No Evidence for a Tradeoff between Competitive Traits and Ejaculate Quality in Humans. Tara DeLecce, Todd K. Shackelford, Bernhard Fink, Mohaned G. Abed. [in press, Evolutionary Psychology, June 2020]. https://www.toddkshackelford.com/downloads/Delecce-et-al-EP.pdf
Abstract: Research in nonhuman animals (including insects, birds, and primates) suggests a tradeoff in males between investment in competitive traits and investment in ejaculate quality. Previous research reported a negative association between perceived strength and ejaculate quality, suggesting that this tradeoff also applies to human males. We conducted novel analyses of data secured as part of a larger project (Pham et al., 2018) to assess the relationship between competitive traits (shoulder-to-hip ratio, handgrip strength, and height) and ejaculate quality (indexed by sperm morphology, sperm motility, and sperm concentration) in a sample of 45 men (ages ranging 18 to 33 years; M = 23.30, SD = 3.60). By self-report, participants had not had a vasectomy and had never sought treatment for infertility. We controlled for several covariates known to affect ejaculate quality (e.g., abstinence duration before providing an ejaculate) and found no statistically significant relationships between competitive traits and ejaculate quality; our findings therefore do not accord with previous research on humans. We highlight the need for additional research to clarify whether there is a tradeoff between investment in competitive traits and investment in ejaculate quality in humans.
Keywords: tradeoff hypothesis; ejaculate quality; shoulder-to-hip ratio; competitive traits
Check also A preliminary but methodologically improved investigation of the relationships between major personality dimensions and human ejaculate quality. Tara DeLecce et al. Personality and Individual Differences, Volume 153, January 15 2020, 109614. https://www.bipartisanalliance.com/2019/11/a-preliminary-but-methodologically.html
And also Disagreeable men produce higher-quality ejaculates. Tara Lynn DeLecce, Guilherme S. Lopes, Virgil Zeigler-Hill, Todd K. Shackelford. Human Behavior and Evolution Society 31st annual meeting. Boston 2019. https://www.bipartisanalliance.com/2019/07/disagreeable-men-produce-higher-quality.html