Natural Science Forum / Biology / Paleontology / May 2005

Nothing stays the same

Palaeoanthropologist Chris Stringer pieces together the few
clues we have about the history of humankind and reminds us that
we're not the summit of evolution and that there's more to come
By Tim Radford
THE GUARDIAN
Tuesday, May 24, 2005,Page 16

To a palaeoanthropologist, the past is an open book, but one
that fails to tell the whole story. The covers are missing. The
first chapters may never be found. There are hardly any pages,
and most are so smeared and crumpled, so foxed and faded, that
the text could mean almost anything. The cast of characters is
confusing and narrative thread anybody's guess. Its authorship
is the subject of political debate in the US, the beginning is
the stuff of fantasies, and even the latest chapters are
entirely provisional. Is it a detective story, a cliffhanger, or
a romance? Can there be a happy ending?

There is a story-so-far, but that potted version of events is
forever being revised, and nobody knows that better than Chris
Stringer, one of the authors of a book published last week
called The Complete World of Human Evolution.

Complete? Stringer spent eight years on the text. In the course
of it, he had to contemplate plot lines that incorporate
unexpected characters, teasing bits of evidence and relics of
ambiguous adventures from the sere soils of Africa and the
limestone caves of Europe. Then, late last year, he had to sit
down in one night and compose an entirely new chapter to
incorporate the discovery of Homo floresiensis, also known as
the Hobbit.

Homo floresiensis was the mysterious survivor unearthed from a
cave on the island of Flores in Indonesia. It was a pygmy
descendant, perhaps of Homo erectus, perhaps even connected to
an earlier human species, but with this special feature: The
bones were only 18,000 years old. So Homo sapiens, Homo erectus,
Homo neanderthalis and Homo floresiensis must have all shared
the planet at the same time, tantalizingly recently, within the
last 100,000 years perhaps. Now only Homo sapiens survives.

What stories could those bones tell? And who could have dreamed,
before their discovery, that some tree-climbing,
pygmy-elephant-hunting human candidate could have survived on a
tropical island while Homo sapiens moved into the Fertile
Crescent, preparing to invent agriculture, civilization and
global

Stringer, 57, is head of human origins at the Natural History
Museum in London. One of palaeoanthropology's big players, he
has spent his career in pursuit of Homo neanderthalis and is
also one of the great proselytisers of the "out-of-Africa
theory," the one that says the human story begins on just one
continent. Homo floresiensis, however, astonished him.

"Until that turned up, we had no idea that ancient humans had
ever reached as far as Flores. We certainly had no idea that
there was a completely new kind of human -- or is it even human?
That is still being argued about -- living there, and the fact
that it was still around there when modern people passed through
the region. Each of those is astonishing and that shows how
little we knew about human evolution in that part of the world.
We are building up pieces of a huge, complex jigsaw, and we
still have a lot of spaces to fill in," he said.

"Nature is constantly experimenting. I think a lot of people
thought that humans were somehow different, that we had this all
embracing culture and this unifying adaptation, that meant that
human evolution progressed in a somewhat different way, because
of our technology and the way we probably vainly think we are
partly controlling the world now. So people project backwards
and think humans are somehow special. The evidence shows us that
our evolution was as complex and as undirected, I suppose, as
that of any other species we have studied."

Here is the orthodoxy, pieced together over a century or more by
Darwin's disciples: Primate creatures with a capacity for
walking upright emerged perhaps 20 million years ago. From these
emerged the ancestors of all gorillas, all chimpanzees and all
humans. There is no line of evolution; think, instead, of
foliage, and the surviving humans and two species of chimpanzees
are just nearby buds at the ends of twigs close together on the
tree of life.

Nobody knows with any real confidence where to put the other 20
or so extinct candidates -- half of them found in the last 10
years -- that can be classed as humans or proto-humans. Nobody
knows much about what they were like or how they coped.

Brain size expanded, perhaps because of increasing social
interplay. Stone tools emerged. Fire was employed. Weapons and
cooperative hunting became evident long before Homo sapiens.

Modern humans probably popped up within the last 200,000 years,
but the things that make modern humans so distinctive in the
fossil record -- symbolic art, pottery and jewelry -- bloomed
only about 50,000 years ago. Nobody in the world of
palaeoanthropology considers modern humanity to be the flower of
creation, either. A temporary bloom, maybe.

It's humbling, Stringer said.

"We shouldn't see ourselves as the summit of the perfection of
whatever evolution is trying to achieve," he said.

"We seem to be very successful at the moment in terms of our
numbers, but, looking at it on a geological timescale, how
successful will we look in 50,000 years, which is a very short
time, geologically speaking?"

