Paleoanthropologist Tim White

DATE June 18, 2003 ACCOUNT NUMBER N/A
TIME 12:00 Noon-1:00 PM AUDIENCE N/A
NETWORK NPR
PROGRAM Fresh Air

Interview: Professor Tim White discusses the recent find of
hominid skulls in Ethiopia which give new clues about origins of
humans
TERRY GROSS, host:

This is FRESH AIR. I'm Terry Gross.

You may have read the news about the three ancient skulls, over 150,000 years
old, that were discovered in Ethiopia and gave us new clues about the early
origins of human beings. My guest, Tim White, is the paleontologist that led
the team which made the discovery. White is a professor at the University of
California at Berkeley. He has co-directed research projects in Ethiopia
since 1981. He works in a rift valley that was formed 30 million years ago
when the Earth's crust there cracked. It's known as the Afar Triangle, or
Afar depression. White has made several discoveries in Ethiopia of hominid
fossils that advanced our knowledge of evolution. Hominids are the beings
that evolved after the split with the last common ancestor that we share with
chimpanzees.

Let's start with White's latest discovery, the skulls. What do they tell us
about the evolution of our form of hominid, the Homo sapiens?

Professor TIM WHITE (University of California at Berkeley): Well, for a long,
long time people have been wondering where anatomically modern people come
from? That's sort of the last step in our evolutionary journey. There were
forms found in Europe known as the Neanderthals, and these have centered in a
debate on human evolution for about a century and a half. It turns out that
the Neanderthals are a specialized European side branch, and it turns out that
our own ancestors, Homo sapiens, the earliest Homo sapiens, are African. And
we've known this for about the last 20 years; as the genetic data have come
in, they've pointed to Africa.

But the genes can't tell you about the anatomies or the behaviors, the
lifestyles, of these ancient people. You need evidence for that from the
fossil record. And the Afar Triangle in Ethiopia is a place that has now
yielded that evidence at a really key time period that was previously sort of
a blank. It's 160,000 years ago, or roughly 10,000 human generations, and
we've now recovered the remains of these people, not only the adult, but also
a child's cranium that tell us a great deal about the anatomy of these
earliest Homo sapiens.

GROSS: I think a lot of us grew up thinking or learning in school that our
descendants were the Neanderthals, so that's not true?

Prof. WHITE: Well, the Neanderthals were found first, in Europe, but it turns
out that they go extinct about 30,000 years ago, and the genetic data for the
last 20 years have been accumulating and pointing to Africa as the source of
our own species. The problem is, we haven't had a fossil record. Now we have
found people who look very much like you and I who are much older than
Neanderthals, and show that our roots lie outside Europe, and that
Neanderthals evolved in Europe as a special cold-adapted form, a very, very
close relative of ours, but not a direct ancestor.

Most of my colleagues see the strange body forms and strange cranial form of
the Neanderthals as something related to a cold adaptation. I think the thing
that's important to remember here is that Europe was periodically refrigerated
during the last million years. Large portions of Europe were buried deep in
an ice sheet at the same time that our ancestors were living in Africa on the
shore of this tropical lake, butchering hippopotamus.

GROSS: So when you're talking about cold-adapted species, you're not talking
about a foggy day in London town. You're talking about the Ice Age.

Prof. WHITE: That's right. The southern edge of that continental ice sheet
was a very tough place to live and the Neanderthals did so successfully for a
very long time, but eventually seem to have been replaced in western Europe,
and for this we have to think of western Europe as a peninsula, and the tip of
the peninsula is Portugal and Spain, and indeed, that's the very last place
you find Neanderthals at about 30,000 years ago. After that, there are no
more.

GROSS: Now you not only got evolutionary news from your digs about the
anatomy of man, but you learned about the behavior of our ancestors, our
prehistoric ancestors, and the information you've gotten from this isn't just
from this latest dig, it's from a whole series of digs that you've done in
Ethiopia over about the past 20 years. What are some of the behavioral things
that you've learned about ancient man?

Prof. WHITE: Well, we've been able to look at behavior not only from the
anatomy but also from the stone tools, the implements that people have left
behind on these ancient landscapes that have been buried and are now being
eroded and coming available to us to investigate. The very oldest
technologies that we find are, in fact, in this area and a study area just to
the north of us where we find basically broken rocks with sharp edges at
around two and a half million years ago.

