Data from: Natural selection in utero induced by mass layoffs: the hCG evidence

Evolutionary theory, when coupled with research from epidemiology, demography, and population endocrinology, suggests that contracting economies affect the fitness and health of human populations via natural selection in utero. We know, for example, that fetal death increases more among males than females when the economy unexpectedly contracts; that unexpected economic contraction predicts low secondary sex ratios; and that males from low sex ratio birth cohorts live, on average, longer than those from high sex ratio cohorts. We also know that low levels of human chorionic gonadotropin (i.e., hCG) measured in the serum of pregnant women predict fetal death. We do not, however, know whether male survivors of conception cohorts subjected to contracting economies exhibit, as theory predicts, higher hCG than those from other cohorts. We show, in 71 monthly conception cohorts including nearly two million California births, that they do. We thereby add to the literature suggesting that the economy, a phenomenon over which we collectively exercise at least some control, affects population health. Our findings imply that the effect arises via natural selection – a mechanism we largely ignore when attempting to explain, or alter, how collective choice affects our biology.

进化论结合流行病学、人口学与群体内分泌学的研究成果表明，经济收缩可通过宫内自然选择作用于人类群体的健康与进化适应度。例如，现有研究证实：经济突发收缩时，男性胎儿的死亡率增幅显著高于女性；经济意外收缩可预测较低的次级出生性别比；且来自低出生性别比受孕队列的男性，平均寿命高于高出生性别比队列的男性。此外，我们已知孕妇血清中检测到的低水平人类绒毛膜促性腺激素（human chorionic gonadotropin, hCG）可预测胎儿死亡。然而目前尚未明确，暴露于经济收缩环境的受孕队列中的男性存活者，是否如理论预测的那样，体内hCG水平高于其他队列的男性。本研究针对包含近200万加州新生儿的71个月度受孕队列展开分析，证实了这一猜想。本研究为“经济状况——一种我们至少可在一定程度上集体调控的社会现象——会影响群体健康”这一学术观点提供了新的实证支持。我们的研究结果提示，该效应通过自然选择机制实现，而我们在尝试解释或改变集体选择如何作用于人体生物学时，大多忽视了这一关键机制。