The Puzzle of Monogamous MarriageJoseph Henrich, Robert Boyd, and Peter J. Richerson (2012). The puzzle of monogamous marriage. Philosophical Transaction of the Royal Society, 367: 657-669.

Polygyny

• Number of wives associated with power and wealth with more wives meaning greater power and wealth.

• With greater inequality of wealth, polygyny becomes more common among those with greater wealth.

Mating Strategies

• In high competition situations, unattractive low-status males will engage in more risky behavior to avoid fitness oblivion (not mating).

• In low competition situations, status gains do not lead to greater reproductive success and thus a male will be more adverse to risk and more likely to pair bond.

• Females generally seek higher status males.

Marriage Systems

• Distinct from mating strategies.• Part of cultural learning and cultural norms.• Failure to adhere to norms can cause an

individual to be outcast.

Hypotheses• The modern package of norms and institutions

that constitutes monogamous marriage has been shaped by cultural evolution driven by inter group competition.• Because…• Monogamous marriage reduces the intensity of intra

sexual competition.• Normative monogamy reduces intra household conflict.

Method

• Examination of evolution of Mormon communities that adopted normative monogamous marriage over polygamy.

• Cross-sectional analysis of several nations with different normative marital practices.

Results and Findings• Imposition of normative monogamous marriage

decreases intra sexual competition. • Lower rates of crime. • Reduced spousal age gap, gender inequality, and fertility.• Increased GDP per capita.

Normative monogamy reduces intra-household conflict.• Greater paternal investment and elimination of conflict

between co-wives.

Discussion• Normative monogamous marriage likely spread

due to its impact on intergroup competitive success.• Decreased crime likely spurred commerce, travel, and

free flow of ideas and innovations.• Low status males would be more likely to marry and more

likely to look to the future rather than engage in status elevating risky behavior.• Higher status males would invest more in children rather

than the addition of wives which would lead to better education and advancement of society.

Monogamy: The Golden Parenting Standard

http://www.youtube.com/watch?v=oYdqjV4eruY