Conservatism and religiousness participate in fast life history dynamics via elevated reproductive motivation

Abstract

Social attitudes like religiousness and conservatism have been rarely examined in a life history framework. However, there are two competing hypotheses regarding the role of religiousness in human life history: in evolutionary psychological research it is thought to indicate slow life history while the behavioral ecological framework highlights its role in faster life history via elevated reproduction output and lower age of first reproduction. We tested these hypotheses for conservatism and religiousness by analyzing their relations with the variables that measure childhood environmental characteristics, mating effort, and reproductive motivation. The research was conducted via an online study on a sample of young adults in Serbia (N = 528). Bivariate correlations showed that religiousness and conservatism are positively related to reproductive motivation and a beneficial childhood environment, with negative correlations with mating effort. Furthermore, the Network Analysis showed that these two social attitudes are related only to enhanced reproductive motivation when analyzed in a multivariate fashion: conservatism was positively related with reasons favoring parenthood and desired number of children while religiousness was positively related to reasons for parenthood, and negatively for reasons against parenthood and pregnancy planning. Both attitudes had above average centrality indices in the life history network. The results are interpreted in a framework of life history theory and behavioral ecology of social attitudes in general.

Introduction

Fitness is the central tenet of natural selection - selection favors organisms which successfully adapt to their environment; this adaptation is reflected in their number of offspring. Hence, the higher number of offspring, the greater the chance that genes which contributed to the adaptation and reproduction can be transmitted to the next generation. In order to reproduce, organisms must first complete several fitness-related tasks: survive, grow, reach the reproductive stadium, compete in various arenas, and mate. However, some of these tasks are mutually exclusive and have both benefits and costs: delaying first reproduction (Hayward et al., 2015), investing in mating or parenting (Trivers, 1972), fertility and longevity (Williams, 1966), or the quality and quantity of offspring (Lack, 1947). These are evolutionary tradeoffs - their existence prevents individuals from maximizing fitness in a simple and straightforward way; individuals may elevate their fitness via different pathways depending on context (for a recent review of evolutionary tradeoffs see Bolund, 2020).

What are the factors that influence pathways individuals take in order to enhance fitness? They are probably numerous but one of the most important ones is ecological characteristics; research usually points to environmental harshness as a prominent ecological parameter that shapes fitness-related trajectories. In harsh, depriving, and dangerous environments, the fitness maximization dynamics based on early start of mating activity, higher mating effort, early reproduction and higher number of offspring should be the most adaptive; in contrast, when the environment is beneficial, resource abundant, and relatively safe, individuals can benefit more by delaying reproduction, and having less offspring with elevated investment in them. These pathways of fitness maximization are labeled as fast and slow life history trajectories (Del Giudice et al., 2015). There are large amounts of data showing that harsher environmental conditions in early stages of life are indeed associated with the indicators of faster life history dynamics in adolescence or adulthood (e.g. Chisholm et al., 2005; Dunkel et al., 2015; Griskevicius et al., 2011; Međedović, 2019; Sheppard et al., 2016; Webster et al., 2014). However, it should be noted that there are critiques of the slow-fast life history continuum as well. Some scholars claim that the slow-fast life history continuum is not predicted by formal models (Stearns & Rodrigues, 2020) or by existing data (Royauté et al., 2018). Still, others believe that there is enough evidence for fast-slow patterns in life history dynamics and that this framework has explanatory benefits (Del Giudice, 2020). We also believe in a middle point of view: life history dynamics certainly cannot be reduced to the single fast-slow dimension; it represents a more complex system of associated life history events (Međedović, 2020a; b), but the slow-fast life history dynamics framework is still fruitful in interpreting the data.

Behavioral phenotypes can be included in life history dynamics as well. The life history framework was used to analyze personality traits (e.g. Hengartner, 2017) and intelligence (e.g. Međedović & Petrović, 2020) in humans. Social attitudes have rarely been analyzed through the lens of life history theory. Social attitudes are complex behavioral dispositions which include cognitive evaluations of social phenomena, associated emotional reactions, and behaviors related to social events (Kerlinger et al., 1976). Various social attitudes have been empirically explored; among the most common are authoritarianism, dogmatism, conservatism, traditionalism, religiousness and others (reviewed in Petrović, 2020).

