Margo Wilson

Life expectancy, economic inequality, homicide, and reproductive timing in Chicago neighbourhoods

Abstract In comparisons among Chicago neighbourhoods, homicide rates in 1988-93 varied more than 100-fold, while male life expectancy at birth ranged from 54 to 77 years, even with effects of homicide mortality removed. This “cause deleted” life expectancy was highly correlated with homicide rates; a measure of economic inequality added significant additional prediction, whereas median household income did not. Deaths from internal causes (diseases) show similar age patterns, despite different absolute levels, in the best and worst neighbourhoods, whereas deaths from external causes (homicide, accident, suicide) do not. As life expectancy declines across neighbourhoods, women reproduce earlier; by age 30, however, neighbourhood no longer affects age specific fertility. These results support the hypothesis that life expectancy itself may be a psychologically salient determinant of risk taking and the timing of life transitions.

Do pretty women inspire men to discount the future

Organisms ‘discount the future’ when they value imminent goods over future goods. Optimal discounting varies: selection should favour allocations of effort that effectively discount the future relatively steeply in response to cues promising relatively good returns on present efforts. However, research on human discounting has hitherto focused on stable individual differences rather than situational effects. In two experiments, discounting was assessed on the basis of choices between a smaller sum of money tomorrow and a larger sum at a later date, both before and after subjects rated the ‘appeal’ of 12 photographs. In experiment 1, men and women saw either attractive or unattractive opposite–sex faces; in experiment 2, participants saw more or less appealing cars. As predicted, discounting increased significantly in men who viewed attractive women, but not in men who viewed unattractive women or women who viewed men; viewing cars produced a different pattern of results.

Child abuse and other risks of not living with both parents

Abstract This study was undertaken to quantify various risks to children as a function of the identity of the person(s) in loco parentis . The household circumtances of children in Hamilton (a midsized Canadian city) were surveyed by telephone, and combined with information on child abuse victims, runaways, and juvenile offenders, to arrive at victimization rates according to age and household type. Both abuse and police apprehension were least likely for children living with two natural parents. Preschoolers living with one natural and one stepparent were 40 times more likely to become child abuse cases than were like-aged children living with two natural parents. Whereas abuse risk was significantly higher for children living with a stepparent than for those with a single parent, the reverse was true of the risk of apprehension for criminal offenses. Several variables were examined as possible confounds of household composition. Socioeconomic status, family size, and maternal age at the childs birth were all predictors of abuse risk, but these factors differed little or not at all between natural-parent and stepparent families and could not account for the stepparent-abuse association. As predicted from Darwinian considerations, stepparents themselves evidently constitute a risk factor for child abuse.

Reconsidering Violence in Simple Human Societies: Homicide among the Gebusi of New Guinea [and Comments and Reply]

Homicide rates among the Gebusi of lowland New Guinea are among the highest yet reported. This paper characterizes and empirically tests Gebusi homicide data against the predictions of three theories commonly used to explain aspects of human violence: sociobiological theory, fraternal interest-group theory, and learning/socialization theory. The data strongly contravene the predictions of each of these theories. The seemingly exceptional nature of Gebusi homicide is in certain respects urprisingly similar to the dynamics of violence in highly decentralized and egalitarian societies such as the !Kung, the Central Eskimo, the Hadza, the Semai, and the Waorani. On the basis of a review of the evidence from these societies, violence in highly egalitarian human groups is characterized and a set of linked hypotheses forwarded to explain it.

Killing the competition

Sex- and age-specific rates of killing unrelated persons of one’s own sex were computed for Canada (1974–1983), England/Wales (1977–1986), Chicago (1965–1981), and Detroit (1972) from census information and data archives of all homicides known to police. Patterns in relation to sex and age were virtually identical among the four samples, although the rates varied enormously (from 3.7 per million citizens per annum in England/Wales to 216.3 in Detroit). Men’s marital status was related to the probability of committing a same-sex, nonrelative homicide, but age effects remained conspicuous when married and unmarried men were distinguished.These findings and the treatment of age and sex effects by criminologists are discussed in the light of contemporary evolutionary psychological models of sex differences and life-span development. Same-sex homicides in which killer and victim are unrelated can be interpreted as an assay of competitive conflict. In every human society for which relevant information exists, men kill one another vastly more often than do women. Lethal interpersonal competition is especially prevalent among young men, which accords with many other aspects of life-span development in suggesting that sexual selection has maximized male competitive prowess and inclination in young adulthood.