The hominids employing those technologies had much smaller brains than ours,
much more primitive faces. They're placed in the genus called
Australopithecus, very unusual forms, bipedal but with brain sizes that are
only slightly larger than modern chimpanzees, and yet they were on very open
landscapes using these broken rocks to cut meat from carcasses and to break
into the animal bones to retrieve marrow. This starts at around two and a
half million years ago, and we have a succession of technologies that become
more and more sophisticated all the way up through time in this one region in
the middle Awash of Ethiopia, where we can calibrate that evolution of
technology and by the time you get to the uppermost layers, up at around
160,000 years ago, the people are making far more than broken rocks. They're
making very sophisticated stone tools known as hand axes. They're making
flakes in a very specialized preparation known as a Levallois technique where
a core of stone is formed and a single flake is driven off with a very, very
sharp edge. Often these are made on volcanic glass. So we can--in a sense,
we can recapture the evolution of technology by studying these sediments and
their contexts.

GROSS: Now one theory that I've read is when our ancestors start using tools
that allow them to eat animals, to butcher animals, that that helps increase
the size of their brains because the food is so rich in protein. And
therefore when these primitive tools are developed more tools start being
developed by our ancestors more quickly because their brains are developing
because of the ability to eat meat. Do you buy that?

Prof. WHITE: No, I don't. And the reason for that is that a large lion with
a very large brain would be a very scary thing, and lions eat lots and lots of
meat...

GROSS: Good point.

Prof. WHITE: ...and they don't have big brains like we do. I think it's
important to look at the context that these developments occur in, and that's
one of the things we do on this project. It involves a very large team of
people. We have geochemists, geologists, archaeologists all working together
to understand these ancient landscapes, not just the hominids that occupied
them but the entire ecological setting. And I think that we have to think
carefully about what a bipedal primate with small canine teeth and still a
rather small brain at two and a half million years ago was doing in an open
habitat messing around with large animal carcasses. This is a very, very
dangerous place to be in Africa because there are lots of large carnivores out
there. And so as this primate moved into that niche, lots of different new,
selective pressures came to bear on the primate, and I think that those
pressures are responsible over their succeeding two million years of
evolutionary time for producing a lot of the anatomical and behavioral changes
that we see in reading this geological record for human evolution.

GROSS: Do these anatomical changes include being able to run away quickly
from the beasts?

Prof. WHITE: In fact, we're not very good at running away from anything
compared to all of the other quadrupeds, and that's why, in fact, when you
look at mammals most of them are quadrupeds. So we tend to think of our
bipedality as something very special, allowing us to have freed hands to do
lots of things with, but, in fact, it's not very beneficial in terms of
locomotion.

GROSS: But it's helpful in creatively coming up with tools to kill the
animals that are about to attack you.

Prof. WHITE: Once you adopt handheld weapons and things like that, that's
certainly true. But this bipedality we've been able to trace now back in the
African record, back beyond four million years ago, and at that stage in human
evolution there were no stone tools. There were no implements whatsoever that
we have been able to recover from the record. So the origins of bipedality is
a major research question that we're still investigating. In fact, we're
working on a partial skeleton of a creature that lived 4.4 million years ago,
also from the middle Awash. So we have, in one region of Ethiopia, the
ability to examine human evolution from its very beginnings, the earliest
bipeds, all the way up to the earliest Homo sapiens, which are these recent
fossils from Ethiopia.

GROSS: Now you examined--correct me if I'm wrong here--the skeleton of a
Neanderthal that showed that there might have been cannibalism.

Prof. WHITE: Well, that's some work that I have done with a French colleague
at a cave site in southern France, and indeed in the archaeological record not
only of Neanderthals but also of humans--there's a cave site in South Africa
that shows this; there are many occurrences in the American Southwest among a
people known as the Anasazi that show this--we have evidence that human bodies
were processed, butchered and the bones broken to extract the marrow, the
cranial vault broken to extract the brains, and the discard of all of these
broken pieces of bone matching animal bones. And in those instances we have
inferred that cannibalism occurred, cannibalism, of course, being the
consumption of hominid tissue. And for these Neanderthals in southern France
it's pretty clear that what was going here was a form of cannibalism.

