Read an Excerpt

The Wild Life of Our Bodies

HarperCollins

Chapter One

The Origins of Humans and the Control of Nature

In the summer of 1992, Tim White saw the remains that
changed his life. The first thing he saw was a tooth, a single molar.
And then as he approached the spot in the clay bed, there was more.
He could not be sure what he was looking at. They could have been
the remains of a dog almost as easily as those of a teenage girl. He
could not even be sure whether there was just one body or several.
A search party was staged and every bit of potential evidence began
to be collected. Soon, a little farther away, other clues were discovered
—more teeth and an arm bone. The flesh was long gone, yet in
their precise geography, these parts seemed to tell a story.
White stepped back from the bones and walked around them
to gain perspective. The more he looked, the more he was able to
sort out what he was seeing. But it took time. It was not until 1994,
two years later, that enough bones turned up to reconstruct the body,
or at least more of its parts. Ultimately, several individuals would
be discovered, but it was this first one that called to him. All these
years removed from her last breath, she still commanded attention.
He could scarcely look away. She stirred a feeling in him—maybe it
was the heat mixing with his ego, a kind of psychological indigestion
—yet he began to imagine it was something else. Every scientist
who studies fossils hopes that one day his walk in the desert will be
interrupted by a find everyone else missed, a find so important that
the desert itself seems to increase in worth. With time, White began
to believe that this was what had happened to him.

Tim White, a professor of biological anthropology at the
University of California, Berkeley, has been working with the bones
of human ancestors and other primates for decades. He knows the
bones of monkeys, apes, and men as intimately as anyone knows
anything. He has run his fingers over millions of bones, drawn
them, tapped them, dug them out. Time and intuition suggested
to White that these bones in the sand were not quite a woman. Nor
were they quite an ape. White could not prove where they belonged
on the tree of life, not as they lay disordered in the desert, but he
felt in some deep and primitive part of his brain that they were
significant. Not the missing link connecting humans and apes, but
something more. Perhaps they were the bones that made the entire
search for a missing link irrelevant. So much of fossil work has to do
with native intuition, sorting the ordinary from the extraordinary
upon a quick glance or a feel. White's gut knew this was extraordinary.
The skull was unusual. The feet were unusual. And when
White and his colleagues looked at the sediment in which they
were found, it was a thin layer sandwiched between two volcanic
events, events of known ages, between which played out the life of
their quarry, a life whose date of birth was 4.4 million years ago.