Some differential attributes of lethal assaults on small children by stepfathers versus genetic fathers

Abstract Killings of children less than five years of age by stepfathers versus (putative) genetic fathers are compared on the basis of Canadian and British national archives of homicides. In addition to previously reported differences in gross rates, the two categories of killings differed in their attributes. Beatings constituted a relatively large proportion of steppaternal homicides, whereas genetic fathers were relatively likely to shoot or asphyxiate their victims. A substantial proportion of killings by genetic fathers, but almost none of those by stepfathers, were accompanied by suicide and/or uxoricide. These contrasts lend support to the hypothesis that the differential risks incurred by children in different household types reflect the differential parental solicitude that is predictable from an evolutionary model of parental motivation.

Carpe Diem: Adaptation and Devaluing the Future

Organisms typically “discount the future” in their decision making, but the extent to which they do so varies across species, sexes, age classes, and circumstances. This variability has been studied by biologists, economists, psychologists, and criminologists. We argue that the conceptual framework required for an interdisciplinary synthesis of knowledge in this area is the evolutionary adaptationist analysis of reproductive effort scheduling pioneered by George Williams.

Familicide: The killing of spouse and children

A familicide is a multiple-victim homicide incident in which the killers spouse and one or more children are slain. National archives of Canadian and British homicides, containing 109 familicide incidents, permit some elucidation of the characteristic and epidemiology of this crime. Familicides were almost exclusively perpetrated by men, unlike other spouse-killings and other filicides. Half the familicidal men killed themselves as well, a much higher rate of suicide than among other uxoricidal or filicidal men. De facto unions were overrepresented, compared to their prevalence in the populations-at-large, but to a much lesser extent in familicides than in other uxoricides. Stepchildren were overrepresented as familicide victims, compared to their numbers in the populations-at-large, but to a much lesser extent than in other filicides; unlike killers of their genetic offspring, men who killed their stepchildren were rarely suicidal. An initial binary categorization of familicides as accusatory versus despondent is tentatively proposed.

An evolutionary psychological perspective on male sexual proprietariness and violence against wives

A particularly nasty b u s b d migbt hit his wife with the sharp edge of a machete or axe or shoot a barbed arrow into some nonvitrrl area, such as the buttocks or the leg. Aaother brutal p u n i s b a t is to bold the glowing end of a piece of ibwood against the wifes body. producing painful and d o u s b m e . Normally, however, the busbands reprimandu are consistent with the perceived dousncss of the wifes ~hortcomings, his more drastic measures being reserved for infidelity or suspicion of infidelity. I is not uncommon for a man to seriously injure a sexually errant wife. and Borne husbmds have hot and ki l l4 unfaithful wives.

Household composition and the risk of child abuse and neglect.

Using a sample of 87789 abused and neglected children across the US reported in 1976 to the American Humane Association in Englewood Colorado the authors determine the incidence of child abuse and neglect in relation to household composition family income and victims age. Abuse and neglect are maximal in father-only homes and minimal in 2-natural-parent homes. Mother-only households exceed those with 1 natural and 1 step-parent in neglect incidence (poverty being the likeliest cause) but the reverse is true for abuse incidence. Poverty is more strongly associated with neglect risk than abuse risk and cannot account for the high risks of abuse and neglect in father-only and step-parent families. The authors suggest that men left alone with children (especially infants in which group and relative risk of the father-only household was especially high) are not adequately prepared emotionally or otherwise to care for them. The presence of an unrelated adult filling a parental role increases the risk of physical abuse but this is unrelated to poverty in the present sample. Rather a specific parental attachment process to newborn children may prevent maltreatment. Most step-parents have not experienced the attachment process and consequently find it difficult to develop genuine affection for their step-children. Both theory and the data presented in this study suggest that in humans as in other animals parental feeling is most readily directed towards own offspring. Considering that reconstituted families are on the increase (according to US Bureau of the Census Paul Glick as of 1976 10% of US children lived in step-parent households) there is need for more research on the parental attachment process and ways of encouraging the redirection of parental feeling.