I mean, we've been doing it for two million years,

so it's kind of arrogant to assume

that I've got something to say

that hasn't been said and performed better a long time ago.

But the cool thing about running, as I've discovered,

is that something bizarre happens

in this activity all the time.

Case in point: A couple months ago, if you saw the New York City Marathon,

I guarantee you, you saw something

that no one has ever seen before.

An Ethiopian woman named Derartu Tulu

turns up at the starting line.

She's 37 years old,

she hasn't won a marathon of any kind in eight years,

and a few months previously

she almost died in childbirth.

Derartu Tulu was ready to hang it up and retire from the sport,

but she decided she'd go for broke

and try for one last big payday

in the marquee event,

the New York City Marathon.

Except -- bad news for Derartu Tulu -- some other people had the same idea,

including the Olympic gold medalist

and Paula Radcliffe, who is a monster,

the fastest woman marathoner in history by far.

Only 10 minutes off the men's world record,

Paula Radcliffe is essentially unbeatable.

That's her competition.

The gun goes off, and she's not even an underdog.

She's under the underdogs.

But the under-underdog hangs tough,

and 22 miles into a 26-mile race,

there is Derartu Tulu

up there with the lead pack.

Now this is when something really bizarre happens.

Paula Radcliffe, the one person who is sure to snatch the big paycheck

out of Derartu Tulu's under-underdog hands,

suddenly grabs her leg and starts to fall back.

So we all know what to do in this situation, right?

You give her a quick crack in the teeth with your elbow

and blaze for the finish line.

Derartu Tulu ruins the script.

Instead of taking off,

she falls back, and she grabs Paula Radcliffe,

says, "Come on. Come with us. You can do it."

So Paula Radcliffe, unfortunately, does it.

She catches up with the lead pack

and is pushing toward the finish line.

But then she falls back again.

And the second time Derartu Tulu grabs her and tries to pull her.

And Paula Radcliffe at that point says,

"I'm done. Go."

So that's a fantastic story, and we all know how it ends.

She loses the check,

but she goes home with something bigger and more important.

Except Derartu Tulu ruins the script again --

instead of losing, she blazes past the lead pack and wins,

wins the New York City Marathon,

goes home with a big fat check.

It's a heartwarming story,

but if you drill a little bit deeper,

you've got to sort of wonder about what exactly was going on there.

When you have two outliers in one organism,

it's not a coincidence.

When you have someone who is more competitive and more compassionate

than anybody else in the race, again, it's not a coincidence.

You show me a creature with webbed feet and gills;

somehow water's involved.

Someone with that kind of heart, there's some kind of connection there.

And the answer to it, I think,

can be found down in the Copper Canyons of Mexico,

where there's a tribe, a reclusive tribe,

called the Tarahumara Indians.

Now the Tarahumara are remarkable for three things.

Number one is,

they have been living essentially unchanged

for the past 400 years.

When the conquistadors arrived in North America you had two choices:

you either fight back and engage or you could take off.

The Mayans and Aztecs engaged,

which is why there are very few Mayans and Aztecs.

The Tarahumara had a different strategy.

They took off and hid

in this labyrinthine, networking,

spiderwebbing system of canyons

called the Copper Canyons,

and there they remained since the 1600s --

essentially the same way they've always been.

The second thing remarkable about the Tarahumara

is, deep into old age -- 70 to 80 years old --

these guys aren't running marathons;

they're running mega-marathons.

They're not doing 26 miles;

they're doing 100, 150 miles at a time,

and apparently without injury, without problems.

The last thing that's remarkable about the Tarahumara

is that all the things that we're going to be talking about today,

all the things that we're trying to come up with

using all of our technology and brain power to solve --

things like heart disease and cholesterol and cancer

and crime and warfare and violence and clinical depression --

all this stuff, the Tarahumara don't know what you're talking about.

They are free

from all of these modern ailments.

So what's the connection?

Again, we're talking about outliers --

there's got to be some kind of cause and effect there.

Well, there are teams of scientists

at Harvard and the University of Utah

that are bending their brains to try to figure out

what the Tarahumara have known forever.

They're trying to solve those same kinds of mysteries.

And once again, a mystery wrapped inside of a mystery --

perhaps the key to Derartu Tulu and the Tarahumara

is wrapped in three other mysteries, which go like this:

three things -- if you have the answer, come up and take the microphone,

because nobody else knows the answer.

And if you know it, then you are smarter than anybody else on planet Earth.

Mystery number one is this:

Two million years ago the human brain exploded in size.

Australopithecus had a tiny little pea brain.

