It's an enduring enigma in paleoanthropology: when and where did modern human behavior arise? The fossil record suggests that anatomically modern humans appeared in Africa sometime between 150,000 and 100,000 years ago. Yet the earliest convincing indications of behavioral modernity in our species, archaeologists have argued, date to tens of thousands of years later and have turned up in Europe, not Africa. With that in mind, some theorists posited that modern behavior blossomed late and rather suddenly (perhaps as a result of key changes in the brain), shortly after anatomically modern humans began to colonize other parts of the globe.
Now a new discovery is making that scenario difficult to swallow. Researchers have recovered 28 specialized bone tools and related artifacts indicative of modern behavior from 70,000-year-old deposits in a South African cave known as Blombos. This, team member Christopher S. Henshilwood of the Iziko-South African Museum in Cape Town asserts, implies "that there was modern human behavior in Africa about 35,000 years before Europe." An analysis of these tools will appear in the December issue of the Journal of Human Evolution.
Though the ancient shards of bone do not necessarily dazzle the untrained eye, they hold great significance for archaeologists, who regard them as one of several telltale signs of sophisticated behavior. Not only are bone tools difficult to manufacture, study co-author Curtis Marean of Arizona State University explains, a shift toward more specialized tool production tends to accompany them. (Intriguingly, earlier work hinted at another aspect of behavioral modernity among the early Blombos people: symbolic thinking. Large quantities of ochre and an engraved bone have been found in the cave.)
Henshilwood and Marean note that whereas Europe has a long history of archaeological investigation, only a handful of African sites have been well excavated, thus extensive evidence for early behavioral modernity in Africa is likely to surface in the future. "I think that when we start to get a big sample, the picture of modern human evolution is going to look very different. A clear picture is emerging. This puts the behavioral evolution in step with the anatomical evolution," Marean remarks. "Once again, in terms of human evolution, we are seeing Africa as being precocious: Bipedal hominids evolved in Africa; the first real increase in brain size occurred in Africa; and now, we are beginning to see that the last great advance, the development of modern behavior, was made in Africa as well. Now," he muses, "the question becomes where in Africa did this first begin to happen, and why did it happen?"