In a series of recent papers, Kanazawa has extended the Trivers-Willard hypothesis by suggesting that possession of any heritable trait that improves male reproductive success to a greater extent than it does female reproductive success will lead to a male-biased offspring sex ratio (at the individual level). He produces supporting evidence that big and tall parents have more sons than daughters. Here we test this hypothesis using two large datasets from very different populations, one British and one from rural Guatemala. There was no support for Kanazawa's extension of the Trivers-Willard hypothesis in either sample. Maternal marital status was the only predictor of offspring sex ratio but this effect was very small and limited to the British sample. Results are discussed with reference to recent studies of sex-ratio variation in humans.
N. Allal R. Sear A. Prentice R. Mace 2004 An evolutionary analysis of stature, age at first birth and reproductive success in Gambian women Proceedings Royal Society London B: Biological sciences 271 465 470.
D. Almond L. Edlund 2007 Trivers-Willard at birth and one year: evidence from US natality data 1983-2001 Proceedings Royal Society London B: Biological Sciences 274 2491 2496.
J. M. Baeten E. A. Bukusi M. Lambe 2001 Pregnancy complications and outcomes among overweight and obese nulliparous women American Journal of Public Health 91 436 440.
T. Bereczkei R. I. M. Dunbar 1997 Female-biased reproductive strategies in a Hungarian Gypsy population Proceedings Royal Society London B: Biological Sciences 264 17 22.
G. R. Brown 2001 Sex-biased investment in nonhuman primates: Can Trivers & Willard's theory be tested Animal Behaviour 61 683 694.
G. R. Brown J. B. Silk 2002 Reconsidering the null hypothesis: Is maternal rank associated with sex ratios in primate groups? Proceedings of the National Academy of Sciences (USA) 99 11252 11255.
G. Brush A. J. Boyce G. A. Harrison 1983 Associations between anthropometric variables and reproductive performance in a Papua New Guinea highland population Annals of Human Biology 10 223 234.
A. Cagnacci A. Renzi S. Arangino C. Allesandrini A. Volpe 2004 Influences of maternal weight on the secondary sex ratio of human offspring Human Reproduction 19 442 444.
E. Z. Cameron 2004 Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism Proceedings Royal Society London B: Biological Sciences 271 1723 1728.
G. C. Chacon-puignau K. Jaffe 1996 Sex ratio at birth deviations in modern Venezuela: The Trivers-Willard effect Social Biology 43 257 270.
F. Cizmecioglu A. Doherty W. F. Paterson D. Young M. D. C. Donaldson 2005 Measured versus reported parental height Archives of Diseases in Childhood 90 941 942.
CIA 2006 CIA World Fact Book CIA Washington.
Centre For Longitudinal Studies 2003 Millennium Cohort Study, First Survey: CAPI Questionnaire Documentation Institute of Education (University of London) London.
K. Denny 2008 Big and tall parents do not have more sons Journal of Theoretical Biology 250 752 753.
M. R. Devi J. R. Kumari C. R. Srikumari 1985 Fertility and mortality differences in relation to maternal body size Annals of Human Biology 12 479 484.
J. Edwards 2002 Education and Poverty in Guatemala. Technical Paper No. 3 The World Bank Washington, D.C..
S. A. Frank 1990 Sex allocation theory for birds and mammals Annual Review of Ecology and Systematics 21 13 55.
J. Freese B. Powell 1999 Sociobiology, status, and parental investment in sons and daughters: Testing the Trivers-Willard Hypothesis American Journal of Sociology 104 1704 1743.
J. Freese B. Powell 2001 Making love out of nothing at all: Null findings and the Trivers-Willard Hypothesis American Journal of Sociology 106 1776 1788.
S. J. C. Gaulin C. J. Robbins 1991 Trivers-Willard effect in contemporary North-American society American Journal Physical Anthropology 85 61 69.
A. Gelman 2007 Letter to the editors regarding some papers of Dr Satoshi Kanazawa. Journal of Theoretical Biology 245 597 599.
Gelman, A. & Weakliem, D. (2007). Of beauty, sex, and power: Statistical challenges in estimating small effects, http://www.stat.columbia.edu/~gelman/research/unpublished/power.pdf consulted online (8-3-2008).
M. A. Gibson R. Mace 2003 Strong mothers bear more sons in rural Ethiopia Proceedings Royal Society London B: Biological Sciences 270 S108 S109.
J. S. Gillis W. E. Avis 1980 The male-taller norm in mate selection Personality and Social Psychology Bulletin 6 396 401.
D. A. Glei N. Goldman G. Rodriguez 2003 Utilization of care during pregnancy in rural Guatemala Social Science and Medicine 57 2447 2463.
N. Goldman D. A. Glei 2003 Evaluation of midwifery care: results from a survey in rural Guatemala Social Science and Medicine 56 685 700.
