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.

当将进化论与流行病学、人口学及种群内分泌学的研究相结合时，可得出如下推论：经济衰退会通过宫内自然选择过程，影响人类种群的适应性与健康水平。举例而言，我们已知：当经济出现意外衰退时，男性胎儿的死亡率增幅高于女性；经济意外衰退可预示较低的次级性别比；且来自低出生性别比出生队列的男性，平均寿命高于来自高出生性别比出生队列的男性。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）可预示胎儿死亡。但目前我们仍不清楚：经历过经济衰退期的受孕队列中存活的男性，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200万例加州新生儿的71个月度受孕队列展开分析，证实了这一推测。据此，本研究为相关学术文献补充了新证据，表明经济——这一人类群体至少可在一定程度上施加影响的现象——会对种群健康产生影响。本研究结果提示，该影响是通过自然选择机制实现的——而我们在尝试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。