Habitual food carrying has been suggested as a possible major factor in making bipedal locomotion biologically advantageous so that it was selected for in early hominid evolution. This speculation, supported by slight observations of captive macaques, has now acquired greater plausibility from four recent independent reports of wild and semi-feral bipedal, food-carrying apes and monkeys from the Congo, Tanganyika, Japan, and a Puerto Rican monkey colony. The most striking evidence of the relationship between food-transport and bipedal walking comes from a troop of Japanese monkeys where the locomotor habit emerged as part of a chain of new behaviors initiated with a changed food supply.