The sexual appetites of the sacred monkeys of India brought feminism and fame to oil heiress Sarah Hrdy. Lucy Hodges profiles her

When Sarah Hrdy set out as a postgraduate student to study the sacred langur monkeys in Rahasthan, India, a project which brought her fame and changed the way biologists interpreted the behaviour of primates, she found she was identifying with the plight of the female langurs.

Why, she wondered, did they put up with strange predatory males coming along and attempting to kill their offspring every two years or so. More to the point, why did the wretched females go and mate with said infanticidal males afterwards?

The answer is pure Darwin: sexual selection. The invading males killed the infants of the vanquished to get the females to mate with them more quickly, and thereby produce their own offspring. The females tolerated the deaths of their babies and mated with the killers because that way they ensured the survival of their sons. "It would be to her progeny's detriment that a female refused to breed with an infanticide," she wrote in what has become a classic text and was her PhD thesis, The Langurs of Abu: Female and Male Strategies of Reproduction. "If possession of that trait is indeed advantageous, her sons would suffer in competition with the offspring of less discriminating mothers."

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A research project which had begun as a simple attempt to test the Malthusian theory that infanticide by male langurs was brought about by overcrowding grew into an ambitious study of sexuality, competition, and dominance among that species. Hrdy's book received terrific reviews, though her new ideas also caused a furore among eminent anthropologists because they overturned the prevailing ideology laid down by the British academic, Alfred Radcliffe-Brown, that primates behaved in ways that promoted peace and happiness and the interests of the group. Clearly, something was amiss with this dogma if male langurs were busily biting to death the offspring of male competitors.

It did not take long for anthropologists to realize that langurs were not alone in this respect. A host of species, including lions, hippos, bears and wolves are driven to kill babies for motives other than eating them. By patient observation, year after year, in the blazing heat of the Indian sun, Hrdy saw what previous researchers had ignored - that life for the langurs is nasty, brutish and short.

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At the same time, she pioneered a whole new branch of feminist primatology, highlighting how male-biased early animal behavour studies were. "No one will ever again be permitted to make pronouncements about primate breeding systems after having studied only one sex or after watching only the conspicuous animals," she wrote in a contribution to the book, Feminist Approaches to Science. In that same chapter, she asks whether women are better observers than men, quoting Louis Leakey, the Kenyan primatologist, who liked to use women researchers: "You can send a man and a woman to church, but it is the women who will be able to tell you what everyone had on."

Today, at the age of 49, Sarah Hrdy is a highly regarded professor at the University of California at Davis where she teaches anthropology. She has four books and numerous articles behind her, and travels widely, giving papers and talks. Her latest interest is motherhood - how much time, money and energy parents invest in their offspring. And her ideas about infanticide - heterodox when they were published in the 1970s - are the new orthodoxy.

Scrupulously, Hrdy devoted equal space to both sexes of langur monkey. She was not only interested in the male infanticide - so seized on by reviewers at the time - but also the behaviour of the females. The latter, however, was virtually ignored. Female langurs, Hrdy discovered, were nymphomaniacs, forever stealing away from their harem to copulate with outsiders, even when they were pregnant. In almost every case of copulation she found the females soliciting males by sticking their behinds in the air and shaking their heads. What were they up to? Hrdy speculated that they were often trying to fool the invading males. By showing estrus (on heat) behaviour to the new master of the troop, they might deceive him into thinking the unborn child was his and should not be killed, she suggested. It was only when the new male made clear he was determined to kill the infant that the females gave up and abandoned their child.

From there Hrdy embarked on an altogether bigger canvas in her book The Woman That Never Evolved, which tried to dispel some long-held myths about female primates. Hrdy suggested that the female orgasm might be on its way out. Her theory is that the female orgasm is adaptive, a hangover from our pre-hominoid past, connected to the fact that our ancestors mated with a bunch of males, a bit like the langur monkeys of Abu. That way our female ancestors could gain access to good genes (the "let the best sperm prevail" theory) and cast their nets wide to bring in care for their offspring from a number of males. Many case studies show male primates helping out with children, according to the likelihood that they are the fathers. As Hrdy found with the langurs, males who were possibly the father were less likely to kill an infant too.

Underpinning such rampant sexual behaviour was a psycho-physiological reward - the female orgasm. It worked best after a female had mated with a number of males, which is why the human female is left with a "cumulative" orgasm, according to Hrdy. "If humans are no longer living in breeding systems where females are mating simultaneously with multiple males - and I have to tell you I don't know of any evidence that they are - then you have to say this is a legacy," says Hrdy. "This was something that was adaptive in our pre-hominoid past and it's there as a vestige."

These ideas were all the more radical coming from someone who fell into primatology by accident. A fifth-generation Texan who grew up in Houston, the heiress to an oil fortune, Hrdy found herself out of place in that state because of her intellectual leanings. She was happy to be sent away to an all girls boarding school in Maryland at the age of 16 which nurtured her love of reading and writing. Wellesley, the elite all-female liberal arts college outside Boston, followed. But she later transferred to Radcliffe where she read anthropology.

