Free Wanderlust: A History of Walking by Rebecca Solnit Page B

evidence that contradicts it (though Stern and Sussman impressed me as being exceptionally committed to evidence rather than ideology). Only one thing seemed agreed upon in all these competing stories of the bones, the thing that Mary Leakey had said when she wrote about the footprints her team had found in Laetoli: “One cannot overemphasize the role of bipedalism in hominid development. It stands as perhaps the salient point that differentiates the forebears of man from other primates. This unique ability freed the hands for myriad possibilities—carrying, tool-making, intricate manipulation. From this single development, in fact, stems all modern technology. Somewhat oversimplified, the formula holds that this new freedom of forelimbs posed a challenge. The brain expanded to meet it. And mankind was formed.”
    Falk wrote the most devastating reply to Lovejoy’s hypothesis in a 1997 essay titled “Brain Evolution in Human Females: An Answer to Mr. Lovejoy.” She declared, “According to this view, early hominid females were left not only four-footed, pregnant, hungry and in fear of too much exercise in a central core area, they were also left ‘waiting for their man.’ ” And she went on to say, after reviewing details such as the unlikelihood of monogamy between such differently scaled males and females, to comment, “The Lovejoy hypothesis may also be viewed at an entirely different level, i.e., as being preoccupied with questions/anxieties about male sexuality. At its most basic level, the hypothesis focuses on the evolution of how men got/get sex.” She goes on to point out that the behavior of terrestrial female primates suggests that female ancestral hominids chose multiple partners for reproductive and recreational sex, and “much of the world appears to fear that this might still be the case as indicated by the universal close observation and control of sexual conduct in human communities, not to mention all those male insecurities simmering beneath the surface of Lovejoy’s hypothesis.”
    Having dismissed the notion that a providing male brought home the bacon to a monogamous, immobilized mate, Falk took up the alternate and much simpler theory that walking upright minimized the amount of direct sun the earliest hominids received as they moved in the open spaces between patches of trees, thereby freeing them to move farther and farther out from the shade of the forest. Falk explains that Peter Wheeler, whose hypothesis it was, proposed that “these features led to ‘whole-body cooling’ that regulated temperature of bloodcirculating to (among other regions) the brain, helped prevent heatstroke, and thereby released a physiological constraint on brain size in Homo. ” Thus the changes freed the species to grow larger and larger brains, as well as to wander farther and farther. She buttresses Wheeler’s theory with information drawn from her own research into brain evolution and structure and concludes, as Mary Leakey did, though for a different reason, that becoming upright walkers didn’t create but did make possible the rise of intelligence.
    Intelligence may be located in the brain, but it affects other parts of the anatomy. Consider the pelvis as a secret theater where thinking and walking meet and, according to some anatomists, conflict. One of the most elegant and complicated parts of the skeleton, it is also one of the hardest to perceive, shrouded as it is in flesh, orifices, and preoccupations. The pelvis of all other primates is a long vertical structure that rises nearly to the rib cage and is flattish from back to front. The hip joints are close together, the birth canal opens backward, and the whole bony slab faces down when the ape is in its usual posture, as do the pelvises of most quadrupeds. The human pelvis has tilted up to cradle the viscera and support the weight of the upright body, becoming a shallow vase from