In the autumn of 1913, two farmers were arguing about hominid skull fragments they had uncovered while digging a drainage ditch. The location was Boskop, a small town about 200 miles inland from the east coast of South Africa.
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They brought the find to Frederick W. Fitz*Simons, director of the Port Elizabeth Museum, in a small town at the tip of South Africa. The scientific community of South Africa was small, and before long the skull came to the attention of S. H. Haughton, one of the country’s few formally trained paleontologists. He reported his findings at a 1915 meeting of the Royal Society of South Africa. “The cranial capacity must have been very large,” he said, and “calculation by the method of Broca gives a minimum figure of 1,832 cc [cubic centimeters].” The Boskop skull, it would seem, housed a brain perhaps 25 percent or more larger than our own.
The idea that giant-brained people were not so long ago walking the dusty plains of South Africa was sufficiently shocking to draw in the luminaries back in England.
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The naturalist Loren Eiseley made exactly this point in a lyrical and chilling passage from his popular book, The Immense Journey, describing a Boskop fossil: “There’s just one thing we haven’t quite dared to mention. It’s this, and you won’t believe it. It’s all happened already. Back there in the past, ten thousand years ago. The man of the future, with the big brain, the small teeth. He lived in Africa. His brain was bigger than your brain. His face was straight and small, almost a child’s face.”
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We have seen reports of Boskop brain size ranging from 1,650 to 1,900 cc. Let’s assume that an average Boskop brain was around 1,750 cc. What does this mean in terms of function? How would a person with such a brain differ from us? Our brains are roughly 25 percent larger than those of the late Homo erectus. We might say that the functional difference between us and them is about the same as between ourselves and Boskops. Expanding the brain changes its internal proportions in highly predictable ways. From ape to human, the brain grows about fourfold, but most of that increase occurs in the cortex, not in more ancient structures. Moreover, even within the cortex, the areas that grow by far the most are the association areas, while cortical structures such as those controlling sensory and motor mechanisms stay unchanged.
Going from human to Boskop, these association zones are even more disproportionately expanded. Boskop’s brain size is about 30 percent larger than our own—that is, a 1,750-cc brain to our average of 1,350 cc. And that leads to an increase in the prefrontal cortex of a staggering 53 percent. If these principled relations among brain parts hold true, then Boskops would have had not only an impressively large brain but an inconceivably large prefrontal cortex. The prefrontal cortex is closely linked to our highest cognitive functions. It makes sense out of the complex stream of events flowing into the brain; it places mental contents into appropriate sequences and hierarchies; and it plays a critical role in planning our future actions. Put simply, the prefrontal cortex is at the heart of our most flexible and forward-looking thoughts.
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Our big brains give us such powers of extrapolation that we may extrapolate straight out of reality, into worlds that are possible but that never actually happened. Boskop’s greater brains and extended internal representations may have made it easier for them to accurately predict and interpret the world, to match their internal representations with real external events. Perhaps, though, it also made the Boskops excessively internal and self-reflective. With their perhaps astonishing insights, they may have become a species of dreamers with an internal mental life literally beyond anything we can imagine.
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There is another, again poignant, possible explanation for the disappearance of the big-brained people. Maybe all that thoughtfulness was of no particular survival value in 10,000 B.C. The great genius of civilization is that it allows individuals to store memory and operating rules outside of their brains, in the world that surrounds them. The human brain is a sort of central processing unit operating on multiple memory disks, some stored in the head, some in the culture. Lacking the external hard drive of a literate society, the Boskops were unable to explo20easier for them to accurately predict and interpret the world, to match their internal representations with real external events. Perhaps, though, it also made the Boskops excessively internal and self-reflective. With their perhaps astonishing insights, they may have become a species of dreamers with an internal mental life literally beyond anything we can imagine.
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There is another, again poignant, possible explanation for the disappearance of the big-brained people. Maybe all that thoughtfulness was of no particular survival value in 10,000 B.C. The great genius of civilization is that it allows individuals to store memory and operating rules outside of their brains, in the world that surrounds them. The human brain is a sort of central processing unit operating on multiple memory disks, some stored in the head, some in the culture. Lacking the external hard drive of a literate society, the Boskops were unable to exploit the vast potential locked up in their expanded cortex. They were born just a few millennia too soon.
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Just about 100 miles from the original Boskop discovery site, further excavations were once carried out by Frederick FitzSimons. He knew what he had discovered and was eagerly seeking more of these skulls. At his new dig site, FitzSimons came across a remarkable piece of construction. The site had been at one time a communal living center, perhaps tens of thousands of years ago. There were many collected rocks, leftover bones, and some casually interred skeletons of normal-looking humans. But to one side of the site, in a clearing, was a single, carefully constructed tomb, built for a single occupant—perhaps the tomb of a leader or of a revered wise man. His remains had been positioned to face the rising sun. In repose, he appeared unremarkable in every regard...except for a giant skull.
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