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、人口统计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机制影响人类群体的适合度与健康水平。举例而言，现有研究已证实：经济意外收缩时，男性胎儿的死亡率增幅高于女性；经济意外紧缩可预示较低的次级性别比；且来自低性别比出生队列的男性，其平均寿命高于高性别比队列的男性。我们还已知，孕妇血清中检测到的低水平人绒毛膜促性腺激素（human chorionic gonadotropin, hCG）可作为胎儿死亡的预测指标。然而，我们尚不清楚，经历过经济收缩的受孕队列中的男性幸存者，是否如理论预测的那样，体内hCG水平高于其他队列的男性。我们针对包含近200万加州出生人口的71个月度受孕队列展开分析，证实了这一推测。由此，我们为“经济状况——一种我们至少可在一定程度上集体掌控的现象——会影响群体健康”这一学术论点补充了新证据。我们的研究结果表明，该效应通过自然选择机制产生——而我们在试图解释或改变集体选择如何作用于人类生物学特征时，大多忽略了这一机制。