A new method that use DNA to peer into the history of humanity is rewriting what experts know about the Neanderthals, US researchers said Monday.
Previous research has shown that near the end of their existence some 40,000 years ago, only about 1,000 Neanderthals were left on Earth.
However, a new study shows that their population was far larger – likely numbering in the tens of thousands -across Europe, said the report in the Proceedings of the National Academy of Sciences.
The genetic clues used in the experiment include Neanderthal DNA that contains mutations that usually occur in small populations with little genetic diversity.
Using a new method to analyze DNA sequence data, researchers also found that Neanderthals split from another mysterious lineage, known as the Denisovans, about 744,000 years ago, much earlier than any other estimation of the split.
After that, the global Neanderthal population grew by tens of thousands.
Very little is known about the Denisovans, sometimes described as the Eastern cousins of Neanderthals.Only a few pieces of their remains – including some teeth and a pinkie bone – have ever been found.Both Denisovans and Neanderthals mated with the ancestors of modern humans, who emerged from Africa about 60,000 years ago.
The study was based on comparing the genomes of four human populations: Modern Eurasians, modern Africans, Neanderthals and Denisovans.
This improved statistical method, called legofit, helped researchers estimate the percentage of Neanderthal genes flowing into modern Eurasian populations – which they confirmed was about two percent.
The method revealed the date at which these ancestral populations diverged from each other, and their population sizes.