Eli5 Why are women so much shorter than men?
In: 60
As I so often begin in ELI5: Your question contains a false premise.
1) Average male in US is 5′ 9″. Average female is 5′ 4″ . That’s a 7% difference. Women are not “so much shorter” they are quite close.
2) We live in a time of abundance which may not align with the environment in which we evolved over the last few million years. In times of scarcity, the height difference may have shrunk a little with women being 5′ 1″ and men down to 5′ 4″ (but this is speculative)
In conclusion: men and women are surprisingly similar in height. The slight difference in height may be an accident of sex hormones sealing up growth plates sooner for women. While evolution has pretty clearly favored more muscular strength in men, it has not had as strong a say in height, and in fact height can be an evolutionary disadvantage depending on the environment.
Humans are sexually di-morphic. Which essentially means one sex is larger than the other.
Because rape is the natural order of sex in the animal kingdom, what happens is the larger men were more likely to reproduce and pass on their male size genes.
Most of your ancestors are actually female. The overwhelming majority of your ancestors were in fact. The few males historically that were able to reproduce, reproduced with many, many partners.
Sexual dimorphism. Although, it’s a lot less in humans now than it used to be in our ancestors. Sexual dimorphism is usually a result of intrasexual selection. This is when organisms of the same gender compete over the right to mate with the opposite gender. This competition allows sexual selection to take place. Larger males will win more often and as a result pass on their genes to their sons who will also grow larger. Sexual dimorphism isn’t as high in humans because there isn’t much physical competition over mates and there is also female competition with male choice in our societies.
What I really noticed as a Dad of a couple of kids is by and large the females also mature just a bit quicker than the young males, so in early years they are not subject to the whims or advances of less mature, less developed males.
There’s about a year where the girls seem bigger than most of the boys. So during those really awkward years girls tend to be a bit larger than the boys.
Then the testosterone hits and well, all bets are off.
It’s because male have more testosterone which leads to more muscle mass, bigger frames, taller etc. From an evolutionary perspective, I’m sure there are some good answers in the comments.
In short, hormones. Testosterone itself does not spur height but it does affect HGH (Human Growth Horimone) and IGF-1 (Insulin Growth Factor) which both affect height.
Not sure why so many of the answers here have *nothing* do do with the actual biological reasons when this is tagged ‘biology’.
I always thought becuz our male ancestors had to hunt and fight, therefore our height had to be adjusted to fight.
Excellent question. Typically we ask why men are larger, but not why are women smaller.
Nutrition. Less mass means fewer calories are required. When you get pregnant or breastfeed your calorie requirements go up dramatically, and it can be hard to get the required amount of calories, even for many women who have access to modern foods that are calorie dense.
Evolution doesn’t favor traits that make your life easier, it favors traits that can promote reproduction.
This is also why the only people to survive in the donner party without resorting to cannibalism were women. We just need less food to survive.
Are we? 🤔 I’m a white lady living in Japan and I’m as tall as most of the men or taller.
Edit: I’m around 5’6″ for reference.
Most women find taller men more attractive, over many generations those become the more prevalent genes I guess.
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