Laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees
Tóm tắt
Bipedalism is a key adaptation that shaped human evolution, yet the timing and nature of its evolution remain unclear. Here we use new experimentally based approaches to investigate the locomotor mechanics preserved by the famous Pliocene hominin footprints from Laetoli, Tanzania. We conducted footprint formation experiments with habitually barefoot humans and with chimpanzees to quantitatively compare their footprints to those preserved at Laetoli. Our results show that the Laetoli footprints are morphologically distinct from those of both chimpanzees and habitually barefoot modern humans. By analysing biomechanical data that were collected during the human experiments we, for the first time, directly link differences between the Laetoli and modern human footprints to specific biomechanical variables. We find that the Laetoli hominin probably used a more flexed limb posture at foot strike than modern humans when walking bipedally. The Laetoli footprints provide a clear snapshot of an early hominin bipedal gait that probably involved a limb posture that was slightly but significantly different from our own, and these data support the hypothesis that important evolutionary changes to hominin bipedalism occurred within the past 3.66 Myr.
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Tài liệu tham khảo
Lamarck JBPA, 1809, Philosophie zoologique
Darwin C, 1871, The descent of man, and selection in relation to sex
Tuttle RH, 1987, Laetoli: a Pliocene site in northern Tanzania, 503
Kullmer O, 2003, High-resolution 3D-image analysis of ape, hominid and human footprints, Cour. Forsch. Inst. Senckenberg, 243, 85
D'Août K, 2010, Experimentally generated footprints in sand: analysis and consequences for the interpretation of fossil and forensic footprints, Am. J. Phys. Anthropol, 141, 515
Hay RL, 1987, Laetoli: a Pliocene site in northern Tanzania, 23
Jones PR, 1987, Laetoli: a Pliocene site in northern Tanzania, 551
Leakey MD, 1987, Laetoli: a Pliocene site in northern Tanzania, 490
R Core Team, 2013, R: a language and environment for statistical computing
Schlager S Jefferis G. 2015 Package 'Morpho': calculations and visualisations related to geometric morphometrics. Version 2.3.0. See http://cran.r-project.org/web/packages/Morpho/index.html.
DeSilva JM, 2010, Revisiting the ‘midtarsal’ break, Am. J. Phys. Anthropol, 141, 245, 10.1002/ajpa.21140
Harcourt-Smith WE, 2002, Form and function in the hominoid tarsal skeleton
Rose MD, 1991, Origine(s) de la Bipedie chez les Hominides, 37