In the change for the twentieth century, biologist Nettie Stevens ended up being driven to resolve a medical secret which had perplexed humanity for millennia. The secret ended up being therefore easy but daunting: Why do men be girls and boys become girls? In her own 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 guys or girls
Compliment of Stevens’s work — plus the work that built we now know that sex is hereditary, and that dads’ sperm in particular determine the sex of offspring upon it.
However for the majority of history, this concern had been an absolute mystery — also it yielded some interesting theories.
Aristotle believed a child’s intercourse had been dependant on your body heat associated with daddy during intercourse. “Aristotle counseled senior guys to conceive into the summer time should they wanted to have male heirs, ” the textbook Developmental Biology describes. Continue reading