1] Dipartimento di Scienze Chimiche e Geologiche, Università di Modena e Reggio Emilia, l.go S. Eufemia 19, 41121 Modena, Italy [2] Centre for Anatomical and Human Sciences, University of Hull, Cottingham Road, Hull HU6 7RX, UK [3] Center for Anatomical and Human Sciences, University of York, Heslington, York YO10 5DD, UK [4] Centre for Forensic Science, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Nat Commun. 2013;4:2458. doi: 10.1038/ncomms3458.
Facial length is one of the best known examples of heterochrony. Changes in the timing of facial growth have been invoked as a mechanism for the origin of our short human face from our long-faced extinct relatives. Such heterochronic changes arguably permit great evolutionary flexibility, allowing the mammalian face to be remodelled simply by modifying postnatal growth. Here we present new data that show that this mechanism is significantly constrained by adult size. Small mammals are more brachycephalic (short faced) than large ones, despite the putative independence between adult size and facial length. This pattern holds across four phenotypic lineages: antelopes, fruit bats, tree squirrels and mongooses. Despite the apparent flexibility of facial heterochrony, growth of the face is linked to absolute size and introduces what seems to be a loose but clade-wide mammalian constraint on head shape.
面部长度是节律变化的一个著名实例。人们认为面部生长时机的变化是我们从长面灭绝亲属那里获得短脸的机制。这种节律变化可以说是具有巨大的进化灵活性，允许哺乳动物的面部通过简单地改变产后生长来重塑。在这里，我们提出了新的数据，表明这种机制受到成年体型的显著限制。尽管成年体型和面部长度之间存在潜在的独立性，但小型哺乳动物比大型哺乳动物具有更短的颅面（短面）。这种模式在四个表型谱系中都存在：羚羊、果蝠、树松鼠和猫鼬。尽管面部节律变化明显具有灵活性，但面部的生长与绝对大小有关，并引入了一种看似松散但在哺乳动物中广泛存在的对头部形状的限制。
