A model of Lucy (left) and her mate. With 40 percent of her skeleton remaining, Lucy
gives us a glimpse of one of our oldest upright ancestors, A. afarensis, dating back
over three million years.
Tattersall’s sketch of our family bush.
Mystery hangs over the top skull: scientists are not sure if it is Neanderthal...
...as
below, or from a related species.
|
© Ian Tattersall
Specimen:
Ian Tattersall
Species: Homo sapiens
Age: 55
Origin: Born in England, raised in East Africa
Status: Curator of Anthropology at the American Museum of Natural History,
New York City
Personal evolution: Followed in the footsteps of his illustrious predecessor
Charles Darwin by studying at Cambridge University’s Christ’s College of where he
majored in anthropology and archaeology. However, he strayed from the path of human
evolution as a PhD student by leaping to the study of primates, notably lemurs (small
monkey-like creatures) in Madagascar as well as monkeys in Mauritius.
Distinguishing features: Two unusual traits resulted from time spent in the
jungle with our primate cousins: first, a critical eye to recognize the diversity
of our human ancestors; second, a deep respect for nature which has led to the conclusion
that his own species is a monster, whose ravenous appetite and irrational behaviour
imperils the world.
Historical significance: Leader of the camp to knock our species off the pedestal
of human evolution.
|
The
Homo sapiens skull above, found in South Africa, may be over 100,000 years old.
Below, the Nariokotome boy has yet to be definitively classified but seems to date
about a million years. |
A
world renowned paleoanthropologist cuts down old notions of our family tree to reveal
a host of unknown ancestors: extinct human species
Like most people,
I was taught to think of human evolution as a linear chain, with a “missing link”
connecting apes and a series of prototype humans in a process of perfection reaching
the pinnacle that we occupy today. This is the traditional view of paleoanthropologists,
veritable human fossil hunters who try to piece together our history. But the field
is now increasingly divided and you are seen as the leader of a new and growing camp.
Please explain.
This notion of human evolution as being a linear trudge from primitivism to perfection
is totally wrong. I came to paleoanthropology from the study of lemurs [monkey-like
primates] in Madagascar where you have a huge diversity of animals. You cannot help
asking, “How did these creatures become so diverse?” Yet this question is not asked
in paleoanthropology because there is only one species of humans today. Somehow we
believe it is normal and natural for us to be alone in the world. Yet in fact, if
you look at the fossil record, you find that this is totally unusual—this may be
the first time that we have ever had just one species of humans in the world.
We have a history of diversity and competition among human species which began some
five million years ago and came to an end with the emergence of modern humans. Two
million years ago, for example, there were at least four human species on the same
landscape. Maybe they got along by basically ignoring each other or even having peaceful
interactions. We don’t know.
In any event, we are now the sole surviving twig on a big branching bush produced
by this process of evolutionary experimentation. We’re not the pinnacle of a ladder
that our ancestors laboriously climbed.
How do your views on human evolution differ from traditional Darwinian notions?
According to Darwin, you have legions of organisms that over time evolve themselves
into a new species. It’s like a fine-tuning process, guided by natural selection,
in which the individuals best-adapted to their environment reproduce and pass on
their “favourable” characteristics, so that each generation improves upon its predecessor.
So we tend to think of evolution in terms of characteristics, rather than species.
For example, we speak of the “evolution of upright walking” or the “evolution of
the hand,” often without realizing that legs and hands can only be part of the story.
The reality is that natural selection is a blind mechanism which can vote up or down
only on entire organisms, warts and all. Individual organisms are mindboggingly complex
and integrated mechanisms: they succeed or fail as the sum of their parts, not because
of a particular characteristic.
It’s the same with populations and species. Species are out there competing with
others in a real world of limited resources. What’s more, the ecologies of which
they form a part have an alarming tendency to change abruptly. If your habitat is
covered by an ice sheet, it’s pretty irrelevant how well you are adapted to the meadows
and forests now buried beneath the ice.
Finally in the Darwinian notion you have a slow accumulation of changes over generations
leading to the creation of a new species [when individuals of the same lineage can
no longer reproduce]. However a population will change morphologically [biologically]
with time but this doesn’t necessarily lead to the creation of a new species. For
meaningful genetic changes to take hold, the population must be small. [The larger
the population, the more difficult it is for major genetic changes to spread.]
