There’s a whole field of study in the evolutionary development of the body and what it signals.
Women, for example are softer and less muscular (except Turkey?) as well as less facial hair. This signals the proper balance of estrogen vs. testosterone that indicates the female has the correct balance of hormonse to be fertile.
Women also are “rounder” (“except in that dress dear, honest”) to indicate they have the overall layer of fat necessary to feed a baby for 9 months, even if the roots and berries crop fails.
These also make a woman appear younger and more child-like so that they signal “still a lot of child bearing years left”. It’s an attractor. It says “pick me for your trophy wife, you alpha male!”
One theory says that this is what blonde is too. Many children are much fairer haired when young, getting darker with age. Blonde appears to be a mutation where the darkening did not happen; it has the bonus of making the woman appear to be a youngster.
To balance the “young” there are signals that the woman is mature enough to be fertile. Wide hips indicate the pelvis can pass a baby’s skull, somewhat useful in the days before c-sections. The ratio of leg length to torso length is another. Women have longer legs. there’s an interesting essay on the “transformation” scenes in Sailor Moon, one major feature (which many adolescent males miss, concentrating on other things) is that the super-hero legs are significantly longer.
Breasts -duh! - are another maturity indicator, which have child-rearing advantages.
I suspect pubic hair is one of these indicators, as well as, like Cecil suggests, doing duty as a fluffy air-freshener in the days before pine-scented cardboard tree outlines. Like eyebrows and armpit hair, it also probably sops up sweat to prevent dripping that could annoy and cause chafing in sensitive areas.
BTW, there is an area of India where body hair is another one of these “maturity” indicators locally. Women from there have noticeable thin but long sideburns and arm hair (I’ve only seen a few, and I have no idea what their covered parts are like - if their arms are any indication, they probably go through a razor every day shaving their legs.)
I read some article once on maturity and visual indicators; it pointed out that typically men are reproductively capable before they display significant obvious outer signs like size and beards. This means they can get some breeding done before other males consider them rivals (we wish!) with all the head-butting male rivalry that ensues. Women, on the other had, tend to develop the signals before they are fertile, in order to already have a mate around and supplying protection and gazelle meat when reproduction starts happening.