This chapter provides a theoretical and empirical framework for understanding the relation between life history strategy and mating strategies. The current scientific debate regarding the structure of life history and its connection to mating behaviors inspired the authors of this chapter to conduct several theoretical and empirical examinations of this subject. For example, phylogenetic confirmatory factor analysis across a sample of 503 eutherian mammals supports the presence of a higher-order life history factor comprised of lower-order factors that have been labeled fast–slow and neoteny, respectively. Consistent with past publications, the present chapter also found evidence supporting the predicted relation between life history indicators with mating strategies. Also consistent with previously published findings, one set of phylogenetic generalized linear models identified that polygynandrous mating systems in nonhuman primates, along with the [lactation/(lactation + gestation)] ratio, positively predicted infanticide by males. These constructive replications, however, also revealed the novel finding that the higher-order life history factor did not predict these infanticides when statistically controlled for the effects of the lower-order indicators. Hence, the specific variance associated with the lower-order indicators eliminates any significant residual contribution made by the higher-order life history factor. These results are not unexpected given the principle of Brunswik symmetry, wherein to attain optimal predictive power the predictor and criterion variable must be measured at the same level of data aggregation. These findings led us to conduct a theoretical examination of the psychometrically expected relations between higher-order factors, such as life history strategy, and lower-order factors, such as mating strategies, in general. We therefore explore the characteristics of the latent hierarchical structure of life history strategy that has been found in numerous empirical studies for the purpose of deriving more specific predictions regarding the effects of general life history strategy on specific mating strategies. We afterwards test the principle of Brunswik symmetry by reporting additional analyses of the expected moderating effect of slow life history strategy on the relation between short-term and long-term mating orientations, r(STM,LTM), in humans. A sequential canonical analysis revealed that the positive effect of slow life history strategy on r(STM,LTM) was fully mediated by a general strategic differentiation-integration factor (SD-IE) on life history traits. Individuals with slower life history strategies exhibited greater integration between short-term and long-term mating strategies. Consequently, this analysis counters a long-held position regarding any fixed association between slow life history strategy and the relationship between short-term and long-term mating orientations.

Relationship maintenance is a central topic in relationship science. Most relationship scholars examine relationship maintenance at the proximate level of causation by examining how variables such as immediate threats to a relationship or an individual’s degree of commitment elicit the motivation to maintain it. Far less attention has been granted to distal factors, such as each partner’s developmental history or the possible evolutionary origins of relationship maintenance tendencies. The primary goal of this chapter is to shed clarifying light on these understudied levels of analysis by viewing relationship maintenance processes from an evolutionary-developmental perspective. We first review two central evolutionary frameworks (the Strategic Pluralism Model and Life History Theory) and integrate them within a single model called Developmental Strategic Pluralism. Drawing from this novel framework, we derive a set of testable predictions regarding relationship maintenance processes with the ultimate goals of contextualizing proximate relationship processes within evolutionary thinking and stimulating new avenues for future research in this rapidly growing area of relationship science.

The detailed genetic study of Taï chimpanzees, now in its third generation, has made important contributions on several levels. As a pioneering instance of the use of non-invasive sources of DNA for elucidation of individually specific genetic profiles, results from Taï have illustrated the potential and the pitfalls of using challenging genetic sample materials. Paternity distribution assessment has elucidated the role of social rank in reproductive competition among male chimpanzees. Analysis of average levels of dyadic relatedness challenged the long-standing assumption of high relatedness levels among males, leading to a more nuanced understanding of the impact of kinship on cooperation within as well as competition between groups. Finally, analyses of genetic differentiation among groups at Taï have contributed to understanding the relationship between genetic and cultural variation and the impact of differentiation on cooperation and competition. Future insights on how the population has been shaped by selective processes such as culture, ecology or disease will come from work on adaptive variation of immune system genes and genome-scale sequence variation.