Are Humans Still Evolving?

We may not have mutant powers like the X-Men, but natural selection is still changing humanity… for the better.

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Episode Transcript

Speaker 1 (00:00):
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(01:04):
slash brain Stuff. Welcome to brain Stuff from how Stuff Works.
Welcome to brain Stuff. I hope you survived the experience.
I'm Christian Sager, and I'm the best there is at
what I do. And today I'm going to tell you

(01:25):
how human beings are still evolving. But into what I mean, like,
where are cool mutant powers that cause fear and hate
in those were sworn to protect? Where's my organic steel
skin or my optic I beams? Well, contrary to some
professor's assertions, evolution does not leap forward. Most experts agree

(01:47):
that to give rise to a new species like mutants,
we need some kind of geographic isolation from other humans. Otherwise,
cross breeding makes it less likely that mutations will be
established in our gene pool, and with a densely packed
planet full of planes and cars, it's highly unlikely we're

(02:07):
going to find that kind of seclusion. Think of it
this way. Genetic mutations are only passed down if they
afford us some kind of benefit through natural selection. That
doesn't mean we've stopped evolving. In fact, over time, we've
already developed powers well sort of like how about the
power to drink milk or fight disease because these, along

(02:30):
with tiny teeth and small brains, are the mutant powers
most of us are born with. Let's start with the
milk powers, otherwise known as lactase persistence see. Milk contains
a sugar called lactose, and people need an enzyme called
lactase to digest it. Most mammals lose this enzyme after
they stop breastfeeding, but certain human populations have evolved so

(02:53):
their lactase persists, allowing the digestion of milk. This was
nutritionally advantage, just especially when we domesticated cows and goats.
Now this genetic mutation is carried by more than of
people of Northern European descent. Researchers have also found signs
of another set of human mutations that were devoted to

(03:16):
fighting off infectious diseases. Afflictions like malaria or tuberculosis. Used
to mean bang, you're dead, But over the last forty
thousand years we evolve to be more resistant to disease
because our ancestors happen to have the right genes to
fight off these viruses and bacteria. Our mutant power to

(03:37):
resist disease may not last much longer, however, as we
become more dependent on medications for survival, our immune systems
will slowly weaken. The more that pathogens are defeated by drugs,
the less our body will need the internal functions to
withstand them. This is not to say that modern medicine
or vaccinations are bad, because without them we'd see a

(03:58):
huge increase in zas related death, which I'm going to
assume you also think is a bad thing. So maybe
milk powers or anti disease genes aren't what you were
hoping for. What about smaller jaws and less teeth. Our
ancestors had huge jaws so they could chew on tough
foods like roots and nuts, and wisdom teeth helped them

(04:20):
replace their worn down pearly whites from tearing meat apart
with no quarter asked and none given. But today our
food is softer, easier to chew, and we use utensils
to cut the portions we put into our mouths. Consequently,
our jaws got smaller, our teeth are half the size
they used to be, and we don't really need wisdom

(04:40):
teeth anymore. They're already gone in some ethnic groups, and
many predict they'll disappear entirely now I don't need telepathy
to know that you think these are really lame powers.
How about one more mutation. Did you know that our
brains have been shrinking for the last thirty thousand years.
Some researchers think this means we're getting dumber, because the

(05:02):
safety of modern society doesn't require intelligence for survival, but
others argue that smaller brains just mean they're more efficient.
Maybe our wiring up there takes up less room because
it's faster, like when you get a newer, smaller phone
that has better RAM than your old one. Hopefully, as
my brain reaches peak efficiency, I'll be able to focus

(05:24):
the totality of my psyche into some kind of weapon.
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