INFANTICIDE: ANIMAL BEHAVIOR SCRUTINIZED FOR CLUES TO HUMANS
By BAYARD WEBSTER
Published: August 17, 1982
IN Brooklyn a young mother threw her hours-old baby out of an apartment window to the street 18 floors below. In Tokyo the corpse of a newborn child was abandoned in a coin locker in a railway station.
In Manhattan a father beat his 3 1/2-month-old son to death. These are a few of many reported cases of infanticide, the most vicious form of child abuse. It is a human crime so abhorrent and disturbing that little has been written about it, and it is behavior so mystifying that scientists are still far from fathoming its underlying causes.
Scientists agree that the history of human infanticide probably goes back to the cave. Records from medieval times show that a parent would kill either male or female infants, depending on which sex was needed more in society at a particular time in history. And in some primitive cultures today infanticide is not an uncommon practice.
Although no precise figures are available, it is estimated that each year hundreds of thousands of children in the United States are subjected to some form of violence by their mothers or fathers that causes injury and sometimes leads to death. This violence and abuse has become a nationwide problem that is causing increasing concern among psychologists and psychiatrists.
Ethologists, or animal behaviorists, however, know that infanticide is not confined to humans and that it is often practiced by animals. African wild dogs bite and kill infant dogs. Male lions will slay the offspring of a neighboring pride. Female gerbils will often kill and eat their young. Bears sometimes kill small cubs during the mating season. And many other species batter, slaughter and cannibalize their offspring.
But why, scientists ask, do animals and humans abuse and slay their young? In an effort to find out, about three dozen psychologists, anthropologists, zoologists and ethologists from 13 countries who have studied animal infanticide are participating in a week-long conference at Cornell University in Ithaca on animal and human infanticide. Too Unpleasant to Think About
''Infanticide has not received much study because it's a repulsive subject,'' said Glenn Hausfater, a Cornell ethologist and coorganizer of the conference. ''Many people regard it as reprehensible to even think about it, but we're trying to see if there's any connection between animal infanticide and child abuse, neglect and killing by humans.''
Sarah Hrdy, a Harvard primatologist who has studied many species of primates in their forest habitats, noted that adult male infanticide has been reported for all the major groups of higher primates: monkeys, the great apes and man.
Dr. Hrdy, co-organizer of the conference with Dr. Hausfater, reported in a scientific paper that most primate infant killings seemed to be caused by males who invaded primate colonies, usurping the resident males and killing those males' infants.
In this way, scientists reason, the newly dominant males benefit by eliminating unrelated infants who would be potential competitors of the invading males' offspring.
Researchers point out that such reasoning does not necessarily apply to all cases of infant-killing among such animals as lions, bears, foxes, wolves, rodents, insects and fish.
Dr. Hausfater said in an interview that scientists who had studied animal infanticide often offered controversial theories for the practice. But he said they generally agreed that there were several still unproven but plausible hypotheses that help explain such behavior. These theories fall into several main categories.
- Adaptive strategy. When a male kills offspring of another male and copulates with the other male's mate, he increases his own reproductive success by eliminating the offspring of his competitors while perpetuating his own strain. Another benefit to the male is that a nursing mother who loses her offspring quickly returns to estrus and is ready to mate with the invading male and bear his children. The male thus reduces his waiting time for insemination of the female and gains a reproductive advantage over a noninfanticidal counterpart. This is believed to be the case among primates.
- Population regulation. Infanticide in high-density populations is believed to be a mechanism by which the population can be kept from expanding to an unmanageable size. It can also be useful when there is not enough food to feed a large family. Rodents and many other species are believed to kill their offspring for these reasons.
- Psychosocial pathology. Social stress such as the antagonism suffered by a new male in a community can lead to sexual frustration and rage, which are released as infanticide. Replacement of the adult male in a bisexual animal community is also considered to break down social relations. This, in turn, leads to increased aggression by all members of the group, and the more vulnerable infants suffer a disproportionately high frequency of wounds that often lead to death. In these circumstances the animal committing infanticide does not benefit. Inborn Factors May Be Involved