H. floresiensis shoulder recalls that of H. erectus

doi:10.1016/j.jhevol.2007.06.003

Homo floresiensis and the evolution of the hominin shoulder

Susan G. Larsona, , William L. Jungersa, Michael J. Morwoodb, Thomas Sutiknac, Jatmikoc, E. Wahyu Saptomoc, Rokus Awe Duec and Tony Djubiantonoc

aAnatomical Sciences, Stony Brook University School of Medicine, Stony Brook NY, USA

bSchool of Human and Environmental Studies, University of New England, Armidale, Australia

cIndonesian Centre for Archaeology, Jakarta, Indonesia

Received 1 September 2006;

accepted 14 June 2007.

Available online 13 August 2007.

Abstract

The holotype of Homo floresiensis, diminutive hominins with tiny brains living until 12,000 years ago on the island of Flores, is a partial skeleton (LB1) that includes a partial clavicle (LB1/5) and a nearly complete right humerus (LB1/50). Although the humerus appears fairly modern in most regards, it is remarkable in displaying only 110° of humeral torsion, well below modern human average values. Assuming a modern human shoulder configuration, such a low degree of humeral torsion would result in a lateral set to the elbow. Such an elbow joint would function more nearly in a frontal than in a sagittal plane, and this is certainly not what anyone would have predicted for a tool-making Pleistocene hominin. We argue that Homo floresiensis probably did not have a modern human shoulder configuration: the clavicle was relatively short, and we suggest that the scapula was more protracted, resulting in a glenoid fossa that faced anteriorly rather than laterally. A posteriorly directed humeral head was therefore appropriate for maintaining a normally functioning elbow joint. Similar morphology in the Homo erectus Nariokotome boy (KNM-WT 15000) suggests that this shoulder configuration may represent a transitional stage in pectoral girdle evolution in the human lineage.

“Calling in gay”

Some opponents of California’s Proposition H8 in the U.S., which passed and thus took away the right of gays to marry the consenting adult of their choice, are organizing a protest called “Day without a gay.” They are asking gay people to take one day off work and demonstrate that they’d be missed. Naturally, some wit has named the phenomenon, “Calling in gay.”

That inevitably reminds me of the old joke, “I’ve used up my sick days so I’m calling in dead.”

Good luck to them.

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