In the more recent discoveries, the ones that we've just announced from
Ethiopia, we can't make a statement as strongly about cannibalism because the
hominid remains themselves were found as isolated skulls on a landscape. They
were within about 200 meters of one another, and they show clearly that some
form of mortuary ritual was going on. Sometimes cannibalism is a part of
these rituals. We know that from looking at ethnographic reports in modern
people from places like Papua New Guinea.

But with the ones in Ethiopia we don't find that pattern of breakage and
discard with animal bone that characterizes other cannibalized assemblages.
Rather, we find some sort of a removal of the cranium from the body--we know
this because we found no other body parts with these ancient Ethiopians--and
some sort of a processing which involved the removal of tissues. And
subsequent to the removal of the tissue the cranium, the cranial base of the
child, was expanded to the point where bone was broken away to open up the
bottom of the vault, and then the cranium of this child was repeatedly handled
for some period of months or years before it came to be fossilized in this
sand unit. And so we're looking at some kind of a mortuary ritual that we
don't understand the full dimensions of yet. We don't have the rest of the
body, which would be critical in understanding what's going on with the whole
sequence of sort of ritual that's happening after the death of the individual.

GROSS: When you say mortuary ritual, do you mean something like ancestor
worship?

Prof. WHITE: Yeah. The place that we see this in the ethnographic record is
particularly in Papua New Guinea where a lot of people have heard about the
cannibalism there. These people did involve cannibalism in their mortuary
practice, and, of course, the kuru disease is one result of that. But the
bones themselves, after those rituals were completed, were kept around, and
they were sometimes placed on poles outside the men's houses. I've seen
photographs of individuals who are actually using the skull of an ancestor as
a pillow to sleep on.

And that sort of handling of the cranium involves sometimes decorations.
Sometimes they paint them. Sometimes they acquire a polish, and we see those
traces on these very early fossils from Ethiopia at 160,000 years ago. And
what that suggests to us is that there was some sense of a mortuary practice.
Whether you call it a religion or ritual, something was going on after the
individual was dead, and we really don't understand it. It's a sort of an
ancient mystery without very many clues, and we've just gotten the first ones,
and we may be able to figure out more about it.

GROSS: So cannibalism might not be a question of eating other similar
hominids to stay alive, but rather it might be a kind of almost spiritual way
of imbibing the remains of the dead to keep them around after they have
departed.

Prof. WHITE: Exactly. That's the kind of ritual cannibalism that we see most
often in the ethnographic record. And if indeed cannibalism were practiced in
the Ethiopian past of 160,000 years ago, that's probably what's involved. We
do know that these crania were removed from the bodies, manipulated, the flesh
removed from them and then handled quite a bit before they were buried in this
sand unit. And so that shows the earliest evidence of this concern with the
body after the death of the individual.

GROSS: My guest is paleontologist Tim White. He led the team of researchers
that discovered three ancient skulls in Ethiopia which reveal new clues about
human evolution. We'll talk more after a break. This is FRESH AIR.

(Soundbite of music)

GROSS: If you're just joining us, my guest is paleontologist Tim White, and
he led the team that recently found three skulls in Ethiopia dating back to
about 160,000 years ago.

Do any of the findings you have been responsible for contradict the way
Darwinian evolution was taught to you?

Prof. WHITE: Well, the way that Darwinian evolution was taught to me was in
the somewhat gradualistic mode, the idea that there was a progress, a gradual
acquisition of the various parts of our anatomy through time, and it all
pretty much came together. And my late colleague Steve Gould was perhaps the
best spokesman for a somewhat different point of view, that the evolution of a
species can take place not just gradually, but many times it can take place
where we have a stasis through time and then a rapid evolution into a
different form. And for the hominid fossil record, unfortunately the record
is not yet intact enough to test between those two models.

We no longer, because of the work of Steve and his colleague Niles Eldridge,
assume gradualism, but we're trying to understand exactly what the rate of
acquisition that various characters were. For example, we know now that this
peculiar locomotor mode that all humans employ today, walking on two
feet--very strange for a mammal to do--that this mode of locomotion has been
with us for the last four million years. And yet the other structure that
sets us apart as very unique among mammals is this very enlarged brain, which
actually didn't happen until the last million years.

