Neanderthals and Denisovans find their place in human family tree

New analysis confirms Neanderthal genes in living human populations outside Africa and pins down relationship to the mysterious Denisovans

A woman looks at a model of a Neanderthal man's head.
A woman looks at a model of a Neanderthal man's head.
Ullstein Bild / Getty

If someone calls you “a Neanderthal”, you shouldn’t take offence: there might be some truth in it.

A new genetic study has confirmed the results of earlier research showing that modern Eurasians carry about 2% Neanderthal DNA in their genes.

Population trees with embedded gene trees.
Population trees with embedded gene trees. The branches each gene tree represent four populations: modern Africans, modern Eurasians, Neanderthals, and Denisovans. In the left tree, the mutation (shown in blue) is shared by the Eurasian, Neanderthal and Denisovan genomes. In the right tree, the mutation (shown in red) is shared by the Eurasian and Neanderthal genomes.
Alan Rogers / University of Utah

A team of researchers led by Alan Rogers, of the University of Utah, USA, published their results in the latest edition of the US journal, Proceedings of the National Academy of Sciences.

The scientists compared the gene sequences of four human groups – modern Africans, modern Eurasians, Neanderthals (who died out around 40,000 years ago), and Denisovans, who are known only from a scant fossil record and have long been thought to be close cousins of the Neanderthals.

They found that the Neanderthal lineage separated from that of the mysterious Denisovans about 744,000 years ago. Only 300 generations before that, our own ancestor’s lineage had separated.

The team also calculated a Neanderthal population size in the tens of thousands.

Colin Groves, an emeritus professor in biological anthropology at the Australian National University, in Canberra, who was not involved in the study, said: “This contrasts with the earlier suggestions that the final Neanderthal population was tiny.

“The authors point out that, after all, we have discovered quite a large number of Neanderthal remains, which would have been most unlikely if there had been only a small population.

“They propose, reasonably, that the species was divided into numerous, more or less isolated populations, which only occasionally exchanged mates.”

The research team said it had developed a new statistical method “that accounts for multiple populations in the gene pool”.

Groves said the method could be applied to other animals and plants. “For example, there’s a lot of questions about different species of dolphin known to be close to each other. This method could be applied to that.”

Cheryl Jones is a science writer and co-author of “The Bone Readers: atoms, genes and the politics of Australia’s deep past”, published by Allen & Unwin.
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