See me I switch up hoopties
Women have breasts, whereas men have flat chests (but still with nipples on them). Why?
Women are the only primates who are busty all the time, even when they aren’t nursing. Alternative theories exist, but most scientists think breasts are an evolutionary trick for snagging men; though they’re actually filled with fat, not milk, they signal a woman’s bountiful ability to feed her children.
Breasts also help men figure out who to pursue to achieve reproductive success. Prepubescent girls don’t have breasts, and the breasts of post-menopausal women are often shrunken and saggy. A full, buoyant bosom can therefore demonstrate fertility.
Men aren’t trying to trick women into thinking they can breastfeed, so they don’t have breasts. They do, however, have nipples: This is because the genes that code for nipple development switch on in utero, and at a very early embryonic stage — even before the genes gear up that turn us into males or females. (…)
Whatever your sex, everyone starts off as a woman in the womb. For the first several weeks a developing embryo follows a “female blueprint,” from reproductive organs to nipples. Only after about 60 days does the hormone testosterone kick in (for those of us with a Y chromosome), changing the genetic activity of cells in the genitals and brain. But by then those mammary papillae aren’t going anywhere.
{ Men vs. Women: Key Physical Differences Explained | Continue reading }
