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Monkey business

June 30, 2005 By Michael Hopkin This article courtesy of Nature News.

Can primate studies really tell us anything useful about child abuse in human families? Michael Hopkin thinks not, and says we should spare the monkeys the pain.

Apes and monkeys, our fellow primates, hold up a mirror to much of our own biology. There is much to be learned from studying how they behave in the arenas of mating, tribalism and family life. But is it worth inflicting suffering on the animals in pursuit of such studies? Surely not.

Research published this week in Proceedings of the National Academy of Sciences1 aims to shed light on child abuse in rhesus macaques and therefore, by implication, in humans. Such abuse occurs naturally in both species, with around 5-10% of young macaques suffering varying degrees of physical aggression from their mothers, including biting, crushing and throwing.

In both humans and macaques, child abuse is passed down through the generations - some 70% of abusive human parents are estimated to have suffered similarly as children. This has led biologists to wonder whether the trend is forged by experience or genes; whether it is nurture or nature.

By studying macaques at the Yerkes National Primate Research Center in Lawrenceville, Georgia, biologist Dario Maestripieri of the University of Chicago set out to answer this riddle. To this end, he placed young macaques with biologically abusive or non-abusive mothers in the foster care of other females, some with a history of abusive behaviour and some not. Other monkeys stayed with their biological mums, again either abusive or not. That's every possible combination of monkeys with a supposed genetic or learned disposition to be kind or cruel to their own children.

Motherly love

Nine of the 16 monkeys raised by abusive mothers went on to abuse their own offspring. None of those raised by non-abusive mothers did. The only thing that affected the outcome was how they were raised. It made no difference at all whether the monkeys had abusive or non-abusive biological mothers.

The implication of this rather small study is that a tendency to abuse offspring is forged by early experience rather than genes - a conclusion that some may be tempted to extend to human families.

But is using monkeys the best way to answer questions about human behaviour? And now that we have this (tentative) knowledge at our fingertips, does it tell us anything about how we should go about tackling child abuse in our own societies? The answer on both counts, I would argue, is no.

Undoubtedly the research was based on laudible intentions. But although abuse does occur naturally in these animals, housing a young monkey with a foster mother that is very likely to cause it pain surely counts as indirect cruelty. The Yerkes centre is fully approved by the Association for the Assessment and Accreditation of Laboratory Animal Care International, so in the eyes of experts of such things it is ethically sound. But I'm not sure I agree.

A better way

There are other ways to find out about human problems. The issue of whether abuse is learned or genetic is of little consequence when it comes to preventing kids from being harmed - far more relevant is a proper network of social care. And even if it were, should we not turn first to the rafts of data from fostering agencies as a source of clues?

The United States has always been the hub of experimental primate research, and there are many countries, particularly in Europe, where this kind of work might have had trouble getting approved. The cornerstone of research animal ethics should be whether the pain involved can be justified in light of the knowledge that will be gained.

Pain is often an unavoidable part of experimental research, even on humans. But there's something heartbreaking about studies in which young animals are intentionally deprived of a caring upbringing. In the 1960s, one study housed baby monkeys with artificial mothers made of metal spikes, and watched the creatures attempting to cuddle up to the cold lumps for comfort. Did we really need a primate study to tell us that young creatures seek out love from their parents?

All animals sit on a spectrum of sentience that should inform ethical considerations of their use in science. In the case of primates, which are capable of feeling genuine emotional pain, I think we should keep such scientific intrusions to a minimum.


  1. Maestripieri D. Proc. Natl Acad. Sci. USA, 102. 9726 - 9729 (2005).


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