The evolutionary anthropology of fertility decline in rural Poland

• Main Author: Colleran, H.
• Published: University College London (University of London) 2013
• Subjects: 301
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.626019

Demographic transition to low fertility appears maladaptive from the standpoint of genetic fitness. In their search for causality, evolutionists and demographers alike have found it difficult to separate individual characteristics from wider sociocultural and interpersonal influences on fertility, with research tending to focus on either micro or macro levels of analysis. This thesis is concerned with understanding fertility decline from an integrated evolutionary perspective, by combining and testing hypotheses from two different theoretical frameworks: human behavioural ecology, which emphasises individual factors and a socioeconomic model of behaviour; and cultural evolution, which emphasises social interactions, cultural norms and group level effects. I collected ethnographic and survey data designed to test these hypotheses from 1,995 women in 22 populations (21 villages and 1 town) in rural southern Poland. The area is characterised by high completed fertility (>3 births) and low contraceptive prevalence, but is rapidly ‘modernising’ from a peasant agrarian to a fully market-integrated economy. I use multilevel regression models to explicitly examine both individual and group-level effects on fertility decline. Specifically, I examine how fertility is influenced by: (1) changes in the effects of wealth and status; and (2) changes in the structure and frequency of social interactions. I also examine (3) the extent to which contraceptive use is driven by social influence and cultural dynamics in addition to socioeconomic factors. Ultimately, the aim of this thesis is to evaluate the extent to which low fertility can be understood as: (a) a tradeoff between the quantity and ‘quality’ of children, as advocated by human behavioural ecologists; and (b) a compromise between cultural and reproductive success, advocated by cultural evolutionists. The results show that the characteristics of individuals are not the only things that matter. I find that fertility decline is associated with interactions between individuals, the environments in which they live, and the behaviour of the people that surround them. The findings partially support both approaches to fertility decline. However the combined assumptions of both frameworks are more successful in explaining low fertility than is either framework alone. A comprehensive evolutionary explanation of the demographic transition will therefore require a principled synthesis of both.