1) women are most fertile from 20-25. womens' chance of having unhealthy babies increase as they age. an example is down-syndrom. they chance of a woman having a baby with down-syndrome exponentially increase as she ages after 25.
2) there are many "preferences" that are human universals. there are certain behaviors, that once proven to work well, become common to the entire species and isn't just heriditary. like men's preference for firm breasts is seen in western culture, eastern culture, indigenous people, etc.
there's a book called yanomamo (by napoleon chagnon). they are a one of the last 2 or 3 completely isolated indeginous societies. they're naked people. but if anyone checks it out, on page 69, it mentions that women of higher status wear a vine from around their neck to under their breasts (probably to lift and accentuate them--just my guess).