Jantz Richard L, Jantz Lee Meadows, Devlin Joanne L
1 Department of Anthropology, University of Tennessee, Knoxville, Tennessee.
Hum Biol. 2016 Jan;88(1):65-75. doi: 10.13110/humanbiology.88.1.0065.
Secular change in height has been extensively investigated, but size and shape of the postcranial skeleton much less so. The availability of large, documented collections of nineteenth- and twentieth-century skeletons makes it possible to examine changes in skeletal structure over the past 150 years. We examined secular changes in long bone lengths and proportions, their allometric relationship to stature, and crosssectional properties of long bone shafts. Bone measurements and stature were organized into 10-year birth cohorts, ranging from 1840 to 1989. Variation among cohorts was tested by one-way ANOVA, and secular trend was examined visually by plotting mean measurements by birth decade. Allometry was examined by regressing log bone lengths onto log stature, using least squares regression. Allometry was also examined using the geometric mean of log bone lengths as the size variable. All bone lengths and stature showed positive secular change. Stature and the distal long bones showed the most pronounced changes. Proportions also changed, as revealed by the brachial and crural indices. Both indices increased, but the brachial index change was the most pronounced. Allometric relationships suggest that brachial index changes result from positive allometry of the radius and negative allometry of the humerus. Similar but less marked allometric relationships were found in the tibia and femur. Long bone shaft properties changed in the following ways: femur midshafts and tibia shafts at the nutrient foramen became more mediolaterally narrowed, and the femur became more mediolaterally thickened at the subtrochanteric level, approaching platymeria. All major long bones became more gracile. These remarkable changes in the postcranial skeleton are a response to the unparalleled changes in the environment in which modern Americans now live. Changes in growth resulting from plentiful and secure nutrition, reduced disease load, and marked reduction in bone loading from reduced activity levels are mainly responsible.
身高的长期变化已得到广泛研究，但颅后骨骼的大小和形状却较少被研究。19世纪和20世纪有大量有记录的骨骼收藏，这使得研究过去150年骨骼结构的变化成为可能。我们研究了长骨长度和比例的长期变化、它们与身高的异速生长关系以及长骨干的横截面特性。骨骼测量和身高数据被整理成10年出生队列，范围从1840年到1989年。通过单因素方差分析检验队列间的差异，并通过按出生年代绘制平均测量值直观地检查长期趋势。通过最小二乘法回归将对数骨长度与对数身高进行回归来研究异速生长。也使用对数骨长度的几何平均值作为大小变量来研究异速生长。所有骨长度和身高都呈现出正向的长期变化。身高和远端长骨的变化最为明显。比例也发生了变化，如臂指数和腿指数所示。两个指数都增加了，但臂指数的变化最为明显。异速生长关系表明，臂指数的变化是由桡骨的正异速生长和肱骨的负异速生长导致的。在胫骨和股骨中发现了类似但不太明显的异速生长关系。长骨干特性的变化如下：股骨中轴和营养孔处的胫骨干在内外侧变得更窄，股骨在转子下水平在内外侧变得更厚，接近扁平股骨。所有主要长骨都变得更加纤细。颅后骨骼的这些显著变化是对现代美国人现在所生活的环境中前所未有的变化的一种反应。丰富和安全的营养、疾病负担的减轻以及活动水平降低导致的骨负荷显著减少所引起的生长变化是主要原因。
