Hugo Zeberg, at the Max Planck Institute for Evolutionary Anthropology and the Karolinska Institutet, published an interesting study with colleagues Janet Kelso and Svante Pääbo on Neandertal admixture and its impact on modern day fertility. Diverging from a common human lineage over 600,000 years ago, Neandertals and modern humans began an exchange of genetic material between 47,000 to 65,000 years ago. We now that certain populations, such as Europeans, carry 2.6% Neandertal genes in there genomes. Many implications of this genetic trade haven’t been known to us until now.
Published in Molecular Biology and Evolution this team identified that one in three women in Europe inherited the receptor for progesterone from Neandertals. As you may know progesterone is an important hormone that plays in the menstrual cycle and in pregnancy. They found that inheritance of this ancient allele has associated with increased fertility, fewer bleeds during early pregnancy and ultimately less miscarriages.
They did so by looking at Biobank data over 450,000 individuals. Amongst this database, there were 244,000 women. They found out that one out of three European women have inherited the progesterone receptor from Neandertals. In fact 29% carried one copy and 3% carried two copies of this allele. Furthermore, there has been in interesting selection phenomenon as the proportion of women who inherited this gene is ten times greater than other Neandertal alleles.
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. This suggests the Neandertal progesterone receptor has had a favorable effect on fertility.