The Earliest Human Mind
By 2 million years ago¸ there were probably several species of early Homo¸ but¸ for convenience¸ we can group them under a single toolmaking species¸ Homo habilis. What¸ then¸ were the specialized mental processes found in these earliest humans as opposed to much earlier¸ non–toolmaking hominids?
Some clues lie in stone manufacture. Chimpanzees shape termite twigs with their teeth from convenient wood fragments¸ removing leaves so they can poke the “artifact” down a small hole. The making of stone tools requires good hand–eye coordination¸ the ability to recognize acute angles in stone¸ and the mental processes necessary to shape one tool by using another. However¸ the Oldowan stoneworkers were carrying out simple tasks¦ shaping stones so they can hold them in one hand to crack bones and striking off sharp–edged flakes. Their artifacts defy precise classification in the way that one can subdivide later stone tools into forms such as choppers¸ scrapers¸ and knives¸ for example. Their lumps and flakes display continuous variability¸ an understanding of basic fracture mechanics¸ not the ability to impose standardized forms¸ or to choose easily worked raw materials. Could chimpanzees have made such tools¸ as has been suggested? When Nicholas Toth tried to train a pygmy chimpanzee named Kanzi to make Oldowan tools¸ he found that Kanzi could make sharp flakes¸ but he never mastered the art of recognizing acute angles in stone¸ or other flaking. Archaeologist Steven Nithen argues for two–possibilites either a more general intelligence had evolved¸ or some mental processes for basic stone working had appeared—intuitive physics in the mind of Homo habilis.
Oldowan stone tools were mainly used to process animal carcasses¸ for skinning¸ cutting joints and meat¸ and breaking open bones. However¸ how did Homo habilis interact with the natural world?
One obvious and significant difference between Homo habilis and chimpanzees appears in the archaeological record of 2 million years ago¦ a dramatic rise in meat consumption. In practice¸ Homo habilis was probably a behaviorally flexible¸ nonspecialized forager¸ whose lifeway was marked by diversity¸ by shifts between hunting and scavenging¸ and between food sharing and feeding on the move. The larger brain of Homo habilis would have required the consumption of more energy and a higher quality of diet. The stable basal metabolic rate was maintained by a reduction in the size of the gut¸ which could only become reduced as a result of a higher–meat diet¸ since a high–fiber diet requires more intestinal action.
Steven Mithen believes that this need for more required another cognitive ability as opposed to that for toolmaking—that of being able to use one's knowledge of the environment to develop ideas about where to find predator kills and high densities of animals. He argues that the presence of toolmaking stone up to 6 miles (10 kilometers)from its source is a sign that Homo habilis was moving not only stone but meat to different¸ sometimes third¸ ever–changing locations. Such ability suggests a relatively sophisticated interaction with the environments when compared with chimpanzees who only transport “tools” to fixed locations.
Homo habilis was so far confined to tropical Africa¸ and to relatively narrow range of savanna and grasslands environments¸ in contrast with later humans who adapted to every kind of climate imaginable. Many groups live close to permanent water¸ tethered¸ as it were¸ to places like the shallow lake at Olduvai¸ where sites are “stacked” one above another over considerable periods of time. Many animal species appear in the Olduvai caches¸ as if our ancestors ranged widely over the surrounding landscape¸ but they may have transported much of their food to well–defined locations.
Homo habilis shared the ability of its earlier ancestors to “map” resources over wide areas. However¸ it may also have possessed additional cognitive abilities¦ to developed ideas about where food might be found¸ and to use tell–tale signs as animal droppings to find it—within a relatively narrow environmental settings. At the same time¸ its general intelligence was supplemented by some specialized abilities in artifacts manufacture¸ which were to be an important foundation for environmental intelligence in later millennia.
Social intelligence may have evolved significantly. Anthropologist Robin Dunbar has studied living primates and discovered evidence for larger groups¸ developing an equation for relating brain to group size. He then estimated the brain size of Homo habilis¸ and applied his figures to the chimpanzee equation. Chimpanzees lived in predicted group sizes of about 60 individuals. In contrast¸ he predicted that australopithecines lived in groups with a mean size of about 67 individuals¸ whereas Homo habilis flourished in larger groups of about 81. Group living was an essential for Homo habilis¸ which lived in an environment teeming with carnivores¸ often competing with then for meat with only the simplest of weaponry for protection. Large group living has dramatic advantages for hominids living in environments where resources come in large “parcels” that are irregularly distributed across the landscape. Members of a group can search for food individually or in pairs¸ then share it with others¸ allowing the group as a whole to cover a much larger area. Mithen believes the larger brain of the first humans allowed for greater social intelligence¸ for coping with the complexities of living in closer juxtaposition to others¸ where assuming that the others know things is of vital importance.