So why haven’t we seen this diversity in the fossil record? According to traditional
readings, there are about six or seven species of humans. Yet you argue that there
are at least 17 and probably more.
Paleoanthropologists have basically not paid enough attention to morphology when
comparing fossils and tend to overlook differences in the shape of the skull, for
example, the jaw or the spine. They seem to think that once they have measured the
age and the brain size of the fossil, they can shoehorn it into a particular species.
It is very clear that over the long haul, the brain size of hominids has increased.
However, this “trend” has distracted attention away from diversity and led scientists
to focus on continuity, thereby reinforcing the notion that our evolutionary history
has been one of a slow, single-minded progress from primitiveness to perfection.
In addition, paleoanthropology has been practiced largely by people who come from
a human anatomical background. So many don’t know what the rest of the living world
is like.
You’ve spent the past seven years travelling around the world with a colleague, Jeffrey
Schwartz, to study every major human fossil ever found. Why?
We started out looking at the Neanderthals, thinking “My God, the Neanderthals
have been known for 150 years now. What can we possibly find that nobody has noticed
before?” And the very first one we picked up we saw some structures inside the nasal
cavity that had never been noticed before. By extracting more information out of
the record, we hope to get a better idea of the diversity that exists out there.
I don’t think anyone has ever seen the entire fossil record. How did you get past
the politics in the field to gain access?
It is very difficult, especially for more recently discovered fossils. They are
often very personal discoveries and there is a tendency to say, “How can you make
comments about a fossil I found?” Also, most human fossils are found in the Third
World and are sometimes seen as bargaining chips for extracting money from Westerners.
There can be a tremendous amount of commissions, bureaux and administrative hoops
to jump through before you can get access to the fossils. But I have been very impressed
by the ways in which our colleagues have helped us. The whole process could have
been a lot more gruesome and a lot more expensive.
There’s a pile on your desk of about 2,000 pages describing the fossils which, along
with photos, will be published in a three-volume set beginning this March. The photos
alone will mark a major step in the field because most PhD students never even see
the fossils they study. Why is it so important just to describe, let alone analyze,
fossils that have been known for over a century?
One of the big problems has been that everyone describes fossils differently. They
use different terminologies that are all based on Homo sapiens and are not necessarily
appropriate for other kinds of fossil hominids. By using Homo sapiens as a kind of
reference point or template, the existing body of literature tends to distort the
fossil record. We’re describing everything the same way so that even if you haven’t
seen the original fossils, you can consult and compare these descriptions and come
to your own conclusions. For the first time, hundreds of fossils will be compatibly
described.
By studying lemurs, you may have developed the critical eye needed to recognize diversity
in human fossils. But can you hold up the skull of one of our ancestors, say a Neanderthal,
and really maintain the same detachment as when looking at a monkey’s skull?
I don’t think that you should look at a human fossil with a different eye than
you would use for any other fossil. They are both documents of species that have
now vanished. They are part of the world’s history of diversity. Besides if you study
hundreds of fossils, you don’t have time to ponder the existential aspects of being
human.
Some might argue that this detachment is your weakness. By focusing solely on biological
differences between fossils, you pigeonhole them into narrow categories that ignore
other factors, namely culture.
I don’t think that we’re excluding anything. But if you don’t start with morphology,
you’re going to be misled all the way down the line. Once you have a systematic structure
into which to place your species, then you can mix in everything else—like the tools
that they used or their settlement patterns.
Do you ever find it surreal to try to piece together such a vast history with such
meagre clues—bits of jaw here, some brain case fragments there? It must take a solid
ego to come to a firm conclusion.
No, because you’re not creating anything. You’re doing your best to reconstruct
evolutionary history and you know that science in general is a system of provisional
knowledge—it’s not an authoritarian system of belief where you make “a” discovery
and that stays definitive for the rest of time. All that scientists know is that
what we believe today is probably not going to be what we believe tomorrow. Science
is grounded in doubt.
But some people are more willing to accept this provisional nature than others. You
probably have colleagues fuming with your ongoing list of human species.
It’s just because they’re not used to it. It’s hard to convince people to reconsider
fossils they thought they have known for over 30 years. But they are more flexible
with new fossils because they don’t have any received wisdom about species no one
knew existed before.
This seems to be the heyday of geneticists. There is a strong feeling that if they
can just manage to extract the DNA from human fossils, we will finally get to the
bottom of our evolutionary history. Do you think genetic research will transform
the field of paleoanthropology?
