Atzeva M, Demes B, Kirkbride M L, Burrows A M, Smith T D
School of Physical Therapy, Slippery Rock University, Slippery Rock, PA 16057, USA.
J Hum Evol. 2007 Mar;52(3):231-42. doi: 10.1016/j.jhevol.2006.08.009. Epub 2006 Sep 23.
Little ontogenetic data exist to indicate whether muscular organization of neonates reflects adult locomotion (e.g., leaping) or infant activities like clinging or the initial quadrupedal phase of locomotion that typifies most infant primates. In the present study, five species of primates with contrasting modes of locomotion were examined. Twenty-eight preserved neonatal and adult cadavers were studied by careful dissection of the hip, thigh, and leg muscles. Wet weights were taken of limb muscles after removal, and the muscles were combined into major functional groups (e.g., flexors, extensors) of each limb segment. Results demonstrate that the distribution of muscle mass within the thigh and within the leg are similar between neonates and adults for all species, with major groups varying by 5% or less in all but two age comparisons. Crural indices of the neonates are nearly identical to those of the adults, but leg/thigh muscle mass ratios were higher in the neonates. Species vary greatly in the percentage of adult limb segment muscle mass present in neonates, with Tarsius syrichta having the greatest percentage for all segments and two lemurids showing the least. These results primarily track differences in relative body mass at birth rather than developmental differences. The adaptive distribution of muscle, as discussed previously for adult prosimians, appears to be established at birth. Neonates of leaping species already have much larger quadriceps muscles than quadrupeds. Differences between large- and small-bodied leapers (e.g., pronounced superficial plantarflexor masses in tarsiers and pronounced deep plantarflexor masses in sifakas) also are present in neonates. Ratios of muscle mass over body mass are smaller in all neonates than in their adult counterparts, suggesting that the neonates are relatively poorly muscled, and that muscle mass must increase with positive allometry during growth.
几乎没有个体发育数据能表明新生儿的肌肉组织是反映了成年后的运动方式（例如跳跃），还是婴儿的活动，如抓握，或者是大多数灵长类婴儿典型的运动初始四足阶段。在本研究中，对五种具有不同运动方式的灵长类动物进行了检查。通过仔细解剖髋部、大腿和腿部肌肉，研究了28具保存的新生儿和成年尸体。去除肢体肌肉后测量湿重，并将肌肉合并为每个肢体节段的主要功能组（例如，屈肌、伸肌）。结果表明，所有物种的新生儿和成年人在大腿和腿部的肌肉质量分布相似，除了两次年龄比较外，所有主要组的差异都在5%或更小。新生儿的小腿指数与成年人几乎相同，但新生儿的腿/大腿肌肉质量比更高。不同物种新生儿的成年肢体节段肌肉质量百分比差异很大，跗猴的所有节段百分比最高，而两种狐猴科动物的百分比最低。这些结果主要反映了出生时相对体重的差异，而不是发育差异。如先前对成年原猴亚目的讨论，肌肉的适应性分布似乎在出生时就已确立。跳跃类物种的新生儿已经比四足类动物有更大的股四头肌。大小不同的跳跃类动物之间的差异（例如跗猴有明显的浅层跖屈肌团块，而冕狐猴有明显的深层跖屈肌团块）在新生儿中也存在。所有新生儿的肌肉质量与体重之比都比成年同类小，这表明新生儿的肌肉相对较少，并且在生长过程中肌肉质量必须以正异速生长的方式增加。
