All in the Family

1. All in the Family • Many issues related to family life, particularly dealing with children, related to parental investment theory (Trivers, 1972)

2. Mothers provide more parental care than fathers. Why? • Some maternal investment is obligatory • Paternity uncertainty hypothesis • Abandonability hypothesis • Mating opportunity cost hypothesis

3. Investing in Children • Allocating resources to an infant not only limits one’s own ontogeny and mating efforts, but also compromises opportunities to invest in other offspring, both those born and unborn • What factors influence decisions people make about investing in their offspring?

4. Childrearing in the Ancient Past: The Role of Alloparents • Alloparenting refers to the provisioning of care to children by individuals other than the genetic mother • Alloparenting is not unique to humans • Communal suckling is often found in animals who live in matrilineal groups, e.g., elephants, lions, cebus monkeys, and bats • In traditional societies childrearing is performed by an interconnected group of mainly female relatives • Among the Ache, of eastern Paraguay, mothers with young children forage less than women without children, but the deficit is made up through the efforts of other women, most (but not all) of them blood relatives • In many societies, “baby sitting” is done by pre-adolescent girls (often older siblings) and grandmothers

5. The Calculus of Maternal Investment • Mothers will invest most in children who have the greatest chance of reaching reproductive age, and thus carrying forth the mother’s genes • Mothers who are adept at identifying cues to a child’s future reproductive success are more likely to invest the most time, energy, and resources in those children

6. Reduced maternal care can take many forms • Neglect/abuse • Receiving less attention, medical care, and food than they might need • Fostering out the child with relatives • Oblation (leaving the child in the custody of some religious institution) • Abandonment • Infanticide/Filicide

7. Factors Influencing amount of maternal investment • Child’s health • Child’s age • Mother’s reproductive status • Social support • Parent-child conflict

8. Child’s health • Children with mental retardation or who have other congenital defects, such as Down’s syndrome, spina bifida, cystic fibrosis, or cleft palate, are abused at rates two to ten times higher than are nonafflicted children • Mann (1992) looked at maternal investment in seven pairs of premature and extremely low-birth weight twins in the United States • At 8-months (but not at 4): Every single one of the mothers demonstrated more positive behavior toward the healthier of the two infants, support for “healthy baby hypothesis” • Infanticide: The intentional killing or abandonment of children who were deformed or seriously ill was noted in 21 of the 35 traditional societies

9. Child’s age • The reproductive value of a child increases with age, with the implication that mothers should be more likely to invest in older versus younger children • In traditional societies, when a child was born to a situation of scarce resources, he/she was more likely to be killed at birth. In situations involving an older sibling, the younger of the two was always the one put to death • Infanticide rare in modern societies, but does occur • When an infant is killed, a natural parent is 7 times more likely to be the perpetrator than a nonrelative, and the mother is more likely to commit the homicide than the father (especially neonatalcide) • The probability of a child being killed by a parent decreases sharply after the first year and continues to fall until young adulthood, when it is effectively zero

10. Children’s risk of homicide by a natural parent in relation to age (from Daly & Wilson,1988)

11. Mother’s reproductive status • As a woman’s reproductive years diminish, the cost of abandoning a child increases • Maternal age in U.S. is predictor of child abuse and infanticide • Canadian date for 1974 and 1983: teenage mothers were more than four times as likely to kill their infants as are mothers in their 20s

12. Social support • Mothers should only attempt to raise a child alone when conditions are favorable, such as having plentiful economic resources • When a mother lacks appropriate support or resources, lower parental investment in children is predicted • a mother’s marital status can be regarded as a cue to her availability of resources, and thus unmarried women would be expected, on average, to have less social support and limited access to resources • Single mothers are much more represented among infanticidal mothers than would be expected by chance • Although the magnitude is the greatest for teenage mothers, the difference does not disappear at later ages

13. Paternal Investment • Why Do Men Contribute as Much as They Do to Their Offspring? • Because of extended juvenile period, paternal investment needed to insure survival and success of offspring • Child survival and success is related to paternal investment, especially in environment of limited resources • Paternity certainty is moderately high in humans, increasing likelihood of paternal investment

14. Who are newborn babies said to resemble? • Newborns consistently said to resemble father more than mother. These claims especially likely to be made by mothers and mothers’ kin. • In actuality, babies to not likely to resemble father more than mother. • Gallup and colleagues found that men more likely to state they would invest in photos of children that looked like them. No effect in women. • Men in domestic violence treatment: those who rated their children as not looking like them inflicted more severe violence on their spouses

