Cobra Effect · Human origins
The Neanderthal inside us
How ancient DNA revealed that many living people carry a little Neanderthal in them.
7 cards, read aloud in 2:49, with a test and sources.
Neanderthals lived across Europe and western Asia for hundreds of thousands of years.
They made stone tools, controlled fire, and buried at least some of their dead. They disappeared around forty thousand years ago. For a long time, nobody knew whether they had ever mixed with modern humans.
A Swedish scientist set out to read DNA from Neanderthal bones.
Svante Pääbo led the work at the Max Planck Institute for Evolutionary Anthropology, in Leipzig. Ancient DNA survives only in tiny broken pieces. It is easily contaminated by DNA from the people handling the bones, so the team worked in extremely clean rooms, in full protective suits.
In 2010, the team published a draft of the Neanderthal genome.
Most of it came from the bones of three Neanderthals found in Vindija Cave, in Croatia. They compared it with the genomes of five people living today, from different parts of the world. Much of it had been read only once or twice, so it was a rough draft.
The comparison held a surprise.
People whose ancestors lived outside Africa carried a small share of Neanderthal DNA. The first estimate was between one and four percent. So modern humans and Neanderthals must have had children together, after modern humans spread out of Africa.
Later, higher quality genomes sharpened the picture.
For people with ancestry outside Africa, the share is now usually put at about two percent. Different people carry different pieces, so much more of the Neanderthal genome survives across humanity as a whole. Studies have since found smaller amounts of Neanderthal DNA in African populations too.
In 2022, the work was awarded the Nobel Prize in Physiology or Medicine.
Svante Pääbo was the sole winner, for discoveries about the genomes of extinct human relatives. His team had also identified another ancient group of humans from DNA alone. Some Neanderthal gene variants that people carry today have been linked to differences in immunity and other traits.
So when two groups are said to be completely separate, ask what the evidence of mixing shows.
Neanderthals were often pictured as a dead end, entirely apart from us. Their DNA showed that our ancestors met them, and had families with them. Traces of those meetings are still carried by billions of people.
Sources
- Ancient DNA and Neanderthals, Smithsonian Human Origins Program. What ancient DNA revealed about Neanderthals and us.
- Neanderthal genome reveals interbreeding with humans, ScienceDaily, 2010. The announcement of the draft genome.
- Neanderthal genome project, Wikipedia. The history of the project and later genomes.
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