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Ritualized combat as an indicator of intrasexual selection effects on male life history evolution
Author(s) -
Graves Brent M.
Publication year - 2009
Publication title -
american journal of human biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.559
H-Index - 81
eISSN - 1520-6300
pISSN - 1042-0533
DOI - 10.1002/ajhb.20933
Subject(s) - sexual selection , biology , reproduction , assortative mating , demography , reproductive success , homo sapiens , life history theory , parental investment , competition (biology) , selection (genetic algorithm) , mating , life history , zoology , ecology , population , sociology , pregnancy , genetics , anthropology , offspring , artificial intelligence , computer science
Trade‐offs between survival, growth, current reproduction, and future reproduction influence life history evolution, leading to adaptive timing of investment in various strategies. If engagement in costly intrasexual contests to gain better access to mates is an important form of male reproductive investment, then the expression of characters that promote success in this process should be influenced by their fitness effects across the lifespan. To test this prediction, the ages at which human ( Homo sapiens ) males exhibit the greatest investment in morphological, behavioral, and physiological characters associated with intrasexual competition was estimated by examining the ages at which males succeed in a form of ritualized combat. The average age of international boxing champions was in the latter half of the twenties, and titles were held for about 2 years on average. Thus, peak investment in traits that enhance intrasexual competition abilities appears to coincide with ages at which males have highest reproductive success. Additionally, larger males reached peak probability of success in this ritualized combat at ages about 2.6 years greater than smaller males. Because body size is highly heritable and there is strong positive assortative mating relative to this character among humans, this may indicate a polymorphic set of reproductive strategies produced through maintenance of coadapted gene complexes. Am. J. Hum. Biol., 2010. © 2009 Wiley‐Liss, Inc.