15. Grandparental Investment • Grandmother hypothesis • Who should be more certain that a grandchild is truly “theirs”? • Euler & Weitzel (1996) asked 1,857 German adults to rate the amount of care they had received from each of their grandparents up to age 7 • Devotion of care • 1. Maternal grandmothers • 2. Maternal grandfathers • 3. Paternal grandmothers • 4. Paternal grandfathers • Maternal and paternal grandparents lived equally close to their grandchildren • A similar pattern has been observed for investment in offspring by maternal versus paternal aunts and uncles

16. One published exception: Alexander Pashos (2000) Germany, urban Greece, and rural Greece • Pattern reversed for rural Greeks • In rural Greece, paternal grandparents have the social obligation of caring for their grandchildren, particularly for their grandsons, who are their primary heirs. • The increased physical closeness of the paternal family may result in greater paternity certainty than in urban settings. • When the movements of women (daughters-in-law) are known and controlled in part by the husband’s family, there is little uncertainty about paternity. • As a result, investment of the paternal family in the grandchildren can be expected to be enhanced, given the patrilineal traditions of the society.

17. Stepparent Investment: Cinderella or Marsha Brady? • Stepparents should show little interest in the welfare of children who are clearly not their biological offspring • Why should stepfathers invest at all? • Stepparenting as mating opportunity. The best strategy for a man when looking for a new mate may be to act solicitously toward the potential mate’s children • It’s more difficult for stepparents to develop strong emotional bonds with stepchildren than with biological children • In one study of middle-class stepfamilies in the United States, only 53% of stepfathers and 25% of stepmothers claimed to have any “parental feelings” whatsoever for their stepchildren (Duberman, 1975)

18. How much do stepparents invest? • Anderson et al. (1999a,b): South Africa & U.S.: stepfathers spent significantly more money on their natural children than on their stepchildren • Zvoch, 1999: Stepfamilies saved less money for their children’s education, started savings accounts for children later, and expected to spend less money for their child’s education in the future. • Stepfathers spend significantly less time with their stepchildren than with their natural children (3 hours less per week with their stepchildren than with their natural children); play with them less often. Pattern found cross culturally: U.s. South Africa, Caribbean islands • less money is spent on food when a child is reared by an adoptive, foster, or stepmother than a biological mother (Case et al.)

19. “Wicked” stepparents? • Daly & Wilson, in survey of Canadian households: Children were 40 times more likely to be abused if they lived with a stepparent versus two natural parents. • This difference remained even when possible influencing factors that may be associated with stepfamilies, such as poverty, the mother’s age, and family size, were statistically controlled. Given these and similar findings • “Stepparenthood per se remains the single most powerful risk factor for child abuse that has yet been identified.” • Child homicide: Studies in different countries report that for children under 2-years of age, homicide 40 to 100 times more likely at hands of stepparent (usually stepfather) than natural parent.

20. The risk of being killed by a stepparent versus a natural parent in relation to child’s age: Canada, 1974-1983 (from Day & Wilson, 1988)

21. Parent-child conflict (Trivers, 1974) • Parents and siblings share 50% of their genes; siblings share 50% of their genes • Parents, all other things being equal, will want to treat each child equally (all children share 50% of their genes with the parent) • Each offspring will want more investment than a parent wants to give, especially in multi-child families • Genetic conflict of interest

22. Trivers proposed that parents and their offspring would have conflict over three major issues: • The period of time parents should continue to invest in a given offspring (parents will want to di vest earlier than offspring); • The amount of investment a parent should impart to an individual offspring (each child will want more parental investment than parents want to give); and • The amount of altruism that an offspring should demonstrate to other relatives, particularly siblings (parents will encourage children to value siblings more than they are inclined to)

23. Competition between siblings leads to the scarcity of resources, thus endangering the wellbeing of both siblings • One such circumstance that provides grounds for this type of parent-offspring conflict is the occurrence of twins. In some traditional societies, when resources are scarce, only one of the twins is allowed to survive, permitting the parents to invest their already scarce resources into only one individual • The child who is killed will often be the second born, the weaker, or the female

24. Sibling cooperation and conflict • Conflict between siblings is common, but so also is warmth and companionship • Consequence of birth of a sibling • Security of attachment measured late in pregnancy of 2nd child & again 4- 8-weeks after birth (Teti et al., 1996) • Security of attachment declined, with the decline being greatest for children 2-years of age and older. • first-born preschool girls, who had a positive relation with their mothers before a second child was born, reacted particularly negatively to the birth of a new sibling (Dunn & Kendrick, 1981). • 14 months after the birth of their sibling, these girls were hostile and negative to their new baby brothers and sisters, and the second-borns similarly had developed a negative attitude toward their older sibling.

