title: What do men want? Re-examining whether men benefit from higher fertility than is optimal for women.
abstract: Several empirical observations suggest that when women have more autonomy over their reproductive decisions, fertility is lower. Some evolutionary theorists have interpreted this as evidence for sexual conflicts of interest, arguing that higher fertility is more adaptive for men than women. We suggest the assumptions underlying these arguments are problematic: assuming that women suffer higher costs of reproduction than men neglects the (different) costs of reproduction for men; the assumption that men can repartner is often false. We use simple models to illustrate that (i) menorwomen can prefer longer interbirth intervals (IBIs), (ii) if men can only partner with wives sequentially they may favour shorter IBIs than women, but such a strategy would only be optimal for a few men who can repartner. This suggests that an evolved universal male preference for higher fertility than women prefer is implausible and is unlikely to fully account for the empirical data. This further implies that if women have more reproductive autonomy, populations should grow, not decline. More precise theoretical explanations with clearly stated assumptions, and data that better address both ultimate fitness consequences and proximate psychological motivations, are needed to understand under which conditions sexual conflict over reproductive timing should arise.
authors.affiliation: Department of Human Evolutionary Biology, Harvard University, 11 Divinity Ave, Cambridge, MA 02138, USA moya@g.harvard.edu.
authors.forename: Cristina
authors.identifier: http://orcid.org/0000-0001-7100-9115
authors.initials: C
authors.lastname: Moya
authors.affiliation: Department of Anthropology, Boise State University, 1910 University Drive, Boise, ID 83725, USA.
authors.forename: Kristin
authors.identifier: http://orcid.org/0000-0002-6573-6751
authors.initials: K
authors.lastname: Snopkowski
authors.affiliation: Department of Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Sear
mesh_terms: D002755:Choice Behavior; D005191:Family Characteristics; D005260:Female; D005298:Fertility; D006801:Humans; D008297:Male; D008954:Models, Biological; D043762:Reproductive Behavior / Q000523:psychology*; D015996:Survival Rate; D016387:Women's Health
keywords: adaptive sexual strategies; costs of reproduction; female autonomy; optimal family size; sexual conflict