N. Goldman A. R. Pebley M. Beckett 2001 Diffusion of ideas about personal hygiene and contamination in poor countries: evidence from Guatemala Social Science and Medicine 52 53 69.
Gragnolati, M. & Marini, A. (2006): Health and poverty in Guatemala technical paper no. 5, World Bank working paper (36206).
V. J. Grant 1994 Maternal dominance and the conception of sons British Journal of Medical Psychology 67 343 351.
S. Helle 2008 Height, weight, body mass index and offspring sex at birth in contemporary Finnish women Journal of Theoretical Biology 252 273 275.
W. E. Hensley 1994 Height as a basis for interpersonal attraction Adolescence 29 469 474.
P. Heuveline N. Goldman 2000 A description of child illness and treatment behavior in Guatemala Social Science and Medicine 50 345 364.
R. L. Hopcroft 2005 Parental status and differential investment in sons and daughters: Trivers-Willard revisited Social Forces 83 1111 1136.
K. Hansen 2006 Millennium Cohort Study: First and Second Surveys. A Guide to the Datasets Institute of Education (University of London) London.
D. Hosmer S. Lemeshow 1989 Applied Logistic Regression Wiley & Sons New York.
T. K. Jensen A.-M. Andersson N. Jørgensen A.-G. Andersen E. Carlsen J. H. Petersen et al.2004 Body mass index in relation to semen quality and reproductive hormones among 1,558 Danish men Fertility and Sterility 82 863 870.
S. Kanazawa 2005 Big and tall parents have more sons: further generalizations of the Trivers-Willard Hypothesis Journal of Theoretical Biology 235 583 590.
S. Kanazawa 2006 Violent men have more sons: Further evidence for the generalized Trivers-Willard Hypothesis (gtwh) Journal of Theoretical Biology 239 450 459.
S. Kanazawa 2007 Beautiful parents have more daughters: A further implication of the generalized Trivers-Willard Hypothesis (gTWH) Journal of Theoretical Biology 244 133 140.
M. C. Keller R. M. Nesse S. Hofferth 2001 The Trivers-Willard hypothesis of parental investment: No effect in the contemporary United States Evolution and Human Behavior 22 343 360.
S. Kirchengast 2000 Differential reproductive success and body size in !Kung San people from northern Namibia Collegium Anthropologicum 24 121 132.
S. Kirchengast E. M. Winkler 1995 Differential reproductive success and body dimensions in Kavango males from urban and rural areas in Northern Namibia Human Biology 67 291 309.
S. Kirchengast E.M. Winkler 1996 Differential fertility and body build in !Kung San and Kavango females from northern Namibia Journal of Biosocial Science 28 193 210.
S. Koziel S. J. Ulijaszek 2001 Waiting for Trivers and Willard: Do the rich really favor sons? American Journal of Physical Anthropology 115 71 79.
J. Kuha 2004 AIC and BIC: comparisons of assumptions and performance Sociological Methods and Research 33 188 229.
G.W. Lasker R. Thomas 1976 Relationship between reproductive fitness and anthropometric dimensions in a Mexican Population Human Biology 48 775 791.
J. Lazarus 2002 Human sex ratios: adaptations and mechanisms, problems and prospects I. C. W. Hardy Sex Ratios: Concepts and Research Methods Cambridge University Press Cambridge 287 311.
O. Leimar 1996 Life history analysis of the Trivers-Willard sex-ratio problem Behavioral Ecology 7 316 325.
W. Linné 2004 Effects of obesity on women's reproduction and complications during pregnancy Obesity Reviews 5 137 143.
S. C. Litell J. Pendergast R. Natarajan 2000 Modelling covariance structure in the analysis of repeated measures data Statistics in Medicine 19 1793 1819.
R. Mace 1996 Biased parental investment and reproductive success in Gabbra pastoralists Behavioral Ecology and Sociobiology 38 75 81.
J. T. Manning R. Anderton S. M. Washington 1996 Women's waists and the sex ratio: evolutionary aspects of the ideal female body shape Journal of Human Evolution 31 41 47.
R. Martorell H. L. Delgado V. Valverde R. E. Klein 1981 Maternal stature, fertility and infant mortality Human Biology 53 303 312.
F. Mathews P. J. Johnson A. Neil 2008 You are what you eat: Evidence for maternal preconception diet influencing foetal sex in humans Proceedings Royal Society London B: Biological Sciences 275 1661 1668.
S. Menard 1995 Applied Logistic Analysis, Quantitative Applications in the Social Sciences Series #106 Sage Publications Thousand Oaks.
W. H. Mueller 1979 Fertility and physique in a malnourished population Human Biology 51 53 166.
N. J. D. Nagelkerke 1991 A note on a general definition of the coefficient of determination Biometrika 78 691 692.
D. Nettle 2002 Height and reproductive success in a cohort of British men Human Nature 13 473 491.
D. Nettle 2002 Women's height, reproductive success and the evolution of sexual dimorphism in modern humans Proceedings Royal Society London B: Biological Sciences 269 1919 1923.