25. Cooperation among siblings • Most cultures encourage cooperation/affiliation among sibs, making it difficult to claim such cooperation is result of evolved mechanisms rather than cultural traditions. • Jankowiak and Diderich (2000) interviewed families from a polygamous, Mormon community in the SW U.S. • father is the head of the family and the official dogma of family life is that all of a man’s children are equal • unity of the family, with the father as head, is stressed in church services, Sunday school, and in local schools. • Children (officially) get their family identification through the father, not the mother, and cooperation within the polygamous family is paramount. • The social stereotype, then, is for a high degree of within-family cooperation, with no distinction between full and half siblings (same father, different mother).

26. Jankowiak and Diderich interviewed 70 individuals from 32 polygamous families who had both full and half siblings about issues related to solidarity • lending money • baby sitting for a sibling (functional solidarity) • feelings of closeness to their various siblings • nominated their favorite baby in the paternal household (affectional solidarity) • they were asked a series of questions concerning how frequently they interacted with one another, such as attending birthday parties and weddings.

27. Percentage of full and half siblings nominated for different measures of solidarity (based on data from Jankowiak & Diderich, 2000)

28. Incest Avoidance • Westermark (childhood familiarity results in incest avoidance) versus Freud (Oedipal and Electra complexes) • Wolf: “minor marriages” in Taiwan • Compared to “major marriages,” minor • produced 40% fewer children • had three times higher divorce rate • wives more likely to admit to extramarital affairs • Shepher: Israeli kibbutzim • Of 2869 couples from 211 kibbutzim, no marriages between members from the same kibbutz.

29. Bevc & Silverman • Study 1: Questionnaires to 500 college students • “Mature” post-childhood sexual activity (attempted or successful intercourse) more frequent among siblings who had been separated early in childhood than nonseparated siblings • Separation did not predict incidence of “immature” post-childhood sexual behavior, e.g., fondling, exhibitionism • Study 2: Response to newspaper ad on sibling sexual activities • Replicated findings of first study • Sibling pairs who were separated during early childhood were more likely to have engaged in genital intercourse than nonseparated pairs, although there was no effect of separation for “immature” sexual behaviors.

30. Post-adoption incest and genetic sexual attraction • highly intense, sexual attraction, often leading to incestuous relations, experienced by close kin who have been separated at or soon after birth and reunited as adults. • Most data on this phenomenon are anecdotal • Greenberg and Littlewood’s (1995) survey of post-adoption counselors in London indicated that about 50% of clients who had been reunited with kin as adults experienced, “strong, sexual feelings.”

31. Mechanisms for Westermark effect • Olfaction • Evidence of the functions of pheromones in animals and humans for both kin recognition and sexual attraction • Parents can distinguish between the odors of their biological children, except in the case of identical twins • Mothers cannot identify stepchildren by odor • Preadolescent children can identify their full sibs but not half sibs or stepsibs by odor • Olfactory cues may mediate favoritism of blood relatives

32. Weisfeld et al. (2003), studying human families • immediate family members exhibited particular patterns of aversions to each other’s odors. • Fathers showed aversions to their daughters’, but not to their sons’ odors. • Mothers did not display any aversions • Opposite-sexed, but not same-sexed sibling pairs, showed aversions to each other’s odors. • These patterns occurred whether or not the source of the odor was recognized, and whether or not the individuals involved were biologically related.

33. Dispositions toward social life • Judith Harris proposed that human group behavior is predicated on four evolutionary adaptations that humans share with other primates. • group affiliation and in-group favoritism • fear of, and/or hostility toward, strangers • within-group status seeking • the seeking and establishment of close dyadic relationships • These “evolutionary adaptations” are though of as built-in predispositions, which are operating early in life but nonetheless develop over childhood.

