During the turn for the century that is 20th biologist Nettie Stevens ended up being driven to resolve a clinical secret which had perplexed mankind for millennia. The secret ended up being therefore easy but daunting: Why do men be girls and boys become girls? Inside her pioneering work on Bryn Mawr university, Stevens — whoever birthday celebration is today, July 2 — found the intercourse chromosomes that produce the distinction.
Before Stevens, we had been utterly clueless exactly how embryos become men or girls
Because of Stevens’s work — additionally the work that built upon it — we currently understand that sex is hereditary, and therefore dads’ sperm in particular determine the sex of offspring.
But also for almost all of history, this question had been an absolute secret — plus it yielded some interesting theories.
Aristotle believed a child’s intercourse was dependant on your body heat regarding the daddy during intercourse. “Aristotle counseled men that are elderly conceive in the summertime when they desired to have male heirs, ” the textbook Developmental Biology describes.
In 19th-century European countries, it absolutely was commonly thought that nourishment had been the answer to intercourse determinant. Poor nutrition resulted in men, good nourishment to females.
And through the entire centuries, other theories that are gonzo.
The 18th-century anatomist that is french Procope-Couteau (the writer associated with Art of Having males) thought that testicles and ovaries were either man or woman. prettybrides.net/latin-brides
Procope-Couteau “suggested the easiest way to regulate a child’s intercourse is always to eliminate the testes or ovary connected with the undesirable intercourse; though a less extreme mean for ladies should be to lie in the proper part, and let gravity perform some rest, ” according to The development of Intercourse Determination, a guide by biologists Leo W. Continue reading “Nettie Stevens discovered XY intercourse chromosomes. She don’t get credit because she had two X’s.”