A sex-specific test of selection in utero

Catalano, Ralph; Saxton, Katherine; Bruckner, Tim A.; Goldman, Sidra; Anderson, Erik

doi:10.1016/j.jtbi.2008.12.008

Cited by 34 publications

(27 citation statements)

References 26 publications

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“…Unlike gestations involving male twins, those producing female twins ultimately yield as many, and in stressful circumstances may yield more, grandchildren than do female singletons (Lummaa, 2001). This circumstance implies that gestations of female singletons may spontaneously abort before those of female twins with increasing risk aversion in the population (Catalano et al, 2009).…”

Section: Discussionmentioning

confidence: 99%

Twins Less Frequent Than Expected Among Male Births in Risk Averse Populations

et al. 2015

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Male twin gestations exhibit higher incidence of fetal morbidity and mortality than singleton gestations. From an evolutionary perspective, the relatively high rates of infant and child mortality among male twins born into threatening environments reduce the fitness of these gestations, making them more vulnerable to fetal loss. Women do not perceive choosing to spontaneously abort gestations although the outcome may result from estimates, made without awareness, of the risks of continuing a pregnancy. Here, we examine whether the non-conscious decisional biology of gestation can be linked to conscious risk aversion. We test this speculation by measuring the association between household surveys in Sweden that gauge financial risk aversion in the population and the frequency of twins among live male births. We used time-series regression methods to estimate our suspected associations and Box-Jenkins modeling to ensure that autocorrelation did not confound the estimation or reduce its efficiency. We found, consistent with theory, that financial risk aversion in the population correlates inversely with the odds of a twin among Swedish males born two months later. The odds of a twin among males fell by approximately 3.5% two months after unexpectedly great risk aversion in the population. This work implies that shocks that affect population risk aversion carry implications for fetal loss in vulnerable twin pregnancies.

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Section: Discussionmentioning

confidence: 99%

Twins Less Frequent Than Expected Among Male Births in Risk Averse Populations

et al. 2015

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“…Any such tests should focus on infant characteristics known to reduce the fitness of offspring. Gestations of male twins, for example, yield relatively few grandchildren for women suggesting that the odds of a twin among male births should fall after when the population becomes increasingly risk averse (Catalano et al, 2009; Helle et al, 2004). Outcomes such as the male twin ratio have less clinical significance than does very low birthweight, but they may provide equivalently strong tests of the theory.…”

Section: Discussionmentioning

confidence: 99%

Very low birthweight: Dysregulated gestation versus evolutionary adaptation

Catalano

Karasek

Gemmill

et al. 2014

Social Science & Medicine

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Much medical literature attributes persistently high rates of very low birthweight (VLBW) to “dysregulated” gestation. We offer the alternative view that natural selection conserved well-regulated, though nonconscious, decisional biology that protects the reproductive fitness of women by spontaneously aborting gestations that would otherwise yield frail infants, particularly small males. Modern obstetric practice, however, converts some fraction of these erstwhile spontaneous abortions into live births of very small infants. We further propose that the nonconscious decisional biology of gestation exhibits preferences also seen in consciously made decisions. We hypothesize that the incidence of VLBW among male infants should vary with the population's self-reported intentions to assume financial risk. We apply time-series modeling to monthly birth counts by sex and weight from the Swedish Medical Birth Registry between January 1993 and December 2010. We gauge risk aversion with monthly data from the Micro Index of the Swedish Consumer Tendency Survey (MISCT). Consistent with our argument that nonconscious decisional biology shares risk aversion with conscious decisions, we find that the incidence of VLBW among male infants in Sweden varies with the population's self-reported intentions to assume financial risk. We find increases above expected odds of a very low weight infant among males born 1 month after increases above expected levels of self-reported risk aversion in the Swedish population. We offer this finding as support for the argument that persistently high rates of VLBW arise, at least in part, from a combination of medical interventions and mechanisms conserved by natural selection to protect reproductive fitness.

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“…Much of Catalano's work has been indirect, depending on interpretation of time series of sex ratio data prior to, and following, suspected stressors. He has also offered direct data showing sexselective loss in utero (Catalano et al, 2009b).…”

Section: Catalano's Hypothesismentioning

confidence: 99%

Hypotheses on the stability and variation of human sex ratios at birth

James

2012

Journal of Theoretical Biology

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A sex-specific test of selection in utero

Cited by 34 publications

References 26 publications

Twins Less Frequent Than Expected Among Male Births in Risk Averse Populations

Twins Less Frequent Than Expected Among Male Births in Risk Averse Populations

Very low birthweight: Dysregulated gestation versus evolutionary adaptation

Hypotheses on the stability and variation of human sex ratios at birth

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