Killer Dads (8 page)

Several researchers before Hrdy had viewed langur and other primate societies as almost idyllic communities in which each individual did its bit to help ensure the survival of as many members of its own species as possible. Young male vervet monkeys who hung around the periphery of troops, for example, were even seen by some researchers as placing themselves as willing “buffer” primate sacrifices to predators stalking a troop to protect the more valuable members. “Not surprisingly,” wrote Hrdy in
Langurs of Abu
, “when we first began to intensively study our closest nonhuman relatives, the monkeys and the apes, an idealization of our own society was extended to theirs.”
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Monkeys, like humans, appeared to “maintain complex social systems geared towards ensuring the group's survival,” wrote Hrdy, convinced that the perception of such societies was more wish fulfillment than science. In a much later book,
Mother Nature
, Hrdy pointed out that, as a mother of three in the modern world, she's “partial” to a “companionate
monogamous marriage” as the most satisfying for her and the most beneficial for her children.
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Yet, she admits, that's not necessarily the case for primates, early man, nor even for modern human moms in different situations. “It would scarcely be wise, or fair, to extrapolate my self-interested priorities to them,” she adds, referring to early mothers. “Nevertheless, from Victorian times to the present, this is what many anthropologists and evolutionists have done.”

Far from the idealized visions of primate societies popular at the time she made her discovery, Hrdy realized that an individual's drive toward evolutionary fitness could be so selfish that it could even potentially threaten the survival of a community of langurs, such as in the Hillside troop, whose population was decimated by mass baby murder.

Righting idealized misconceptions in theories about primates and early man is critical because it promises to help us more effectively understand some of our own drives, Hrdy argued in
The Langurs of Abu
. It is exactly our “peculiar misconception about ourselves, and about primates, that lends the history of langur studies its significance,” Hrdy wrote.
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“By revealing our misconceptions about other primates, the langur saga may unmask misconceptions about ourselves.”

If langurs provide an insight into human community, it's clearly not a touchy-feely vision of male baby love—nor does it argue for an easy relationship between the sexes, whose evolutionary interests are so disparate they're almost “two different species,” Hrdy noted.
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Rarely, she wrote, “do the best interests of the female langur coincide” with those of her consort. “Sexuality means conflict,” Hrdy matter-of-factly added, quoting playwright August Strindberg. “Apart from insemination, langur females have little use for males except to protect them from other males.”

Other scientists intrigued by Hrdy's research and analysis began to look out for, and record, a system of infanticide by males—and some by domineering females—among several other species, particularly among the Colobine subfamily of primates. Similar behavior is also well known today among lions, wild dogs, rhinos, mice, ducks, hippos, bears, rats, rabbits, and wolves, among scores of other species.

Within a few short years after Hrdy developed her theory, other
primate researchers were witnessing infanticides with increasing frequency. Silverback gorillas, perhaps most notably observed by primatologist Dian Fossey, can be attentive fathers, and may even take over care for their young in cases of maternal death or rare desertion. Imposing, long-living silverbacks have an advantage of being in charge of a troop for extended periods of time, sometimes up to 30 years, so they don't have to deal with frequent challenges to their dominance. Nevertheless, Fossey alone documented nine cases of infanticide of offspring of a rival male.
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After studying chimpanzees in Tanzania's Gombe Park for ten years, Jane Goodall witnessed her first infanticide—but this time, it was by a mother and daughter team of chimps Goodall had named Passion and Pom. The pair hunted down and killed at least five (possibly as many as eight) infants of rival females in their troop by biting them in the neck—and then eating them. The “barbarous murders” so appalled Goodall that she very unscientifically chased the deadly duo away in the middle of one attempted infant-kill mission by yelling.
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The killings stopped when Pom had a baby, whom Goodall named Pax. But Goodall was unnerved by what she had witnessed, and it rattled her view of pleasant chimp life as an idealized view of a simpler, pre-human parenting and community. “I had believed . . . that the Gombe chimpanzees were, for the most part, rather nicer than human beings. Then, suddenly, we found that chimpanzees could be brutal—that they, like us, had a dark side to their nature,” she noted later in her book
Reason for Hope: A Spiritual Journey
.
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The infanticide she witnessed rattled her view of the essential nature of chimps—and man—and she recognized for the first time that human capacity for aggression and violence was as deeply rooted in our evolutionary past as our ability for cooperation and compassion. It was a lesson many didn't want to learn. When she first published her findings in “Life and Death at Gombe” in
National Geographic
in 1979, the magazine was attacked for the graphic description and photos of the killings. Again, the behavior was viewed as aberrant, just as the langur killings were initially regarded, and Goodall's eyewitness accounts were criticized as merely “anecdotal,” she recounts.
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This was “patently absurd,” Goodall wrote. “We had watched, at close range, not just one but five brutal attacks. Even more significantly, other field researchers had observed similar
aggressive territorial behaviors in other parts of the chimpanzees' range across Africa.”

