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Author: Ross S. Feldberg

1. Kin Selection and Violence

The idea that kin selection could provide an evolutionary rationale for altruistic behavior marked a major advance in our understanding of animal behavior. More recently, a number of evolutionary psychologists have attempted to extend this concept to include what I would term “counter-altruistic” behavior in humans. That is, they have looked at data on violence and homicide to determine if evolutionary “modules” might explain this behavior. The major proponents of this idea are Martin Daly and Margo Wilson. The initial material below is extracted from the textbook Evolutionary Psychology 2nd (Gaulin and McBurneye, eds.) (p330)

In 1988 Martin Daly and Margo Wilson, in their book Homicide, suggested that our tactics of conflict resolution had been shaped by selection. They tested a wide range of evolutionary predictions about the situational factors that make homicide more or less likely, specifically testing to see if genetic kinship reduced lethal violence. Since killing clearly requires access to the victim and this would be a major confounding factor in any study of homicide, Daly and Wilson decided to restrict their study to domestic violence.

They asked the question “Are relatives the victims of domestic homicide less often than we would expect on the basis of their prevalence in the household? (Remember, spouses are not blood relatives).

Using 1970 Detroit census data on homicides committed by people 14 years or older, they looked at household composition and victim. Consider the table below.

(Note: the table indicates that the average homicide perpetrator lived with 0.6 spouses – simply meaning that 60% of Detroiters over 14 who committed homicide lived with a spouse. they studied 98 domestic homicide.)

Number of Cohabitants

% of Cohabitants

B = A/30

Expected Homicides

C = B x 98

Actual Homicides

D

Relative Risk

E = D/C

Non-Kin

Spouse

0.6

0.2

19.6

65

3.32

Other non-kin

0.10

0.03

3.27

11

2.27

Total non-kin

0.70

0.23

22.87

76

3.32

Kin

Offspring

0.90

0.30

29.40

8

0.27

Parents

0.40

0.13

13.07

9.0

0.69

Other kin

1.0

0.33

32.67

5.0

0.15

Total kin

2.30

0.77

75.13

22

0.25

Grand total

3.0

1.0

98

98

The authors suggest that these data show a clear pattern. Each type of nonrelative is killed more often than expected by chance and each type of blood relative is killed less often than expected by chance. Non-kin overall are at 11 times greater risk of domestic homicide than corresponding kin. Daly and Wilson conclude that people are much less inclined to use extreme violence against individuals with whom they share genes.

In their book, Daly and Wilson present a variety of types of evidence to support their claim of an evolutionary origin for this behavior.

Just looking at the above data, do you find their argument convincing?

2. Child Abuse and Other Risks of Not Living with Both Parents M. Daly and M. Wilson

From Human Nature: A Critical Reader Laura Betzig, ed. Oxford, 1997

When a new lion becomes the alpha male in a pride, we are told that the first thing he does is to kill all the cubs that have been sired by the previous alpha male. This behavior can be understood since in doing so, the new alpha male increases the likelihood that his genes will increase in the next generation. Daly and Wilson have attempted to extend this idea to human behavior. Reasoning that child-rearing is a stressful and costly task, they ask if it isn’t reasonable to expect that parental affection for and care of a child would reflect genetic relatedness? If this were the case, we might argue for an evolved module of behavior that favors close kin over unrelated individuals.

Use your critical reading skill to assess the validity of their argument.