F. C. Pampel 2000 Logistic Regression: A Primer, Quantitative Applications in the Social Sciences Series #132 Sage Publications Thousand Oaks.
B. Pawlowski R. I. M. Dunbar A. Lipowicz 2000 Evolutionary fitness: Tall men have more reproductive success Nature 403 156.
B. Pawlowski S. Koziel 2002 The impact of traits offered in personal advertisements on response rates Evolution and Human Behavior 23 139 149.
A. R. Pebley N. Goldman 1995 Guatemalan Survey of Family Health (EGSF), [Computer file] RAND [producer] Santa Monica, CA.
C. Peterson N. Goldman A. R. Pebley 1997 The 1995 Guatemalan Survey of Family Health (EGSF): Overview and Codebook RAND Santa Monica, CA.
I. Plewis 2004 Millennium Cohort Study: Technical Report on Sampling Institute of Education (University of London) London.
Plewis, I. & Ketende, S. (Eds) (2006): Technical Report on Response: First Edition. London: Institute of Education (University of London).
T. V. Pollet D. Nettle 2008 Taller women do better in a stressed environment: Height and reproductive success in rural Guatemalan women American Journal of Human Biology 20 264 269.
T. V. Pollet T. W. Fawcett A. P. Buunk D. Nettle 2009 Sex-ratio biasing towards daughters among lower ranking co-wives in Rwanda Biology Letters 5 765 768.
D.-D. Qin W. Yuan W.-J. Zhou J.-Q. Cui J.-Q. Wu E.-S. Gao 2007 Do reproductive hormones explain the association between body mass index and semen quality? Asian Journal of Andrology 9 827 834.
I. J. Rickard 2008 Kanazawa's ‘Generalized Trivers-Willard Hypothesis’ and the heritability of offspring sex-ratio Journal of Evolutionary Psychology 6 255 260.
R. Sear 2006 Height and reproductive success: How a Gambian population compares to the West Human Nature 17 405 418.
R. Sear N. Allal R. Mace 2004 Height, marriage and reproductive success in Gambian women Research in Economic Anthropology 23 203 224.
B. C. Sheldon S. A. West 2004 Sex ratio variation in ungulate mammals American Naturalist 163 40 45.
J. A. Shepperd A. J. Strathman 1989 Attractiveness and height: The role of stature in dating preference, frequency of dating, and perceptions of attractiveness Personality and Social Psychology Bulletin 15 617 627.
E. A. Spencer P. N. Appleby G. K. Davey T. J. Key 2002 Validity of self-reported height and weight in 4808 EPIC-Oxford participants Public Health and Nutrition 5 561 565.
SPSS 2005 Linear Mixed-Effects Modeling in SPSS: An Introduction to the MIXED Procedure SPSS Inc Chicago.
D. Steele 1994 Guatemala G. Psacharopoulos H.A. Patrinos Indigenous People and Poverty in Latin America: An Empirical Analysis World Bank Washington, DC 105 140.
A. Stein P. G. Barnett D. W. Sellen 2004 Maternal undernutrition and the sex ratio at birth in Ethiopia: Evidence from a national sample Proceedings Royal Society London B: Biological sciences 270 S37 S39.
R. L. Tamimi P. Lagiou L. A. Mucci C.-C. Hsieh H.-O. Adami D. Trichopoulos 2003 Average energy intake among pregnant women carrying a boy compared with a girl British Medical Journal 326 1245 1246.
R. L. Trivers D. E. Willard 1973 Natural selection of parental ability to vary the sex ratio of offspring Science 191 249 263.
UNPD 2005 World Population Prospects: The 2004 Revision UN New York.
G. Verbeke G. Molenberghs 2001 Linear Mixed Models for Longitudinal Data Springer New York.
A. Vetta 1975 Fertility, physique and intensity of selection Human Biology 47 283 293.
J. X. Wang M. J. Davies R. J. Norman 2002 Obesity increases the risk of spontaneous abortion during infertility treatment Obesity Research 10 551 554.
E. M. Winkler S. Kirchengast 1994 Differential fertility and body dimensions in Namibian !Kung San males American Journal of Human Biology 6 203 213.
World Health Organization. (2006): Working together for health: The world health report. Available at http://www.who.int/whr/2006/whr06_en.pdf. (Retrieved on 8-3-2009).
M. E. Zaldivar R. Lizarralde S. Beckerman 1991 Unbiased sex ratios among the Bari: an evolutionary interpretation Human Ecology 19 469 498.
S. Zhu M. Heo M. Plankey M. S. Faith M.B. Allison 2003 Associations of body mass index and anthropometric indicators of fat mass and fat free mass with all-cause mortality among women in the first and second National Health and Nutrition Examination Surveys follow-up studies Annals of Epidemiology 13 286 293.