How HUMAN got pregnant

Yale researchers have shown that the origin and evolution of the placenta and uterus in mammals is associated with evolutionary changes in a single regulatory protein, according to a report in Proceedings of the National Academy of Sciences.

Pregnancy is a biologically unusual situation where one organism lives and develops inside another that is genetically different. Ordinarily, the immune system identifies and destroys the dissimilar tissue as if it were a parasite. But in some early mammals, changes 'turned down' the immune system, allowing the developing embryo to grow and thrive unchallenged by the maternal immune response.

"New functions arise by using an existing tool from the gene regulatory 'toolbox' in a new or different place.

According to Yale graduate student Vincent Lynch, lead author of the study, "We are writing a different chapter. In this case the function of a major regulatory tool was altered — it is like we found a redesigned hammer."

Storyteller: Vincent Lynch, Yale graduate student

Source:Redesigned hammer that forged evolution of pregnancy in mammals found