ABCC11 (Body Odor)

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Gan ABC11.

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The year is 38,000 BC somewhere in

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northern China. It's the middle of the

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winter and the glaciers have pushed your

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tribe into a narrow valley. Your whole

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tribe has been huddled inside shelters

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of animal hide and mammoth bone. There

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is a fire in the middle of your shelter

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keeping you warm and cozy. The air

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inside is rancid. Sweat, smoke, wet fur,

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and 40y bodies that haven't seen water

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in weeks. But you don't smell like

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everyone else. In fact, you don't smell

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at all. You carry a mutation on the

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ABCC11 gene, a single letter swap in

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your DNA that shuts down the proteins

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your sweat glands would normally

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secrete. You produce no body odor, and

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your ear wax is dry and flaky instead of

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wet and sticky. The other men in your

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tribe can't figure out why the women

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keep choosing to sleep near your side of

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the shelter. One of them, a girl you've

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had your eye on, leans in close to you

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one evening and whispers,

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"You smell like nothing."

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She's never said that to anyone before,

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mainly because it's never been true

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until now. They will later write about

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you in history books and refer to you as

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the genuine man. But for now, you're

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about to experience natural selection.

ACTN3 (Speed)

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Gene act three. It's 200,000 years ago

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on the East African savannah. You suffer

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through one of the worst dry seasons you

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can remember. Food has been scarce and

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many people in your tribe have perished.

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Your hunting party has been tracking a

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wounded kudu since dawn. Hours of

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walking, following blood trails through

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tall grass. The animal is limping now,

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slowing down, but it's still faster than

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any of you. Your group fans out wide,

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driving it toward a rocky outcrop where

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it has nowhere to run. Then it makes a

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break for a gap between the rocks. The

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other hunters hesitate. You don't.

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Tonight, your group eats because of you.

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And when you walk back into camp with

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meat over your shoulders, every pair of

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eyes turns your way. You carry something

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scientists will later call the ACC N3

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gene, the original speed gene.

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Scientists will later discover that over

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1.5 billion people alive today have lost

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this gene entirely. Those who lost it

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traded speed for energy efficiency as

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they adapted to colder climates. But in

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your world, the fastest hunter who makes

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the kill isn't just fed, he's chosen.

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You're about to experience natural

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selection. FTO. It's the year 7,000 BC

FTO (Fat Storage)

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on the island of Cree. Your village has

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just had their best harvest in decades.

2:25

[music]

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Weeks of wheat, lentils, and roasted

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goat. More food than anyone has seen in

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months. You prepare a feast and most of

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your tribe eat until they can't move.

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But while everyone else stops

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eventually, you don't. You carry the A

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variant of the FTO gene, the most common

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obesity related gene in the human

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genome. It increases your levels of

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ghrein, the hunger hormone. So even

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after a full meal, your brain keeps

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whispering more.

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You eat another roasted goat and your

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body converts every spare calorie into

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fat. After the feast is done, the women

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in your village don't exactly look your

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way.

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They prefer the lean fishermen and the

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strong farmers. You're not that. But

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then the rains don't come. The crops

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fail. The goats have no more grass to

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eat. One by one, the lean men start to

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succumb to the famine. Those with flat

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stomachs and visible veins, the ones

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you've envied your whole life. Months

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pass and more of your tribe perishes.

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You're still hanging on, living on a few

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wild nuts in your fat reserves. When the

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rain finally returns, you're a changed

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man. You're not taller or stronger, but

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you are noticeably thinner. And most of

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all, you're alive. The survivors do not

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have much choice. You are about to

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experience a natural selection.

HERC2 (Blue Eyes)

3:37

H E RC2 15,000 BC Southern Italy. You're

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born to your mother's scream and

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father's silence. Up until this point,

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every human ever born has had brown

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eyes. Yours are blue like a winter sky.

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You carry a mutation in the Herc C2

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gene, a switch that turned off the

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pigment your eyes were supposed to have.

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But nobody thinks you're special in a

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good way. You don't hunt better. You

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don't run faster. Your special eyes

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don't help you at all. Most tribesmen

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just think you're weird or cursed. You

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learn to keep your head down as you grow

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up. One day when you sit and ponder how

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you could have been so unlucky. You

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notice a girl your age watching you from

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behind the trees. And she doesn't look

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afraid. She looks curious. She comes

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closer, closer than anyone has in years.

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She doesn't say anything. She just

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stares straight into your eyes like

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she's trying to understand what she's

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seeing. 17,000 years from now, 300

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million people will carry your exact

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mutation. Every one of them trace back

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to you. But for now, you're about to

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experience natural selection. And it all

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started right here.

ALDH2 (Alcohol Flush)

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ALDH2.

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3,200 BC in southern China. You're part

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of the Pyu tribe, and your village has

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just discovered something amazing. If

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you leave rice in water long enough, it

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turns into something that makes the

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whole tribe feel incredible. Rice wine

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catches on fast. Every gathering is an

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excuse to drink. Your family loves it.

