Simulating the emergence of population-wide marriage
patterns
produced by individual mate-search heuristics
The choice of a partner for marriage or cohabitation is
one of the key events in the course of our lives. But the scientific
study of marriage is typically pursued by two single research traditions
that themselves should be wedded: demographic research with data on aggregate
population-level patterns such as age at marriage and proportion ever marrying,
and psychology and economics with models of the (often heterogeneous and
culturally varying) individual-level processes that can end in the decision
to cohabit or marry. How can the former top-down macro perspective
and the latter bottom-up micro view be brought together to speak to each
other?
To bridge the gap in the study of the marriage market,
we have developed agent-based models that simulate the mate search and choice
behavior of individual agents interacting in a group. These simulations
allow us to control and monitor the micro-level decision mechanisms of each
agent, and observe the patterns that emerge at the macro-level as a consequence
of their choices and interactions. In this paper, we combine demographic
and psychological approaches to marriage via this agent-based modeling approach.
We start with population-level empirical evidence on the distribution of
ages at marriage and review existing explanations of the common invariant
features of this distribution across cultures. We then take the bottom-up
approach and simulate the behavior of a cohort of satisficing agents looking
for (marriage) partners in situations of both one-sided and mutual choice.
We find that plausible psychological mechanisms of choice suggested by the
framework of bounded rationality need some refinements in order to be reconciled
with the macro patterns of marriage choice. In particular, we show
how population heterogeneity in strategies is compatible with observed macro
patterns. Our results point to a wide range of future research possibilities,
including both empirical studies and further modeling of demographic behavior.
Peter M. Todd
Max Planck Institute for Human Development
Center for Adaptive Behavior and Cognition
http://www-abc.mpib-berlin.mpg.de/users/ptodd
ptodd@mpib-berlin.mpg.de