So we have a mosaic happening. We have parts of the body evolving early and
parts evolving later. And in order to track this evolution through time, to
understand what actually happened in human evolution, we just need more and
more evidence from the fossil record. And that's, in fact, what this research
in Ethiopia is all about. It's designed to go out and acquire new evidence
from previously unknown time periods. It's sort of like an exploration of the
past without time machines. We use the fossils. We use the contexts that
those fossils were found in, and we're trying to bring back lost worlds and to
place our ancestors into those worlds.

GROSS: Is creationism having an effect on your work?

Prof. WHITE: No, it's not. Creationism is the notion that human beings were
created a long, long time ago and there hasn't been any evolutionary change.
In our work, we have a very interesting laboratory situation. We have the
ability to go back in time and actually test this model of creationism, and
what we have found is that it fails entirely. We should find, according to
the creationist model, human beings, modern people, all the way back to six
million years ago. And yet when we go to the deserts of Ethiopia and recover
these fossils, let me tell you what we find. We find at 160,000 years ago
some skulls that are human beings. They're a little bit different from
ourselves, a little more primitive.

We go back to half a million years ago and we have a form that has very large
brow ridges, a very projecting face and a smaller brain case. Not a modern
human by any stretch of the imagination. Now let's go back to a million years
ago, and a graduate student here at Berkeley, Henry Gilbert, found a Homo
erectus cranium, right in the same study area, in a different set of rocks.
This thing has a cranial capacity of only a thousand cubic centimeters. It's
about two-thirds as large. We go back to two and a half million years in this
study area. Do we find any modern humans? None at all. We find
Australopithecus. We go back to 4.4 million years ago and we find the most
primitive hominid ancestors ever found and we don't find any modern humans at
all.

And so what we're finding, the facts that are coming out of the sediments, are
completely at odds with the creationist model and completely concordant with
the Darwinian evolutionary model for human origins and evolution.

GROSS: So are you ever invited to debate a creationist, and do you
participate in those debates, or do you think it's not worth debating?

Prof. WHITE: Well, what we find is that the creationists have reached
conclusions. They're not interested in getting answers, as we scientists are.
They already have the answers. And that's fine because they're operating
really in the religious realm, whereas in science we have lots and lots of
questions and we seek to get evidence to answer those questions. There are
many scientists who are religious. There are many religious people who
understand the contributions of science. And it is only the religious
fundamentalists that refuse to accept the results that science brings us, at
least about our evolutionary history.

GROSS: Paleontologist Tim White led the team of researchers that discovered
three ancient skulls in Ethiopia which reveal new clues about human evolution.
He's a professor at the University of California at Berkeley. White will be
back in the second half of the show. I'm Terry Gross, and this is FRESH AIR.

(Soundbite of music)

(Announcements)

GROSS: Coming up, we continue our conversation with paleontologist Tim White
about his fossil discoveries in Ethiopia and what they tell us about the
evolution of human beings. And we remember the actor Hume Cronyn; he died
last weekend of prostate cancer.

(Soundbite of music)

GROSS: This is FRESH AIR. I'm Terry Gross, back with paleontologist Tim
White. He led the team of researchers that discovered three ancient skulls
over 150,000 years old in Ethiopia. These skulls give us new clues about
human evolution. White has been leading research projects in Ethiopia since
1981. He's a professor at the University of California at Berkeley.

Now the fossils that you've found that led you to be able to put together
these skulls, would those of us who are not trained in paleontology recognize
them as fossils, recognize them as bones if we had come across them?

Prof. WHITE: If you had come across them whole, sitting on the surface,
pristine and shiny, you'd have had no problem in recognizing them. The
problem is when these fossils erode onto the surface they break. They're
very, very fragile. They shatter into many pieces. Many of them are still
partially buried. And so it requires some special anatomical skills to find a
little piece and say, `Yeah, this one looks like a hominid cranial vault,'
rather than the hundreds of turtle shell fragments that you find out on this
landscape. And so that's why we have people on the ground, in the field, who
know how to recognize all the different kinds of mammals that we find.
Remember, we're finding literally thousands of fossils on any given day. Most
of them turn out to be crocodiles and fish and turtles and things like that,
but the people who find these bones can recognize even small pieces as
belonging to a hominid.

