In her book "Gulp: Adventures on the Alimentary Canal," Mary Roach explores the origins of human dietary preferences, highlighting how our ancestors adapted to their environment as hunters and foragers in the dry savannah. These early humans developed a craving for essential nutrients that were hard to come by, particularly salt and various high-energy sources such as fats and sugars. This evolutionary need influenced their food choices and has left a lasting impact on human nutrition.

Roach's discussion underscores the significance of these nutrient requirements in shaping the diets of our forebears, who had to navigate a landscape where such resources were limited. The emphasis on salt and energy-dense foods not only reflects the challenges faced by early humans but also provides insight into our modern eating habits, indicating that some of our cravings are deeply rooted in our evolutionary history.