People talk a lot about the merits (or not) of the prehistoric hunting-and-gathering “Paleo diet”: the idea is that eating the way we had to eat over thousands, even millions, of years would be most conducive to salubrious lives. And it makes some sense that providing the right kind of fuel for our bodies is valuable. But regardless of the exact foods in our diet, as you will learn in our cover story, it's far more important for us to be active to be healthy.

“Our taking fewer than 10,000 daily steps is associated with increased risk of cardiovascular and metabolic disease,” writes Herman Pontzer of Duke University, author of the feature article “Evolved to Exercise.” Unfortunately, he adds, “U.S. adults typically clock about 5,000 steps, which contributes to the alarming rates of type 2 diabetes, affecting one in 10 Americans, and heart disease, which accounts for a quarter of all deaths in the U.S.” In contrast, our ape cousins are relatively sedentary yet experience none of the health ailments that we would suffer at similarly low levels of activity. And although chimpanzees have naturally high levels of cholesterol, they do not develop humanlike heart disease. Even in captivity they stay lean and rarely develop diabetes. What's going on? Why are humans the “odd ape out,” as Pontzer calls us? Skip your fingers over to “Evolved to Exercise” to learn what research is revealing about our endlessly fascinating species.

Whereas exercise has many positive effects on our well-being, Pontzer reminds us that weight loss unfortunately isn't really one of them. (He explained the reasons more fully in his feature “The Exercise Paradox” in the February 2017 issue.) Many of us struggle to avoid excess calories, even though we know we should be swapping in vegetables and fruit instead of reaching for those tempting bags of chips and cookies.

Are we instead being sabotaged by the microbes that live in our own gut? Recent research in rodents and in patients who have undergone bariatric surgeries suggests that may be the case. These operations reduce the size of the stomach, and they have now been found to have additional effects; namely, they can change how the brain areas involved in communicating with the gut behave. In “Mind over Meal,” medical writer Bret Stetka discusses how these parts of the brain become hyperactive compared with their earlier activity. As a result, people may become satiated sooner, enabling new, beneficial eating habits. The story is ready to be consumed. Bon appétit!