Men and women are physically equal

Now that I've got your attention...

No they're not, but they might become so.

Humans already have a good deal less sexual dimorphism than other primates in terms of size and strength. Add to that the fact that there is no real reason nowadays to select for the biggest and strongest males. Unlike some other mammals, mate competition in human males is more about acquiring status and resources than about physically dominating the other males.

In prehistoric times, and even on to agricultural times, the biggest and strongest male had an easier time of amassing status and resources, but nowadays, brains and finesse are more selected for than physical strength and size. Strength and size can even be a liability, selection-wise, as the biggest and strongest males tend to enter more dangerous fields of work than more intelligent but smaller and weaker counterparts.

Add to that the advances in the field of science. It's possible that the future holds new ways for humans to reproduce, such as cloning, Artificial Humans, artificial wombs, Homosexual Reproduction, and new fertility drugs and treatments. Because of these, even high testosterone in women and low testosterone/high estrogen in men may not be as strongly selected against in the future.

So with this in mind, is it possible that over the course of the millenniums, sexual dimorphism for size and strength will be greatly reduced?

Rich, high status people are more sexually desirable, but lots of sex no longer means lots of reproductive success.

All evolutionary biology predicts is "the alleles of those who have more grandchildren will become more common within the gene pool, potentially even species-typical."

edited 8th Nov '11 6:46:54 PM by Rottweiler

@Rott: Not "more" necessarily. Or at least, not over any finite span of time; the alleles of those who have more surviving descendents period will become more common over time.

@Leigh:

Call me a romantic, but I don't think this is how it EVER worked in humans (and their recent ancestors). It's not status now and it hasn't been size ever. For one, if men were competing for women by hitting each other they would be FAR bigger than women. Male gorillas actually do that and they're about twice the size of female gorillas. But human men are only a little (around 10%) bigger than human women; that's a small enough difference that there are some human women that are bigger than the vast majority of human men, which just doesn't happen with gorillas.

"It's not status now" is harder to say definitively. Of course it's a LITTLE bit status now, because of course a rich man is more likely to have sex than a poor man, but it's only one factor out of TONS. Hotness, for example, totally does count.

Also what Rott said; a poor person with a lot of children may or may not be more evolutionarily successful than a rich person with a few children. It's hard to tell, honestly, but supposing they all get a reasonable standard of healthcare there's no reason to think the rich person's kids would be evolutionarily better off.

EDIT: Oh, and intelligence has clearly been selected for in both sexes for at least the past million years.

edited 8th Nov '11 7:00:39 PM by BlackHumor

This is exactly the point that I was arguing!

I don't know that I want the whole estrogen and testosterone thing to balance out between the sexes, I kind of like things the way they are.

@Leigh: Uh, okay?

But we haven't done (much of) that at least since our ancestors split off from gorillas. Because neither bonobos nor chimps do (much of) that either (same amount of sexual size dimorphism as proof) and they're much more closely related to us than the gorillas are.

No, I don't think that would happen, as "not being selected for" does not mean "being selected against". Furthermore, that seems to imply that the genome has a tendency to drift towards some sort of genetic average (in the absence of selective pressures) , which I don't think it does either.

edited 8th Nov '11 7:22:14 PM by GreatLich

I agree. Unless you can come up with a reason why dimorphism would be selected against, it should stay as is unless something happens to create pressure.

I fully expect human genetic engineering within the next millennium, and a probable effect of that engineering will be to make the children of rich men and women tall, strong, and smart regardless of gender. However, I wouldn't bank on it happening within my lifetime, especially if poor men and women rally against it.

Unless physically diminuitive, low testosterone guys suddenly start becoming the most sexually desirable type of man, I don't think the big fellas are going away any time soon.

Men, on average, are physically stronger, but women are more endurant. There's also the factor of will - in a field where physical fitness is important and which is dominated by men, women will strive to overachieve their male colleagues in order to break steroetypes. For example, since Serbia allowed female soldiers in all branches of the military, two years ago, female spec-ops have actually shown to be harder trainers and more successful on average.

Nachthexen.

It's a very Nietzschean phenomenon.

What is and how so?

Edit: Women fighting on the battlefield isn't a new thing.

edited 9th Nov '11 3:06:53 AM by whaleofyournightmare

It really doesn't matter anymore who has the most sex. What matters is who has the most surviving bearers of their alleles. Have one night stands with a thousand women, all of whom use protection and don't get pregnant? Evolutionarily useless.

That said, provided there's no selection pressure for men to be bigger and stronger than women, then unless there's a selection pressure for the reverse, we shouldn't expect the relative sizes to change.

edited 9th Nov '11 6:29:48 AM by HiddenFacedMatt

"Add to that the fact that there is no real reason nowadays to select for the biggest and strongest males."