Although social attitudes were rarely a subject of evolutionary analysis there is an evolutionary-psychological life history model which includes religiousness. The model is based on the Arizona Life History Battery (ALHB), a set of self-report measures assumed to measure the slow-fast life history continuum in humans (Figueredo et al., 2005; Figueredo et al., 2007). Hence, religiousness is viewed as one of the behavioral dispositions which marks slow life history in this model. However, psychometric measures of life history have been recently criticized in regard to their validity (Međedović, 2020b; Sear, 2020). This critique is related to the role of religiousness in life history dynamics as well. In fact, empirical research is quite congruent in findings that religiousness is related to a lower age of first reproduction (Pearce & Davis, 2016; Strayhorn & Strayhorn, 2009) and higher reproductive success (Blume, 2009; Fieder & Huber, 2016; Međedović, 2020c; Sanderson, 2008). Hence, religious individuals tend to have their first child earlier in their lifetime and they have a higher number of biological children; these are the markers of fast life history trajectory par excellence. They show that religiousness is associated with observed fitness and that individuals with high expression of this trait are maximizing their fitness by increasing reproductive output.

Human behavioral ecology has largely neglected social attitudes in evolutionary analysis of human behavioral traits so far (but see Međedović, 2020c). However, social attitudes are plausible candidates for behavioral ecological exploration. They show large individual differences, and at least some of them (like religiousness) are related to fitness, which suggests that they may be targeted by natural selection. Furthermore, social attitudes show genetic variation as well (Ludeke et al., 2013), which means that they can respond to selection and change, both in regard to the frequency of associated genes and phenotypic mean values.

The main goal of the present manuscript is to advance behavioral ecology of social attitudes, more specifically, religiousness and conservatism. Religiousness is widely defined as a belief in divine entity and frequently includes practices of worshiping that entity (Argyle & Beit-Hallahmi, 1975). Conservatism is a complex attitude which can be defined as “a political and social philosophy promoting traditional social institutions in the context of culture and civilization. The central tenets of conservatism include tradition, organic society, hierarchy, authority, and property rights” (Heywood, 2017). We have chosen these two attitudes because they represent some of the major social attitudes in general and the existing theory and empirical research provides us with an adequate interpretative framework. The current study aims to provide a more precise localization of these two attitudes in life history dynamics in regard to the slow-fast continuum as a conceptual framework. Two competing general hypotheses can be posited: the first is based on the ALHB model and maps religiousness on the slow end of a slow-fast continuum; conversely, the existing data on the relations between religiousness and fertility indicate that this attitude is related to fast life history dynamics. We were not able to find the data regarding conservatism and the psychometric measures of life history. However, there are studies which suggest that conservatism, similarly to religiousness, is related to elevated reproductive output: conservatism is positively related with having children and parental motivation (Kerry and Murray, 2018, Kerry and Murray, 2020). In general, since religiousness and conservatism are reliably positively correlated (Bouchard Jr, 2009; Ludeke et al., 2013), we expect them to have similar positions in the network of examined life history indicators.

We assessed life history relying on the list of psychosocial-biodemographic indicators of life history dynamics (Međedović, 2020b). This set of indicators is based on the measures of environment, mating, and reproduction. In the present research we were not focused on the measures of observed reproductive success, but more to the reproductive motivation. Reproductive motivation represent valid proxy measures of observed reproductive output because they are related to actual reproductive events. For example, the desired age of first reproduction is significantly related to the actual timing of first reproduction (Nettle, 2011) and motives to reproduce are significantly related to the observed reproduction (Miller et al., 2010). Hence, high reproductive motivation is one of the predictors of elevated reproductive output and thus it can be viewed as an indicator of fast life history trajectory. To sum up, fast life history dynamics in a context of indicators measured in the present study is characterized by higher environmental harshness, elevated mating effort, and heightened reproductive motivation.