Manipulative Monkeys:The Capuchins of Lomas Barbudal

Non-specialists' familiarity with the manipulative monkeys of Lomas may come from Ross's pet capuchin in the TV comedy series Friends. Leaving aside the ethical questions raised by performing animals, Susan Perry and Joseph H. Manson's book reveals capuchins as having social lives as rich and as complex as those of Ross, Rachel and other humans. Indeed, the soap-opera analogy in studies of wild animals, be they capuchins or elephants, is well established. The question might be better phrased: do soaps succeed because they reduce human motivations and interactions to behavioural vignettes rather than illustrate the full complexity of thoughts?

Perry's book, with her husband and research partner, is far more than just stories about monkeys' social lives. It offers fascinating biology from Costa Rica's tropical forests, including the small, somewhat ugly, Machiavellian capuchin monkeys. They act as the focus for a discourse that ranges over "big questions": why evolve large brains and intelligence; how do youngsters learn group-typical behaviour; why does lethal aggression occur? These questions are embedded in the human drama of fieldwork; snakes, bugs of all kinds, plants with deadly toxicity, ill-fated collaborations, deep friendships and human poachers.

Perry begins by recounting a typical day, introducing the human and capuchin cast of characters acting in the drama of forest life. How she developed her major research questions and her insights into capuchins is explored. These monkeys rub their fur with sap and fruit pulp (possibly as insect repellent); hunt and devour lizards, squirrels and coatis; and eat insects of all descriptions, including the wasps that plague researchers.

Capuchins communicate by poking each other, dancing, gargling, bird-like trills; a diversity of signals and sounds. They use signals to indicate conflict, bond and show intentions. Social conflict and its resolution are major parts of a capuchin's life, and both females and males form alliances and behave strategically, as detailed in several chapters. Sitting helplessly watching a favourite animal die from hideous wounds after being attacked by conspecifics is a story familiar to field biologists. However, Perry's oft-restated caveat - "we never intervene" - seems rather smug, given that the mere presence of researchers or tourists will affect the animals' local ecology, disease exposure, risk of predation and so on. By watching, we participate in their world; to do nothing makes a moral assumption that humans have no place in a natural ecology. Why divorce ourselves even further from nature merely in the name of "scientific rigour"?

Life "in the bush" is tough for woman and monkey. The hardest part - other than survival in a regime of dawn-to-dusk battles with the tropical environment to obtain a few more recordings of grunts or observations of suckling - is keeping a research site going for long enough to make Perry's unique observations, to challenge existing theories and to provide the next generation of researchers and local conservationists.

Funders often look on long-term studies as "stamp collecting". But how would we understand the behaviour detailed here without known individuals followed from birth until death? We desperately need such studies to be sustained. Let's hope this fascinating book will go some way towards achieving this aim.