The lemurs of Madagascar offer an exciting glimpse into man's own history. Isolated for fifty million years from all other primate groups, they diverged from our common ancestors before the evolution of New World monkeys or of Old World monkeys, which gave rise to apes and men. They thus provide a third evolutionary line by which to compare social behaviour. The fact that some species are solitary, while others live in groups, offers further clues to the origins of primate society.
Alison Jolly's study follows the pattern of recent work in the growing field of ethology. Like George B. Schaller, author of The Mountain Gorilla, Mrs. Jolly devoted many months to intensive observation of lemurs, both in troops and as individuals – their appearance; eating, sleeping, and sexual habits; their relations with one another and with other species; troop structure; and individual idiosyncrasies. Her observation was confined mainly to two species of social lemur – the placid, arboreal Propithecus verreauxi, which, in the presence of humans or other intruders, utter the strange "sifaka" that has given them their local name, and the cocky, swaggering, irascible Lemur catta, or ring-tailed lemur.
Both species, like many monkeys, form troops composed of all ages and both sexes. They have cohesive bonds of contact, grooming, social play, and troop attraction to infants. Unlike most species of monkey, however, lemurs display little aptitude for handling objects or for examining unfamiliar things. Mrs. Jolly is thus led to the important conclusion that primate society could develop without the peculiar cleverness of man's own ancestors. Man's social emotions, in other words, are older than his general ingenuity.
Quite apart from its contribution to evolutionary studies, Mrs. Jolly's excellently documented and clearly written report is the first – and perhaps the last – field study of a rare primate which is in danger of becoming extinct in its wild state.