快猫短视频

A chunk of Neanderthal DNA carried by some people living today appears to reduce the chance of miscarriage and promote fertility. The finding is the latest evidence that Homo sapiens benefitted from Stone Age sexual encounters with other human species.

Genetic studies suggest anatomically modern humans interbred with Neanderthals on several occasions, and that people of non-African descent carry about 1 to 2 per cent Neanderthal DNA in their cells. For about 10 years we have suspected that some of that Neanderthal DNA proved useful. It might have helped Homo sapiens cope with Eurasian diseases that they hadn鈥檛 encountered during their evolution in Africa, for instance.

But some Neanderthal DNA is probably detrimental to modern humans. In 2018, Jingjing Li at Stanford University and his colleagues found an example. They were studying the PGR gene, which plays a role in pregnancy, and realised a form (or allele) of the gene that increases the chance of premature birth .

The finding puzzled Hugo Zeberg at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. Any harmful Neanderthal DNA that entered the modern human gene pool should have disappeared with time because it left carriers at a competitive disadvantage. But in some modern populations the PGR Neanderthal allele is carried by about 20 per cent of people. 鈥淭he high allele frequency was surprising given the report of a detrimental impact,鈥� says Zeberg.

With his colleagues, Zeberg has found an explanation: the Neanderthal allele is probably beneficial after all. The researchers examined data from the UK Biobank, which includes the genetic and lifestyle information of more than 450,000 people in the UK. They found that women who carry the Neanderthal allele were less likely to have experienced a miscarriage or unexpected bleeding during early pregnancy.

The 2018 result still stands: the Neanderthal allele is also linked with a higher chance of premature birth. But the new study puts that earlier finding in a new light. Zeberg speculates that some of these premature births would have been miscarried if the woman lacked the Neanderthal allele. 鈥淸It] might preserve pregnancies that would otherwise be lost at an early stage,鈥� he says.

鈥淚t鈥檚 great to see other effects from this allele,鈥� says Li. But he cautions against attempts to define a given allele as simply positive or negative. For instance, the PGR Neanderthal allele . 鈥淪o it鈥檚 hard to say whether it鈥檚 beneficial or detrimental,鈥� he says.