Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, 1060 William Moore Drive, Raleigh, NC, 27607, USA; Department of Evolutionary Anthropology, Box 90383, Duke University, Durham, NC, 27708, USA; Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa.
Department of Evolutionary Anthropology, Box 90383, Duke University, Durham, NC, 27708, USA.
J Hum Evol. 2018 Feb;115:65-77. doi: 10.1016/j.jhevol.2017.03.009. Epub 2017 May 3.
Body mass is an ecologically and biomechanically important variable in the study of hominin biology. Regression equations derived from recent human samples allow for the reasonable prediction of body mass of later, more human-like, and generally larger hominins from hip joint dimensions, but potential differences in hip biomechanics across hominin taxa render their use questionable with some earlier taxa (i.e., Australopithecus spp.). Morphometric prediction equations using stature and bi-iliac breadth avoid this problem, but their applicability to early hominins, some of which differ in both size and proportions from modern adult humans, has not been demonstrated. Here we use mean stature, bi-iliac breadth, and body mass from a global sample of human juveniles ranging in age from 6 to 12 years (n = 530 age- and sex-specific group annual means from 33 countries/regions) to evaluate the accuracy of several published morphometric prediction equations when applied to small humans. Though the body proportions of modern human juveniles likely differ from those of small-bodied early hominins, human juveniles (like fossil hominins) often differ in size and proportions from adult human reference samples and, accordingly, serve as a useful model for assessing the robustness of morphometric prediction equations. Morphometric equations based on adults systematically underpredict body mass in the youngest age groups and moderately overpredict body mass in the older groups, which fall in the body size range of adult Australopithecus (∼26-46 kg). Differences in body proportions, notably the ratio of lower limb length to stature, influence predictive accuracy. Ontogenetic changes in these body proportions likely influence the shift in prediction error (from under- to overprediction). However, because morphometric equations are reasonably accurate when applied to this juvenile test sample, we argue these equations may be used to predict body mass in small-bodied hominins, despite the potential for some error induced by differing body proportions and/or extrapolation beyond the original reference sample range.
体重是研究人科生物学的一个具有生态和生物力学重要意义的变量。根据最近人类样本得出的回归方程，可根据髋关节尺寸合理预测更晚出现的、更像人类的、通常体型更大的人科动物的体重，但人科各分类单元的髋关节生物力学存在差异，这使得这些方法在某些早期分类单元（例如南方古猿属）的应用受到质疑。使用身高和双髂宽的形态测量预测方程可以避免这个问题，但这些方法在早期人科动物中的适用性尚未得到证明，因为其中一些动物在体型和比例上与现代成年人不同。在这里，我们使用来自全球儿童样本的平均身高、双髂宽和体重数据，这些样本的年龄在 6 至 12 岁之间（来自 33 个国家/地区的 330 个年龄和性别特定组的年平均值），来评估几种已发表的形态测量预测方程在应用于小型人类时的准确性。尽管现代人类青少年的身体比例可能与体型较小的早期人科动物不同，但人类青少年（与化石人科动物一样）的体型和比例经常与成人参考样本不同，因此他们是评估形态测量预测方程稳健性的有用模型。基于成年人的形态测量方程系统地低估了最小年龄组的体重，适度地高估了最大年龄组的体重，这些年龄组的体重落在成年南方古猿的体重范围内（约 26-46 公斤）。身体比例的差异，特别是下肢长度与身高的比例，影响预测的准确性。这些身体比例的发育变化可能会影响预测误差的变化（从低估到高估）。然而，由于这些形态测量方程在这个青少年测试样本中应用效果相当准确，因此我们认为，尽管可能由于身体比例的差异和/或超出原始参考样本范围的外推而导致一些误差，但这些方程可用于预测小型人科动物的体重。
