Why Chimpanzees Kill
Chimpanzees are mostly peaceable creatures, spending much of their time foraging for food and grooming each other. But occasionally they kill their own kind. Why they engage in these lethal bouts of aggression has been uncertain. One theory holds that killing is an evolved strategy for reducing competition for resources; another posits that human disturbance—including hunting and deforestation—has triggered the behavior. Now a large study of killings in chimp communities across Africa has cast new light on the dark side of our closest living relatives.
Michael Wilson of the University of Minnesota and his colleagues amassed data on chimps in 17 communities at 10 sites in west, central and east Africa whose members had long been observed by researchers. For each community the team obtained data on demography, population size, ranging behavior of the group, and so forth. The team also compiled data on bonobos from four communities, to determine whether bonobos really are less aggressive than chimps, as is commonly asserted. Wilson presented the study results on April 12 at the annual meeting of the American Association of Physical Anthropologists in Portland, OR.
Focusing on 86 cases in which scientists had observed the killings or had inferred them based on compelling evidence, Wilson and his collaborators found that kills occurred in most of the chimpanzee communities and that victims tended to be infant and adult males outside the killer’s social group. Most of the killings were conducted by groups of males. [continue]
I read, or saw a documentary that said that different groups have different levels of violence. The theory was that the level of violence was learned behavior particular to each group and some groups were extremely violent, while others weren't. That study was at least ten years old. This one sounds more thorough. Using the information in this study would lead one to wonder if in human societies where baby boys are more 'valuable' and there are more men than women if that society would be more violent. I wondered this about China with it's one child policy. In China where the ratio of men to women is 116/100 there is worry that surplus males could pose a threat to China's stability. Analysis of studies in China showed low-status young adult men with little chance of forming families of their own are "much more prone to attempt to improve their situation through violent and criminal behavior in a strategy of coalitional aggression." Would high sex ratio imbalances increase homosexuality?
I agree that women can be violent. At first I thought that if there were an overabundance of women that they might resort to violence, but then remembered an ethnic group of Chinese where the women have overnight marriages.Unlike men, women are locked into menstrual, and gestation cycles that effects their reproduction. No on the demographics? I wonder if the environment of too many men and the associated violence would change the development of the fetus effecting sexuality. I read something a long time ago that said under times of high stress - like the London bombings during WWII more homosexuals were born. I don't know how many studies have been done on this.
I read something a long time ago that said under times of high stress - like the London bombings during WWII more homosexuals were born. I don't know how many studies have been done on this.
That can't be true. How in the world can they quantify that? They'd have to interview all those people and ask them if they were homo.