Zuk (Univ. of California, Riverside; Sex on Six Legs: Lessons on Life, Love, and Language from the Insect World, 2011, etc.) takes on those who say we are ill-suited to modern life because we are trapped in our Stone Age bodies.
That’s pure “paleofantasy,” writes the author, and a denial of evolution. Humans emerged in the Pleistocene, beginning 1 million years ago, and have continued to evolve since. Zuk cites dozens of studies of changes in gene frequencies (the mark of evolution) when our genomes are compared with ancient DNA. One classic example is the ability of many adults to digest milk, thanks to the retention of a working lactase enzyme. Prior to the birth of agriculture and the domestication of animals—only a few thousand years ago—the lactase gene was turned off in early childhood. Adaptations to living at high altitudes are also recent, and genetic analyses show that Andean dwellers accomplish it differently than Tibetans. These and countless other examples attest to the continued interactions of our species and cultures with nature and the environment, with consequences that affect diet, disease risk/resistance and lifestyles. So it makes no sense that we should eat the “paleo” diet of meat and root vegetables like hunter-gatherers, run barefoot (as in pursuit of game) or take as models of sex behavior what our primate friends do. Zuk is particularly sharp in this area, pointing to how diverse sexual behavior is for chimps, bonobos, gorillas, gibbons and orangutans. The mistake that the back-to-paleo folks make is the belief that human evolution stopped at some point thousands of years ago. Zuk explains that evolution (in all organisms) can and does happen by genetic drift (an isolated group may, over time, concentrate particular genes), by gene inflow (when new groups mix with an existing group), by mutation (gene errors) and by natural selection, which looks at traits associated with greater reproductive success.
Nothing beats good hard data to debunk myths, and Zuk offers plenty.