Cameron N, Tobias P V, Fraser W J, Nagdee M
Department of Anatomy and Human Biology, Medical School, University of the Witwatersrand, Parktown 2193, Johannesburg, South Africa.
Am J Hum Biol. 1990;2(1):53-61. doi: 10.1002/ajhb.1310020106.
Two hundred eighteen South African Negro male crania were arranged in 5-year birthdate cohorts from 1880-1884, 1890-1894, up to 1930-1934 inclusive and investigated for the presence of a secular trend in their dimensions. Maximum breadth, maximum length, basibregmatic height, cranial base height, and bi-auricular breadth (BAB) were measured, and cranial index (CI), cranial capacity (CC), and cranial base height index (CBHI) were determined. Cranial length exhibited a significant increase from 1890 to 1930. Cranial base height and CBHI exhibited statistically significant declines over the same period. The absence of secular trends in the other dimensions studied corresponds to previous analyses of the lengths of the femora and tibiae of the same sample. The secular trends in cranial length, cranial base height and its index, and the absence of trends in the other dimensions, are discussed in relation to an apparent decrease in the standard of living occurring in this population after 1900. It is unlikely that the absence of a positive secular trend denotes the attainment of a genetically determined ceiling to the physical size of the subjects represented by these skeletons. It is more likely that the environmental factors believed to produce a positive secular trend were absent in the years from which this sample was drawn and that signs of improvement in these factors, if any, would be so recent that evidence of their effect is not yet available from our cadaver-derived skeletons.
218个南非黑人男性颅骨按照出生年份分为5年一组的队列，时间跨度从1880 - 1884年、1890 - 1894年直至1930 - 1934年（含），并对其尺寸的长期变化趋势进行了研究。测量了最大宽度、最大长度、颅底高度、颅基高度和两耳间宽度（BAB），并计算了颅指数（CI）、颅容量（CC）和颅基高度指数（CBHI）。颅长在1890年至1930年间呈现出显著增加。颅基高度和CBHI在同一时期呈现出统计学上的显著下降。在其他所研究的尺寸上未出现长期变化趋势，这与之前对同一样本的股骨和胫骨长度的分析结果一致。结合1900年后该人群生活水平明显下降的情况，讨论了颅长、颅基高度及其指数的长期变化趋势，以及其他尺寸上无变化趋势的情况。这些骨骼所代表的受试者身体尺寸未出现正向长期变化趋势，不太可能意味着达到了基因决定的上限。更有可能的是，在抽取该样本的年份中，被认为会产生正向长期变化趋势的环境因素并不存在，而且这些因素（如果有）的改善迹象出现得非常晚，以至于我们从尸体骨骼中尚未获得其影响的证据。