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Your neighbors loves it. Your elders

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loves it. And why wouldn't you? It's

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cheap and makes you feel good. Except it

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doesn't make you feel good. Every time

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you drink it, your face goes red, your

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heart starts racing, and your stomach

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turns inside out. You feel incredibly

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unlucky, and all you want to do is join

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in on the fun. You don't know it yet,

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but you carry a variant of the ALDH2

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gene, a mutation that cripples your

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body's ability to break down

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acetalahhide, the toxic byproduct of

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alcohol. But as the years go on,

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something changes. The men who drink

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every night starts falling apart. They

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start fighting at night and in the

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morning they miss the harvest too hung

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over to work the patties. And the most

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beautiful woman in your village has just

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left the guy who's currently faced down

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in the dirt. And tonight you'll make

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sure your descendants won't exactly be

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chugging kegs at Harvard.

DRD4 (Novelty Seeking)

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DRD4. It's 50,000 years ago. East

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Africa. Your tribe has everything it

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needs. Fresh water, game, shelter.

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Everyone around you is content. They

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eat. They sleep. They sit by the fire

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every night. and tell the same stories.

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Everything is blissful and you should be

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too. But you can't stop looking at the

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horizon. You carry a mutation on the

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DRD4 gene, a change in your dopamine

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receptor that makes it less sensitive to

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reward. What satisfies other people

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barely registers for you. You need more.

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More risk, more novelty, more of

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whatever's on the other side of that

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mountain. While the other men stay close

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to camp, you disappear for days. They

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hunt on the same side of the river as

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always. You cross it and find new

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animals no one has ever seen before. You

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do things that make no sense to the

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careful and sensible people around you.

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One day, you come back with meat nobody

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has ever tasted. The women take notice.

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They don't pick you. Not yet. But some

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do think you're exciting. Everyone else

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thinks you're kind of weird. The elders

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shake their heads. Why leave when

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everything you need is right here? But

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good times never last. And when the dry

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season hits harder than everyone

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expected, the elders say to wait it out.

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They have always waited it out. But you

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are not someone who waits. You decide to

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leave one last time. A few women decide

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to follow you. Not because they have to,

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but because they've been watching you

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leave and come back alive for years. And

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this time, they'd rather take their

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chances with the restless one than sit

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and wait with the men who never left.

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Scientists will later discover that the

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further a population migrate from

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Africa, the more likely they carry your

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gene. The people who crossed into the

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Americas, the longest migration in human

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history, carry it at the highest rate on

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Earth. But you didn't leave because you

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had to. You left because you wanted to.

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And now the women want you, too.

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MC1R, your ancestors were the restless

MC1R (Red Hair)

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ones. The ones who left Africa when no

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one else would. They kept moving north

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through deserts, across mountains, over

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ice. And now, 1,600 generations later,

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you're standing at the edge of the

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world. But maybe that was a mistake,

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because you've ended up on cold, dark

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land that is cursed by evil spirits. The

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sun barely shows itself, and when it

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does, it's low and pale, barely breaking

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through the gray mist. And the spirits

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are taking their toll. All the children

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in your tribe are bow-legged, and most

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adults walk like their bones are made of

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wet wood. The evil spirits gather in

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wounds, refusing to let them heal. It's

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like this place sucks the life out of

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everyone who stays here. Your parents

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are sick like everyone else. They have

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brown skin and dark hair and look like

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nothing unusual, but they both carry one

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silent copy of a mutation they don't

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know about. On its own, it does almost

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nothing. But when two carriers have a

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child, you get a threshold effect, and

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that child is you. Your skin is pale and

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your hair bright red, you look like a

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mistake, which you are in a way. But

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every weak ray of winter sun that

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touches your skin passes straight

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through and gets converted into vitamin

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D, the molecule that keeps bones hard,

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immunity sharp, and wounds closing.

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While the others are aching and

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exhausted, you're still pulling fish

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from the shallows. When you get a bone

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fish hook through your palm, you just

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pull it out and keep working. The same

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mutation that turned your hair red also

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quietly rewired your pain system. Your

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body produces more of its own

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painkillers than everyone else's.

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Scientists will later call your special

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gene MC1R, a recessive mutation that was

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invisible in your parents but explosive

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in you. One gene changed your hair, your

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skin, and your relationship with pain.

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Only 1 to 2% of people alive today carry

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two copies. But on your cursed land,

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which will one day be called Scotland,

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that number is 13%. Because in a land

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with almost no sun, the pale one with

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the red hair was the last one still

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standing. And around here, that's

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enough. MCM6.

MCM6 (Lactose Tolerance)

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It's 1,00 BC somewhere in central

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Europe. Your tribe moves with the herd.

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When the grass runs thin, you pack up

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and follow the cattle to the next

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valley. It's a simple life, but it

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works. Your herd is the lifeblood of

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your tribe. The cattle give you

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everything you need. Leather for

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clothes, meat for sustenance, and milk

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for breakfast. Most of your tribe drink

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the milk fresh, still warm from the

10:00

animal poured into clay bowls every

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morning. But your body has never been

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able to handle it. Every time you try,

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your stomach cramps, your gut twists,

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and you spend the next few hours losing

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more fluids than you took in. Sure,

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fermented cheese sits a little easier,

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but cheese takes days to make, and your

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tribe has been on the move for weeks.