The bones had been left there long before the origin of humans or
that famous fossil Lucy, on which so much of our existing under-
standing hinged. If White was right, this find would immortalize
him. If he was wrong, well, he might be just one more anthropologist
left half mad in the dust of his own imagination.
Certainly there were things that pointed to White's madness.
The odds of finding a fossil as unique and important as he thought
this one might be were extraordinarily low, a billion to one, if not
worse. Yet, if White was looking for affirmation, he could also find
it. The context of this discovery alone suggested he could be on to
something. He and his colleagues were working in Ethiopia's Afar
desert. Their site, called Aramis, was not far from a place where
other early-hominid bones had been found in 1974. Nor was it far
from where he and colleagues had discovered the very earliest bones
of humans, some 160,000 years ancient. If White was going to
excavate these bones, he wanted to do it right. "Right," though, is
expensive in both time and money. The temptation to do it quickly,
to make a surgical but dirty strike, would have been great. He
resisted. Credibility in the study of human evolutionary history is
hard to come by but easy to lose. What would come next—the
many tiny bones and fragments of bones, each one picked from the
ground, treated, and pieced together slowly and carefully—would
have to be done perfectly. A single fragment of jaw would come to
occupy months of an anthropologist's time. A shard of pelvis, weeks
more. And there were just so many bones. It seemed as if this body
had been trampled on by ancient hippos, only to be punished a little
more each year by the grinding movement of the earth, the tunneling
of termites and ants and, more simply and less forgivingly, the
passage of time. These bones had 4.4 million years to fall apart. He
hoped it would not take quite that long to put them back together.
All of Tim White's assistants and all of his colleagues struggled. It
was not just that the bones had been smashed to pieces. The pieces
themselves were brittle. When handled incautiously, they would
turn to dust. A few did.
One hopes for a breakthrough, a great and leaping moment
of "Aha!" None came. White published a small paper on the find
in 1994, more to spray his territory than as a revelation. At that
point, nothing yet seemed done. What seemed particularly
unresolved was the broader story of who these bones belonged to—
what she ate, how she moved, and, more generally, how she lived.
White and his colleagues would have to have all the bones in
place to see that. Once they did, they would be able to compare
this skeleton to other younger ones and, of course, to their own
bodies. What White and company wanted to see were the differences.
White thinks it was actually trampled by hippos, literally.
Some things in particular would be telling: the size of the
skull and hence the brain, the shape of the hips and thus how this
woman walked, and the feet. (It could be said that biological
anthropologists have a thing for feet; the point of a toe can mean
the difference between a foot that clings to a branch and one that
sprints.) Nor were the intricate bones all that White and his crew
sought. They also gathered the other fossils they found around this
woman, all of them—other animals, even the remains of plants.
They wanted to see this whole world for what it was, whatever
that might be. Jamie Shreeve, a National Geographic editor, has
described White as being "hard and thin as a jackal,", but maybe he
is more like a hyena, an animal that gathers all that it can from
each broken-down piece of bone.
White and his team scarcely talked to anyone about what they
were doing. No one outside the group knew exactly what had been
discovered. Details were leaked one year to the next, but the
details seemed to conflict, almost as though false clues were being
left intentionally. Meanwhile, what White was beginning to think
was that the woman in the sand—Ardi, as he would affectionately
come to call her—was the earliest complete skeleton of a human
ancestor.6 If so, hers would arguably be the most important hominid
fossil ever discovered. This was enough to keep White ardently
at his work. In fact, ardent does not begin to be a strong enough
word.
As White and his team worked, it was clear that the bones they
were assembling looked, in many ways, human. The differences
between what White and his team had found and the bones of modern
humans were, in the broader context of evolution, tiny. She may
have been 4.4 million years old, but much of her was like a human
child. The same would have been true for her organs and cells, had
they lasted. She was like us for the simple reason that the main
features of our bodies evolved far earlier than the earliest hominid or
even the earliest primate. To find the bones of animals with much
different parts, you must go far deeper into the layers of dirt. By the
time Ardi was born, we were almost completely who we are today,
minus a few bells and whistles, or perhaps better said, big brains,
tools, and words.
Most of our parts evolved in some context not only different
from that in which we use them today but different even from that
in which the fossil woman discovered by White would have used
them. We share nearly all our genes with chimpanzees and, even
more, Tim White would come to argue, with the bearer of the
bones he discovered. But we also share most of our traits and genes
with fruit flies, a fact upon which modern genetics depends for its
succor and funding. We even have many genes in common with
most bacteria, genes that exist in each of our cells.
The layer in which Tim White was studying his fossil find
was, at its deepest, about two feet beneath the surface of the desert
sand and sediment. Two feet is the depth of sediment that built up
across 4.4 million years, sometimes a few grains at a time, sometimes
more. The layers of sediment in which fossils and history
are trapped are not laid down evenly, but if they were, the layer
in which the story of life begins would be nearly half a mile in the
earth. At the bottom of that sand pile, one can find the era of the
first living cell. Already it was a little bit like each of us. It had
genes that we still have, genes necessary for the basic parts of any
cell. Between that moment and Ardi was the origin of the
mitochondria, the tiny organs in our cells that render energy from non
non-energy, the first nucleus in a cell, the first multi-cellular organisms,
and the first backbone. When primates show up, just thirty feet
below the surface, the depth of a well, they were small, runty even,
and, no offense, not very smart, but they were already nearly identical
to us genetically.
When the individual that White found had evolved, our hearts
had been beating, our immune systems had been fighting, our joints
clicking and clacking, and our parts otherwise being tested in our
vertebrate ancestors against the environment for several hundred
million years. Across these vast stretches of time, climates waxed
and waned, continents moved against each other. Yet a few realities
remained unperturbed by these machinations of dirt and sky.
The sun rose and fell. Gravity pulled every action and inaction to
the earth. Parasites attached themselves. No animal has ever been
free of them. Predators ate everything; no animal has ever been free
of them either. The pathogens that cause disease were common,
though perhaps less predictably present than parasites and predators.
Every species existed in mutual dependency with other species,
in relationships that evolved essentially with the origin of life.
No species was an island. No species had ever, in all of that time,
gone it alone.
All these things were true not just across most of Ardi's life, or
most of primate evolution, but since the very first microbial cells
evolved and another cell realized the possibility of taking advantage
of them. The interactions among species are life's gravity, predictable
and weighty. Beginning in the layers of earth in which Tim
White was digging, or perhaps slightly more recently, these
interactions would begin to change. For the first time in the entire
history of life, our lineage began to distance itself from other species
on which it had once depended. This change would make us human.
We were not the first species to use tools or to have big brains.
We were not even the first species to be able to use language. But
once we had big brains, language, culture, and tools, we were the
first species that set out to systematically (and at least partially
consciously) change the biological world. We favored some species over
others and did so each place we raised a home or planted a field.
Anthropologists have been arguing for a hundred years about what
makes a modern human, but the answer is unambiguous. We are
human because we chose to try to take control. We became human
when the earth and all of its living things began to look like wet
clay, when our hands, meaty with flesh, began to look like tools.

(Continues...)

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Excerpted from The Wild Life of Our Bodies by Dr. Rob Dunn Copyright © 2011 by Dr. Rob Dunn. Excerpted by permission of HarperCollins. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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