Human pregnancy is weird – new research adds to the mystery

This shows a pregnant womanStudy reveals the progesterone receptor gene evolved rapidly in humans, but there is no evidence to support this happened because the changes were advantageous to our species. Researchers report the evolutionary force of selection was so weak that the gene accumulated harmful mutations as it evolved in humans. Progesterone receptor genes are vital during pregnancy as it supplies developing cells the ability to create progesterone receptors.