What do evolutionary researchers really believe about human psychology and behavior?

– by Daniel Kruger, Maryanne Fisher, & Catherine Salmon

Research in evolutionary psychology attracts considerable attention, from both enthusiasts and critics. You might ask, why study what evolutionary minded researchers believe? Why would anyone be interested in knowing such details? There are several important reasons. For one, we repeatedly see articles in journals, as well as the popular press, that are misrepresentations or misconceptions of what those in the field perceive most evolutionary scholars to believe. As a result, many evolutionary-based researchers have devoted considerable effort in pointing out errors in people’s conceptions of what an evolutionary approach to human behavior entails. Researchers spend a non-trivial portion of their time attempting to correct such misconceptions and they seem to end up having to do so repeatedly.

Second, those who utilize an evolutionary perspective in their research are often viewed uniformly by those who use different approaches. The field itself is not monolithic in belief: there are competing theoretical models and phenomena which are accepted to greater and lesser degrees. There were even debates on what the focus of evolutionary research should be: studying actual behavior, counting offspring, or identifying design features of the mind. Several topics studied under an evolutionary umbrella are contentious or controversial, both within and outside the field. The perception of homogeneity by others should not be surprising, as it is well established that members of an in-group see the uniqueness between individual members while ignoring the variability across members of other groups (the “outgroup homogenization effect”).

Third, evolutionary theory continually advances, and different models or beliefs may rise or fall in popularity over time. Assessing beliefs at multiple points of time would allow us to see how theories become established and how beliefs change, or become more sophisticated, over time. Documenting the heterogeneity in scholars’ views allows us to clarify the level of belief on specific topics, as well as demonstrate the overall variability in beliefs within the field.

We investigated the extent of belief in several key and contested aspects of human psychology and behavior in a broad sample of nearly 600 evolutionary-informed scholars. This study was part of a larger project, the Survey of Evolutionary Scholars on the State of Human Evolutionary Science, which is an international collaboration to assess the state of the field. Results indicate there are both core beliefs shared among evolutionary scholars, as well as phenomena accepted by varying proportions of scholars. The misperception that everyone who approaches the study of human behavior from an evolutionary perspective holds the same views was challenged by variation in agreement across items. There are also differences in the prevalence of beliefs between those trained in Anthropology and Psychology.

Nearly all participants believed that developmental environments substantially shape human adult psychology and behavior, refuting accusations of genetic determinism. Nearly all participants believed that there are differences in human psychology and behavior based on sex differences from sexual selection, and that there are individual differences in human psychology and behavior resulting from different genotypes. These concepts are currently controversial in mainstream social science.

About three-quarters of participants believed that there are within-person differences in psychology and behavior across the menstrual cycle, an area which generates considerable debate and sometimes contradictory findings. Three-fifths believed that the human mind consists of domain-specific, context-sensitive modules, another focus of criticisms from outside and even from within the field. Psychologists were more likely to believe in menstrual cycle effects and mental modularity than Anthropologists were.

About half of participants believed that behavioral and cognitive aspects of human life history vary along a unified fast-slow continuum. Life histories represent investments in important aspects of survival and reproduction – growth and development, acquiring reproductive partners, taking care of offspring, etc. Biologists tend to examine differences in life histories between species, whereas psychological research has focused on life history variation among humans, especially in relation to experiences in childhood. Anthropologists tend to use biodemographic measures of life history (e.g., pubertal timing, age at first birth, number of children), whereas psychologists have used psychometric life history assessments (e.g., self-report surveys). Initial survey measures assumed that human life history varied along one continuous dimension, whereas more recent work has indicated that human life history may have multiple, though related, dimensions. Previous work has also shown that the scientific literature on life history is separated by field, suggesting that this work lacks a common focus.

Only about 40% of participants believed that group-level selection has substantially contributed to human evolution. Belief in group selection has waxed and waned over the decades, with the rise of increasingly complex models such as multi-level selection. Natural selection depends on variation, and academic progress is facilitated by tests of competing hypotheses from different theoretical models or research programs. The extent of specific beliefs may change over time, as research accumulates additional evidence to support or refute specific claims.

Also, it is important to note that as many as a third of participants answered “Don’t know” for some of the items. Participants commented on these topics in open-ended items, some saying that they really did not know enough about an area, others noting they had complex beliefs or that their beliefs depended on the way a construct was defined. Some indicated that they had seen mixed support, and thus there was not enough evidence to decide either way.

Overall, the paper clarifies the actual positions of evolutionary researchers, which should help reduce some misunderstandings and shows that there are competing perspectives even among those who identify as evolutionists. Scientific progress is facilitated when critics have an accurate understanding and can direct arguments and research at the beliefs which are actually held.

Read the original paper: Kruger, D.J., Fisher, M.L., & Salmon, C. (2022). What do evolutionary researchers believe about human psychology and behavior? Evolution and Human Behavior, 44(1), 11-18.