Im trying to figure out what happened in China 35,000 years ago to cause the "people" living there to develop a mutation in the common gene, EDAR, leading to thicker hair, more sweat glands and smaller breasts.

Source:
https://www.nytimes.com/2013/02/15/science/studying-recent-human-evolution-at-the-genetic-level.html

The changes in hair and sweat glands can be directly related to climate changes. But smaller breast? What purpose does that serve?

Smaller breast don't affect milk production but they do inhibit how much milk breast can hold. In other words, smaller breasted women have to feed their children more often compared to larger breasted women.

Breast feeding more often can lead to nipple destruction:

https://www.insider.com/woman-on-tiktok-says-her-nipple-fell-off-while-breastfeeding-2023-3

Hence the need for things like milk pumps and nipple guards. No nipple means inability to feed children.

Given these facts it seems safe to say, large breast are better in the long term, so why would this common EDAR gene just mutate itself and start giving everyone mosquito bites instead of normal sized breast? What evolutionary need could they have served? It's almost as if the mutation was like "let your babies starve"............

Discuss