The origin of mammals

A recent study by researchers of the Yale University, published in Nature Genetics, led to the conclusion that the function that the uterus plays in the reproduction of mammals evolved from the insertion into the genome of early mammals of some transposons.

Transposons are sequences of DNA that can move to new positions in the Genome of a cell, through the action of enzymes encoded by the transposons themselves. This particular kind of genetic material has several similarities with viruses, and in fact they are thought to be descended from them. For this reason they are often compared to parasites, which can enter and multiply within the genome.

The researchers analyzed and compared the genetic heritage of the endometrial cells of humans and opossums placenta. They discovered 1532 genes expressed only in placental mammal's uterus, whose expression is regulated by transposons. This discovery, as stated by one of the authors of the article, Gunter Wagner, also contributes to a better understanding of evolution, which is often thought to be based only on mutations of small stretches of DNA.