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You don't carry the mutation near the

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MCM6 gene. Your body shut off lactase

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production when you were a child, just

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like nature intended, just like it does

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for 65% of all humans alive today. When

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times are good, it doesn't matter.

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There's grain, there's meat, there's

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plenty to go around. But right now,

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times are tough. The grain ran out days

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ago, and the hunting has been poor. All

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that's left is the herd, and the milk it

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produces every morning. Everyone else

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drinks. You can't. You're about to

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experience natural selection. HBB. It's

HBB (Sickle Cell)

10:49

1,000 BC in the forests of West Central

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Africa. Your tribe has been pushing

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deeper into the jungle for generations,

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burning and clearing the land to plant

10:56

crops. Where your grandparents hunted,

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you now farm. The farms brought

11:01

stability. More food, more people, a

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reason to stay in one place. But they

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also brought something else. Where the

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trees once stood, puddles of still water

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collect in the sun. And the fever that

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had always lingered in the forest now

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thrives. The fever has no name yet, but

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everyone knows it. It starts with

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chills, then heat so intense you feel

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like your blood is boiling. Children die

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first, then the adults who can't fight

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it off. Your mother died of the fever.

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So did two of your siblings, but not

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you. You carry one copy of a mutation on

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the HBB gene, just one. It changes the

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shape of some of your red blood cells.

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When the parasite enters your blood,

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your misshapen cells kill it before it

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can take hold. You survive the fever

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again and again and again. You have

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children, strong children. Most of them

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carry what you carry, one copy. And they

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survive the fever, too. But one of them

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doesn't get one copy. She gets both. One

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from you, one from her mother. And two

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copies don't protect you. Two copies

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kill you. You survived the fever so your

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daughter could die of the cure. This is

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what natural selection feels like. HMG

HMGA2 (Height)

12:04

A2. It's 1860 in the Netherlands. The

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average Dutch man stands 5'5, one of the

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shortest populations in Europe. American

12:12

men tower over them by 3 in. But you're

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different. You are almost 5'8. You're

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not a giant, but you're a full head

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taller than most men in your village.

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You carry a handful of gene variants,

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including one on the HMG A2 gene that

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have pushed your height above the rest.

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Tonight is the village dance, and she'll

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be there. The most beautiful girl in

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your village. You and your mate both

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agree beforehand to ask her to dance.

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You watch him walk up, say something,

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and walk back alone. Now it's your turn.

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You finish your drink, straighten your

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back, and walk up to her. She somehow

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agrees. During the dance, her hand rests

12:49

on your shoulder. She has to look up to

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meet your eyes and something clicks.

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When the dance ends, you both slip out

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into the shadows. You cast one quick

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look back and see your friend standing

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alone where you left him. The scientists

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will later discover that men his height

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were half as likely to find a partner at

13:04

all. You feel a sting of guilt. But

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right now, you have more important

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things on your mind. You are about to

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experience natural selection.

EPAS1 (Altitude)

13:13

EPA1.

13:15

It's the year 800 on the Tibetan

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plateau. 4,000 m above sea level. The

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air holds 40% less oxygen than the world

13:22

below. For your people, this is not the

13:25

roof of the world. It's just the world.

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One day, traders arrive from the

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lowlands. Strong men, broad shoulders.

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They laugh loud and walk with

13:34

confidence. By the second night, they

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can barely stand. They're gasping,

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bleeding from their noses, stumbling

13:40

like drunks. One of them asks you how

13:43

you breathe up here. You don't

13:44

understand the question. You've never

13:46

had trouble breathing. The reason lies

13:48

in a single gene, EPA S1, and your

13:52

version of it is unlike almost any other

13:53

on Earth. Because you didn't evolve it.

13:56

You inherited it from a species that

13:58

isn't even human tens of thousands of

14:00

years ago. Your ancestors made it with

14:02

the Dennisovvens, an ancient species

14:04

that once lived in the mountains of

14:06

Siberia. We've only ever found a finger

14:08

bone, a toe, and two teeth. But in their

14:10

genome was the exact variant that now

14:12

lets you breathe where no one else can.

14:15

The Dennisovvens are gone. But their

14:17

gift lives on in you. 87% of Tibetans

14:20

still carry it. Only 9% of Hanchinese

14:22

do. The traitors leave after a week,

14:25

still pale and shaking. They'll tell

14:27

stories about the people who live on the

14:28

roof of the world. You won't think about

14:30

them again. This is just home. You just

Outro

14:33

experience natural selection. Every gene

14:36

in this video is real. Every story is

14:38

based on actual research. I spent way

14:40

too long fact-checking ancient cave

14:42

dwellers so you don't have to leave a

14:44

like for my efforts. Also, remember your

14:46

genes are still being selected for,

14:48

still being selected against. You carry

14:51

some of them right now. You just don't

14:53

know which ones are winning yet. So, go

14:54

out there and make some new variants.