Copes L E, Schutz H, Dlugsoz E M, Judex S, Garland T
Department of Medical Sciences, Frank H. Netter MD School of Medicine, Quinnipiac University, Hamden, Connecticut, 06518.
Department of Biology, Pacific Lutheran University, Tacoma, Washington, DC, 98447.
Am J Phys Anthropol. 2018 Jun;166(2):442-458. doi: 10.1002/ajpa.23446. Epub 2018 Feb 23.
To use a mouse model to investigate the relationships among the components of the systemic robusticity hypothesis (SRH): voluntary exercise on wheels, spontaneous physical activity (SPA) in cages, growth hormones, and skeletal robusticity, especially cranial vault thickness (CVT).
Fifty female mice from lines artificially selected for high running (HR) and 50 from nonselected control (C) lines were housed in cages with (Active) or without wheels (Sedentary). Wheel running and SPA were monitored daily. The experiment began at 24-27 days of age and lasted 12 weeks. Food consumption was measured weekly. Mice were skeletonized and their interparietal, parietal, humerus, and femur were µCT scanned. Mean total thickness of the parietal and interparietal bones was determined, along with thickness of the cortical and diploe layers individually. Geometric cross-sectional indicators of strength were calculated for the long bones. Blood samples were assayed for IGF-1 and IGFBP-3.
Physical activity differed significantly among groups, based both on linetype (C vs. HR) and activity (A vs. S). However, contrary to our predictions, the ratio of IGF-1 to IGFBP-3 was higher in C mice than in HR mice. Neither CVT nor postcranial robusticity was affected by linetype or activity, nor were most measures of CVT and postcranial robusticity significantly associated with one another.
Our results fail to provide support for the systemic robusticity hypothesis, suggesting it is important to rethink the long-standing theory that increased CVT in Homo erectus reflects increased physical activity compared other hominin species.
使用小鼠模型研究系统强健性假说（SRH）各组成部分之间的关系：在轮子上的自愿运动、笼内自发身体活动（SPA）、生长激素和骨骼强健性，尤其是颅顶厚度（CVT）。
将50只经人工选择的高奔跑能力（HR）品系的雌性小鼠和50只非选择对照（C）品系的雌性小鼠饲养在有（活跃组）或没有轮子（久坐组）的笼子里。每天监测轮子跑步情况和SPA。实验从24 - 27日龄开始，持续12周。每周测量食物消耗量。对小鼠进行骨骼化处理，并对其顶间骨、顶骨、肱骨和股骨进行μCT扫描。确定顶骨和顶间骨的平均总厚度，以及皮质层和板障层各自的厚度。计算长骨的几何横截面强度指标。检测血样中的IGF - 1和IGFBP - 3。
基于品系类型（C组与HR组）和活动情况（活跃组与久坐组），各组之间的身体活动存在显著差异。然而，与我们的预测相反，C组小鼠中IGF - 1与IGFBP - 3的比值高于HR组小鼠。CVT和颅后强健性均不受品系类型或活动的影响，CVT和颅后强健性的大多数测量指标之间也没有显著相关性。
我们的结果未能为系统强健性假说提供支持，这表明有必要重新思考这一长期存在的理论，即与其他古人类物种相比，直立人CVT增加反映了身体活动的增加。
