In search of the australopithecines

Abstract

Evidence from strontium isotope ratios preserved in fossil teeth provides a glimpse into the group dynamics and ranging habits of the australopithecines that can be compared with the patterns for modern primates. See Letter p.76 How do you estimate the home ranges and land-use habits of extinct species? One method is to measure the strontium isotope content of fossil teeth, because strontium isotope ratios are a good indicator of the source of the water that the creature drank during its life. This watermark is determined by the underlying geology. A strontium-isotope study of Australopithecus africanus and Paranthropus robustus specimens from South Africa shows that the smaller individuals, inferred to have been females, ranged further than the males. This suggests that females tended to move away from their natal groups and joined others, whereas males tend to stay at home, a behaviour characteristic of humans and chimpanzees, but not of most gorillas and other primates.