Department of Orthopaedic Surgery, University of California, San Francisco, CA 94110, USA.
Proc Natl Acad Sci U S A. 2010 Feb 23;107(8):3400-5. doi: 10.1073/pnas.0911856107. Epub 2010 Feb 1.
The long legs and short arms of humans are distinctive for a primate, the result of selection acting in opposite directions on each limb at different points in our evolutionary history. This mosaic pattern challenges our understanding of the relationship of development and evolvability because limbs are serially homologous and genetic correlations should act as a significant constraint on their independent evolution. Here we test a developmental model of limb covariation in anthropoid primates and demonstrate that both humans and apes exhibit significantly reduced integration between limbs when compared to quadrupedal monkeys. This result indicates that fossil hominins likely escaped constraints on independent limb variation via reductions to genetic pleiotropy in an ape-like last common ancestor (LCA). This critical change in integration among hominoids, which is reflected in macroevolutionary differences in the disparity between limb lengths, facilitated selection for modern human limb proportions and demonstrates how development helps shape evolutionary change.
人类的长腿和短臂是灵长类动物的特征，这是我们进化历史上不同时期四肢在相反方向上选择的结果。这种镶嵌模式挑战了我们对发育和可进化性关系的理解，因为四肢是串联同源的，遗传相关性应该对它们的独立进化起到重要的限制作用。在这里，我们测试了灵长类动物四肢变异的发育模型，并证明与四足猴相比，人类和猿类的四肢之间的整合显著降低。这一结果表明，化石人科动物可能通过减少似猿的最后共同祖先（LCA）中的遗传多效性，从而逃脱了对独立肢体变化的限制。这种在人科动物之间的整合的关键变化，反映在肢体长度差异的宏观进化差异中，促进了对现代人肢体比例的选择，并展示了发育如何帮助塑造进化变化。
