A Deeper Introgression Of Ancient Humans and Neanderthals

New ancient DNA discoveries from an ancient 124,000-year-old Neanderthal femur suggests modern human ancestors interbred with Neanderthals between 470,000 and 220,000 years ago. This is much earlier than previously thought. Cosimo Posth at the Max Planck Institute for the Science of Human History led analysis of mitochondrial DNA from an ancient Neanderthal thigh bone discovered 80 years ago in Germany, the Hohlenstein-Stadel femur, discovered in German in 1937. He picked and compared the sequences to Denisovans, and ancient humans with the premise that the more similar the sequences are, the more closely related the specimens.

A Neanderthal thigh bone known as the Hohlenstein-Stadel femur, discovered in German in 1937. Photo by Oleg Kuchar/Museum Ulm
A Neanderthal thigh bone known as the Hohlenstein-Stadel femur, discovered in German in 1937. Photo by Oleg Kuchar/Museum Ulm

We’ve studied DNA from a 130,000-year-old Siberian Neanderthal and found genetic chunks that looked human, but humans didn’t engage in mass migration from Africa, their home turf, to Europe, Neanderthal territory, until 75,000 years ago. Unless that happened earlier, from a small group of archaic humans who left Africa more earlier and interbred with Neanderthals before the big migration of more modern humans which fits with other recent findings that our lineage is possibly older.

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One limitation is that mtDNA is one small piece of the larger genetic puzzle and does not give the resolution that nuclear DNA does to trace deep lineage. The particular sample studied is limited from contamination and nuclear DNA is a mute point.

2 thoughts on “A Deeper Introgression Of Ancient Humans and Neanderthals

  1. The most parsimonious explanation to my eyes is that Sima de los Huesos mtDNA is the actual introgressor from Homo heidelbergensis (aka Denisovans) and not the mainline Neanderthal mtDNA, more related to ours than to Denisovans’.

    Both (mainline) mtDNA and Y-DNA are more closely related between Neanderthal and us than with Denisovans/Heidelbergensis. ONLY the autosomal DNA appears to show that Neanderthals would be closer to Denisovans than to Homo sapiens, but this can be explained via H. heidelbergensis admixture into Neanderthals and vice-versa.

    In other words: to my eyes, proto-Neanderthals were also proto-Sapiens who emigrated from Africa early on and, besides evolving on their own from then on, also admixed heavily with our cousins Homo heidelbergensis (which seems to be the species of Denisovans) but retained the sapiens-related uniparental lineages because that admixture was gradual enough not to cause massive shifts.

    Which is the correct chronology is not something that molecular clock speculations will solve, only archaeology will.

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