National Geographic: Mysteries of Mankind Page #4

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Every week during the field season,

a light plane from Nairobi brings

expedition leader Richard Leakey,

son of Louis and Mark Leakey.

Despite an early decision not to

follow in his parents' footsteps,

Richard's passion for

paleontology won out.

For two decades he has been

digging here with remarkable success.

Over the years since 1968 the Turkana

region has yielded ten

to fifteen thousand fossil remains.

Most are animal, but amazingly

more than 300 are early human.

Leakey has been called the '"organizing

genius of modern paleontology'".

He heads a team that scours

the exposures daily

for several months at a time.

They cover every foot of

the 600 square mile area each year.

Looking for new evidence in any

scientific discipline is exciting.

In our field it's

particularly rewarding

because every year there

is a new opportunity.

These vast areas of desert

are periodically washed by rain.

And every time it rains,

there's a chance that something new

will be exposed something new

that's going

to tell us something that

we never knew before.

It's going to expose

a completely new chapter

in our understanding of human origins.

And it's really great fun

to be out there

on the desert realizing that although

you were there the year before,

this year it will be different

because it rained a few months ago

and something new must have

washed up somewhere.

It's simply a question of finding it.

In 1984 a small piece

of skull was found.

It was immediately recognized as human

by Leakey's colleague Kamoya Kimeu.

With anatomist Alan Walker

and the rest of the team,

he went on to unearth a seemingly

endless array of bones.

The rest of the skull

and face were found

and painstakingly glued together

from 70 separate pieces.

The bones were clearly those

of a Homo erectus,

a species on the path

that eventually led to modern humans.

The skeleton, a boy of about 12,

was dated at more than a million

and a half years old.

Far more complete than even Lucy,

it is one of the most remarkable finds

in the study of human evolution.

The boy differs little

from a modern human

in stature and body proportions.

An artist imagines

what he might have looked like;

Richard Leakey reconstructs

what his life may have been like.

The area that he was living

in was probably lake margin,

swampy ground near the lake edge.

There was grassland;

there were forests;

there were permanent rivers running

into the lake.

Probably an enormous amount of

animals plains animals,

carnivores, scavengers.

I suppose one could visualize an area

like one of the better national parks

in East Africa today,

teeming with wildlife ideal conditions

for an early human.

I think it's remarkable

because it's so complete.

But perhaps another aspect that is

often overlooked

is that many people

who don't like the idea

of human evolution have been able to

discount much of the work we've done.

On the basis that it was built

on fragmentary evidence

iust little bits and pieces.

And who knows.

Those little bits of

bone could belong to anything.

To confront some of these people

with a complete skeleton that is

so manifestly human

and is so obviously related to us.

In a context where it's definitely one

and a half million years or a little

more is fairly convincing evidence.

And I think many of the people who

are fence sitters on this discussion

about creationism versus evolution are

going to have to get off the fence

in the light of this discovery.

A Homo erectus head would have

looked very different from our own.

It had a heavy brow ridge,

iutting face, and a smaller braincase.

It is very likely their skin was dark

nature's protection against

the tropical sun.

Some scientists believe Homo erectus

was the first hominid to hunt.

In earlier times our ancestors,

themselves prey,

were probably accepted without fear

at Africa's water holes.

But when they began to hunt,

the other animals would sense them

as a threat.

Exactly when hunting began may never

be known.

But it is clear that the tools made

by erectus were far more sophisticated

than any that had been made before.

Even the earliest and

most primitive tools marked

a momentous advance for humankind

the first evidence of culture.

And, as intelligence grew over time,

tools became ever more refined

and specialized.

Learning how tools

may have been made and used

provides a window into the behavior

of our ancestors.

Dr. Nicholas Toth of Indiana University

has become a master of the technique.

Many scientists had believed

that the obiective

of the earliest toolmakers was to

create these large cobbles

and that the chipped off flakes

were merely the debris.

Toth's experimentation led him

to conclude it was quite the reverse.

The razor sharp flakes, he believes,

were often the tools our

ancestors made and used.

If you take a hard look

at your average human being,

we're very poor carnivores.

We have small canines;

we don't have slashing claws;

we're not very strong;

we don't look anything like

a hyena or a lion.

And I think with

the simplest flake stone technology,

you can butcher an animal

from the size of a gazelle

to the size of an elephant

with absolutely no problem.

Even hyenas will not tackle

the biggest bones on a carcass.

But with the simplest tools used

like a hammer and anvil,

an early hominid could get

at the marrow inside.

Almost completely fat,

marrow is high in calories,

essential to a hominid roaming

the African landscape.

When an animal bone is butchered,

the edge of the tool leaves cutmarks.

Often ignored in the past,

cutmarks are now recognized as vital

clues to the behavior of early humans.

They can tell us, for instance,

which animals our ancestors ate,

which parts of these animals

they may have favored,

and ultimately they may reveal when

hominids became successful hunters.

In the past scientists often

suspected cutmarks were man made

if tools were found nearby.

Today they know many factors from the

natural world can plant false clues.

One factor not often considered came to

light in unusual experiment conducted

by Dr. Kay Behrensmeyer.

In Asia she had been puzzled

by grooves and scratches

on bones eight to

nine million years old,

long before hominids existed.

Later, in Africa,

she saw how bones frequently

are trampeled by migrating game herds.

Could random trampeling, she wondered,

leave marks that could be confused

with those made purposefully by a tool.

Dr. Pat Shipman of

Johns Hopkins University

has been experimenting

with cutmarks since 1978.

She believes that

by creating them herself

and examining them microscopically,

she and other can better define

what is a true cutmark and what is not.

Into a scanning electron microscope,

or SEM,

she inserts a gold coated cast

of the marks she has made.

Compared with regular microscopes,

the SEM offers greater depth

of field to look

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