Selection in utero: A biological response to mass layoffs

Abstract

Most research describing the biological response to unemployment appears appropriately motivated by clinical or public health concerns and focuses on death, disease, and medical care. We argue that expanding the work to include other outcomes could contribute to basic science. As an example, we use the response to mass layoffs to discriminate between two explanations of low ratios of male to female live births in stressed populations. One explanation asserts that ambient stressors reduce the ratio of males to females conceived. The other argues that the maternal stress response selects against males in utero. We show that selection in utero better explains the observed data. We conclude that human adaptation to the economic environment deserves scrutiny from a wider array of scientists than it now receives.

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

“…This loss is not at random: it reportedly occurs preferentially in the first or second trimesters, to male foetuses and to foetuses that are frail (Bruckner and Catalano, 2007;Catalano, 2003;Catalano and Bruckner 2006a,b;Catalano et al 2005aCatalano et al ,b, 2006Catalano et al , 2009aCatalano et al , 2010. Much of Catalano's work has been indirect, depending on interpretation of time series of sex ratio data prior to, and following, suspected stressors.…”

Impact of earthquakes on sex ratio at birth: Eastern Marmara earthquakes

“…The answer of the question of whether the embryo loss rate increases after large earthquakes, however, is not yet clear. Catalano and Bruckner reported severe psychological stress after the 9/11 terrorist attacks, economic crises, and in collective dismissal issues, all of which reduce SSR (44,(46)(47)(48). In their study investigating the effects of stress after the 9/11 terrorist attack, they stated the reduction in SSR, not after 8, 9 and 10 months, but within the first 3 months, suggesting that this result is not related to fertilisation, but rather a greater increase in loss associated with male foetuses (46).…”

Feeling the Heat? Substantial Variation in Temperatures Does Not Affect the Proportion of Males Born in Australia

“…Male foetuses appear to be more vulnerable to stressors (Catalano 2011), with political unrest, natural disasters (e.g. earthquakes) and layoffs from employment being just several in a long list of traits that are associated with lowering the male bias in SSRs (Catalano et al 2010;James 2009James , 2010Navara 2010). In contrast, more favourable economic, political and nutritional circumstances are associated with an increase in the male bias in SSRs (Catalano et al 2010;James 2010).…”

“…earthquakes) and layoffs from employment being just several in a long list of traits that are associated with lowering the male bias in SSRs (Catalano et al 2010;James 2009James , 2010Navara 2010). In contrast, more favourable economic, political and nutritional circumstances are associated with an increase in the male bias in SSRs (Catalano et al 2010;James 2010). More males were also born during the First and Second World Wars in Europe, which may be in response to greater mortality of young reproductively capable men (James 2009).…”