Here is my theory on why women are smaller.

Way back when humans hnted and struggled to survive, woimen were vey often pregnant. This made them need more food, and also made them much weaker contributors to hnting. Thus a lot bigger women (women the same size as men) starved.

Has anyone else heard something similar or something different on why females are smaller on average?

If you don't like a single Frank Ocean song, you have no soul.

If you're curious about it...

I don't think your theory works, for the simple reason that in our closest relatives, chimpanzees and bonobos, the males and females are the same size.

Jared Diamond's  ^*

theory is that it has to do with mating habits. Among mammals, larger male size tends to correlate with inter-male competition for mates, since a bigger dude will have the edge in a shoving match. The larger the discrepancy between male and female size, the larger a "harem" a dominant male can collect.

My friend's theory is that the demands of caring for our exceptionally helpless offspring prevented hominid women from hunting large game, and thus they didn't experience any evolutionary pressure to grow big muscles.

There is no consensus among evolutionary biologists. Almost no fossils representing our ancestors during the time period of divergence from the chimps have been found, so we don't know when our sexual dimorphism began, let alone why.

Stuff what I do.

It's more about sex selection really. Women desire people who are fairly tall while men don't particularly care about height.

Reference

and that's how Equestria was made!

Wikipedia says females are smaller in both species, although not by how much.

...eventually, we will reach a maximum entropy state where nobody has their own socks or underwear, or knows who to ask to get them back.

I've seen plenty of representatives of both species, in zoos. The difference is small enough to be invisible to casual inspection.

Really, if the demands of pregnancy were the culprit, we would expect larger males to be universal among placental mammals, and they aren't. And we would expect the discrepancy to be larger in the more prolific species, but in, for example, mice, there is no size difference between the sexes, or only a negligible one.

Stuff what I do.

My theory was always sexual selection. Being pregnant sucks, and after figuring out how to avoid it (by avoiding sex), only smaller females could be forced. Of course, I'm not a doctor. I suppose societal sexual pressure would help too, the whole "smaller people need less food to live" might help.

Fight smart, not fair.

I agree with Kara's friend's theory, combined with C Banana's:

A hominid woman presumably would want her offspring to have access to meat, because it's pretty nutrient rich. But she cannot hunt when she's pregnant, which means if she tries to hunt herself she won't have enough offspring to give her genes a reasonable chance of survival. So she needs someone who is also interested in the interests of the child to get her child meat, and that would be her mate.

A particularly large or strong mate would have a better chance of successfully getting game, so women who had genes that selected for big strong mates prospered genetically, which meant that big and strong men also prospered genetically.

However, since the woman, as mentioned above, cannot hunt herself, men don't have any incentive to seek particularly big partners. Which means that the average size of women didn't increase (much; big strong men will tend to have big strong women as children, but they're not particularly likely to survive so the pressure isn't as strong.)

So, we are as a species bigger and stronger than chimps, and men are slightly bigger and stronger than women.

I'm convinced that our modern day analogues to ancient scholars are comedians. -0dd1

From Just-So Stories for Undergraduates

... Once 'pon a time, oh Best Beloved, when the world wasn't quite Done and Dusted, and all the men and women lived on safaris and deserts and plains, the men used to go out and hunt the 'scrutiatingly tough buffalo, and frighteningly fast antelope, and the furocious Woolly Mammoth(like your socks, oh Best Beloved), and the women stayed home and watched babies.

One day, one of the women went out('cause she had no son or daughter) and saw some bushes, containing the yummy, gummy pink berries, and icky, licky blue berries. 'course she soon found out how yummy, gummy the pink berries were, and how icky, licky the blue berries were. So she went out and told the chief man that the women could eat the berries, and the men could eat the meat. The men took a while to figure this out, because they weren't All Educated yet(this process is still ongoing, and is known as the White Man's Burden, which is a Very Scientific idea I will tell you of later), but eventually 'cepted it.

And so to this day, women like the color pink.

What's that Best Beloved? You think that this is a pseudo-scientific attempt to justify tired old prejudices?

Is Uncle Rudyard Kipling going to have to cut a bitch?

That's what I thought, Best Beloved.

Kill all math nerds

You know, you can't dismiss all of evolutionary psychology as just-so stories; some of it is quite well founded.

