One in three European women have inherited a gene variant from Neanderthals, leading to increased fertility, a new study suggests.
The receptor for progesterone is a gene variant associated with increased fertility, fewer miscarriages and fewer bleedings during early pregnancy.
The gene variant has been passed down to modern humans from Neanderthals, an extinct species of ancient humans that existed in Ice Age Euroasia between 35,000 and 120,000 years ago. They were characterised by a receding forehead and prominent brow ridge and have become widely known as cavemen in popular culture.
The findings were discovered by researchers at the Max Planck Institute for Evolutionary Anthropology in Germany and Karolinska Institutet in Sweden. The study was published on May 21 in the Molecular Biology and Evolution journal.
"The progesterone receptor is an example of how favourable genetic variants that were introduced into modern humans by mixing with Neanderthals can have effects in people living today," Hugo Zeberg, a researcher at the Department of Neuroscience at Karolinska Institutet and the Max Planck Institute for Evolutionary Anthropology, said in a statement.
The hormone progesterone plays a significant role in the menstrual cycle and in pregnancy. The study analysed biobank data from more than 450,000 participants - 244,000 of which were women - which found almost one in three women in Europe have inherited the progesterone receptor from Neanderthals.
Twenty-nine percent carry one copy of the Neanderthal receptor and 3 percent have two copies.
Zeberg said the findings suggest that the Neanderthal variant of the receptor has a positive effect on women's fertility.
Molecular analyses revealed these women produce more progesterone receptors in their cells, which may lead to increased sensitivity to progesterone and protection against early miscarriages and bleeding.
The research was supported by the NOMIS Foundation and the Max Planck Society.