Collaborative Research: The Evolutionary Biology and Health Consequences of Human Inactivity

最近的研究表明，久坐不动的生活，特别是长期坐在椅子上的西式生活，与心血管疾病(CVD)的高水平相关，表明这种行为可能是西方社会心血管疾病相关发病率和死亡率上升的重要组成部分。这种风险的增加被归因于久坐导致的腿部肌肉活动减少，同时从血液中吸走脂肪的酶的产生也减少了。其他文化中的个人也经常长时间不活动，但似乎不会发展成同样的心血管疾病风险。因此，休息的方式可能比坐着的时间更重要，其他社会中的人以保持肌肉活动的方式休息，从而降低心血管疾病的风险。例如，在非西方社会，蹲着可能需要与站立类似的肌肉活动水平，这可能是一种突出的休息姿势，可能与增强心血管健康有关。由于这种休息行为可能具有类似的早期人类祖先的特征，与改变休息姿势形式相关的健康成本也可能具有进化基础。这项研究测试了一种假设，即与西式坐相比，非西方社会的坐姿可以增加肌肉活动，改善血脂状况，从而促进有益的健康效果。对这一假设的初步检验将需要对当代人类狩猎采集者(坦桑尼亚的哈扎人)进行实地研究，以检查传统生活的人类的休息和不活动方式。其次，针对一组有蹲坐经验的受试者，将采用随机交叉实验设计，测量长时间蹲坐和坐姿后肌肉活动和血脂的变化。使用这些方法，这项研究将在健康和幸福的背景下探索休息姿势的进化和当代人类生物学。作为第一个从跨文化和进化的角度明确研究人类不活动的研究，这个项目可能会改变我们目前对更多久坐的生活方式如何影响现代人类生理功能的理解。在评估这种行为对与美国疾病和死亡率相关的人类生物学的影响时，这项工作也可以转化为改善西方社会公共健康的行为干预措施，以及在向更多西式不活动模式过渡的社会中的应用。

Recent research has associated sedentary living, and specifically, long periods of Western-style chair-sitting, with high levels of cardiovascular disease (CVD), suggesting that such behavior may be an important component of elevated rates of CVD-related morbidity and mortality in Western society. This increased risk has been attributed to a sitting-induced reduction in lower limb muscle activity, with concurrent decrease in the production of enzymes that siphon fat from the blood stream. Individuals in other cultures also are often inactive for long periods of time, yet do not seem to develop the same risk of CVD. It therefore is possible that styles of resting are more important than time spent sitting, and that people in other societies rest in ways that maintain muscle activity and thereby reduce cardiovascular disease risk. For example, it may be that squatting, potentially requiring levels of muscle activity similar to standing, is a prominent form of resting posture in non-Western societies which can be related to enhanced cardiovascular health. And as such resting behavior may have similarly characterized early human ancestors, the health costs associated with alteration in forms of resting posture also may have an evolutionary basis. This research tests the hypothesis that the style of sitting in non-Western societies increases muscle activity and improves blood lipid profiles compared to Western-style sitting, thereby promoting beneficial health effects. Initial testing of this hypothesis will entail a field study of contemporary human hunter-gatherers (the Hadza people of Tanzania) in order to examine styles of rest and inactivity in traditionally-living humans. Second, focusing on a population of subjects experienced in squatting, a randomized crossover experimental design will be employed to measure muscle activity and changes in blood lipids following prolonged periods of squatting versus chair-sitting. Using these methods, the research will explore the evolutionary and contemporary human biology of resting postures in the context of health and well-being. As the first study to explicitly examine human inactivity from a cross-cultural and evolutionary perspective, this project could transform our current understanding of how more sedentary lifestyles impacted functionality of modern human physiology. And in the assessment of the impact of such behavior on human biology relevant to disease and mortality rates in the US, this work also could find translation into behavioral interventions which improve public health in Western societies, as well as application in societies undergoing transitions to more Western-style inactivity patterns.