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Home / Science / Humans and Neanderthals have been breeding – and breeding – for centuries

Humans and Neanderthals have been breeding – and breeding – for centuries



Humans are mosaics today, our genomes are rich in tapestries of interwoven ancestors. With each fossil discovered and each DNA analysis performed, history becomes more complex: we, the only survivors of the genus Homo harbor genetic fragments from other closely related but long-extinct lines. Modern man is the result of a long history of shifts and distractions, separations and reunions – a story characterized by far more variety, movement and mixing than seemed imaginable a decade ago.

Original History Approved by Quanta Magazine An editorially independent publication of The Simons Foundation whose mission is to enhance the understanding of science in the public domain by addressing research developments and trends in mathematics as well as in nature ̵

1; and biosciences are treated the ancestors of modern Europeans, or that the recently discovered Denisovans mingled with an older mystery group or that they all mixed together. It is another matter to give specific details about when and where these pairings occurred. "We have this picture where these events take place everywhere," said Aylwyn Scally, an evolutionary geneticist at the University of Cambridge. "But it's very hard for us to record a specific event and say, yes, we're really confident that it happened – unless we have an old DNA."

You think you are just looking at a Neanderthal man. It is indeed a mixture of Neanderthals and modern humans.
Adam Siepel, Cold Spring Harbor Laboratory

The events that are recorded are therefore usually relatively new and begin with the exodus of modern humans. 60,000 years ago, they met on their way with hominin relatives (like the Neanderthals and Denisovans). Proof of crossing during previous hikes or events that occurred earlier in Africa is difficult to provide.

Now this is starting to change. Partly because of more computing power, "we are seeing the next wave of method development," said Joshua Akey, a professor of genomics at the Lewis Sigler Institute of Integrative Genomics at Princeton University. "And that allows us to draw new conclusions from the data … that the previous generation of methods could not draw."

As scientists look back in time and uncover evolutionary relationships in unprecedented detail, their findings complicate the narrative of human history and rescue some of the previously missing chapters from the darkness. There are indications of the unexpected influence of gene flow from ancient antiquities on the modern human population before it left Africa. Some researchers even identify the genetic contributions that modern humans may have made to these other lineages, in a complete reversal of the usual scientific focus. As confusing and intertwining as these many effects may be, they have all shaped humanity as we know it today.

Old People, New Tricks

When researchers first recovered DNA from Neanderthal bones, the techniques available to understand them were powerful but relatively simple. Scientists compared old and modern sequences, analyzed common sites and mutations, and conducted mass statistical analyzes. In 2010, they discovered that Neanderthal DNA accounts for approximately 2 percent of the genome of people of today's non-African descent, due to a cross between 50,000 and 60,000 years ago across Eurasia. In this way, they also found that the Denisovan DNA in Papua New Guinea and Australia interacted with about three percent of the human genome to account for lost populations, said John Hawks, a paleoanthropologist at the University of Wisconsin, Madison. It also does not allow researchers to test specific hypotheses on how this crossbreed has developed.


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