Behaviour and beliefs related to male aggression: Evidence of intrasexual selection in humans?
- Subject Areas
- Anthropology, Ecology, Evolutionary Studies
- sexual selection, polygyny, sex ratio, aggression, behavioural ecology, contest competition, human evolution, subsistence effort
- © 2016 Carter et al.
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2016. Behaviour and beliefs related to male aggression: Evidence of intrasexual selection in humans? PeerJ Preprints 4:e1802v2 https://doi.org/10.7287/peerj.preprints.1802v2
Sexual selection favors traits that increase mating and, thus, reproductive success. Some scholars have suggested that intrasexual selection driven by contest competition has shaped human male aggression. If this is the case, one testable hypothesis is that beliefs and behavior related to male aggression should be more prevalent in societies where the intensity and strength of sexual selection is higher, as measured by factors such as the presence and scope of polygyny, the number of same-sex competitors relative to potential mates, and the amount of effort males have available to allocate to mating. Using mixed-effect linear regression models with data from 78 societies from the Standard Cross-Cultural Sample, we found strong support for this hypothesis. We were able to rule out some potential alternative explanations by controlling for confounding variables such as political complexity, warfare and geographic clustering.
In this version of the manuscript, we have: (1) revised the wording of the hypotheses and dropped one measure of polygynous practices based on feedback from peers; (2) redrawn the results figure so that it is more informative with regards to effect sizes and confidence intervals; and, (3) provided further discussion of the efficacy of our measure of 'aggressiveness,' providing a table and examples showing what various values of the variable mean.
Table S1: Variables
Table S1 - Detailed summary of variables used in the study
Table S2 - Data
Table S2 - Data. Column headings: (a) Frequent Interpersonal Violence; (b) Warriors Have Prestige; (c) Wives Taken From Hostile Groups; (d) Male Scarification; (e) Beliefs and Behaviour Related to Male Aggression (1st PCA of A-D); (f) Polygyny; (g) Wives (Mean): Upper 50th %ile; (h) Wives (Median): Upper 50th %ile; (i) Sex Ratio: Upper 50th %ile; (j) Male War Mortality; (k) Males Expend Subsistence Effort; (l) Frequent Warfare; (m) Political Complexity; and, (n) Region
Table S3: Correlations
Table S3 - Tetrachoric correlations amongst predictors of interest. We could not calculate the correlation between the two polygyny predictors because there are no cases of non-polygynous societies in the upper 50th %ile for variance in number of wives