Department of Anthropology, CUNY Hunter College, New York, New York, USA.
New York Consortium in Evolution Primatology, New York, New York, USA.
Am J Phys Anthropol. 2021 Aug;175(4):834-846. doi: 10.1002/ajpa.24297. Epub 2021 Apr 28.
Evolutionary theorists have debated the adaptive significance of developmental plasticity in organisms with long lifespans such as humans. This debate in part stems from uncertainty regarding the timing of sensitive periods. Does sensitivity to environmental signals fluctuate across development or does it steadily decline? We investigated developmental plasticity in brown adipose tissue (BAT) among indigenous Siberians in order to explore the timing of phenotypic sensitivity to cold stress.
BAT thermogenesis was quantified using infrared thermal imaging in 78 adults (25 men; 33 women). Cold exposure during gestation, infancy, early childhood, middle childhood, and adolescence was quantified using: (1) the average ambient temperature across each period; (2) the number of times daily temperature dropped below -40°F during each period. We also assessed past cold exposure with a retrospective survey of participation in outdoor activities.
Adult BAT thermogenesis was significantly associated with the average temperature (p = 0.021), the number of times it was below -40°F (p = 0.026), and participation in winter outdoor activities (p = 0.037) during early childhood.
Our results suggest that early childhood represents an important stage for developmental plasticity, and that culture may play a critical role in shaping the timing of environmental signals. The findings highlight a new pathway through which the local consequences of global climate change may influence human biology, and they suggest that ambient temperature may represent an understudied component of the developmental origins of health and disease.
进化理论家一直在争论具有长寿命的生物体（如人类）中发育可塑性的适应意义。这场争论部分源于对敏感时期时间的不确定性。对环境信号的敏感性是在整个发育过程中波动，还是逐渐下降？我们研究了西伯利亚原住民棕色脂肪组织（BAT）的发育可塑性，以探索对冷应激表型敏感性的时间。
使用红外热成像技术在 78 名成年人（25 名男性；33 名女性）中量化 BAT 的产热。通过以下方法量化怀孕期间、婴儿期、幼儿期、儿童中期和青春期的冷暴露：（1）每个时期的平均环境温度；（2）每个时期每天温度降至-40°F 以下的次数。我们还通过对户外活动参与情况的回顾性调查评估了过去的冷暴露。
成人 BAT 的产热与平均温度显著相关（p=0.021）、每天降至-40°F 以下的次数（p=0.026）以及幼儿期参加冬季户外活动的次数（p=0.037）显著相关。
我们的结果表明，幼儿期代表了发育可塑性的重要阶段，而文化可能在塑造环境信号的时间方面发挥关键作用。这些发现强调了一条新途径，即全球气候变化的局部后果可能会影响人类生物学，并且表明环境温度可能是健康和疾病发展起源的一个被低估的组成部分。
