Who Am I and If So How Many? (3 page)

This is the story of three stories. The first goes like this: on February 28, 1967, the United States was bombarding North Vietnam with napalm and Agent Orange; students were protesting in Berlin; Kommune 1, the first politically motivated commune in West Germany, had just formed a few weeks earlier; and Che Guevara was beginning his guerrilla war in the central Bolivian highlands. Paul McCartney, John Lennon, George Harrison, and Ringo Starr had been holed up in the Abbey Road Studios in London for the past couple of months, recording
Sgt
.
Pepper’s
Lonely Hearts Club Band
. One of the songs on the album was ‘Lucy in the Sky with Diamonds.’ The title and surreal text convinced many Beatles fans that John Lennon had written the song during an LSD trip and that the whole colorful dreamscape paid homage to the hallucinatory drug. Some still believe this account, but the truth is somewhat simpler and sweeter. Lucy was a classmate of Lennon’s son Julian, who had drawn a picture of her and shown it to his father, titling it
Lucy in the Sky with Diamonds.

Now on to the second story. Donald Carl Johanson was in his twenties when he arrived in the dusty and dry highlands of Ethiopia near the town of Hadar in 1973 with an international
team of paleoanthropologists. Johanson was considered an expert on chimpanzee teeth, a reputation that rattled him. He had spent three years writing a dissertation on the teeth of chimpanzees, combing through all the museums of Europe and searching for hominid skulls, and his interest in chimpanzee teeth had run dry. But a man with his knowledge was worth his weight in gold to some of his more renowned French and American colleagues. An expert on teeth is invaluable when investigating human fossils, because teeth are often the best preserved element in the fossil record, and human teeth bear a strong resemblance to chimpanzee teeth. Johanson was delighted to join the expedition. As a son of Swedish immigrants who grew up in Hartford, Connecticut, he had not exactly been destined for a career in science. His father had died when Don was just two years old, and Johanson had spent his childhood in poverty. An anthropologist in the neighborhood took little Don under his wing, gave him advice, and awakened his interest in prehistory and ancient history. Johanson went on to study anthropology in college and graduate school, and followed in the footsteps of his mentor, whose achievements he wound up surpassing. But back when the dark-haired, gangly young man with the long sideburns was down on the ground in the scorching desertlike region of the so-called Afar Triangle in the camp near the Awash River hunting for remains of prehistoric creatures among stones, dust, and earth, he did not anticipate the future that lay before him. After a short time there, he stumbled upon a couple of strange bones: the upper part of a shinbone and the lower part of a thigh. The two fit together perfectly. Johanson determined that the bones were the knee of a small bipedal primate, about 90 centimeters tall, that must have lived more than 3 million years ago. What a find! No one had known, or had even suspected, that humanlike creatures had walked upright 3 million years ago. Who would ever believe
him
, a young, unknown chimpanzee-tooth expert? There was only one thing for him to do: he had to find a complete skeleton. Johanson soon returned home, but a year later he traveled back to the Afar Triangle, and on November 24, 1974,
he and an American student named Tom Gray headed to the site of the discovery. On the way, Johanson made a little detour and found an arm bone in the debris. Everywhere he looked, he found more bones: pieces of a hand, vertebrae, ribs, skull fragments. They were parts of an ancient skeleton.

And this is the connection to the third story – the story of a small female who lived in an area that is now part of Ethiopia. She walked upright, and although her hand was quite a bit smaller than an adult’s hand today, it was amazingly similar. The little lady was small in stature, but her male relatives may have been up to four and a half feet tall. For her size, she was very strong. She had stable bones, and her arms were relatively long. Her head resembled that of a hominid, not a human. Her upper jaw jutted out, and she had a flat braincase. Presumably she had dark hair, like other African hominids, but we cannot establish this with any certainty. It is also difficult to determine how intelligent she was. Her brain was almost exactly the size of a chimpanzee’s, but who can say what went on inside it? She died at the age of twenty, of unknown causes; 3.18 million years later, ‘AL 288-1’ is by far the oldest reasonably complete skeleton of a humanlike individual that has been found to date. The young lady was a member of the species
Australopithecus afarensis
.
Australopithecus
means ‘southern ape,’ and
afarensis
designates the site in the Afar Triangle where Johanson and Gray discovered her.

