any other female of any animal species with breasts doesn’t really ‘develop’ them unless they’re pregnant so why do human women develop breasts at puberty, just for them to develop even more during pregnancy?
In: Biology
I may be way off base here but Id like to share my thoughts on this, maybe someone can speak to the validity of what I’ve always believed:
The human body was never intended to feed on milk from other species, i.e. the cow. When a cow gives birth, she is able to produce milk because Hormones in her body tell her to produce it, as well as telling her udders to prepare her to “dispense” it. Hormones in cows milk, mostly resulting in added hormones that cows are given to produce more milk, get passed along to those that drink it and effect the human body in a way that increases certain hormones in a human female’s body to do basically the same thing, preparing the girl’s “udders” for milk delivery, causing growth in the human breast. I believe it happens at puberty because that is the time when the human female is experiencing the physical changes to prepare her body to bear children. (again I have no idea if I’m right about this) I also believe that the female human body goes through more physical changes than most other species. I don’t see it very much these days, but about 10 years ago it seemed like girls were developing in the chest at younger ages regardless of puberty, this was a period of time when the added hormones were being fed to dairy cows, as well as other food sources, was at its peak. People started protesting and speaking out against our food sources being fed growth hormones as well as other GMO’s, the trends slowed down quite a bit and it seems as though the younger development of breasts has also trended away. To sum up my theory, I believe it has a lot to do with the combination of drinking cows milk, combined with the changes a girl’s body is going through during puberty.
Sexual dimorphism. The sexes being different from each other. It’s to help members of the species identify who to have sex with. They exist to look sexy.
When species don’t have anything else to compete with externally; they’re fed and safe, they start competing with each other to decide who gets to mate. Some birds and spiders dance, some build fancy nests, “mating rituals”. Typically it’s hard things to do that sickly members of the species fail at. In humans, it’s fat. Breast tissue is fatty material and excess calories were hard to come by for a long time. Fat people are wealthy when food is scarce.
Things like breast size is a secondary sex characteristic which develop during puberty. The belief is that humans evolved to develop breasts due to sexual selection which gives females an advantage over rivals in courtship.
Most of these answers are… unsatisfactory, so I’ll try my best. And just so you know, the science isn’t exactly conclusive either. It is also interesting to note that the pressures discussed below can also explain concealed ovulation.
So, once upon a time, women developed breasts during pregnancy and lost them after the youngens were weaned. Essentially, breasts were around at the same times a women was barren. Not a turn-on at all.
But, humans are a little more complicated than that. Humans are clever, and social, so sex required negotiation. It required relationships. As it happens, sex is also fun. So, men would have sex with infertile women in order to bond with them, and gain an advantage in the contest for her body once she was fertile again.
Then, of course, in evolution, there is the variation. The mutation. A woman with, if not permanent breasts, them breasts that stayed on for a little while longer, even into her fertility…
This woman had power. She would still have sex, sure, and as men didn’t know when she was fertile, she could take selection of her mate a little further into her own hands.
As such, she had an advantage in the contest to produce the best babies (as women’s bodies limit are the limiting factor in population growth, women themselves must focus on best babies, rather than mist babies). And such advantages are… advantageous. She would have had an edge over her sisters, and over time, her kind would predominate.
And in response, men too had to change. As a man turned off by breasts would now have a disadvantage in the male pursuit of ‘most babies’, the variation associated with attraction to breasts would have become more common.
And, as breasts became an established feature of female humanity, they would be under selective pressures themselves; larger breasts displayed good nutrition, and more importantly, the larger breasts would better show a woman’s symmetry (or lack thereof). So, breasts became larger. In different cultures, different tastes would emerge, and so sexual selection would bring above the large racial variation in breast shape, as well as in facial structure, colouration, etc.
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