Descent Of Man

A couple of years ago two neuroscientists wrote a book about a supposedly little-studied extinct group of humans whose bones were found in South Africa. A very large skull with child-like facial features was discovered, and the skeleton was dubbed “Boskop Man”.

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.

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Might the very large Boskop skull be an aberration? Might it have been caused by hydrocephalus or some other disease? These questions were quickly preempted by new discoveries of more of these skulls.

As if the Boskop story were not already strange enough, the accumulation of additional remains revealed another bizarre feature: These people had small, childlike faces. Physical anthropologists use the term pedomorphosis to describe the retention of juvenile features into adulthood. This phenomenon is sometimes used to explain rapid evolutionary changes. For example, certain amphibians retain fishlike gills even when fully mature and past their water-inhabiting period. Humans are said by some to be pedomorphic compared with other primates.Our facial structure bears some resemblance to that of an immature ape. Boskop’s appearance may be described in terms of this trait. A typical current European adult, for instance, has a face that takes up roughly one-third of his overall cranium size. Boskop has a face that takes up only about one-fifth of his cranium size, closer to the proportions of a child. Examination of individual bones confirmed that the nose, cheeks, and jaw were all childlike.

An extinct race of humans much smarter than us? Possibly killed off by their less evolved, savage human neighbors? Curious, I did a web search on the Boskops and found a debunking of sorts of the book by John Hawks.

That is pretty much where matters have stood ever since. “Boskopoid” is used only in this historical sense; it is has not been an active unit of analysis since the 1950’s. By 1963, Brothwell could claim that Boskop itself was nothing more than a large skull of Khoisan type, leaving the concept of a “Boskop race” far behind.

Today, skeletal remains from South African LSA are generally believed to be ancestral to historic peoples in the region, including the Khoikhoi and San. The ancient people did not mysteriously disappear: they are still with us! The artistic legacy of the ancient peoples, clearly evidenced in rock art, is impressive but no more so than that of the European Upper Paleolithic or that of indigenous Australians.

And their brains were not all that big. Boskop itself is a large skull, but it is a clear standout in the sample of ancient South African crania; other males range from 1350 to 1600 ml (these are documented by Henneberg and Steyn 1993). That is around the same as Upper Paleolithic Europeans and pre-Neolithic Chinese. LSA South Africans fit in with their contemporaries around the world.

To be sure, there has been a reduction in the average brain size in South Africa during the last 10,000 years, and there have been parallel reductions in Europe and China — pretty much everywhere we have decent samples of skeletons, it looks like brains have been shrinking. This is something I’ve done quite a bit of research on, and will continue to do so, because it’s interesting. But it is hardly a sign that ancient humans had mysterious mental powers — it is probably a matter of energetic efficiency (brains are expensive), developmental time (brains take a long time to mature) and diet (brains require high protein and fat consumption, less and less available to Holocene populations).

OK, so Boskop Man is not a separate human lineage. But at least one sample did have a very big skull. (According to the authors of the book, numerous other skeletons with oversized skulls were found in the dig area.) Was it then possible that a small tribe of very smart ancients in South Africa once existed? Did they suffer from a disease? Or were they just exceptional individuals on the upper end of skull sizes for their time?

Hawks mentions the fact that brains have been shrinking over time across the world. I have also read that Neandertals had larger brain volumes than modern humans. These leads to all sorts of depressing conjecture. Is it possible we are getting stupider? Our cultural achievements would suggest otherwise, but maybe Neandertals would have accomplished even greater intellectual feats than modern humans had they been born during a time with a supportive industrial infrastructure.

And is there an upper limit on just how smart humans can get? As brain volumes grow, women’s pelvises must grow wider in proportion, otherwise more big-brained infants die during childbirth. But very wide-hipped women would have trouble walking or running, not to mention they would look sexually grotesque to men searching for a mate. Northeast Asians and Ashkenazi Jews are known to have the highest average IQs in the world. Do their women have correspondingly greater than average hip widths to accommodate all those big brained babies?

Because of this inherent pelvic width limitation, there may be (anti)evolutionary forces at work that select against smarter babies. The direction of evolution is not necessarily one of progress; it is, instead, in the direction of survival and replication. Which is not synonymous with ever-expanding intelligence. A sobering thought that we could just as easily devolve backward to a more aggressive distant ancestor archetype than evolve forward into bulbous headed little grey men. Not to say that there couldn’t be ways around the pelvic trap. If the selection forces for smarts are strong enough (and in a cognitively demanding society like ours the evidence for smarts selection has disappeared under the lower fertility rate of educated women), then perhaps Darwinian expedience will jerry-rig a system to ensure our brains can continue growing larger. Maybe by moving most of the skull and brain growth post-natally, or rewiring the neurons to become more efficient.

Anyhow, it’s amusing to wonder if there was an ancient human population much smarter than our own who were killed off by the envious and aggressive idiocrats in their midst at the time. Is that what happened to the Neandertals?