As a baseline Smith amassed data for humans and apes she then looked at a range of human fossils to determine how

Posted by admin · · Jump to comments

As a baseline, Smith amassed data for humans and apes; she then looked at a range of human fossils to determine how they compared. Three life-history patterns emerged: a modern human grade, in which first-molar eruption occurs at six and life span is 66; an ape grade, with first-molar eruption at just over three and a lifespan of 40 years; and an intermediate grade.Later Homo erectus - that is individuals who lived after 800,000 years ago - fit the human grade, as did Neanderthals. All the much older and more ape-like australopithecine species, however, slotted into the ape grade. Early Homo erectus, like Turkana Boy, was intermediate: the boy's first molar would have erupted when he was a little more than four years old; had he not met an early death, he could have expected to live about 52 years.Smith's work showed that the australo-pithecines' pattern of growth was not like that of modern humans; it was apelike. She further showed that early Homo erectus was intermediate between modern human and ape in its growth; we now conclude that the Turkana Boy was about nine when he died and not 11.The ability to infer biology from fossils through research in life-history factors and tooth development is enormously important to anthropology; it allows us metaphorically to put flesh on the bones. For instance, we can say that the Turkana Boy would have been weaned just before his fourth birthday and, had he lived, would have become sexually mature at about 14.His mother probably had her first baby at 13, after a nine-month pregnancy, and thereafter would have been pregnant every three to four years.

These patterns tell us that by the time of early Homo erectus, human ancestors had already moved in the direction of modern human biology while the australo-pithecines remained in their ape grade.SO MUCH for the biology of Homo erectus. What about its behaviour and social organis-ation? We can glean something about this from the tools these early hominids made. A crucial question, for instance, is whether they were hunters, requiring a sophisticated social structure, or merely scavengers.In the late 1970s, my friend and colleague Glynn Isaac addressed this contentious question by embarking on a three-year excavation in Kenya, on the shore of Lake Turkana, at a place known as Site 50. When a small group of Homo erectus visited this spot 1.5 million years ago, they chose a sandy, tree-shaded bank on a curve in a seasonal river. In the riverbed was a plentiful supply of lava cobbles from which to make flake tools. 'For some short period of time, these protohumans used this riverbank, and they left behind them what at first sight looks like an unpromising jumble of bones and stones,' Isaac wrote.Some of the bones at Site 50 bore the tell-tale marks of ancient butchery - the cut marks left by the sharp edges of stone flakes - and some bones had been broken open with a stone hammer, presumably to give access to the nut-ritious marrow inside.

Isaac could therefore reasonably conclude that the association between stones and bones was meaningful, not some accident of nature.The bone pieces - parts of giraffe, hippo-potamus, antelope and a bit of catfish cartilage - were not strewn randomly over the ancient site but were concentrated in the north-west corner. Significantly, stone tools were collected here, too, and the picture one got was of an area of activity: individuals making tools and using them to but-cher pieces of carcass that they or others had brought to the site. The earliest tools were small flakes, produced by striking one stone against another. They measured about one inch long and were surprisingly sharp. Though simple in appearance, they were put to a variety of uses, as we know from miscroscopic analysis carried out by Lawrence Keeley of the Unversity of Illinois, and Nicholas Toth of Indiana University. They found marks on the flakes indicating that some had been used to cut meat, some to cut wood, and others to cut soft plant material, like grass.When we find a scattering of flakes like this, we have to be inventive to imagine the complexity of life that took place there long ago because the relics themselves are sparse Gone is the meat, the wood, and the grass. We can imagine a simple riverbank campsite, where a human family group butchered meat in the shade of a structure made from saplings and thatched with reeds, even though all we see today are the stone flakes.The flakes designed to cut through meat were highly effective implements, capable of cutting through all but the toughest of hides to expose the flesh inside.