What Doesn't Kill Us: How Freezing Water, Extreme Altitude, and Environmental Conditioning Will Renew Our Lost Evolutionary Strength

by Scott Carney

“We’re overlit, overfed, and overstimulated, and in terms of how long we’ve been on Earth, that’s all new,” he says to me while summer is settling in Alabama. We’re missing out on what he calls “metabolic winter,” a time when the body adjusts to discomfort and scarcity between times of plenty. As he writes in his opus article on the subject, “Our 7-million-year evolutionary path was dominated by two seasonal challenges—calorie scarcity and mild cold stress. In the last 0.9 inches of our evolutionary path we solved both.” The inevitable result of losing seasonal variation is obesity and chronic disease. As proof, he doesn’t point only to the population of his home state, which ranks at #5 of the most obese states in the nation, but also to the fact that our pets are fat, too. “The only two animals in the world that suffer chronic obesity are humans and the pets we keep at home,” he says. “There’s a connection.”