Naturalis Biodiversity Center, 2333 CR Leiden, the Netherlands.
Department of Anthropology, University at Albany, SUNY, Albany, NY 12222.
Proc Natl Acad Sci U S A. 2022 Dec 6;119(49):e2208772119. doi: 10.1073/pnas.2208772119. Epub 2022 Dec 2.
Trabecular bone-the spongy bone inside marrow cavities-adapts to its mechanical environment during growth and development. Trabecular structure can therefore be interpreted as a functional record of locomotor behavior in extinct vertebrates. In this paper, we expand upon traditional links between form and function by situating ontogenetic trajectories of trabecular bone in four primate species into the broader developmental context of neural development, locomotor control, and ultimately life history. Our aim is to show that trabecular bone structure provides insights into ontogenetic variation in locomotor loading conditions as the product of interactions between increases in body mass and neuromuscular maturation. Our results demonstrate that age-related changes in trabecular bone volume fraction (BV/TV) are strongly and linearly associated with ontogenetic changes in locomotor kinetics. Age-related variation in locomotor kinetics and BV/TV is in turn strongly associated with brain and body size growth in all species. These results imply that age-related variation in BV/TV is a strong proxy for both locomotor kinetics and neuromuscular maturation. Finally, we show that distinct changes in the slope of age-related variation in bone volume fraction correspond to the age of the onset of locomotion and the age of locomotor maturity. Our findings compliment previous studies linking bone development to locomotor mechanics by providing a fundamental link to brain development and life history. This implies that trabecular structure of fossil subadults can be a proxy for the rate of neuromuscular maturation and major life history events like locomotor onset and the achievement of adult-like locomotor repertoires.
小梁骨——骨髓腔内的海绵骨——在生长和发育过程中适应其机械环境。因此，小梁结构可以被解释为已灭绝脊椎动物运动行为的功能记录。在本文中，我们通过将四种灵长类动物的小梁骨发育轨迹置于神经发育、运动控制以及最终的生活史的更广泛的发育背景中，扩展了形态与功能之间的传统联系。我们的目的是表明，小梁骨结构提供了关于运动负荷条件在个体发育过程中变化的见解，这是体重增加和神经肌肉成熟之间相互作用的产物。
我们的研究结果表明，小梁骨体积分数（BV/TV）与运动动力学的个体发育变化强烈且线性相关。运动动力学和 BV/TV 的年龄相关变化反过来又与所有物种的大脑和身体大小的生长密切相关。这些结果表明，BV/TV 的年龄相关变化是运动动力学和神经肌肉成熟的有力替代指标。最后，我们表明，骨体积分数的年龄相关变化斜率的明显变化与运动开始的年龄和运动成熟的年龄相对应。
我们的发现通过为大脑发育和生活史提供基本联系，补充了将骨骼发育与运动力学联系起来的先前研究。这意味着，化石亚成体的小梁结构可以作为神经肌肉成熟率以及运动起始和获得成年运动模式等主要生活史事件的替代指标。
