern human is not defined by those sub-saharan Africans, as most writers on this subject seem to assume.

There appears to be an ideological push to convince everyone that humanity began in sub-saharan Africa, and not in Europe. They say humanity emerged when African "modern humans" outcompeted the more primitive European Neanderthals. Then these new humans invented farming and civilization, and spread to all the world.

I am just reporting the scientific facts. Modern humanity was formed when competing groups interbred, and produced a small group of hybrids that grew to create civilizations.

You could say that we got more genes from the Africans than the Neanderthals and Denisovans, and lost the brow ridge genes that made Neanderthals visually distinctive.

While this new research has identified some genes, we don't know the importance. We do know that Neanderthals, Denisovans, and sub-saharan Africans did not create complex civilizations. Only the hybrids did.