I do admit what we're doing in this thread is making plausible sounding guesses instead of anything with any actual weight. But come on, this is an internet forum, give us a break.

I'm convinced that our modern day analogues to ancient scholars are comedians. -0dd1

I'm just kind of sick of "Evolution is completely non-teleological but we have to view every little thing as adaptational".

Kill all math nerds

Myrmidon, what aren't you sick of?

Except for 4/1/2011. That day lingers in my memory like...metaphor here...I should go.

Vests.

Kill all math nerds

That's fair. I can agree to disagree with you there.

Except for 4/1/2011. That day lingers in my memory like...metaphor here...I should go.

Well, since we evolved, and nothing else but evolved, everything we do must either be an adaptation or a side effect of evolution.

I'm convinced that our modern day analogues to ancient scholars are comedians. -0dd1

@Black Humor:

Ah...you may want to check your numbers. We naked apes may be physically larger than our closest hairy cousins, but they could totally thrash us in a straight-up strength contest. Which would likely consist of, um, them thrashing us. Which is why we don't challenge them. (Why they don't challenge us is a mystery for the ages.)

Stuff what I do.

Because the last time they tried it, we stoned them to death.

Expergiscēre cras, medior quam hodie. (Awaken tomorrow, better than today.)

^^

Guns. Lots of guns.

Before that it was swords.

Or perhaps because the similarities make us lax to fight eachother? I mean I'm sure there are tribes in Africa that eat monkeys, but for the most part neither species has hunted the other in mass, just kept a respectful distance, with the occasional nod.

edited 9th Feb '11 10:11:46 PM by Barkey

Running speed. We're the plains ape.

Fight smart, not fair.

The average male chimp is actually about 150 lbs, which is probably more than a human is likely to weigh on a foraging diet. The degree by which they are stronger than us is frankly staggering. According to the Guiness book of world records (1975 edition,) a 100 lb female chimp has been observed to deadlift 600 lbs with apparent ease, and chimps aren't even anatomically suited to doing deadlifts. Another female chimpanzee, while in a rage (the only way researchers are likely to see chimps exert their full strength) registered a pull force of 1260 lbs on a dynamometer one handed. A 150 lb chimp is, quite probably, stronger than any human ever to live.

...eventually, we will reach a maximum entropy state where nobody has their own socks or underwear, or knows who to ask to get them back.

Right, so never mind that part.

I think the argument still holds regardless.

I'm convinced that our modern day analogues to ancient scholars are comedians. -0dd1

I wonder why that is.

Fight smart, not fair.

OK, what follows is my poor recollection of speculation I engaged in as an aftermath of sociobiology class (so take it with a grain of salt):

Sexual dimorphism occurs in primates primarily as a result of male-male competition over resources and mates. Thus whether or not it occurs depends upon the nature of sexual relationships and the distribution of resources for that species. IIRC Chimps by and large do not form permanent male-female pair bonds, and thus male-male competition is no more intense than that for other members of the group. Among the Gorillas, however, powerful males control territories along with all the food and females within that territory. Thus, within-male competition is very intense, much more intense than that among the females. Hence males are strongly selected for size and power, while females are not so much. Humans fall approx. halfway between these two extremes. Historically, human societies have been a mix of monogamous and polygamous cultures, depending upon the type of economy involved and hence how resources are distributed within that society. On average then, male competition has been more intense than within the Chimps, less intense than the Gorillas, and our degree of sexual dimorphism reflects that.

Pretty good for a just-so story, eh Myr?

"We learn from history that we do not learn from history."

My (tongue-in-cheek) theory as to why men are bigger and stronger: Because women have a built-in Crowning Moment Of Awesome when they have their first child, men are bigger and stronger than women so that men can have an equal number of Crowning Moments.

"All pain is a punishment, and every punishment is inflicted for love as much as for justice." — Joseph De Maistre.

Sexual dimorphism always intrigued me enough that when I created the seprentine race (who are grounded bipedal descendants of flying reptiles) I made the boys incredibly short at around 4 feet tall while the girls were about the average height of human girls. The guys still act like they're twenty feet tall, though.

♥♥II'GSJQGDvhhMKOmXunSrogZliLHGKVMhGVmNhBzGUPiXLYki'GRQhBITqQrrOIJKNWiXKO♥♥