Free The Dawn of Human Culture by Richard G. Klein Page B

lion kills were far more abundant than they are in most historic African environments. In addition, the most nutritious limb bones at Oldowan sites often show cut marks from flesh removal, which suggests that the people got the bones before someone else picked them bare.
    The bottom line is that the available evidence can be read to favor either hunting or passive scavenging, and the surviving data may never allow a firm choice. Still, the uncertainty over hunting vs. scavenging should not be allowed to obscure a far more fundamental point.
    About 2.5 million years ago, bipedal creatures that were probably no more technological or carnivorous than living chimpanzees evolved into ones who mastered the physics of stone flaking and then used their newfound knowledge to add an unprecedented amount of meat and marrow to their traditional vegetarian diet.

    * * *
At this point, the reader is surely wondering just who these Oldowan people were. What species did they belong to and what did they look like? To address this question, we must return briefly to the australopiths and their evolutionary history. Anthropologists disagree on the relationships among the australopith species that existed before 2.5
    million years ago, and the recent discovery of Kenyanthropus platyops can only fuel the debate. Before platyops was found, most authorities agreed that Australopithecus afarensis was the only human species 03 Whodunit.r.qxd 1/29/02 5:04 PM Page 77
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    between 3.5 and 3 million years ago and that it was ancestral to all later people. It may still be the most plausible ancestor for some or all, but platyops provides an alternative that cannot be ruled out a priori.
    Equally important, it suggests that fresh finds may only expand the choices, if like platyops they reveal yet additional, unexpected australopith species. What remains clear is that when Oldowan tools appeared around 2.5 million years ago, people were divided between at least two distinct evolutionary lines. One led to the later robust australopiths and the other to the genus Homo (Figure 3.5).
    We do not know when the two lines separated, but a reasonable working hypothesis is that they diverged abruptly between 2.8
    and 2.5 million years ago, when a climatic inflection reduced moisture across much of Africa and sparked extinctions and new species in antelopes and other mammalian groups. The key point here is that the lines were already separate when Oldowan tools appeared, and we must therefore contemplate more than one potential tool maker. No one doubts that early representatives of Homo produced stone tools, but what about the robust australopiths? The question is not hypothetical, since flaked stones have been found with robustus at Swartkrans Cave in South Africa and with its east African cousin, boisei, at Olduvai Gorge and other sites in eastern Africa.
    Anthropologist Randall Susman of the State University of New York at Stony Brook has proposed a rule of thumb for determining whether robust australopiths produced Oldowan artifacts. He notes that chimpanzees have curved, narrow-tipped fingers and short thumbs.
    This hand structure promotes a power grip that is helpful for grasping tree limbs. Humans, in contrast, have shorter, straighter fingers with broad tips and larger, stouter thumbs. The human hand promotes a 03 Whodunit.r.qxd 1/29/02 5:04 PM Page 78
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    | THE DAWN OF HUMAN CULTURE
    Homo
    Homo
    Homo
    Artifact Traditions
    millions of
    neanderthalensis
    sapiens
    erectus
    millions of
    Later Stone Age &
    years ago
    years ago
    Upper Paleolithic
    0
    0 0.05
    0.25
    Middle Stone Age
    Paranthropus
    & Mousterian
    Homo
    boisei
    heidelbergensis
    1
    1
    Acheulean
    Homo (or
    Kenyanthropus )
    rudolfensis
    Homo
    Paranthropus 1.65
    Homo
    habilis
    robustus
    2
    ergaster
    2
    Oldowan
    ?
    Australopithecus
    2.5
    garhi
    ?
    ?
    Paranthropus
    3
    aethiopicus
    3
    Australopithecus ?
    africanus
    Australopithecus
    afarensis
    Kenyanthropus
    platyops
    (flaked