This is the first in a four-post series on church attendance and fast/slow life history patterns (which I explain below). As discussion of fast/slow life history has become popular in evolutionary circles, we’re currently in a situation where some smart people claim that fast life histories drive religiosity and other smart people claim that slow life histories drive religiosity. It’s an unusually stark disagreement. In this post and following two, I’m going to lay some groundwork before providing the resolution in the fourth post.

What are fast and slow life history patterns? As Del Giudice, Gangestad, and Kaplan (2016) explain: “At the broadest level of analysis, the life history strategies of different species can be arranged on a continuum from ‘fast’ (early maturation and reproduction, fast growth, small body size, high fertility, short lifespan, and low investment in offspring quality) to ‘slow’ (late maturation and reproduction, slow growth, large body size, low fertility, long lifespan, and high investment in offspring).”

Within species, there are group-level and individual-level differences in fast/slow patterns. As applied to humans, typical discussions note that some groups face more dangerous, unpredictable, harsh environments, leading to faster life history patterns—earlier age at first child, higher completed fertility, reduced investments in embodied capital (e.g., less time spent pursuing formal education), earlier sexual maturation, earlier sexual debut, less stable mating relationships, and so on—while safer and more reliable environments encourage slower patterns.

What does this have to do with religiosity? On the one hand, the secularization hypothesis has long noted that increased economic development in societies over the past century has tended to lead to reduced religiosity in those societies (McCleary & Barro, 2006). Because economic development plays a key role in producing slower life history patterns, the thought is that faster life histories are associated with more religiosity and slower life histories with less religiosity. Further, state-level analyses from the U.S. have shown solid relationships such that states with higher rates of teen births, lower household incomes, and higher STD rates are also states with higher levels of church attendance (Hackman & Hruschka, 2013; Strayhorn & Strayhorn, 2009). In addition, African Americans have both faster life history patterns than white Americans as well as higher rates of church attendance. So it looks pretty good for the fast/religious slow/secular idea, right?

Not so fast. According to Baumard and Chevallier (2015), religiosity could be a tool employed by slow life history strategists to fight off threats from fast life history strategists. Taking a longer view, they see the initial rise of world religions as coinciding with the widespread appearance of slower life history strategies, while the recent decline in religiosity in developed countries could be the result of a waning threat, given how rare genuinely faster patterns have become in these developed countries. They use their slow/religious fast/secular thesis to draw together lots of findings regarding religiosity—its association with prosociality, family values, and various forms of delayed gratification (frugality, work ethic, etc.).

So who’s right? We’ll get there. Before that, I need to make a couple of broad points. To set up tomorrow’s episode: Did you notice earlier that all the evidence for the fast/religious slow/secular hypothesis comes from group-level data?

[Update: The next post in this series is here.]