In recent years, scientists have found evidence that modern humans and Neanderthals share an intertwined genetic past. Over the course of human history, these two hominin species would have interbred not just once, but multiple times.
A new study published in Genetics supports this notion, finding that people in Eurasia today have genetic material linked to Neanderthals from the Altai Mountains in present-day Siberia. This is noteworthy because previous research has shown that Neanderthals connected to a different and distant location – the Vindija Cave in present-day Croatia – have also contributed DNA to populations in present-day Eurasia.
The results reinforce the concept that Neanderthal DNA has intermingled with the modern human genome multiple times, as our ancestors encountered Neanderthals over and over again in different parts of the world.
Not a single introgression of Neanderthal genetic material says lead researcher Omer Gokcumen, a biologist at the University at Buffalo. It's a whole web of interactions happening over and over again, where different ancient hominins are interacting with each other.
We have all these archaic hominid populations in Europe, in Asia, in Siberia, in Africa. For one reason or another, the ancestors of modern humans in Africa begin to expand their population, and as they expand their range, they meet these other hominins and incorporate their DNA Gokumen says. We probably encountered different populations of Neanderthals at different times in our expansion to other parts of the globe.
Scientists analyzed the DNA of hundreds of people of Eurasian descent. The goal was to search for bits of genetic material that might have been inherited from Neanderthals.
The research found that the Eurasian populations studied could trace some genetic material back to two different Neanderthal lineages:one represented by a Neanderthal whose remains were discovered in the Vindija cave in Croatia, and another represented by a Neanderthal whose remains were discovered in the caves. Altai mountains in Russia.
The scientists also discovered that the modern populations they studied also share genetic deletions – areas of DNA that are missing – with the Vindija and Altai Neanderthal lineages.
The DNA of the Vindija and Altai Neanderthals, along with the modern human populations studied, were previously sequenced by different research teams.
It seems that the history of human evolution is not so much like that of a tree with branches that only grow in different directions. Turns out the branches have all these connections between them , says Gokcumen.
We're discovering these connections, which is really exciting. The story is not as clear as it once was. Every ancient genome that is sequenced seems to create a whole new perspective on our understanding of human evolution, and every new genome that is sequenced in the future may completely change history all over again.