Gang welfare

Our great-ape relatives are some of the most endangered species on the planet and gorillas are no exception. Taxonomists are not quite agreed on the status of some gorilla populations in central Africa but one group, the Cross River gorilla in Nigeria, is thought to be one of the most critically endangered species worldwide with an estimate of only around 150 individuals remaining. Its neighbours, the western gorillas, while more dispersed, also face increasing threats and a rapidly dwindling population. The situation is more alarming because the great apes display a rich variety of social behaviours not only of inherent interest but also of interest because they may throw light on our own behaviour. While some gorilla taxonomy may still be debatable, researchers distinguish between the mountain gorillas of eastern Africa and the lowland western gorillas. Mountain gorillas live in groups in relative isolation: when contact between groups does occur it often involves highly aggressive interactions between the males. However, the much less well-studied western gorilla groups appear to encounter other groups more frequently and with little or no physical aggression between the males. New work with western gorillas, reported in this issue of Current Biology, has uncovered evidence for why the relationship between different groups of western gorillas differs so markedly from encounters between mountain gorilla groups. A team headed by Brenda Bradley at the Max Planck Institute for Evolutionary Anthropology in Leipzig, and the department of anthropology at the State University of New York at Stony Brook, has studied the genetic relationships between male western gorillas near the Mondika research station in the Central African Republic and the Republic of Congo. The team took DNA extracts from hair and fecal samples found at fresh nest sites of 12 social groups. Unlike mountain gorillas, where the evidence suggests that females migrate from their original social group, their DNA evidence suggested that senior males in neighbouring groups were related, implying that it is males that leave their original groups but do not move too far creating a 'dispersed male network'. That any such research results can be gathered from this species is all the more remarkable because of their parlous state. Two years ago researchers at Leipzig organised a meeting to discuss new research results on the western gorilla but it rapidly became apparent that the overwhelming priority was to improve the protection and conservation of these animals across their …