Neanderthal-Human Breeding Was Hard, But Yielded Benefits

Hairiness -- allowing adaptation to warmer environments -- was among gains

Roughly 500,000 year ago, the breeding populations that would evolve into humans (Homo sapiens) and Neanderthals (Homo neanderthalensis) separated. Neanderthals came to dominate the mountainous, forest terrain of Europe, while humans spread out across the warm grasslands of Africa and the Middle East. But the long estranged relatives would come into contact in an intimate way once more when mankind thrust its way into Europe roughly 80,000 years ago. And by intimate, yes, we mean there was sex. I. Understanding Our Shared Family Secret -- Neanderthal Sex Ever since researcher and entrepreneur J. Craig Venter, Ph.D. became the first human to have his or her genome sequenced in 2007, the race was on to sequence the Neanderthal genome and find what secrets it might hold. Led by led by the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and its top ancient-DNA expert, Svante Pbo, the project yielded a draft genome in May 2010, followed by a "finished" Neanderthal genome in March 2013. With the initial 2010 announcement, definitive proof of our ancestors' steamy romance with European Neanderthals was laid bare for the first time. Today researchers are still worker to chronicle that mysterious engagement and what impacts it has on modern human genetics. Harvard Medical School (HMS) geneticist Professor David Reich's lab -- working with collaborators at the Max Planck Institute -- is the latest to offer new insight into this relationship.

It suggests the introduction of some of these Neanderthal mutations was harmful to the ancestors of non-Africans and that these mutations were later removed by the action of natural selection.

Now that we can estimate the probability that a particular genetic variant arose from Neanderthals, we can begin to understand how that inherited DNA affects us. We may also learn more about what Neanderthals themselves were like. [The barren DNA stretches] suggest that when ancient humans met and mixed with Neanderthals, the two species were at the edge of biological incompatibility. It is fascinating that these types of problems could arise over that short a time scale.

The researchers next goals include making tests for the Neanderthal genes identified available to the public, enhancing the hunt for Neanderthal genomes by sequencing other Neanderthals' full gene sequences, and sequencing the DNA of Denisovans (Denisova hominins) -- another close relative of man that bread with early humans in Oceania.

The ongoing research is funded by the Max Planck Institute, the Howard Hughes Medical Institute (HHMI), the National Science Foundation, and the National Institutes of Health (NIH).

Sources: Nature, Science, Harvard Medical School

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Neanderthal-Human Breeding Was Hard, But Yielded Benefits