The two researchers raced back to the camp in their off-road vehicle. ‘We’ve got it,’ Gray was shouting. ‘Oh, Jesus, we’ve got it. We’ve got The Whole Thing!’ The mood was euphoric. ‘That first night we never went to bed at all. We talked and talked. We drank beer after beer,’ Johanson recalled. They laughed and danced. And this is where the first story links up with the second and third: the tape recorder was blaring ‘Lucy in the Sky with Diamonds’ at full volume over and over again under the Ethiopian sky. At some point everyone began to refer to the 40 percent complete skeleton as ‘Lucy,’ and the name stuck. Lucy O’Donnell, Julian Lennon’s classmate, could take pleasure in being the
namesake for what may be the most famous discovery of all of prehistory.

Don Johanson’s Lucy proved what had already seemed highly likely: that human civilization emerged in Africa. But more problematically, Johanson’s discovery also raises hope for
identifying
the boundary between animal and man, not only locating precisely where humankind first came into existence but also pinpointing the time when man emerged from the great geological Gregory Rift in East Africa and gradually developed into a
Homo
erectus
, a hand-ax-wielding big game hunter capable of speech. But was Lucy really the same species as human beings today? And was she really a member of the first and only primate species to choose to walk upright, use tools, and hunt game?

Fossils of the first
Hominoidea
superfamily of primates are estimated to be 30 million years old. The only thing we know about them is that we really know nothing at all. All that scientists have to go on are a couple of incomplete, damaged lower jaw halves and two or three skulls. In classifying later hominids, paleoanthropologists also have little concrete evidence dating from before the era when the forests cleared and there was open grassland. Powerful forces lifted the earth’s crust in the eastern part of Africa almost 15 million years ago and raised it more than 9,000 feet above sea level. The continental rock stretched to form a geological gash that ran more than 3,000 miles and created conditions for a wholly transformed vegetation. The renowned paleoanthropologist Richard Leakey describes the formation of the Gregory Rift and the Great Rift Valley as crucial for the evolution of new kinds of primates, and thus of man: ‘A geological episode of unimaginable proportions, the formation of the rift played a vital role in the evolution of our species. It is possible that had the Gregory Rift not formed when and where it did, the human species might not have evolved at all – ever.’

In the western region of the Great Rift, primeval forests with ample food offered climbing apes an ideal habitat. Four or five million years ago, in the new, varied habitats in the east, by
contrast, where deforestation resulted in semideserts, savannas, small riverside woods, and swampy fluvial topographies, some hominids – such as the australopithecines – began to walk upright. Some of them died out eventually, while others continued to evolve. Approximately 3 million years ago, the australopithecines split off into several somewhat better known species, including one species,
Australopithecus robustus
, that was probably vegetarian, with a large skull and strong cheekbones, traces of which were lost about 1.2 million years ago, and another,
Australopithecus africanus
, with a thinner skull and smaller teeth. The latter is now considered the base form of
Homo habilis
, the first hominids, which consisted of at least two species that may or may not have been closely related.

The brains of the australopithecines were typical of apes. As in the case of all primates, the eyes are at the front of the skull, which means that apes can look in only one direction. To expand their range of vision, they have to turn their heads, with the apparent consequence that primates can have only one state of consciousness at a time. Since they are unable to make out several things simultaneously, things enter into their consciousness only in succession. An angle of view this limited is uncommon among mammals, not to mention in other animal classes, some of which – notably flies and octopuses – have an extremely wide range of vision. The visual acuity of all apes is neither as sharp as that of birds of prey nor as weak as that of horses or rhinoceroses. Like most vertebrates, primates have a right and a left side of perception. The notion of ‘right’ and ‘left’ informs primate thinking and experience of the world. By contrast, the perception of jellyfish, starfish, and sea urchins is not bifurcated, but circular. Primates are also unable to detect changes in electricity the way sharks and other animals can. Primates’ sense of smell is quite poor; dogs and bears, as well as many insects, are far superior to us in this regard. Primates have reasonably sharp hearing, but dogs and bears outshine us in that regard as well.

