To understand how human behavior has evolved through time and responds to local environments, human behavioral ecologists collect data on populations across the world. Globally, people are choosing to have fewer children than in the past. Some countries are still dealing with overpopulation, but an even larger number are dealing withpopulation aging and fear of depopulation. Understanding decisions about how many children to have is important in today’s world and is the focus of my research. To examine how family size is changing, researchers calculate total fertility rate, which is specific to a given year and is calculated as the total number of children that would be born to a female if she were to give birth at that particular year’s age-specific fertility rate for each age. This is a value that represents the fertility of females at all ages in a particular year but does not represent any particular person (since a real person experiences fertility across many years). I conducted fieldwork in rural Bolivia, a place where the total fertility rate was approximately 6 children per woman in 1970 but fell to only 3 children per woman by 2013 (World Bank 2022). By interviewing people who live in communities that are undergoing rapid changes in fertility rates, I attempt to understand how people make decisions about family size.
Figure C.8 shows me walking from house to house during my fieldwork in Bolivia. My interviews with over 500 Bolivian women found that those who had more education or those who expected their children to go further in school had fewer children and that family size was similar across groups of friends (Snopkowski and Kaplan 2014). While the conflict between work and childcare is particularly difficult for parents in postindustrialized contexts, in this rural Bolivian community, most women were able to integrate their daily work with childcare. For instance, a woman may own a shop where she could engage in childcare and run the shop simultaneously. To fully understand human behavior cross-culturally, we need to examine many different societies. Using large datasets collected in 45 different countries, my collaborator and I were able to examine how factors such as education and wealth may have different effects on fertility across the world (Colleran and Snopkowski 2018). Our results showed that in every country surveyed, more education for women was associated with having fewer children, but the effect of wealth varied. In countries with high fertility, more wealth typically associated with more children, but in countries with low fertility, more wealth was typically associated with fewer children. These results show that as people have access to more education and choose to educate themselves and their children, small families will become the norm everywhere in the world.