European women with this gene have fewer miscarriages and more children.

We have known for years that modern humans and Neanderthals lived side by side for quite some time. And sometimes it clicked so well between the two types that they shared the sheets. The consequences of this can still be found in our genome. There are, to this day, gene variants that we have inherited from the Neanderthals.

Position
For many of these genes, it is not yet known exactly how they affect the functioning of our body. But researchers are busy figuring that out. Many of the genes – since they have been passed down from generation to generation for tens of thousands of years in a row – are thought to have a positive effect in either left or right direction. But how exactly is that? In many cases, this is not yet easy to determine.

Yet it is researchers of it Max Planck Institute for Evolutionary Anthropology and the Karolinska Institute now succeeded in determining the function of one such Neanderthal gene variant very accurately. And the gene variant in question appears to have a positive effect on the fertility of the woman. That can be read in the magazine Molecular Biology and Evolution.

The research
The researchers studied the genomes and personal data of more than 450,000 people, including 244,000 women living in Europe. As many as one in three women appeared to have the relevant gene variant of Neanderthals.

Receptors
“People with this variant have more progesterone receptors,” explains researcher Hugo Zeberg Scientias.nl from. Progesterone is a sex hormone that plays an important role in the menstrual cycle and pregnancy. “It prepares the uterus for implantation of the fertilized egg and its concentration increases significantly after ovulation,” says Zeberg. Because women with the Neanderthal gene variant have more progesterone receptors, they are more sensitive to this hormone. And so this Neanderthal gene positively influences female fertility. “Progesterone protects against miscarriages and bleeding in early pregnancy.” Indeed, the women who possessed this gene variant appeared to bleed less often at the beginning of their pregnancies. They also had fewer miscarriages and generally had more children.

Frequent
What is particularly surprising, according to Zeberg, is that as many as one in three women turned out to have the Neanderthal gene variant in question. “That is quite a lot. Normally, you see that Neanderthal gene variants only occur in 1 to 2 percent of the population. ” The fact that so many women have this gene variant can probably be traced to the positive effect that the variant has on fertility.

According to Zeberg, research into the effect that Neanderthal genes have on us modern humans is very important. “We learn more about our evolution and what it means to be human. In the meantime, it is also a lot of fun to do. ” For now, the study by Zeberg and colleagues at least endorses what had been suspected for some time. “Namely that at least part of the legacy of our interaction with the Neanderthals has a beneficial effect.”