ABSTRACT
Contemporary hunter-gatherers, whose lifestyles may represent the last couple of million years before the emergence of fully modern humans, have been conspicuously free from obesity and abdominal overweight.1,2 In a hunter-gatherer society, physical tness has a tremendous impact on evolutionary tness. In case of attacks from predators on you or your family, even a slight overweight could mean death, and leanness can markedly increase your skills both as a hunter and as a gatherer. When obesity causes disability such as stroke, heart disease, or joint disease, the tness of a huntergatherer further decreases. And children who must care for their disabled parents cannot be 100% efcient in taking care of their own children. In addition, the disabled parents themselves cannot fully contribute to foraging, which indirectly decreases tness for the offspring. Obesity can also cause infertility in females, birth defects, and fetal death.2 Hence, natural selection has strongly favored leanness during primate and human evolution.