In the case of the two fossils that we've just announced in Nature, the
child's cranium had eroded out some years ago and was all broken, scattered in
many pieces, over 200 pieces on the surface, whereas the adult was still
embedded in the sand. But being imbedded in the sand, it was pretty much
covered and obscured by the sand. And it really wasn't until we got to the
laboratory and started to piece this child's cranium together that we saw the
humanlike conformation of the skull and the face. And as we cleaned the sand
away from the adult, slowly a face emerged. And it was a face that was very
different from the face of Neanderthals in Europe, who were contemporaries,
and very different from the face of earlier forms from even the same study
area in Ethiopia that are evolutionarily more primitive. This was the face of
a human being.

GROSS: Can you share one of your favorite discovery moments, where you or one
of your colleagues discovered a fossil that led you to uncover a very
important finding?

Prof. WHITE: Well, I'll just tell you the story of how this one happened.
The '97 season was an El Nino year. We were trapped in Addis Ababa because
the area we work in is very, very remote. It's in a lowland of Ethiopia; one
has to get there by driving a couple days. The first day you can drive on a
winding asphalt road. The second day you turn right and you drop into the
Great Rift. And it's a very steep, very rocky terrain until you get to the
valley floor, and then you hit the mud if it's been raining and you can't move
at all and you can't cross the rivers.

So we had to wait for these El Nino rains to stop. It delayed us in Addis.
We finally got to the field site. We were heading out to find a series of
bones out in the two-and-a-half-million-year-old deposits, and we came across
the Afar village of Herto, which is a nomadic pastoralist village. It was
abandoned that year. The people had moved all of their cows and their sheep
and their goats somewhere else. And that created a great opportunity for us
because all of the dust that you usually have in this area around the village
had all been washed away by the El Nino rains. And we saw a lot of stone
tools and fossils on the surface, and we said, `Yeah, we'd better come back to
this.'

But we were really keen to get to the two-and-a-half-million-year-old place,
so we drove on out there, did the work there. My colleague, Berhane Asfaw,
went back to Addis Ababa to get more food and fuel to run this operation in
the field and it rained again. So he was cut off up in the highlands, we were
down in the lowlands. It wasn't raining down there. It wasn't muddy, so we
could still move around on the outcrops and do our work. But one of my
colleagues, a French archaeologist from Marseilles, had to get back and do his
job. And so we said, `Well, you know, it's a long way to walk, Alban(ph).
You're going to have to go across the Awash River so you can reach the
asphalt, which is about a five-hour walk away, and hitch a ride on a truck to
get back to town to get on your flight to get back to Marseilles.'

And Alban agreed to all of this. So we took him out to the river in the
morning, and the local Afar people living there, who were working with us on
the site, bundled some papyrus reeds together with a nylon rope and put Alban
on the top of this thing. I was going to accompany him across the river and
the guy said, `You'd better not do that. You stay here.' And I said, `No,
no. Let me go with him across the river. He hasn't been to the other side
yet.' And they said, `No, if you go out across the river and the crocs get
you, who's going to pay us?' because they were my workmen.

So I said, `All right. All right. See you later, Alban,' and he left. And
he never got to see the skulls that we found about an hour later, because we
drove up to the Herto abandoned village, where we'd seen this hippopotamus,
started to survey and a Turkish colleague and one of the graduate students
here at Berkeley, David Degusta, found a little piece of cranial vault that he
recognized as hominid. And as we went back to that site and started to put
yellow pin flags in the ground, we saw the outline of the rest of the cranium
there in the sand.

And so we knew, based on the archaeology there, that we were in this critical
time period in Africa, between 100 and 200,000 years ago. We didn't know
exactly where we were in that period, and we didn't know exactly what that
face looked like. And to make a very long story short, the fossils were then
cleaned up, the sediments were dated, the archaeologists did their work, the
paleontologists did the identifications, we published the paper last week in
Nature.

GROSS: So it's really a mix of, like, hard work, scouting and serendipity.

Prof. WHITE: That's right. The last little, tiny bit is luck. Everything
before that is not luck.

GROSS: That's right. Right, right, right.

Once you realize you've made a really important discovery of a fossil-rich
site, what do you do to secure that site?