Suddenly humans show up -- Homo erectus --

big, old melon-head.

To have a brain of that size,

you need to have a source of condensed caloric energy.

In other words, early humans are eating dead animals --

no argument, that's a fact.

The only problem is,

the first edged weapons only appeared about 200,000 years ago.

So, somehow, for nearly two million years,

we are killing animals without any weapons.

Now we're not using our strength

because we are the biggest sissies in the jungle.

Every other animal is stronger than we are --

they have fangs, they have claws, they have nimbleness, they have speed.

We think Usain Bolt is fast. Usain Bolt can get his ass kicked by a squirrel.

We're not fast.

That would be an Olympic event: turn a squirrel loose --

whoever catches the squirrel, you get a gold medal.

So no weapons, no speed, no strength, no fangs, no claws --

how were we killing these animals? Mystery number one.

Mystery number two:

Women have been in the Olympics for quite some time now,

but one thing that's remarkable about all women sprinters --

they all suck; they're terrible.

There's not a fast woman on the planet

and there never has been.

The fastest woman to ever run a mile did it in 4:15.

I could throw a rock and hit a high school boy

who can run faster than 4:15.

For some reason you guys are just really slow.

(Laughter)

But you get to the marathon we were just talking about --

you guys have only been allowed to run the marathon for 20 years.

Because, prior to the 1980s,

medical science said that if a woman tried to run 26 miles --

does anyone know what would happen if you tried to run 26 miles,

why you were banned from the marathon before the 1980s?

(Audience Member: Her uterus would be torn.) Her uterus would be torn.

Yes. You would have torn reproductive organs.

The uterus would fall out, literally fall out of the body.

Now I've been to a lot of marathons,

and I've yet to see any ...

(Laughter)

So it's only been 20 years that women have been allowed to run the marathon.

In that very short learning curve,

you guys have gone from broken organs

up to the fact that you're only 10 minutes off

the male world record.

Then you go beyond 26 miles,

into the distance that medical science also told us would be fatal to humans --

remember Pheidippides died when he ran 26 miles --

you get to 50 and 100 miles,

and suddenly it's a different game.

You can take a runner like Ann Trason, or Nikki Kimball, or Jenn Shelton,

you put them in a race of 50 or 100 miles against anybody in the world

and it's a coin toss who's going to win.

I'll give you an example.

A couple years ago, Emily Baer signed up for a race

called the Hardrock 100,

which tells you all you need to know about the race.

They give you 48 hours to finish this race.

Well Emily Baer -- 500 runners --

she finishes in eighth place, in the top 10,

even though she stopped at all the aid stations

to breastfeed her baby during the race --

and yet, beat 492 other people.

So why is it that women get stronger

as distances get longer?

The third mystery is this:

At the University of Utah, they started tracking finishing times

for people running the marathon.

And what they found

is that, if you start running the marathon at age 19,

you will get progressively faster, year by year,

until you reach your peak at age 27.

And then after that, you succumb

to the rigors of time.

And you'll get slower and slower,

until eventually you're back to running the same speed you were at age 19.

So about seven years, eight years to reach your peak,

and then gradually you fall off your peak,

until you go back to the starting point.

You would think it might take eight years to go back to the same speed,

maybe 10 years -- no, it's 45 years.

64-year-old men and women

are running as fast as they were at age 19.

Now I defy you to come up with any other physical activity --

and please don't say golf -- something that actually is hard --

where geriatrics are performing

as well as they did as teenagers.

So you have these three mysteries.

Is there one piece in the puzzle

which might wrap all these things up?

You've got to be really careful any time

someone looks back in prehistory and tries to give you some sort of global answer,

because, it being prehistory,

you can say whatever the hell you want and get away with it.

But I'll submit this to you:

If you put one piece in the middle of this jigsaw puzzle,

suddenly it all starts to form a coherent picture.

If you wonder, why it is the Tarahumara don't fight

and don't die of heart disease,

why a poor Ethiopian woman named Derartu Tulu

can be the most compassionate and yet the most competitive,

and why we somehow were able

to find food without weapons,

perhaps it's because humans,

as much as we like to think of ourselves as masters of the universe,

actually evolved as nothing more

than a pack of hunting dogs.

Maybe we evolved

as a hunting pack animal.

Because the one advantage we have in the wilderness --

again, it's not our fangs and our claws and our speed --

the only thing we do really, really well is sweat.

We're really good at being sweaty and smelly.

Better than any other mammal on Earth, we can sweat really well.

But the advantage

of that little bit of social discomfort