Genetic evidence suggests humans may have come close to
extinction a number of times in the past. Modern humans shared
the Middle East with Homo neanderthalis 120,000 years ago and,
as Cro-Magnons, became the sole tenants of Europe 30,000 years
ago, a terrain held successfully by the Neanderthals for more
than 100,000 years. Did they compete? Did they co-exist? Did
they trade or cohabit?

Stringer's devotion to the Neanderthals began with a primary
school project and continued with a body of groundbreaking
research that ultimately earned him a fellowship of the Royal
Society.

"OK, why aren't they here now, and why are we here?" And did we
have a role in their extinction?" he asked.

And how different were the Neanderthals anyway? Sixty years ago
a US scientist said that if a Neanderthal, shaved and dressed,
got on the New York subway, nobody would bat an eyelid. That,
says Stringer, tells you more about New York than about the
Neanderthals.

Stringer prefers an observation by the geneticist Steve Jones,
of University College London, who said that if you were on the
Tube and a Cro-Magnon got on, you might move seats. If a
Neanderthal got on, you might change carriages.

"Neanderthals were certainly human and evolved as us in their
own way, but they were different. They had several hundred
thousand years of evolving their own anatomy and behavior. But
when these people met in Europe. would they have seen each other
as people? Or as someone different?" he said.

"I still tend to the view that the primary message would have
been different. They would have had a different body language, a
completely different way of communication; they would have had
different behaviors."

He thinks the Neanderthals perished at a moment of maximum
stress in the stop-go, hot-cold pattern of climate during the
last ice age.

Though they left their mark in the Pyrenees, they never got to
Britain at all. But then the human occupation of Britain is
itself a bit of a riddle. Boxgrove man, whoever he was -- Homo
ergaster? Homo heidelbergensis? -- got to Boxgrove near
Chichester, hunted, chipped flints and butchered a rhino. They
may not have killed the rhino -- a very dangerous adventure --
but even if they were just scavenging, it must have taken some
degree of cooperation and organization to have driven off the
lions, or wolves, and secured the carcass for themselves. And
then Boxgrove man and his tribe departed, leaving one human shin
as evidence that they walked in and walked out.

There was evidence, most of it indirect, of little pulses of
human occupation, and then a gap of 100,000 years when no humans
appeared to have visited Britain at all. At times, the country
must have looked like the plains of Africa -- hyenas, rhinos,
lions, red deer and so on -- and, at others, like the tundra,
but although the animals came and went, humans did not. Modern
humans finally moved in and stayed only 12,000 years ago.

Stringer and his co-author Peter Andrews -- a former head of
human origins at the Natural History Museum and an expert on the
early part of the human story -- tried to tell the story of
human evolution not just through time, but through its context:
How you set about excavating a site, what a piece of tooth or
jaw can tell you about ancient human behavior. In that, the
title means what it says: Complete.

How much more is there to tell? The past will also reveal more.
The future, paradoxically, might not. Modern humans, after such
a short time on Earth and so many adventures, could have nowhere
to go.

"With our behavior and global warming and so on, we could be
writing ourselves a suicide note. But if humans do get through
that crisis and carry on, evolution is continuing. And under the
skin, in our genes, it is certainly continuing, and will
continue," Stringer says.

"So in the long term, of course, we will evolve and
change.That's the nature of evolution. Nothing stays the same in
the long term. We may look the same, but under the surface the
genes are evolving and changing. That will go on."

CHRIS STRINGER'S LIFE AT A GLANCE

Education: East Ham Grammar school; anthropology at University
College London; PhD at Bristol University in 1974.

Career: Joined Natural History Museum in London in 1973; author
of 200 scientific papers and co-author of three books; director
of the Leverhulme-funded Ancient Occupation of Britain project.

Off-duty: Has a daughter and two sons; listens to Shostakovich,
Vaughan Williams and Joy Division; enjoys astronomy and
supporting West Ham.

They say: ``Stringer is the very antithesis of the drawling,
lackadaisical, elegant, upper-class Englishman for whom
appearing to work too hard is `bad form.' To Stringer, bad form
is doing sloppy science or being too lazy or mentally hidebound
to get at the truth.''

Erik Trinkaus and Pat Shipman, The Neanderthals (1993)

He says:
``That's what science is about. You ask questions all the way
along and you find out that the answers are wrong, and that's
good because you can ask another question.''

The Complete World of Human Evolution by Chris Stringer and
Peter Andrews is published by Thames and Hudson

http://www.taipeitimes.com/News/feat/archives/2005/05/24/2003256469

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Posted By
Robert Karl Stonjek