School of Archaeology, Classics and Egyptology, University of Liverpool, Hartley Building, Brownlow Street, Liverpool L69 3GS, UK.
Proc Biol Sci. 2011 May 22;278(1711):1556-63. doi: 10.1098/rspb.2010.1740. Epub 2010 Nov 3.
Social behaviour of fossil hominoid species is notoriously difficult to predict owing to difficulties in estimating body size dimorphism from fragmentary remains and, in hominins, low canine size dimorphism. Recent studies have shown that the second-to-fourth digit ratio (2D : 4D), a putative biomarker for prenatal androgen effects (PAEs), covaries with intra-sexual competition and social systems across haplorrhines; non-pair-bonded polygynous taxa have significantly lower 2D : 4D ratios (high PAE) than pair-bonded monogamous species. Here, we use proximal phalanx ratios of extant and fossil specimens to reconstruct the social systems of extinct hominoids. Pierolapithecus catalaunicus, Hispanopithecus laietanus and Ardipithecus ramidus have ratios consistent with polygynous extant species, whereas the ratio of Australopithecus afarensis is consistent with monogamous extant species. The early anatomically modern human Qafzeh 9 and Neanderthals have lower digit ratios than most contemporary human populations, indicating increased androgenization and possibly higher incidence of polygyny. Although speculative owing to small sample sizes, these results suggest that digit ratios represent a supplementary approach for elucidating the social systems of fossil hominins.
由于难以根据零碎遗骸估计体型二型性，而且在人科动物中犬齿的二型性也较低，因此化石人科动物的社会行为很难预测。最近的研究表明，第二至第四指骨比率（2D：4D）是一种产前雄激素效应（PAE）的潜在生物标志物，与haplorrhines 中的种内竞争和社会系统有关；非配对的一夫多妻制分类群的 2D：4D 比值（高 PAE）明显低于配对的一夫一妻制物种。在这里，我们使用现生物种和化石标本的近端指骨比率来重建已灭绝的人科动物的社会系统。Pierolapithecus catalaunicus、 Hispanopithecus laietanus 和 Ardipithecus ramidus 的比率与现生的一夫多妻制物种一致，而 Australopithecus afarensis 的比率与现生的一夫一妻制物种一致。早期的解剖学现代人类 Qafzeh 9 和尼安德特人比大多数现代人类群体具有更低的指骨比率，这表明雄激素化程度增加，可能一夫多妻制的发生率更高。尽管由于样本量小，这些结果具有推测性，但它们表明指骨比率代表了阐明化石人科动物社会系统的一种补充方法。