My feeling is that the two sets of data are still pointing in the same general
direction of multiple human species. And that is comforting. But there are paleoanthropologists
out there feeling depressed and saying, “Oh God! Our data don’t have the resolution
that molecules have and we should always believe molecules above morphology.” But
I don’t think that is true. There are no magic bullets. We can widen the field with
genetic and isotope studies but we will learn the most by persuading people to look
more closely at the existing fossils.
A battle is raging between sociobiologists and cultural anthropologists. Basically,
sociobiologists believe that humans all share some kind of essential nature shaped
by evolution. Cultural anthropologists, in contrast, vehemently reject universal
statements about human nature and focus on local context in explaining our behaviour.
Where do you stand?
I’m not certain about what the cultural anthropologists stand for. But the general
feeling is that history is driven in some way by cultural factors. Yet I see a lot
of randomness and contingency in history.
On the other hand, these evolutionary psychologists [sociobiology applied to our
species] are completely misled. For example, say they want to explain something like
violence. They will treat it as a separate category and then develop just-so stories
as to why that particular characteristic emerged in evolution, all the while forgetting
that any characteristic is embedded in a very complex organism.
You’ve raised the issue of violence. Why do you think we have a tendency towards
aggression? Why can’t one generation learn from the next and avoid conflict?
We are psychologically so complex—or perhaps screwed up—at least partly because
of the way in which our brains were built up over the ages, structure on structure.
While the old notion of an inherent conflict between older and newer brain structures
and functions seems oversimplified, it is self-evident that it is in our controlling
organ, the brain, that we must search for the keys to the contradictions that we
all exhibit, every day.
Hold on. I thought you just rejected the evolutionary biologists’ penchant for looking
to biology to explain our behaviour.
In my book Becoming Human, I write that it may seem odd to devote hundreds and
hundreds of pages to ways of looking at the fossil record and then conclude that
you cannot learn much from it about how people behave today. If you really want to
understand what humans are, don’t look to the past, look to how people are in the
present.
Not only do we look to the past to understand the present but we project the present
on interpretations of the past. For example, the Neanderthals are veritable icons,
yet they were just one actor on a huge stage. How do you explain this emotional attachment?
Neanderthals were very happy living in Europe for 200,000 years and suddenly
modern Homo sapiens show up and BOOM! They’re gone. So to make it more palatable,
some people have been suggesting, “Well, maybe they were just genetically swamped
by hordes of invading modern humans.” I don’t think that can possibly have been the
case. Neanderthals and modern Homo sapiens are just too different to have interbred
successfully. But if it makes people feel better about poor old Neanderthal being
genetically swamped than physically annihilated, then so be it.
One thing truly sets us apart from every other species: consciousness. Human consciousness
has been described as a kind of inner eye, which allows the brain to observe itself
at work and therefore permits us to have the complex interpersonal relationships
that far exceed those of any other animal. Modern human anatomy goes back over 100,000
years but it wasn’t until maybe 40,000 years ago that modern cognition suddenly burst
on the scene, as evidenced by the cave art of the Cro-Magnon, for example, in Europe.
What triggered this cognitive explosion?
It is impossible to be sure what this innovation might have been, but the best
current bet is that it was the invention of language. For language is not simply
the medium by which we express our ideas and experiences to each other. Rather it
is fundamental to the thought process itself. It involves categorizing and naming
objects and sensations in the outer and inner worlds and making associations between
resulting mental symbols. It is impossible for us to conceive of thought (as we know
it) in the absence of language, and it is the ability to form mental symbols that
is the fount of our creativity, for only once we create such symbols can we recombine
them and ask questions like “What if…?”
Why haven’t other species developed spoken language?
Many species have very complex vocal, gestural and scent-based systems of communication
but even in the great apes, vocalizations seem limited to expressing emotional states.
We have managed to separate vocal sounds from emotion, and instead to attach them
to symbols that we form in our minds. As far as we know, this is a unique ability
that was only relatively recently acquired. In fact, if we were to set the evolutionary
clock back only a few hundred thousand years and run the whole process all over again,
it’s not clear to me that we could necessarily expect to see a linguistic Homo sapiens
emerge again. There is just so much randomness in nature.
Do you remember the first time you entered the cave of Lascaux in France? The art
inside dates back about 30,000 years ago.