Goodall continued her research into infanticide by females, which she determined was fueled by an evolutionary drive similar to males. Higher-ranking chimp females, similar to Pom and her daughter, were witnessed in several cases killing the young of rival females at a time when the offspring could be easily dispatched and before they could pose any threat to a ranking female's young, whose own evolutionary fitness would be bolstered by the elimination of rivals.

Hrdy reassures readers in
The Langurs of Abu
that such behavior is far in our own evolutionary past, and that alpha humans aren't out to murder other males' offspring. Human males don't have to kill a rival male's baby to win access to and have sex with a woman or to live with her; countless men share a home with a woman and a child or children from previous relationships. “What are the implications of this infanticidal heritage for humans?” she wondered in her book.
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“There is little reliable evidence to support the hypothesis that human males have been selected to murder infants in order to increase their own reproductive success.” Some kinds of culturally sanctioned infanticides do occur, rarely, and usually only if a baby's chances of survival are small and resources limited, she noted. Among “most preindustrial human societies,” infanticide was “primarily practical,” and often involved the acquiescence or even participation of the mother—which, by the time Hrdy began work on
Mother Nature
, would be another focus of her research. Infant abandonment or even outright infanticide by a mother is usually linked to “economic constraints, the probability of infant survival and future marriage potentialities,” Hrdy added. In modern times, men of the Yanamamo in Brazil have been witnessed killing children when they raid another community. Mothers may also be kidnapped and their infants left behind, which is “functionally equivalent to infanticide” by males because the children can no longer nurse and are more likely to starve to death, noted Hrdy in
The Langurs of Abu
. Still, she emphasized in her book, “nothing resembling a genetic imperative for infanticide can be found” among humans. Hrdy does, however, in passing, point to the biblical account of Herod's order of mass murder to slay male toddlers and babies
to eliminate an expected challenge to his rule by the recently born Jesus. Interestingly, she also begins her book referring to the feared murderous jealousy of a Roman ruler in Shakespeare's
Titus Andronicus
over his wife's “blackamoore baby,” clearly fathered by her Moorish lover.
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The mother begs her lover to destroy the baby to save her. He refuses, explaining: “My mistress is my mistress,” but the baby “my self.” If “more primatologists had seen this play before going off into the field, they might better have understood the behavior unfolding before them in the savannas and forests where monkeys are studied,” Hrdy wryly noted.

