Evolution and Kinshi p. ANTH 321: Kinship and Social Organization Kimberly Porter Martin, Ph.D. Two Approaches to the Evolution of Kinship. 1. The Study of Our P rimate R elatives. 2. Evolutionary Psychology. Our Primate Relatives. Prosimians (Lemurs, Lorises , Galagos )
ANTH 321: Kinship and Social Organization
Kimberly Porter Martin, Ph.D.
Galago – solitary and promiscuous
Lemur – multimale and multifemale groups
Loris- monogamous when associate with another animal
Baboon – Polygynous – one male controls multiple females who mate exclusively with him
Tamarin – Polyandrous – one female mates with multiple males who all stay and care for young.
Monogamous for life – territorial and drive our same sex offspring at adolescence.
Solitary in the wild except for mother infant/child pairs.
Male-Centered groups – polygynous – with dominant males having mating priority in groups and
competition between males for mating.
Edward O. Wilson
Sociobiology: The New Synthesis
Lots of Controversy
Fear of Social Darwinism
Arguments about human free will
Arguments about whether humans have instinctive (genetically programmed behavioral tendencies)
First attempts to apply the theories to humans
Evolutionary Psychology Theory
Kin Selection/Inclusive Fitness Theory
Parental Investment Theory
Multilevel Evolutionary Theory
FaSi FaBr Father Mother MoSi MoBr
Cousins Brother EGO Sister Cousins
Grandparent-Grandchild ¼ (½ x ½)
Aunt/Uncle-Niece/Nephew ¼(½ x ½)
Cousin-Cousin 1/8 (½ x ½x ½)
MalesFemalesParental Investment TheoryRelative Contributions of Males and Females to Offspring
200,000 times larger
5 to 7 years
5 to 7 years
A few minutes
Gamete size and contribution to embryo
Minimum time investment to birth of a child
Minimum emotional investment to autonomous healthy child
Minimum economic investment to autonomous healthy child
What characteristics are most sexy?
It varies. Commitment to a single female is one of many strategies for a male. The male can offer fidelity to a single female to help support their offspring. This is only one of the male options. At the other end of the spectrum is “free copulation” leaving females to care for offspring.
Very important. The female needs help with the large time, emotional and economic investments she must make to produce a healthy adult offspring. She would like her mate to stick around and help.
How important is exclusivity and commitment?
The Nerd: Males who do not attract lots of females who are willing to have sex with them can offer commitment as an inducement for sex. They promise long term fidelity and support for the female and her offspring, allowing the female to have more children, or to raise more successful children because she has the time, emotional and economic investments of a male on whom she can count.
The Swinger: Males who attract lots of females who are willing to have sex with them are better off not making a commitment to a single female. They will hope that some of the women with whom they copulate will get pregnant, and that the women will find a way to support/raise the child, either alone, or with the help of another male. This way they have the potential for having large numbers of children in whom they will have invested very little.
The risk of pregnancy and the investment that follows conception for women will make them more careful about sexual partners, and more interested in commitment from partners than will ever be true for males.
Females will be attracted to wealthy, powerful males who can help them support and raise their children. This will be especially true in cultures where males control resources. They may tolerate such men having multiple wives or partners as long as they and their children are supported.
Females will be less exclusively monogamous when they have access to economic resources or earning power themselves. However, they will never be as promiscuous as the most promiscuous males.