File this one under “who knew?” According to a study published in Molecular Biology and Evolution by researchers at the Max Planck Institute for Evolutionary Anthropology in Germany and Karolinska Institutet in Sweden, one in three women in Europe inherited the receptor for progesterone from Neanderthals—a gene variant associated with increased fertility, fewer bleedings during early pregnancy and fewer miscarriages.
“The progesterone receptor is an example of how favorable genetic variants that were introduced into modern humans by mixing with Neanderthals can have effects in people living today,” says Hugo Zeberg, researcher at the Department of Neuroscience at Karolinska Institutet and the Max Planck Institute for Evolutionary Anthropology, who performed the study with colleagues Janet Kelso and Svante Pääbo.
Progesterone is a hormone which plays an important role in the menstrual cycle and in pregnancy. Analyses of biobank data from more than 450,000 participants, among them 244,000 women, show that 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 three percent have two copies.
“The proportion of women who inherited this gene is about ten times greater than for most Neanderthal gene variants,” says Zeberg. “These findings suggest that the Neanderthal variant of the receptor has a favorable effect on fertility.”
The study shows that women who carry the Neanderthal variant of the receptor tend to have fewer bleedings during early pregnancy, fewer miscarriages, and give birth to more children. Molecular analyses revealed that these women produce more progesterone receptors in their cells, which may lead to increased sensitivity to progesterone and protection against early miscarriages and bleeding.