Laboratory of Physical Anthropology, Graduate School of Science, Kyoto University, Kyoto, Japan.
Faculty of Business Administration, Ryukoku University, Fushimi, Kyoto, Japan.
Am J Phys Anthropol. 2020 Oct;173(2):276-292. doi: 10.1002/ajpa.24098. Epub 2020 Jun 11.
The bony labyrinth of the inner ear has special relevance when tracking phenotypic evolution because it is often well preserved in fossil and modern primates. Here we track the evolution of the bony labyrinth of anthropoid primates during the Mio-Plio-Pleistocene-the time period that gave rise to the extant great apes and humans.
We use geometric morphometrics to analyze labyrinthine morphology in a wide range of extant and fossil anthropoids, including New World and Old World monkeys, apes, and humans; fossil taxa are represented by Aegyptopithecus, Microcolobus, Epipliopithecus, Nacholapithecus, Oreopithecus, Ardipithecus, Australopithecus, and Homo.
Our results show that the morphology of the anthropoid bony labyrinth conveys a statistically significant phylogenetic signal especially at the family level. The bony labyrinthine morphology of anthropoids is also in part associated with size, but does not cluster by locomotor adaptations. The Miocene apes examined here, regardless of inferred locomotor behaviors, show labyrinthine morphologies distinct from modern great apes.
Our results suggest that labyrinthine variation contains mixed signals and alternative explanations need to be explored, such as random genetic drift and neutral phenotypic evolution, as well as developmental constraints. The observed pattern in fossil and extant hominoids also suggests that an additional factor, for example, prenatal brain development, could have potentially had a larger role in the evolutionary modification of the bony labyrinth than hitherto recognized.
内耳的骨迷路在外显型进化的追踪中具有特殊的相关性，因为它在化石和现代灵长类动物中通常保存完好。在这里，我们在中上新世-更新世期间追踪了人科灵长类动物的骨迷路进化，这一时期产生了现生的大猿和人类。
我们使用几何形态测量学来分析广泛的现生和化石人科灵长类动物的迷路形态，包括新世界和旧世界猴、猿和人类；化石分类群由埃及古猿、小狐猴、埃及猿猴、纳科拉皮提猴、原康修尔猿、地猿、南方古猿和人类代表。
我们的结果表明，人科动物的骨迷路形态传达了一个具有统计学意义的系统发育信号，特别是在科的水平上。人科动物的骨迷路形态部分与体型相关，但与运动适应无关。这里检查的中新世猿类，无论推断的运动行为如何，其迷路形态都与现代大猿类明显不同。
我们的结果表明，迷路形态的变化包含混合信号，需要探索替代解释，例如随机遗传漂变和中性表型进化，以及发育限制。在化石和现生人科动物中观察到的模式也表明，一个额外的因素，例如产前大脑发育，可能在骨迷路的进化修饰中发挥了比以往认识到的更大的作用。