The spectacular process that began with a few primates about 3 million years ago continues to puzzle scientists. In a relatively brief
period of time, the size of the australopithecine brain tripled. The brain of the australopithecines originally weighed between 400 and 550 grams, but
Homo habilis
, about a million years later, had a brain that weighed between 500 and 700 grams. Only 200,000 years after that,
Homo heidelbergensis
and
Homo erectus
brains weighed between 800 and 1,000 grams. The brain of modern man,
Homo
sapiens
, who first appeared about 400,000 years ago, weighs between 1,100 and 1,800 grams.

In the past, scientists tended to explain this major increase in brain mass with reference to the new demands that were placed on man’s ancestors. The savanna of the Rift Valley offered living conditions that differed from those of the rainforest, and the australopithecines and early forms of humans adapted, possibly causing the brain to increase in size. But this kind of rapid increase in brain size in response to a change in environment deviates substantially from the norm. While it is not unusual for animal species to adapt to their environment, sometimes by changing in size, their brains never increase in size in such a dramatic fashion. But in the early stages of humans, there was a highly unusual development: their brains grew faster than their bodies – a process that has evidently occurred in only two species, humans and dolphins.

In the 1920s, the Frenchman Émile Devaux and the Dutchman Louis Bolk found the mechanism responsible for the human brain’s remarkable development. Independently, each discovered that man, in contrast to other primates, is not fully developed at birth. Man remains in the fetal stage far longer than other mammals do, and thus remains highly receptive to learning. Neuroscience can now confirm this hypothesis. While the brain of all other mammals grows more slowly than the body after birth, in man it continues to develop for quite a while at almost the same pace as in the womb. In this way, the human brain grows to a size that substantially surpasses that of other primates. The cerebellum and the cerebral cortex in particular profit from this continued growth. And within the cerebral cortex, it is above all the regions that are
important for orientation in space, musicality, and powers of concentration that continue to develop.

Although Devaux’s and Bolk’s findings explain
what
began happening in the human brain about 3 million years ago, we have yet to figure out
why
. A change this momentous cannot be explained by adaptations to the environment, even if we think – and this is by no means certain – that life on the savanna required major shifts and adaptations. It is certainly true that walking upright altered the flight response, and most likely the savanna gave rise to a different way of life from that in the rain forest. That man developed different forms of sustenance is certainly logical, too. But none of these facts accounts for a tripling of the volume of the brain. The human brain is far too complex for a transformation of this magnitude to arise as a response to the environment. ‘Man,’ writes Gerhard Roth, a neuroscientist in Bremen, Germany, ‘does not have this large a frontal or prefrontal cortex because of some pressing need for one. It was more like an added “bonus.”’

The human brain is not merely a reaction to environmental demands. In the first chapter we discussed the fact that the vertebrate brain is an outgrowth of evolutionary adaptation, but the precise connections are still hazy. Scientists have not yet been able to figure out why an ‘optimization’ occurred. Our earliest forefathers evidently made very little use of the high-performance machines that were evolving in their heads. The brain’s increase in size at a colossal pace in the development of
Australopithecus
to
Homo habilis
and
Homo erectus
clearly took some time to yield cultural achievements such as a sophisticated use of tools. Even after the brain had essentially reached its ultimate size about a million years ago, hominids’ high-powered brains took hundreds of thousands of years to produce little more than a measly hand ax. The tools of the Neanderthals, who died out about 40,000 years ago, were still relatively simple and unsophisticated, even though the volume of their brains actually surpassed that of man today.