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PLoS One:美学者证实古人类“露西”攀援树木导致手臂强壮

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摘要 : 近日,国际知名学术期刊《PLOS ONE》在线发表了美国霍普金斯大学医学院Christopher B. Ruff研究员的一篇研究论文,研究对全球著名早期两足古人类——露西的骨骼进行的扫描,证实它拥有异常强壮的上半身,而这要归功于其在攀援树木上花费了大量时间。

近日,国际知名学术期刊《PLOS ONE》在线发表了美国霍普金斯大学医学院Christopher B. Ruff研究员的一篇研究论文,研究对全球著名早期两足古人类——露西的骨骼进行的扫描,证实它拥有异常强壮的上半身,而这要归功于其在攀援树木上花费了大量时间。此项研究被誉为“对露西的生活方式进行了盖棺论定”,并且意味着在一些早期人类祖先发展出在地面行走能力的几百万年后,在树上移动对于它们来说可能仍然非常重要。

作为南方古猿阿法种的成员,露西拥有像猩猩一样的长手臂和手指。这些特征看上去很理想,如果它的生活涉及到大量的树木攀援。然而,露西的腿和像人类一样的脚表明,它是“陆地两足动物”,即能像人类那样行走。因此,研究人员推测,露西像猩猩一样的手臂可能只是它从攀援树木的祖先那里继承而来的特征,并且不再被真正使用。

研究报道其左右上臂骨和左大腿骨(右大腿骨从未被发现)的横截面。他们发现,露西拥有非常厚的臂骨,表明它的手臂异常强壮。而这是一种“不用就作废”的特征:骨骼强度是动物行为造成的直接结果,而非继承来的东西。

“除非露西比大多数现代人类更多地机械性使用其上肢,否则这一特征不会出现。”Ruff表示,“我们的研究结果是证实南方古猿阿法种实际上将很大一部分时间花在了树栖行为上的最好证据。”

原文链接:

Limb Bone Structural Proportions and Locomotor Behavior in A.L. 288-1 ("Lucy")

原文摘要:

While there is broad agreement that early hominins practICEd some form of terrestrial bipedality, there is also evidence that arboreal behavior remained a part of the locomotor repertoire in some taxa, and that bipedal locomotion may not have been identical to that of modern humans. It has been difficult to evaluate such evidence, however, because of the possibility that early hominins retained primitive traits (such as relatively long upper limbs) of little contemporaneous adaptive significance. Here we examine bone structural properties of the femur and humerus in the Australopithecus afarensis A.L. 288–1 ("Lucy", 3.2 Myr) that are known to be developmentally plastic, and compare them with other early hominins, modern humans, and modern chimpanzees. Cross-sectional images were obtained from micro-CT scans of the original specimens and used to derive section properties of the diaphyses, as well as superior and inferior cortical thicknesses of the femoral neck. A.L. 288–1 shows femoral/humeral diaphyseal strength proportions that are intermediate between those of modern humans and chimpanzees, indicating more mechanical loading of the forelimb than in modern humans, and by implication, a significant arboreal locomotor component. Several features of the proximal femur in A.L. 288–1 and other australopiths, including relative femoral head size, distribution of cortical bone in the femoral neck, and cross-sectional shape of the proximal shaft, support the inference of a bipedal gait pattern that differed slightly from that of modern humans, involving more lateral deviation of the body center of mass over the support limb, which would have entailed increased cost of terrestrial locomotion. There is also evidence consistent with increased muscular strength among australopiths in both the forelimb and hind limb, possibly reflecting metabolic trade-offs between muscle and brain development during hominin evolution. Together these findings imply significant differences in both locomotor behavior and ecology between australopiths and later Homo.

doi:10.1371/journal.pone.0166095

作者:Christopher B. Ruff 点击:

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