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Speaker 1: slash brain Stuff. Welcome to brain Stuff from how Stuff Works.
Speaker 1: Welcome to brain Stuff. I hope you survived the experience.
Speaker 1: I'm Christian Sager, and I'm the best there is at
Speaker 1: what I do. And today I'm going to tell you
Speaker 1: how human beings are still evolving. But into what I mean, like,
Speaker 1: where are cool mutant powers that cause fear and hate
Speaker 1: in those were sworn to protect? Where's my organic steel
Speaker 1: skin or my optic I beams? Well, contrary to some
Speaker 1: professor's assertions, evolution does not leap forward. Most experts agree
Speaker 1: that to give rise to a new species like mutants,
Speaker 1: we need some kind of geographic isolation from other humans. Otherwise,
Speaker 1: cross breeding makes it less likely that mutations will be
Speaker 1: established in our gene pool, and with a densely packed
Speaker 1: planet full of planes and cars, it's highly unlikely we're
Speaker 1: going to find that kind of seclusion. Think of it
Speaker 1: this way. Genetic mutations are only passed down if they
Speaker 1: afford us some kind of benefit through natural selection. That
Speaker 1: doesn't mean we've stopped evolving. In fact, over time, we've
Speaker 1: already developed powers well sort of like how about the
Speaker 1: power to drink milk or fight disease because these, along
Speaker 1: with tiny teeth and small brains, are the mutant powers
Speaker 1: most of us are born with. Let's start with the
Speaker 1: milk powers, otherwise known as lactase persistence see. Milk contains
Speaker 1: a sugar called lactose, and people need an enzyme called
Speaker 1: lactase to digest it. Most mammals lose this enzyme after
Speaker 1: they stop breastfeeding, but certain human populations have evolved so
Speaker 1: their lactase persists, allowing the digestion of milk. This was
Speaker 1: nutritionally advantage, just especially when we domesticated cows and goats.
Speaker 1: Now this genetic mutation is carried by more than of
Speaker 1: people of Northern European descent. Researchers have also found signs
Speaker 1: of another set of human mutations that were devoted to
Speaker 1: fighting off infectious diseases. Afflictions like malaria or tuberculosis. Used
Speaker 1: to mean bang, you're dead, But over the last forty
Speaker 1: thousand years we evolve to be more resistant to disease
Speaker 1: because our ancestors happen to have the right genes to
Speaker 1: fight off these viruses and bacteria. Our mutant power to
Speaker 1: resist disease may not last much longer, however, as we
Speaker 1: become more dependent on medications for survival, our immune systems
Speaker 1: will slowly weaken. The more that pathogens are defeated by drugs,
Speaker 1: the less our body will need the internal functions to
Speaker 1: withstand them. This is not to say that modern medicine
Speaker 1: or vaccinations are bad, because without them we'd see a
Speaker 1: huge increase in zas related death, which I'm going to
Speaker 1: assume you also think is a bad thing. So maybe
Speaker 1: milk powers or anti disease genes aren't what you were
Speaker 1: hoping for. What about smaller jaws and less teeth. Our
Speaker 1: ancestors had huge jaws so they could chew on tough
Speaker 1: foods like roots and nuts, and wisdom teeth helped them
Speaker 1: replace their worn down pearly whites from tearing meat apart
Speaker 1: with no quarter asked and none given. But today our
Speaker 1: food is softer, easier to chew, and we use utensils
Speaker 1: to cut the portions we put into our mouths. Consequently,
Speaker 1: our jaws got smaller, our teeth are half the size
Speaker 1: they used to be, and we don't really need wisdom
Speaker 1: teeth anymore. They're already gone in some ethnic groups, and
Speaker 1: many predict they'll disappear entirely now I don't need telepathy
Speaker 1: to know that you think these are really lame powers.
Speaker 1: How about one more mutation. Did you know that our
Speaker 1: brains have been shrinking for the last thirty thousand years.
Speaker 1: Some researchers think this means we're getting dumber, because the
Speaker 1: safety of modern society doesn't require intelligence for survival, but
Speaker 1: others argue that smaller brains just mean they're more efficient.
Speaker 1: Maybe our wiring up there takes up less room because
Speaker 1: it's faster, like when you get a newer, smaller phone
Speaker 1: that has better RAM than your old one. Hopefully, as
Speaker 1: my brain reaches peak efficiency, I'll be able to focus
Speaker 1: the totality of my psyche into some kind of weapon.
Speaker 1: Check out the brain stuff channel on YouTube, and for
Speaker 1: more on this and thousands of other topics, visit how
Speaker 1: stuff works dot com.