34. The problem of altruism • Altruism difficult to explain from selfish gene theory • Altruism among kin consistent with inclusive fitness theory • How can altruism toward nonkin be explained? • Altruism among nonkin observed in all groups of humans and throughout history • Altruism observed in other social animals (e.g., vampire bats, chimpanzees)

35. Reciprocal Altruism • Cooperation between two or more individuals for mutual benefit. • Cooperation between individuals, with the expectation that “one good term deserves another,” i.e. quid pro quo • Similarly, aggression/cheating will also be responded to in kind • In some primates, including humans and chimpanzees, cooperation expressed in terms of alliances

36. Social contract theory (Cosmides & Toobey) • Capacities needed: • 1. The ability to recognize many different individual humans. • 2. The ability to remember some aspects of the histories of interactions with different individuals. • 3. The ability to communicate one’s values to others. • 4. The ability to model the values of others. • 5. The ability to represent costs and benefits, independent of the particular items exchanged.

37. Wason task • “If a card has a vowel on one side, then it must have an even number on the other side. You must determine if the set of cards in front of you conform to the rule or not, and you should turn over the fewest number of cards to determine the truth of the rule. A G 2 7

38. Answer: A 7

39. “If a person is drinking alcohol, then he or she must be at least 21 years old.” • Beer Coke 16 years old 25 years old • Beer 16 years old

40. Deontic reasoning • Reasoning about one may, should,or ought to do. • Contrast with descriptive or indicative reasoning, which is reasoning about “facts” and does not involve a violation of social rules • When does deontic reasoning first appear?

41. Harris & Nunez, working with 3- and 4-year olds • “One day Carol wants to do some painting. Her Mom says if she does some painting she should wear her apron.” (deontic) • “One day Carol wants to do some painting. Carol says that if she does some painting she always puts her apron on.” (descriptive) • Children given 4 drawings • Carol painting with her apron • Carol painting without her apron • Carol not painting with her apron • Carol not painting without her apron

42. Deontic condition: “Show me the picture where Carol is doing something naughty, and not doing what her Mom said.” • Descriptive condition: “Show me the picture where Carol is doing something different and not doing what she said.” • Percentage correct: • Deontic condition: 72% and 83% (3- and 4-year olds) • Descriptive condition: 40% (both 3- and 4-year olds)

43. The psychology of friendship • Is friendship based on reciprocal altruisms?

44. Benefits and Opposite-sex friendships (Bleske & Buss) • Men, more than women, view opposite-sex friendships as possible sexual access. • Women, more than men, view opposite -sex friendship as possible provision of protection. • Opposite -sex friendship provides information about the opposite sex • Both men and women perceive little intrasex rivalry from opposite-sex friendships, although they do from same-sex friendships, especially men

45. Types of social relationships: Interactions, relations, structure (life in groups) - from Hinde (1976) • Interactions occur between two individuals and contain one or more types of behavior. • Relationships are interactions between two individuals over time. • Structure is the description of social behavior at the group level. • Dominance is a construct that can be used to explain social structure, or the processes by which social groups stay together.

46. Interaction • In infancy, roots of social (reciprocal) interaction • During the toddler period, children engage in “games,” characterized by mutual gaze, patterned exchanges, turn taking, and reciprocal imitation • One robust sex difference relevant to social interactions concerns females’ greater orientation toward other people.

47. Zahn-Waxler and her colleagues (1992) • 12- and 20-month-old children’s response to the distress of other people. • girls more often tried to comfort the distressed individual and sought information about the persons distress (“What’s wrong?”) than did boys. • Girls displayed facial expressions, such as sad looks, and made sympathetic statements or gestures to indicate their concern more than boys, who were more apt to be nonresponsive to the distress of others.

48. Peer-directed aggression is first observed at the end of the first year of life and typically occurs in the context of object disputes (Coie & Dodge, 1998). • Up to 50% of the interaction between toddlers is conflictual (up to 50%), though not aggressive

49. Interactions during childhood • During childhood, peer social interaction focuses on play • Sex segregation common • Physical aggression during early childhood, relative to toddlerhood, decreases while verbal aggression shows the opposite pattern (Coie & Dodge, 1998). • Relational aggression: manipulating social relations by shunning and spreading rumors, among other strategies. • Relational aggression increases with age as children’s cognitive abilities improve, but is used more by girls than boys

50. Bullies and victims • The form of aggression that comes to the fore during late childhood and adolescence is bullying and victimization • Bullies are more frequently boys than girls and represent about 10% of the elementary school population in most industrialized counties • boys use physical aggression in bullying same-sex peers and girls use relational aggression with other girls • Victims of bullies tend to be physically frail children with few friends or affiliates