After graduation, Hrdy enrolled at Stanford and began to attend Paul Erlich's classes on population biology. She remembered from an undergraduate course at Harvard that the langur monkeys in India, supposedly because of overcrowding, had been driven to kill babies.

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Her first summer in graduate school saw her in India searching for the langurs. It was a heady period in evolutionary biology at that university. Robert Trivers was beginning what was to be an important transformation of evolutionary perspectives on behaviour and Professor E. O. Wilson was putting together his ideas on sociobiology. "It was an incredibly exciting time," she says.

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The one man she remembers with gratitude and fondness is E. O. Wilson, the great American biologist. He appreciated her work, without making any great fuss about it, arranging to have a paper which particularly impressed him published in a prestigious scholarly journal. Sarah Hrdy agrees that she has been a kind of Trojan horse among anthropologists, infilitrating the profession with feminist ideas. But it has been accomplished only with considerable grief. "It hurt me," she explains. "It caused me great anxiety and stress, and undue misery. I have written letters to the president of Harvard complaining about sexism and then burned them and flushed them in the toilet to be sure no one would see them. And I have seen what's happened to the women who have complained and paid big prices."

But later on, when Hrdy was made a full professor at the University of California at Davis at the age of 38, and elected to the National Academy of Sciences in 1990, six years later, at what was considered a young age for such an honour, she felt the advantages of being a woman. By then affirmative action had taken hold on American university campuses. "I knew at the time that there were men who deserved it more," she says of the National Academy of Sciences election. "They wanted women."

She was also helped at crucial moments by her family money, though she says it was a handicap as well. Her mother funded the early trips to India, and she was accompanied by the man who was to become her husband, Daniel Hrdy, who was then an anthropologist and is now an infectious diseases doctor. But it was gruelling research none the less. She makes light of it now, talking about the "soap opera" of the langurs' lives, as if she were watching something on network television. Each night she would have to note in which trees the monkeys chose to sleep. Next day she was up at the crack of dawn to catch the monkeys before they left the trees. Otherwise she would have to spend hours hunting them down.

The hard part was in the middle of the day, she says. The monkeys would take their naps, but Hrdy could not afford to. She read novels. All in all, she spent ten years flying back and forth to India to research the monkeys. The part of the work she was most anxious about was the part on female dominance hierarchies in langurs. "We thought we had discovered a new type of structuring of a dominance hierarchy, and it seemed kind of odd at the time," she explains. "The young females just about the time they were reaching reproductive maturity were starting to move up the hierarchy and then they would have a stable period near the top during their prime years and then fall again with age. So, you had a dominance hierarchy where the bottom was populated by the very old and the very young, and the prime females were at the top. And it was fluctuating, from three-month period to three-month period, from year to year." Not unlike Hollywood today, points out Hrdy.

That pattern was quite different from the one seen in Old World monkeys where rank is inherited and fixed for life, with offspring playing strict roles. Hrdy worried about what she had found. Was it really right, she wondered. But a young German at Jodphur, in India, had found the same thing, which made her realise her observation was being replicated. She and her husband had been hoping to continue in India doing further research to nail down Hrdy's findings, but they ran into trouble with the Indian government.

They had money from the Smithsonian and the National Science Foundation to go in on a much bigger scale to take blood samples from the monkeys to determine paternity and to research langur epidemiology. But the enterprise fell apart amid nefarious suggestions that the Hrdys were working for a non-existent body called the Defence Pathology Organization. There were objections too about blood being taken from sacred monkeys. Research permission was cancelled. Hrdy is wistful about not having conclusively proved her findings with the wonders of modern technology such as DNA.

Had she been able to take those all-important blood samples she would have avoided some of the criticism to which her research has been subjected since. The criticism has resurfaced again recently in magazines like American Anthropologist and Evolutionary Anthropologist, much to her chagrin. She finds it irritating that the critics are still picking over her research when she freely acknowledged she was taking some big risks. "The data were not all nailed down," she says. "We didn't know for sure that the males who were killing the infants were then siring the subsequent infants." It was an informed guess. "Some of the criticism I am getting now is what right did this woman have to take these risks," says Hrdy. "I feel that scientists take risks all the time. What matters is whether the research can be replicated and whether it is supported by subsequent research."

Running throughout our conversation was the theme of compromise in life - her desire for work and travel against the need for a spouse and family. "I would think for any woman scientist this has got to be one of the major issues: these compromises you make," she says. "As an anthropologist, I was acutely aware of the needs of children. They need to be attached to stable figures." The way she has resolved the conundrum is to hire long-term help. Her eight-year-old son is looked after by a woman who has worked for Hrdy for seven years. As a result he has two mothers. "That has helped me tremendously to continue my work," she says. "But it doesn't take you off the hook."

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