Here we go. If we were going to answer it the same way we’ve long explained the human penis, and other animal penis shapes, then we’ve got a few ideas…
Why is it so big?
veryone’s come across some article somewhere on-line that is thrilled to share how big human penises really are, for primates, and to explain why they evolved to be so big. It’s not really the length, but the girth. Alan Dixson is your go-to on this. He’s conservative in his assessment of the literature on penis size and even he concedes that human penis “circumference is unusual when compared to the penes of other hominoids (apes)”
A favorite explanation for the big phallus is female mate choice, that females selectively make babies with males who have larger and, presumably, more pleasurable semen delivery devices. This is backed up by studies. When life size projections of naked men are shown to female subjects, they say they find the ones with bigger ones to be more attractive.
How the vagina changes in the 20s, 30s and 40s
20's
30's
40's
Male competition
ther explanations include male competition. If you can deliver your package to the front yard but the other guy can deliver to the front door, his is more likely to be carried inside the house first. Or, if he can steal away what you just delivered, then, again, his package has yours beat. Thanks to his big penis he’s more likely to pass on his winning penis genes than you are to pass on your loser penis genes.
The real reason
Childbirth is why the human vagina is so big and, consequently, why the male penis is so big. It’s pretty straightforward. Yet we’re still left scratching our heads as to why the penis question endures.
Sources:
https://evolution-institute.org/blog/why-is-the-human-vagina-so-big/
http://www.womenshealthmag.com/health/vaginal-changes-with-age