Public interest in social and economic equality is burgeoning. In a recent paper in PNAS that examines both nonhuman primates and humans, we measured a related phenomenon, lifespan equality – a measure of whether lifespans in a population tend to vary a lot or be similar to each other. We used data from six well-studied primate populations – our own Amboseli baboon population, and also mountain gorillas in Rwanda, chimpanzees in Gombe Stream National Park in Tanzania, sifaka in Beza Mahafaly in Madagascar, muriqui monkeys in the RPPN Feliciano Miguel Abdala in Brazil, and capuchin monkeys in Santa Rosa National Park, Costa Rica. Read More
Surviving infancy is challenging for wild primates, as decades of research on species ranging from lemurs to gorillas have revealed. For an infant baboon, surviving the first year of life requires learning to identify and successfully consume more than 250 types of food, avoiding fatal disease and predation, and perhaps most importantly identifying and avoiding dangers from other baboons both inside and outside their social group. In Amboseli, first-year mortality has averaged about 30 percent over the four decades of our study, but has climbed as high as 50 percent during difficult times. Just getting through infancy represents a huge piece of the Darwinian gauntlet that every animal must run.