Steven Pinker -- How the Mind Works - Hampshire High Italian ...

Revenge of the Nerds 201According to the standard timetable in paleoanthropology, the humanbrain evolved to its modern form in a window that began with the appearanceof Homo habilis two million years ago and ended with the appearanceof "anatomically modern humans," Homo sapiens sapiens, between200,000 and 100,000 years ago. I suspect that our ancestors were penetratingthe cognitive niche for far longer than that. Both ends of the R&Dprocess might have to be stretched beyond the textbook dates, providingeven more time for our fantastic mental adaptations to have evolved.At one end of the timetable is the four-million-year-old australopithecines-likeafarensis (the species of the charismatic fossil called Lucy).They are often described as chimpanzees with upright posture becausetheir brain size was in the chimpanzee ballpark and they left no clear evidenceof tool use. That implies that cognitive evolution did not begin tilltwo million years later, when larger-brained habilines earned their"handyman" name by chipping choppers.But that can't be right. First, it is ecologically improbable that a treedwellercould have moved onto open ground and retooled its anatomy forupright walking without repercussions on every other aspect of itslifestyle and behavior. Modern chimps use tools and transport objects,and would have had much more incentive and success if they could carrythem around freely. Second, though australopithecines' hands retainsome apelike curvature of the fingers (and may have been used at timesto run up trees for safety), the hands visibly evolved for manipulation.Compared to chimps' hands, their thumbs are longer and more opposableto the other fingers, and their index and middle fingers are angled toallow cupping the palm to grasp a hammerstone or a ball. Third, it's notso clear that they had a chimp-sized brain, or that they lacked tools. Thepaleoanthropologist Yves Coppens argues that their brains are thirty toforty percent bigger than expected for a chimpanzee of their body size,and that they left behind modified quartz flakes and other tools. Fourth,skeletons of the tool-using habilines (handymen) have now been found,and they do not look so different from the australopithecines'.Most important, hominids did not arrange their lives around the convenienceof anthropologists. We are lucky that a rock can be carved intoa cutter and that it lasts for millions of years, so some of our ancestorsinadvertently left us time capsules. But it's much harder to carve a rock