“When you look at the isotope ratios,” Todd Dawson, a Berkeley biologist who’s done this sort of research, told me, “we North Americans look like corn chips with legs.” Compared to us, Mexicans today consume a far more varied carbon diet: the animals they eat still eat grass (until recently, Mexicans regarded feeding corn to livestock as a sacrilege); much of their protein comes from legumes; and they still sweeten their beverages with cane sugar. So that’s us: processed corn, walking.
