The Real Eve Page #5

why do we all look

so completely different?

Natural selection and

adaptation to the environment...

are the most important factors.

Sexual selection is crucial.

Climate dictates body shape.

The colder the environment,

the shorter and more stocky...

you become to retain heat.

Height relates to diet.

The most obvious and

striking difference is color.

And that's also part

of our genetic inheritance.

Mila Jabloski, a scientist looking

at the evolution of skin color...

was working on the importance of

folic acid in fetal development...

when she stumbled,

by chance, on the answer.

I started doing research on

the evolution of skin color...

after preparing a lecture

for a class over 10 years ago.

Preparing for the class, I realized

that there was very little known...

about the evolution of skin color,

and what was known wasn't cogent.

I discovered an interesting paper

when I was preparing that lecture...

that showed that there's an interesting

and important relationship between...

ultraviolet radiation and a very

important biomolecule called folate.

Folic acid is crucial

for embryonic development...

and too much ultraviolet radiation

from the sun destroys it.

So, our ancestors in Africa needed

to be dark to protect their survival.

But too little ultraviolet prevents

the formation of Vitamin D...

causing rickets,

which can kill.

So, as they migrated to the North,

they had to grow paler to survive.

She has uncovered a very simple

evolutionary equation.

When we look at the pattern

of skin pigmentation...

among indigenous people today,

we see very dark people...

in equatorial regions

with high UV...

and significantly lighter people

as we get toward the poles.

And it turns out that melanin,

the natural sun screen...

is phenomenally good at screening

out ultraviolet radiation.

To some extent, it's too good.

In order for us to be able to make

enough Vitamin D in our skin...

we have to reduce the amount

of melanin that exists in the skin.

And so, what we see in the

course of our species' history...

as we've moved from an area

of high UV to areas of lower UV...

our skin has become

more and more depigmented.

She calculates that it takes 20,000

years to turn from black to white.

All that distinguishes color in people

are tiny genetic differences...

laid down long ago.

During the epic beachcombing

migration from Africa to Australia...

our family left behind colonies.

One group made their way up through

Asia into China and beyond.

Another went from north India,

past the Himalayas...

onto the vast Asian steppes. And

another stayed in the Arabian Gulf.

Large fresh water lakes allowed

our Out of Africa families...

to colonize these pockets of lush

vegetation surrounded by desert.

Continuous occupation occurred

here for more than 30,000 years.

Their bones and artifacts becoming

submerged as sea levels rose.

About 50,000 years ago, genetic

lines began for the first time...

to spread north into Europe.

But the timing has

always been a puzzle.

If modern humans were able

to reach Australia...

as early as 70,000 years ago,

why did they not arrive in Europe...

until 50,000 years ago?

It is a much shorter journey.

Steven Oppenheimer

thinks he has the answer.

I think the answer to this question

is that they were stuck.

They were not able to get up to the

near East, Israel and the Lebanon...

because there was

a great desert in their way.

That desert was the Saudi Arabian

desert and the Libyan desert.

And between 80,000

and 50,000 years ago...

this was completely impenetrable.

The climate was so dry

that the fertile crescent...

the route from the gulf into...

Lebanon, and Israel,

and Europe was closed.

Then, 50,000 years ago there was

a sudden improvement of the climate.

After centuries of domination

by the desert, the rains came.

Monsoon rainfall increased

in Arabia and India...

and the fertile crescent

opened up.

Rivers swirled and

game spread north.

Our families and genetic lines

followed them.

They walked north from the Persian

Gulf, into the fertile crescent...

following the rivers between

the Zagros mountains...

and the Syrian desert.

The idea that Europeans

came in through North Africa...

is very firmly fixed.

But Steven Oppenheimer's

evidence does not support this.

Genetic evidence completely

does not support it.

There's no evidence of the

early branches and, in fact...

only one of the main branches that

people the world is found in Europe.

0f course,

that does upset a lot of...

fixed views about the origins

of the Europeans...

and forces us

to consider the fact that...

Europeans were part of

the same single family...

that came out of Africa

through the southern route.

This new genetic evidence

will rewrite European prehistory.

These families founded the first

successful modern human colonies...

in the Middle East,

Syria and Lebanon.

A land that lay between

the rivers Tigris and Euphrates...

Two great rivers flowing from

the high lands of Turkey...

in the north,

down to the gulf.

We have taken the first steps

to the civilizations...

that would develop writing,

warfare and found the great empires.

All from one

direct genetic group...

back to our

Out of Africa migration.

During this time there was also

an explosion of new technology.

The stone tools and spears

modern humans manufactured...

became even lighter

and more effective.

The Zagros were full of game,

and good hunting makes stability.

They began to establish the fixed

geography of burial grounds...

in sacred places.

In Ksar Akil, in the Lebanon...

the burial of a 12-year old

modern child has been found...

dated 44,000 years ago.

His skull is broken.

His body tucked gently in the

shelter in the overhanging rock.

From these points new families spread

quickly to the Mediterranean...

south along the coast of Syria

into North Africa...

up through Turkey,

across the Balkans and into Europe.

This is our new family...

direct descendants of our

marshland Arabs in the gulf...

entering the unknown

territories of Germany.

But the land is not empty.

Others were there before them.

Neanderthals had been the masters

of Europe for over 250,000 years.

In 1 856, in the

Neander Valley in Germany...

quarrymen were digging out mud

from a newly blasted site...

when they discovered some ribs,

part of a pelvis...

some arm and shoulder bones

of a large, humanlike animal.

They thought it was

a bear's skeleton.

Scientists later believed it was

some ancient northern savage...

who terrified

the Roman armies.

Professor Chris Stringer is an expert

on Neanderthals and their world.

They became known as Neanderthals,

and the center of the debate...

about human evolution, whether

these people were our ancestors...

or represented a strange

sidebranch of human evolution.

I've got a more complete skull than

the one found in the Neander Valley.

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