Personal preference is a real reason, Leigh.

@Milos

Not actually true. Men have greater lung and heart capacity, which makes them better at physical activities that require endurance, as well as those that require strength. The sex-based difference is reduced with the former, but remains in favor of men with the possible exception of the very extremes of endurance sports (ultra-marathons, ultra-long distance swimming, etc.). Women's primary physical advantage over men lies in the realm of fine motor control, not endurance.

@BH

Yet human men are, on average, significantly stronger than the weight difference would imply (about five thirds of the strength of an equal-sized, equally trained woman).

There's a much simpler argument against human males having been selected primarily for physical strength, though: the fact that we've gotten consistently weaker and frailer over time. Our Neanderthal once-contemporaries were at least two or three times as strong as we are. Before that, Homo Heidelbergensis stood at over six feet tall on a prehistoric diet, and had a physique that would make bodybuilders cry in shame. Even the Cro-Magnon, who were anatomically modern humans already, were significantly more robustly built than we are today.

It seems that, if anything, being weak (but energy-efficient) has been the survival advantage for us.

That being said, in a few thousand years we'll likely have either blown ourselves to hell or engineered ourselves to be whatever we please, so I suspect that gender differences will be a non-issue, either way.

Human beings weren't made by some creator so that the sexes would have different but equal traits. It seems likely, apriori, that the average man is better or worse than the average woman in the physical realm. It also seems likely that the average man is better or worse than the average woman in the intelectual and emotional realms. Based on my observations, these differences are not so large to prevent both genders from being represented in the top 5% of any category.

I would assume that, taking people without significant training (i.e. not people in the military, or bodybuilding, or some such), that men would at least slightly edge out women, on average.

I would also assume, however, that they are basically capable of equal points after doing some training and purposefully getting into shape. After all, people aren't limited to just what they're born with, necessarily. However, whether or not people have the drive to do this is a different matter, grounded more in sociology than biology.

My observations of people don't agree with this. At the top most level of fitness, men generally beat women (look at weight lifting world records for men and women, sprinting times, and many others (although likely not all other activities)). At a moderate level of fitness this also doesn't seem to be true. I've been lifting weights once a week for seven months, my GF lifts weights five times a week for several years. We're of the same genetic heritage (european jews), I'm much stronger than her (she's much smarter than me).

It's not true on any level of fitness. As Oscredwin said, the women competing in strength events train as hard as the men do, but the strength differential does not disappear - if anything, it's (slightly) amplified.

For the sake of reference, here's some performance standards in weightlifting, based on sex, weight, and level of training. Even as someone who only does random bodyweight exercise at home when he feels like it, I myself am only slightly below elite female athletes in my weight class.

edited 9th Nov '11 3:46:21 PM by MostlyBenign

Well, when I say "basically equal," I mean "as it applies to normal life."

Normal people don't usually need to lift 500+ pounds of weights.

If men and women, with training, can perform the same functions for the military—one of the most physically demanding occupations in the world, regardless of what government we're talking about—then, for all practical purposes, they can become equal, even if in some absurd, artificial conditions men may still be stronger.

Ummm, the physical requirements for men and women in the army aren't the same.

http://usmilitary.about.com/od/army/a/afpt.htm

^ And that's my only condition for full integration of the military. If women want to fight on the lines they better perform to the same standards as men. Why? Enemy fire doesn't discriminate, it won't care if you are big or small, black or white, man or woman. Performing at the same high standards as men only makes you better able to avoid enemy fire and becoming a casualty.

No, but I see few good evolutionary reasons why one sex would be better than the other at anything outside reproduction. It's not a random thing that both sexes are equal; it's that evolution tends to push towards an equilibrium between greater ability and fewer resources expended on that ability, so unless there's a reason why one sex would NEED greater ability it's not likely to have it.

That said, there definitely does seem to be some sexual size dimorphism, but the general principle is sound (and bears out) for all other forms of ability. So there must be, by this theory, some pressure for men to be strong(-er by a little) that women don't have, but otherwise it seems to be borne out by the evidence: many studies have confirmed that there is no significant intellectual difference between sexes, for example, and the most rigorous tests of empathy also show no significant differences.

In fact all the other differences between men and women found are very small. Not quite insignificant but definitely too small to matter much outside of a lab, which would also tend to bear the theory out: the abilities of the sexes both tended towards the equilibrium but did not hit it precisely. It would actually be very strange if evolution hit every equilibrium precisely when all it has to work with is natural mutations; that would imply that for every possible trait some individual was born at some time with the PERFECT balance between the two competing pressures.