Samuel Bowles (joint work with Max Greenberg, Monique Borgerhoff Mulder, Cody Ross, and Seung-Yung Oh)
Marital institutions have a major impact on how wealth is shared, accumulated and transmitted over generations thus affecting the distribution of wealth, which in turn affects the sorts of marital arrangements that men and women (or their parents) choose.
Understanding the coevolution of marital institutions and wealth inequality confronts the following empirical puzzle. It is widely thought that polygyny will be more prevalent where male wealth inequality is greater. But we provide genetic and other evidence that the decline of the practice of polygyny in Western Eurasia co-occurred with the emergence of capital-intensive farming along with unprecedented wealth disparities perhaps 5 millennia ago, and that it persists up to recent times primarily in populations with labor intensive technologies (hoe-farming, not plow-farming) and limited wealth inequalities.
To resolve this puzzle, we develop a model of both male and female mate choice and show that a technical change can drive the decline of polygyny. This change, we propose, was the growing importance of rival wealth (e.g., land or cattle)---which must be divided among one's offspring---relative to non-rival wealth (e.g., lineage membership or genes)---which can be transmitted in its entirety to all of one's children, irrespective of their number.
We calibrate our model for the Kipsigis, a polygynous African agro-pastoralist population, and find that the model's predicted equilibrium marital matches (number of wives for each Kipsigis male in our data set) approximates the observed distribution of polygyny in this population. The calibrated model allows a novel identification strategy to test our hypothesis concerning the evolution of marital arrangements during a time period for which data are not available: we simulate the effect on the Kipsigis of a hypothetical exogenous technical change, an increase in the importance of rival wealth, which, given the parameters of the model estimated from Kipsigis data, we show induces a transition of the Kipsigis to a monogamous population. Our model thus provides a possible resolution of the polygyny puzzle by means of an account of the long term coevolution of monogamy and rival wealth inequality.
Speaker
Sam BowlesProfessor at SFI