Culled males, infant mortality and reproductive success in a pre-industrial Finnish population

Bruckner, Tim A.; Helle, Samuli; Bolund, Elisabeth; Lummaa, Virpi

doi:10.1098/rspb.2014.0835

Cited by 30 publications

(27 citation statements)

References 33 publications

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“…Explanations of male predominance among later spontaneous abortions characterize the loss as a strategic adjustment to optimize the fitness of birth cohorts, given environmental conditions (Catalano et al, ). Prior work (Bruckner, Helle, Bolund, & Lummaa, ; Lummaa, ; Lummaa, Pettay, & Russell, ) suggests that sons born in uncertain environments produce fewer grandchildren for their mothers than do daughters because, despite receiving relatively great maternal investment (Clutton‐Brock, ; Helle, Lummaa, & Jokela, ; Powe, Knott, & Conklin‐Brittain, ), males die more frequently as infants and children than females in virtually every society and every year for which we have dependable vital statistics (Human Mortality Database, ). These facts have led to the assumption that the spontaneous abortion of prospective daughters in a conception cohort appears due primarily to endemic abnormalities in female fetuses whereas the loss of prospective sons, while also due to endemic abnormalities, additionally reflects that male fetuses predominate in the mismatches of low‐resource mothers and high‐need prospective offspring (Trivers & Willard, ; Wells, ).…”

Section: Introductionmentioning

confidence: 99%

Separating the Bruce and Trivers‐Willard effects in theory and in human data

Catalano

Gemmill

Casey

et al. 2017

American J Hum Biol

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Section: Introductionmentioning

confidence: 99%

Separating the Bruce and Trivers‐Willard effects in theory and in human data

Catalano

Gemmill

Casey

et al. 2017

American J Hum Biol

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“…In non-human animals, the Bruce Effect may provide a female counterstrategy to infanticide, or may be an adaptive strategy to limit investment in gestations that face a high risk of death (Labov, 1981). Mechanisms associated with the Bruce Effect likely include the endocrine stress response (Beehner et al, 2005;Cheney & Seyfarth, 2009), suggesting that the Bruce Effect may be part of a generalized female reproductive response to environments that threaten offspring.Theory (Haig, 1999;Schooling, 2014;Stearns, 1987;Trivers & Willard, 1973;Wells, 2000) and empirical work in human populations (Bruckner et al, 2015;Karasek et al, 2015;Orzack et al, 2015) suggest that natural selection has conserved endemic selection in utero that allows women to spontaneously abort gestations least likely to yield grandchildren. Acute stressors on a population appear, moreover,…”

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confidence: 99%

Twinning in Norway Following the Oslo Massacre: Evidence of a ‘Bruce Effect’ in Humans

et al. 2016

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Emerging theory and empirical work suggest that the 'Bruce Effect', or the increase in spontaneous abortion observed in non-human species when environments become threatening to offspring survival, may also appear in humans. We argue that, if it does, the effect would appear in the odds of twins among male and female live births. We test the hypothesis, implied by our argument, that the odds of a twin among male infants in Norway fell below, while those among females rose above, expected levels among birth cohorts in gestation in July 2011 when a deranged man murdered 77 Norwegians, including many youths. Results support the hypothesis and imply that the Bruce Effect operates in women to autonomically raise the standard of fetal fitness necessary to extend the gestation of twins. This circumstance has implications for using twins to estimate the relative contributions of genes and environment to human responses to exogenous stimuli. Keywords: selection in utero, twins, evolution, Bruce EffectOn July 22, 2011, a deranged man killed eight persons in a bomb attack in Oslo and, 2 hours later, began shooting children and staff at a youth camp on an island near the city. Over the ensuing 90 minutes he killed 69 staff and young people. After the initial killings on the island, the perpetrator reportedly waited for survivors to attempt escape so that he could target them as they swam. Police could not reach the island when the shooting began due to the lack of helicopters and vessels. Hundreds of other people were injured in the attacks, scores of them seriously.The Oslo Massacre elicited strong emotional responses, including fear, heightened threat perception, and grief in the general population (Nordanger et al., 2013;Thoresen et al., 2012). Indeed, one in four Norwegians reportedly knew someone bereaved by the attacks (Thoresen et al., 2012). Whether grief arose solely among those closely tied to the deceased or in the larger population, which included witnesses to the pain of those with close ties, the fraction of Norwegians grieving the death of their young surely reached very high levels in late summer of 2011.Dating at least to the work of Bruce (1959), researchers have noted that in several non-human species, environmental threats to the survival of young, proximate conspecifics appear to induce spontaneous abortion in gravid females, both under laboratory conditions and in the wild (Becker & Hurst, 2008;Cheney & Seyfarth, 2009;Labov, 1981;Roberts et al., 2012;Rulicke et al., 2006). Labov (1981) infers that this 'Bruce Effect' functions as an adaptive strategy to limit female investment in offspring likely to die in environments prevailing at birth. In non-human animals, the Bruce Effect may provide a female counterstrategy to infanticide, or may be an adaptive strategy to limit investment in gestations that face a high risk of death (Labov, 1981). Mechanisms associated with the Bruce Effect likely include the endocrine stress response (Beehner et al., 2005;Cheney & Seyfarth, 2009), suggesting that the Bruce Eff...

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“…Our findings appear consistent with research reporting increased lifespan among cohorts experiencing increased spontaneous abortion (Bruckner & Catalano, ; Catalano & Bruckner, ; Catalano, Gemmill, & Bruckner, ). Other suggestions of increased fitness among culled cohorts include increased cognitive function among children in utero during the September 11, 2001, attacks (Bruckner & Nobles, ) and reduced infant mortality among males from low sex ratio cohorts (Bruckner, Helle, Bolund, & Lummaa, ). Together, these findings suggest that reproductive suppression in the form of selection in utero represents an adaptive maternal response to threatening environments (Bruckner & Catalano, ).…”

Section: Discussionmentioning

confidence: 99%

Reproductive suppression and longevity in human birth cohorts

Saxton

Gemmill

Casey

et al. 2019

American J Hum Biol

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Objectives: Reproductive suppression refers to, among other phenomena, the termination of pregnancies in populations exposed to signals of death among young conspecifics. Extending the logic of reproduction suppression to humans has implications for health including that populations exposed to it should exhibit relatively great longevity. No research, however, has tested this prediction.Methods: We apply time-series methods to vital statistics from Sweden for the years 1751 through 1800 to test if birth cohorts exposed in utero to reproductive suppression exhibited lifespan different from expected. We use the odds of death among Swedes age 1 to 9 years to gauge exposure. As the dependent variable, we use cohort life expectancy. Our methods ensure autocorrelation cannot spuriously induce associations nor reduce the efficiency of our estimates.Results: Our findings imply that reproductive suppression increased the lifespan of 24 annual birth cohorts by at least 1.3 years over the 50-year test period, and that 12 of those cohorts exhibited increases of at least 1.7 years above expected. Conclusions:The best available data in which to search for evidence of reproductive suppression in humans support the argument that populations subjected to environments dangerous for children yield birth cohorts that exhibit unexpectedly great longevity.

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Culled males, infant mortality and reproductive success in a pre-industrial Finnish population

Cited by 30 publications

References 33 publications

Separating the Bruce and Trivers‐Willard effects in theory and in human data

Separating the Bruce and Trivers‐Willard effects in theory and in human data

Twinning in Norway Following the Oslo Massacre: Evidence of a ‘Bruce Effect’ in Humans

Reproductive suppression and longevity in human birth cohorts

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