Anyone, or anything, that reproduces sexually
is constantly thinking to itself
"Who am I gonna mate with?"
We spend a lot of time thinking about mate choice
because passing on your genes early and often is how you win at being alive.
From an evolutionary standpoint,
it's the most important thing you will ever do, if you do it.
And due to its extreme importance,
it's also very complicated, you may have noticed.
Our general understanding of it comes from Charles Darwin
who proposed that some individuals get more action than others
because of sexual selection.
You've heard of it.
One gender of a species consistently prefers mates with specific traits
so individuals with those traits pass their genes on more often
and spread their genes, and the traits, throughout a population.
Old Charlie was certainly on to something.
Take a look at this peacock
Some would consider this overkill, but to the ladies,
a big frothy rack of feathers shows that a dude is healthy
and has good genes.
So, as a result of sexual selection, male peacocks
have evolved to look like 1970s Las Vegas showgirls.
Humans, like peacocks, have evolved to like some traits more than others,
and these preferences date back to a time when those traits
gave an individual huge survival advantages.
So in most cases, beauty is actually a language
that conveys information about health and fertility.
But if you're thinking that it's all about boobs and big muscles,
think harder.
You know what really turns us on? Bilateral symmetry.
Humans are attracted to people whose bodies and
faces look the same on both sides.
How am I doing? Anybody?
Symmetrical imbalance can mean someone was exposed to
some kind of stressor during early development
that they weren't tough enough to deal with.
Similarly, a low waist-to-hip ratio drives both
dude and lady humans wild.
Where fat is deposited on a body is determined by
sex hormones: testosterone in men and estrogen in women.
Women who produce the ideal amount of estrogen
generally have waists that are about 70% the width of their hips.
Same goes for men and testosterone.
People with this ideal ratio are often less susceptible
to cardiovascular disorders, cancer, diabetes, and
women in this range also have less difficulty conceiving and giving birth.
Now you might be wondering
why will a nice, symmetical guy with an ideal waist-hip ratio
make you feel kind of meh, but he's got your friend
driving by his house three times a day?
Well, one reason could be in our genes.
Everybody gives off subtle chemical signals called pheromones
which gives potential mates a clue to our genetic profiles.
Crazy, right?
Studies have shown that men and women are generally
attracted to pheromones of individuals that are
genetically similar to themselves, with one major exception.
They prefer mates with a different kind of
immune system gene called
Major Histocompatibility Complex, or MHC.
The combo of two variations of the MHC gene
helps a couple's offspring fight off disease better
and our pheromones basically tell mates
which version of that gene we have.
But even after you account for pheromones
and symmetry and ratios, it's complicated.
And people don't make rational decisions, so really
don't bother with those hair plugs or that boob job.
It's complicated.
And yet so awesome.
Thanks for watching this episode of SciShow.
In the comments, tell us what makes you attracted
to a potential mate.
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you can leave those down in the comments or get in touch with us
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