“Adrian Pablos, from Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) and the Universidad de Burgos (UBU) es is coauthor of a study, published in the Journal of Human Evolution, about the Early Pleistocene hand phalanx (ATE9-2) from the Sima del Elefante in Atapuerca, (Spain), ascribed to Homo sp., which was found in 2008, which evidences that hand morphology has hardly changed since 1,3 million yeras ago.
In this study, a new Early Pleistocene proximal hand phalanx (ATE9-2) from the Sima del Elefante cave site (TE – Sierra de Atapuerca, Spain), ascribed to Homo sp., is presented and comparatively described in the context of the evolution of the genus Homo.
The ATE9-2 specimen is especially important because of the paucity of hand bones in the human fossil record during the Early Pleistocene. The morphological and metrical analyses of the phalanx ATE9-2 indicate that there are no essential differences between it and comparator fossil specimens for the genus Homo after 1.3 Ma (millions of years ago).
Similar to Sima de los Huesos and Neandertal specimens, ATE9-2 is a robust proximal hand phalanx, probably reflecting greater overall body robusticity in these populations or a higher gracility in modern humans. The age of level TE9 from Sima del Elefante and morphological and metrical studies of ATE9-2 suggest that the morphology of the proximal hand phalanges and, thus, the morphology of the hand could have remained stable over the last 1.2–1.3 Ma” (read more).
***Haven’t read it. Does irreverentideas have any thoughts?
This is a really cool addition to our short list of manual remains but it is too little to draw such a dramatic conclusion about. The authors do make an attempt to combine their observations with the VERY modern looking 1.43 million year old 3rd metacarpal (Ward et al. 2014), which is does support their conclusion. If we think about the bones in the hand where we would expect a dramatic change over 1,3 million years of tool use, the 5th proximal phalange would be somewhere on the bottom of the list.
Those at the top of the list include the carpals, and the bones of the thumb. In fact that is where we do see major muscoskeletal reconfiguration when we compare the hands of Neanderthals and AMH. This sounds circular, but the function of the phalanges are really just a series of levers that more or less move in a single plane. The only dramatic change that we might expect is in the length and breadth of the lever (like we see in chimpanzees/gorillas/orangutans/gibbons) along with some adjustments at the base/head for fractional adjustments in rotation and stabilization.
The carpal/metacarpals, however, have to deal with the displacement of loads and a much more sophisticated range of movements. Although I fully subscribe to the neutral theory, I do believe selection has acted on the morphology of these bones and, as such, I find them to be much more convincing lines of argument for the stabilization of manual morphology.
Despite my reservations, I do believe that Lorenzo et al. are correct. Mainly because I suspect that they have access to an array of fossils that are yet to be published, and that I have not seen. So, stay tuned, I suppose.