ArticlePloS one2009
A Trivers-Willard effect in contemporary humans: male-biased sex ratios among billionaires.
Article in PloS one, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 30 papers.
What it found
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Who cites it
30 citing papers in PubMed.
- Is sex at birth a biological coin toss? Insights from a longitudinal and GWAS analysis.Science advances · 2025Article
- Socioeconomic status and sex ratio in the contemporary Hungarian population.Evolutionary human sciences · 2024Article
- The offspring sex ratio at birth in one of the largest human harems.EXCLI journal · 2024Article
- Are brood sex ratios adaptive?-The effect of experimentally altered brood sex ratio on nestling growth, mortality and recruitment.Journal of evolutionary biology · 2023Article
- Sons and parental cognition in mid-life and older adulthood.Journal of psychiatric research · 2022Article
- Girls start life on an uneven playing field: Evidence from lowland rural Nepal.Evolution, medicine, and public health · 2022Article
- Evolutionary dynamics of the Trivers-Willard effect: A nonparametric approach.Ecology and evolution · 2021Article
- Metabolic Hormone Profiles in Breast Milk From Mothers of Moderate-Late Preterm Infants Are Associated With Growth From Birth to 4 Months in a Sex-Specific Manner.Frontiers in nutrition · 2021Article
- No genetic contribution to variation in human offspring sex ratio: a total population study of 4.7 million births.Proceedings. Biological sciences · 2020Article
- The global male-bias in sex ratio at birth is sustained by the sex ratio genotypes of replacement offspring.Genetica · 2019Article
- Revisiting the Trivers-Willard theory on birth sex ratio bias: Role of paternal condition in a Malagasy primate.PloS one · 2018Article
- Frequency-dependent two-sex models: a new approach to sex ratio evolution with multiple maternal conditions.Ecology and evolution · 2016Article
- The Trivers-Willard hypothesis: sex ratio or investment?Proceedings. Biological sciences · 2016Article
- The impact of children's sex composition on parents' mortality.BMC public health · 2014Article
- The primary parental investment in children in the contemporary USA is education : Testing the Trivers-Willard hypothesis of parental investment.Human nature (Hawthorne, N.Y.) · 2014Article
- Article
- Predictions for sex of first born child reflect masculine and feminine characteristics in male and female undergraduates.Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior · 2013Article
- Cognitive ability correlates positively with son birth and predicts cross-cultural variation of the offspring sex ratio.Die Naturwissenschaften · 2013Article
- Testing evolutionary theories of discriminative grandparental investment.Journal of biosocial science · 2013Article
- Article
Corrections and comments
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Authors and funding
2 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundNatural selection should favour the ability of mothers to adjust the sex ratio of offspring in relation to the offspring's potential reproductive success. In polygynous species, mothers in good condition would be advantaged by giving birth to more sons. While studies on mammals in general provide support for the hypothesis, studies on humans provide particularly inconsistent results, possibly because the assumptions of the model do not apply. METHODOLOGY/PRINCIPAL
findingsHere, we take a subset of humans in very good condition: the Forbe's billionaire list. First, we test if the assumptions of the model apply, and show that mothers leave more grandchildren through their sons than through their daughters. We then show that billionaires have 60% sons, which is significantly different from the general population, consistent with our hypothesis. However, women who themselves are billionaires have fewer sons than women having children with billionaires, suggesting that maternal testosterone does not explain the observed variation. Furthermore, paternal masculinity as indexed by achievement, could not explain the variation, since there was no variation in sex ratio between self-made or inherited billionaires. CONCLUSIONS/SIGNIFICANCE: Humans in the highest economic bracket leave more grandchildren through sons than through daughters. Therefore, adaptive variation in sex ratios is expected, and human mothers in the highest economic bracket do give birth to more sons, suggesting similar sex ratio manipulation as seen in other mammals.
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