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Discovery -

Scientists discovered evidence of a "ghost population" of ancient humans that lived in Africa about 43,000 years ago.

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DNA -

Modern humans still carry the genes of this population to this day.

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Ghost population -

A ghost population is a population whose existence has been estimated through statistical techniques. 

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Who were they? -

The hypothesis is based on DNA analysis and statistics, as there is no fossil evidence.

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How scientists uncovered the evidence -

Scientists analyzed genomes from West African populations.

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Ghost population - They couldn't trace 2% to 19% of their genetic ancestry to a known population of early humans.

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Sample -

Scientists analyzed 405 genomes from four West African populations. 

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DNA -

Scientists found links to the Mende people of Sierra Leone.

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DNA -

They also found links to the Yoruba from Nigeria.

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DNA -

And an ethnic group of south Nigeria, the Esan.

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DNA -

Finally, there were also links to western areas of The Gambia.

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We didn't evolve in a linear fashion -

We did not evolve in a straight timeline fashion. Various species shared the same time and space.

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We didn't evolve in a linear fashion -

So it makes more sense to perhaps think of our evolution as a family tree.

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Interbreeding -

For many years, our planet was home to different species and subspecies of humans. 

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Interbreeding -

This means that interbreeding occurred between these various species and subspecies of archaic humans, leading to a mix of genes. 

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Denisovans -

The scientists compared the genes with the Denisovans, a population who lived at the same time as the Neanderthals in Asia.

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Denisovans -

This subspecies of early humans, only known through DNA, mated with Oceanic populations.

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Neanderthals -

Scientists also compared the genes with the ones from Neanderthals, our closest extinct human relatives, who lived about 400,000 to 40,000 years ago.

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Neanderthals -

Neanderthals are believed to have mated with ancient Europeans. 

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Extinction -

As the Guardian reports, it is estimated that this "ghost population" split from the ancestors of Neanderthals and modern humans between 360,000 and 1 million years ago.

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Who were they? -

Scientists estimate that the group had probably around 20,000 individuals.  

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Who were they? -

These then bred with the ancestors of modern West Africans, sometime in the past 124,000 years.

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Unknown species -

It is possible that there are still other unknown archaic human species.

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Exciting times -

John Hawks, an anthropologist at the University of Wisconsin-Madison, said: "We do not know what this African population may have been. It is tempting to speculate. But I've got to say it is just too soon to know."

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See also -

Fascinating ice discoveries frozen in time

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