Prof. WHITE: The Afar people are nomadic pastoralists who live in this
region, and we work there with their permission. They allow us to camp near
the sites, and we work together with them on the sites in the excavations and
in the surveys on the surface. This research is all done under the permit
from the Ethiopian government, and that government is responsible for all of
the things that we find. So not only do they protect the sites, both the
Afar people and the government, but also the antiquities that we find are
worked on and kept in Ethiopia in Addis Ababa in the National Museum, where
they are, in fact, antiquities; they're national treasures.

GROSS: Is it ever difficult for you to connect at the same time with the
suffering during droughts or famines of the people of Ethiopia and the need to
kind of plunge into the distant past and excavate these ancient fossils?

Prof. WHITE: Well, the fossil record takes us back into the past, but it
never gives us a very complete documentation of what happened. It's sort of
like studying snapshots in time. And the snapshots that come out of Ethiopia
during times of drought involve people who are threatened; their very
existence is threatened, by a lack of rain, a lack of crops, a lack of food.
I think that the record thereby gets skewed, even in the modern sense, because
Ethiopia is this amazing, diverse, fascinating country and with a deep
cultural history and with amazing resources, in terms of the natural resources
and the human resources, in the country.

And so the picture that we have when the world turns its attention to Ethiopia
is not an accurate representation of what this country has to offer, and much
of what's there in Ethiopia is conditioned by the very forces that we study.
These geological forces are the things that led to the emplacement of this
unique fossil record that allows us to trace the roots of the modern African
landscape down into time, including the roots of our own ancestors.

GROSS: My guest is paleontologist Tim White. He led the team of researchers
that discovered three ancient skulls in Ethiopia which reveal new clues about
human evolution. We'll talk more after a break. This is FRESH AIR.

(Soundbite of music)

GROSS: Tim White is my guest. He's a paleontologist who led the team that
made the very recent discovery of skulls in Ethiopia that were about 160,000
years old that tell us a lot about the evolution of mankind.

How do you find a specific site? When does something become a site where you
start digging?

Prof. WHITE: We actually don't dig until we find something exposed on the
surface. So in a sense, we let the natural erosion of these sediments do the
digging for us. So the key thing is finding the sedimentary packages, and we
have a couple ways of doing that. The most effective is to look at the
imagery from aerial photographs and satellites to identify these rocks of a
certain reflectance. Of course, you don't know if there's anything in them by
way of fossils until you're actually out on the ground walking around with a
trained crew to see what's eroding out, and most of what erodes out is
crocodile and hippopotamus and fish because those live in environments that
lend themselves to fossilizing things very well. Occasionally, very
occasionally, one finds the remains of these hominids themselves.

GROSS: How do you look for those fossils that have kind of risen to the
surface, or that are on the surface?

Prof. WHITE: Well, some of them aren't very hard to find. The way that we
found this site is I was actually driving the car. I don't find many of the
fossils myself, but I work with a great team. And I was driving this vehicle,
looked out the window and saw a hippopotamus cranium eroding out. And this
thing is about 2 1/2 feet long, so it's hard to miss. And we got out of the
car and looked around. There were a lot of stone tools around it. So that
was not hard to find.

The hominid vaults that had broken and scattered on the surface were much
harder to find. Dr. Asfaw, my Ethiopian colleague, found one that's about a
square inch of the side of the cranium of the child. And then we had to do a
very large operation to collect all of these broken pieces. We run them
through a 2-millimeter sieve and recover all of them. And, of course, if you
get the odd tortoise scutes and so forth that you take out, and then you put
the rest of this back together to make up the fossil that ultimately gets
published.

GROSS: Is your work very seasonal? Are there periods when there's too much
rain, or it's too hot, and you just can't do you work?

Prof. WHITE: Well, it's always too hot, and that's because we're so low in
elevation. We're down there deep in the Rift, one of the hottest places in
the world, in fact. But our biggest problem is rain, because we're way
off-road. We use SUVs, and we need the SUVs, and they're always in four-wheel
drive unlike most of them on the roads in the United States. We reach the
edge of the asphalt and drive for about eight hours to get to the field site,
across rock and through mud and across rivers.

The problem is when it rains in the highlands of Ethiopia, these rivers fill
with water and we can't get the vehicles across them. When we tend to go is
November, December and January of each year, when it is the driest in the
Afar. This particular year, in '97, where we found all these hominids, it
was raining a little more than we had hoped, and that's why we couldn't get to
the field for such a long time that season. But when we finally did, we saw
that there'd been a lot of erosion due to the rains out there, and that was,
in fact, a sort of bumper crop of new fossils on the surface.

