Rib cage anatomy in Homo erectus suggests a recent evolutionary origin of modern human body shape

This research was funded by the Spanish Ministry of Economy and Competitivity (no. CGL 2015-63648-P) to M.B. D.G.-M. was funded by IdEx University of Bordeaux Investments for the Future programme (no. ANR-10-IDEX-03-02) and the European Commission’s Research Infrastructure Action via the Synthesys Projects (nos. SE-TAF-6406, DE-TAF-6404, BE-TAF-5639). Financial support for M.H. was provided by the Swiss National Science Foundation (no. 31003A_176319/1) and the Mäxi Foundation. A.G.-O. received support from the Spanish FEDER/Ministerio de Ciencia e Innovación-AEI (project no. PGC2018-093925-B-C33) and Research Group (no. IT1418-19) from Eusko Jaurlaritza-Gobierno Vasco. A.G.-O. is funded by a Ramón y Cajal fellowship (no. RYC-2017-22558).
The tall and narrow body shape of anatomically modern humans (Homo sapiens) evolved via changes in the thorax, pelvis and limbs. It is debated, however, whether these modifications first evolved together in African Homo erectus, or whether H. erectus had a more primitive body shape that was distinct from both the more ape-like Australopithecus species and H. sapiens. Here we present the first quantitative three-dimensional reconstruction of the thorax of the juvenile H. erectus skeleton, KNM-WT 15000, from Nariokotome, Kenya, along with its estimated adult rib cage, for comparison with H. sapiens and the Kebara 2 Neanderthal. Our three-dimensional reconstruction demonstrates a short, mediolaterally wide and anteroposteriorly deep thorax in KNM-WT 15000 that differs considerably from the much shallower thorax of H. sapiens, pointing to a recent evolutionary origin of fully modern human body shape. The large respiratory capacity of KNM-WT 15000 is compatible with the relatively stocky, more primitive, body shape of H. erectus.
Depto. de Biodiversidad, Ecología y Evolución
Fac. de Ciencias Biológicas
TRUE
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