More food but also disease, craziness, and anomie resulted from the agricultural revolution, according to this diffuse meditation on progress and its discontents. Wells (The Journey of Man), a geneticist, anthropologist, and National Geographic Society explorer-in-residence, voices misgivings about the breakthrough to farming 10,000 years ago, spurred by climate change. The food supply was more stable, but caused populations to explode; epidemics flourished because of overcrowding and proximity to farm animals; despotic governments emerged to organize agricultural production; and warfare erupted over farming settlements. Then came urbanism and modernity, which clashed even more intensely with our nomadic hunter-gatherer nature. Nowadays, Wells contends, we are both stultified and overstimulated, cut off from the land and alienated from one other, resulting in mental illness and violent fundamentalism. Wells gives readers an engaging rundown of the science that reconstructs the prehistoric past, but he loses focus in trying to connect that past to every contemporary issue from obesity to global warming, and his solution is unconvincingly simple: “Want less.” B&w photos. (June 8)