I’ve never had a more profound or powerful experience. It is such extraordinary
art in such an extraordinary environment—the age is only a secondary part of that
experience. This symbolic activity appeared so suddenly: art and carving, engraving,
notation music, people decorating their bodies and burying each other in elaborate
styles and so on.
You’ve maintained that this kind of symbolic activity was for the most part reserved
to Europe. Perhaps it was occurring elsewhere in Africa or Asia but just slipped
through the cracks of a sparse fossil record? You could be accused of Eurocentrism.
We have some early hints in Africa of humans transporting exotic materials over
long distances, some traces of flint mining and 50,000-year-old ostrich eggshell
beads and so on. People may have even been navigating to Australia 60,000 years ago.
These are all things that probably required the same kind of cognitive apparatus
that produced Lascaux. But the record is tantalizingly poor.
This isn’t to suggest that any of this cognition and creativity originated in Europe.
Apparently the first Cro-Magnon brought these capacities with them but from where
we don’t know. It may well have begun in Africa. But right now, the best record that
we have is in Europe. And that’s why it attracts so much attention. Hopefully, we’ll
be learning more from other parts of the world as we make more discoveries.
You’ve suggested that the art at Lascaux reflected a body of mythology, a view of
the world and humanity’s place in it. Do you think this thirst or quest to understand
our origins is a distinctly human trait?
Oh yes. This intense curiosity about our origins, this intense need to know “why”
is a profound part of us. I think the bottom line is that the ability and desire
to ask these questions are deeply embedded in the human psyche. We are trying to
satisfy this curiosity when we study human evolution. Indeed we may not be learning
nearly as much about ourselves as we think we are.
For many people, the ultimate question is whether primitive man was more noble or
“better off” than civilized man. In your opinion, did a state of grace, so to speak,
exist before or after the advent of civilization as we know it?
(Burst of laughter) First, a state of grace is a concept which humans devise
while knowing that it doesn’t exist. Most of us are in states of disgrace and always
shall be.
Second, ethics are all products of the human mind. We cannot derive any concepts
of morality or of natural law from contemplating nature. The reason why is that nature
is indifferent to individual suffering or success and to call such indifference amoral
would be to anthromorphize.
Human evolution has come to a standstill, you say. We haven’t really changed since
acquiring cognition and we cannot expect any major innovations in the future. What
is holding us back?
You’ve got to have small populations in order to get meaningful genetic innovations.
The population is getting larger all the time, individuals are infinitely more mobile
now and the prospect of isolation of populations is lower than it ever has been.
We can imagine some sci-fi scenarios of isolated space colonies but they would inevitably
be sustained by a lifeline from Earth. Or we can imagine genetic engineering. However,
artificially produced genotypes could only be sustained by sequestering “engineered”
individuals which I doubt and hope would never be deemed permissible. But if it was,
these genetic innovations would remain only among these small “laboratory” populations.
So to hope that a bit more evolutionary fine-tuning will solve our problems is foolish
optimism. We have to cope with ourselves as we currently cope with the world and
the problems that we cause in it. We have reached a pinnacle in the sense that Homo
sapiens is truly something unique. Whether you think it is superior or not is up
to you. I suspect that if other species were capable of contemplating this question,
they would not conclude that we represent a pinnacle.
In the world’s richest, most industrialized country, the United States, a debate
rages over the teaching of human evolution in highschools. The “creationist” movement
wants to impose Biblical scriptures in the classroom. Has this movement hampered
your work? The Internet has a long list of sites in which creationists not only attack
your work but also pray for your soul.
It’s absolutely appalling. This is the only country where this is happening.
It’s due to a certain group of fundamentalist Protestants who seem to feel that human
beings need the word of God in order to behave properly. They’re threatened, insecure
and looking for a scapegoat.
I get an occasional letter from creationists who are very concerned about my soul
and insist that I follow the “true path.” But I’ve never received any threats or
felt any restrictions in my work.
For a man who studies dead people, you seem to go out on a limb politically. You
cannot avoid the ire of the creationists but you have gone a step further by writing
that attempts to limit women’s reproductive rights are “the ultimate example of human
hubris” at a time when global human population growth is causing ecological havoc.
Why go so far?
I just draw conclusions on the basis of what I see around me in the world as
a human being, not as a paleoanthropologist. I’m concerned about this emphasis on
the quantity of life because it’s ultimately going to have a deleterious effect on
its quality. There are three times as many people in the world as there were when
I was born. But it cannot go on indefinitely… |
