These may sound like phantasmagorical short stories by the likes of Edgar Allan Poe or Philip K. Dick. Yet they are all true, and these are only a few of the cases you will encounter in this book. An intensive study of these people can not only help us figure out why their bizarre symptoms occur, but also help us understand the functions of the normal brain—yours and mine. Maybe someday we will even answer the most difficult question of alclass="underline" How does the human brain give rise to consciousness? What or who is this “I” within me that illuminates one tiny corner of the universe, while the rest of the cosmos rolls on indifferent to every human concern? A question that comes perilously close to theology.
WHEN PONDERING OUR uniqueness, it is natural to wonder how close other species before us might have come to achieving our cognitive state of grace. Anthropologists have found that the hominin family tree branched many times in the past several million years. At various times numerous protohuman and human-like ape species thrived and roamed the earth, but for some reason our line is the only one that “made it.” What were the brains of those other hominins like? Did they perish because they didn’t stumble on the right combination of neural adaptations? All we have to go on now is the mute testimony of their fossils and their scattered stone tools. Sadly, we may never learn much about how they behaved or what their minds were like.
We stand a much better chance of solving the mystery of the relatively recently extinct Neanderthals, a cousin-species of ours, who were almost certainly within a proverbial stone’s throw of achieving full-blown humanhood. Though traditionally depicted as the archetypical brutish, slow-witted cave dweller, Homo neanderthalensis has been receiving a serious image makeover in recent years. Just like us they made art and jewelry, ate a rich and varied diet, and buried their dead. And evidence is mounting that their language was more complex than the stereotypical “cave man talk” gives them credit for. Nevertheless, around thirty thousand years ago they vanished from the earth. The reigning assumption has always been that the Neanderthals died and humans thrived on because humans were somehow superior: better language, better tools, better social organization, or something like that. But the matter is far from settled. Did we outcompete them? Did we murder them all? Did we—to borrow a phrase from the movie Braveheart—breed them out? Were we just plain lucky, and they unlucky? Could it as easily have been them instead of us who planted a flag on the moon? The Neanderthals’ extinction is recent enough that we have been able to recover actual bones (not just fossils), and along with them some samples of Neanderthal DNA. As genetic studies continue, we will assuredly learn more about the fine line that divided us.
And then of course there were the hobbits.
Far away on a remote island near Java there lived, not so long ago, a race of diminutive creatures—or should I say, people—who were just three feet tall. They were very close to human and yet, to the astonishment of the world, turn out to have been a different species who coexisted alongside us almost up until historical times. On the Connecticut-sized island of Flores they eked out a living hunting twenty-foot dragon-lizards, giant rats, and pigmy elephants. They manufactured miniature tools to wield with their tiny hands and apparently had enough planning skills and foresight to navigate the open seas. And yet incredibly, their brains were about one-third the size of a human’s brain, smaller than that of a chimp.2
If I were to give you this story as a script for a science fiction movie, you would probably reject it as too farfetched. It sounds like something straight out of H. G. Welles or Jules Verne. Yet remarkably, it happens to be true. Their discoverers entered them into the scientific record as Homo floresiensis, but many people refer to them by their nickname, hobbits. The bones are only about fifteen thousand years old, which implies that these strange human cousins lived side by side with our ancestors, perhaps as friends, perhaps as foes—we do not know. Nor again do we know why they vanished, although given our species’ dismal record as responsible stewards of nature, it’s a decent bet that we drove them to extinction. But many islands in Indonesia are still unexplored, and it is not inconceivable that an isolated pocket of them has survived somewhere. (One theory holds that the CIA has spotted them already but the information is being withheld until it is ruled out that they are hoarding weapons of mass destruction like blowpipes.)
The hobbits challenge all our preconceived notions about our supposed privileged status as Homo sapiens. If the hobbits had had the resources of the Eurasian continent at their disposal, might they have invented agriculture, civilization, the wheel, writing? Were they self-conscious? Did they have a moral sense? Were they aware of their mortality? Did they sing and dance? Or are these mental functions (and ipso facto, are their corresponding neural circuits) found only in humans? We still know precious little about the hobbits, but their similarities to and differences from humans might help us further understand what makes us different from the great apes and monkeys, and whether there was a quantum leap in our evolution or a gradual change. Indeed, getting ahold of some samples of hobbit DNA would be a discovery of far greater scientific import than any DNA recovery scenario à la Jurassic Park.
This question of our special status, which will reappear many times in this book, has a long and contentious history. It was a major preoccupation of intellectuals in Victorian times. The protagonists were some of the giants of nineteenth-century science, including Thomas Huxley, Richard Owen, and Alfred Russel Wallace. Even though Darwin started it all, he himself shunned controversy. But Huxley, a large man with piercing dark eyes and bushy eyebrows, was renowned for his pugnacity and wit and had no such compunctions. Unlike Darwin, he was outspoken about the implications of evolutionary theory for humans, earning him the epithet “Darwin’s bulldog.”
Huxley’s adversary, Owen, was convinced that humans were unique. The founding father of the science of comparative anatomy, Owen inspired the often-satirized stereotype of a paleontologist who tries to reconstruct an entire animal from a single bone. His brilliance was matched only by his arrogance. “He knows that he is superior to most men,” wrote Huxley, “and does not conceal that he knows.” Unlike Darwin, Owen was more impressed by the differences than by similarities between different animal groups. He was struck by the absence of living intermediate forms between species, of the kind you might expect to find if one species gradually evolved into another. No one saw elephants with one-foot trunks or giraffes with necks half as long their modern counterparts. (The okapi, which have such necks, were discovered much later.) Observations like these, together with his strong religious views, led him to regard Darwin’s ideas as both implausible and heretical. He emphasized the huge gap between the mental abilities of apes and humans and pointed out (mistakenly) that the human brain had a unique anatomical structure called the “hippocampus minor,” which he said was entirely absent in apes.