GROSS: Once you find a site, do you put something over it to protect it from
future rains?

Prof. WHITE: Well, only if we've excavated it and disturbed it. Then we'll
cover it with rocks and inform the local people so that they can watch it and
protect it. Since most of our work is just walking across the ground and
finding these fossils as they erode out, we don't alter things very much.

GROSS: Do you think you see yourself any differently that you used to because
of everything that you're learning about our hominid ancestors?

Prof. WHITE: I think that what this study does more than anything else is to
really inform you about the extreme brevity of our lifetimes when compared
with the enormity of the geological record.

And we speak of these hominids at 160,000 years ago as if they're recent. And
geologically, they are recent, but if we think of this in terms of
generations, these Ethiopians lived 10,000 human generations in the past. And
what that would mean, if I were to sort of describe that to you, I'd have to
say, great-great-great-great-great-great-great--and I'd have to say it for 40
minutes to get through all of the generations to get back to these, our most
recent of these hominid ancestors.

GROSS: So it makes you feel like your life is about the length of a finger
snap.

Prof. WHITE: It puts it all in perspective; yes, indeed.

GROSS: So what's next for you? What's the next work that you're doing?

Prof. WHITE: Well, we have a study area that is so incredible because of the
great time depth that it offers us. We're always busy on one aspect or
another of this study area, so we're going to target two things for next
season. One is a new lava flow that we've found with animal bones underneath
it. And we've just gotten the dates from this lava flow from the Geochron
Center here in Berkeley. It comes in at six million years ago. So this
affords us a chance to go back beyond the six-million-year mark; a very, very
interesting time period, very close to the time that we split from the
chimpanzees.

And the other time period that we're interested in is around a quarter of a
million years ago. We've located a body of sediments up in the north of the
study area. We have a lot more dating, a lot more field work to do and we're
hoping to find the ancestors of these Herto people in those beds. We're very
interested to see what happens if we can fill that gap in the fossil record.

GROSS: One last question: When you're working in Africa and you see a
rhinoceros or a hippopotamus, do you feel like you are seeing an ancient
animal?

Prof. WHITE: No, not really. When you work in sites that have a lot of
wildlife, for instance, down on the Serengeti, you realize the power of the
fossil record in connecting these animals with their ancestors. We found
footprints of giraffe at this site of Laetoli in Tanzania, and we would look
up from that excavation and see modern giraffes crossing just in front of us.
And then as we were excavating the hominid footprints, we realized we were
looking at the footprints of ancestors who, if they had walked by today--well,
actually, they do walk by today; that's us. That's all about us. And so
that's the power of this fossil record is not only does it inform you about
hominid evolution, but it informs you about the evolution of the entire
African fauna.

GROSS: And so rhinoceroses don't seem any older than, say, giraffes or any
other animal, including hominids?

Prof. WHITE: Well, the interesting thing about us and these hominid ancestors
is they are really, really different from you or I. You would not invite the
four-and-a-half-million-year-old Ardipithecus to dinner. All right?

(Soundbite of laughter)

Prof. WHITE: And yet when you look around at the hippos, they're fully
recognizable at 4.4 million years ago as hippos, and you would probably not
look twice.

And so what that is telling us, of course, is that the hippopotamus hasn't
changed all that much, but human beings have changed a great deal over the
last four million years. We have turned from a creature that is effectively
an ape on two legs to what we are and who we are today. And the process of
that change, that evolution, is what we're really interested in studying. And
the past doesn't yield very many clues. You have to go to special places to
find leftovers of that past. And it just turns out that this part of Ethiopia
is a very, very special place in a very special country that allows us to get
that knowledge to learn about these ancestors who were so different in our
case from ourselves.

GROSS: Thank you so much for sharing some of your findings with us. I really
appreciate it.

Prof. WHITE: Thank you.

GROSS: Paleontologist Tim White led the team of researchers that discovered
three ancient skulls in Ethiopia that reveal new clues about human evolution.
He's a professor at the University of California at Berkeley.

Coming up, we listen back to an interview with actor Hume Cronyn. He died
Sunday at the age of 91. This is FRESH AIR.

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