In 1982 Hrdy, together with zoologist Glenn Hausfater, convened in Cornell a conference of researchers studying infanticide, which resulted in the book,
Infanticide: Comparative and Evolutionary Perspectives.
Hrdy was confident that the evidence presented would convince any remaining skeptics that infanticide could serve an evolutionary-fitness goal. In the introduction to their book, Hrdy and Hausfater stressed how far science had traveled concerning the view of infanticide in a few short years since Hrdy's langur study. “Over the past decade, the intellectual pendulum in behavioral biology and related disciplines has swung from an earlier view that infanticide could not possibly represent anything other than abnormal and aberrant behavior to the current view that in many populations, infanticide is a normal and individually adaptive activity,” they wrote.
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In fact, researchers have “begun to interpret an ever expanding list of behaviors as subtle forms of infanticide or counter-strategies to infanticide,” they added. Scientists were initially resistant to the idea of infanticide in the animal world in part because it's considered such “an abhorrent practice in our own society,” wrote Hrdy and Hausfater. But they also didn't understand what possible role it could play in survival of the species. “Once infanticide began to be explained in evolutionary terms” by Hrdy, “published reports of infanticide in mammals increased dramatically,” they wrote. The pendulum had swung so far, the authors noted, that “quite possibly, readers ten years from now may take for granted the occurrence of infanticide in various animal species, and may even be unaware of the controversies and occasionally heated debate that have marked the last decade of research on this topic.”

Although the matter was settled as far as most evolutionary biologists
were concerned, however, some controversy persisted decades longer within anthropology. There was even a learning curve for Hrdy concerning infanticide among all species, including humans. “From the 1980s onward, there was increasing awareness that infant abuse, neglect, abandonment, and infanticide were far more widespread than even those of us who studied such phenomena had realized,” she wrote in
Mother Nature
.
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“I already knew that abandonment and infanticide—both in humans and other animals—stretched far back in evolutionary time. I just had not realized the magnitude of what was going on.” Despite the grim statistics, Hrdy is surprised there isn't even more infanticide among humans. “Given how prevalent infanticide by males is among primates—reported now for over 50 different species, often with much the same pattern as predicted by the ‘sexual selection' hypothesis I first proposed in 1974—and given how much access to other men's infants men have in our species, what really surprises me is how uncommon infanticide by males turns out to be in humans,” Hrdy wrote to me in a 2012 e-mail. She attributes that to how “different the breeding systems of humans are compared to those of some of our closest Great Ape relations—gorillas and chimpanzees”—as well as the development of human male emotion and the reproductive strategies of women.

These reproductive strategies became a key focus of Hrdy's study over the years. She was one of the few women scientists in anthropology when she began her research, and was drawn to an important player in evolution that her male colleagues tended to ignore: females. Most researchers, just as Darwin did, regarded females as passive players in the evolutionary drama unfolding around them. They were viewed generally as sitting by coyly as they were chosen by strong males. Then they did what they were biologically destined to do: have babies and raise them. From this perspective, Hrdy quipped, it was as though females had never really evolved. Yet she had witnessed how intently and strategically females protected their young. Langur females banded together in attempts to shield offspring from murderous new alpha males. This shared protective parenting—which Hrdy later termed “allo-parenting—was cultivated throughout life as female langurs young to old cared for other females' infants, sometimes within minutes after birth. She also witnessed mothers seeking sex with a range of
mates, she surmised, to confuse males about the paternity of their young, which would likely serve as protection since males only attacked infants being carried by females with whom they hadn't mated.

Human mothers, Hrdy argued, sometimes rely on a similar strategy, by building bonds through sex with more than one interested male, who may then feel protective about her babies, or, at least, view a future when she is carrying their own baby. In such a way, an assertively sexual women can use a man's uncertainty about paternity to her and her child's advantage, and, in addition, have available men “at hand” in the event her primary partner deserts her (she may also deliberately seek out a nurturing good provider mate unlikely to desert her, rather than males with the obvious knock-out handsome, strength or intelligence genes). But the breeding tactic “best suited to the goose will often look different from the one preferred by the gander,” added Hrdy.
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The female “many possible fathers” strategy may particularly frustrate a male, who, while he may himself be interested in sex with a number of women, can become obsessed with his partner's fidelity because he doesn't want to be caught expending resources on an infant secretly plopped in his nest by a rival male. Because fertilization takes place inside a woman's body, a male can only know for certain he fathered her child if he has a guard “eunuch at the gate” or a DNA “lab at his disposal,” she notes in
Mother Nature
.
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