No known hominin species matches the expected dental morphology of the last common ancestor of Neanderthals and modern humans
Aida Gómez-Roblesa,b,1, José María Bermúdez de Castroc, Juan-Luis Arsuagad, Eudald Carbonelle, and P. David Pollyf
aDepartment of Anthropology, The George Washington University, Washington, DC 20052;
bKonrad Lorenz Institute for Evolution and Cognition Research, A-3422 Altenberg, Austria;
cCentro Nacional de Investigación sobre la Evolución Humana, 09002 Burgos, Spain;
dCentro de Investigación Sobre la Evolución y Comportamiento Humanos, Universidad Complutense de Madrid–Instituto de Salud Carlos III, 28029 Madrid, Spain;
eInstitut Català de Paleoecologia Humana i Evolució Social, Universitat Rovira i Virgili, 43007 Tarragona, Spain; and
fDepartments of Geological Sciences, Biology, and Anthropology, Indiana University, Bloomington,IN 47405
Edited by Jukka Jernvall, University of Helsinki, Helsinki, Finland, and accepted by the Editorial Board September 19, 2013 (received for review February 9, 2013)
The identity of the last common ancestor of Neanderthals and modern humans is a controversial issue. This debate has been often addressed by means of descriptive analyses that are difficult to test. Our primary aim is to put questions about human evolution into a testable quantitative framework and to offer an objective means to sort out apparently unsolvable debates about hominin phylogeny. Our paper shows that no known hominin species matches the expected morphology of this common ancestor. Furthermore, we found that European representatives of potential ancestral species have had affinities with Neanderthals for almost 1 My, thus supporting a model of early divergence between Neanderthals and modern humans.
A central problem in paleoanthropology is the identity of the last common ancestor of Neanderthals and modern humans ([N-MH]LCA). Recently developed analytical techniques now allow this problem to be addressed using a probabilistic morphological framework. This study provides a quantitative reconstruction of the expected dental morphology of the [N-MH]LCA and an assessment of whether known fossil species are compatible with this ancestral position. We show that no known fossil species is a suitable candidate for being the [N-MH]LCA and that all late Early and Middle Pleistocene taxa from Europe have Neanderthal dental affinities, pointing to the existence of a European clade originated around 1 Ma. These results are incongruent with younger molecular divergence estimates and suggest at least one of the following must be true: (i) European fossils and the [N-MH]LCA selectively retained primitive dental traits; (ii) molecular estimates of the divergence between Neanderthals and modern humans are underestimated; or (iii) phenotypic divergence and speciation between both species were decoupled such that phenotypic differentiation, at least in dental morphology, predated speciation.
phylogeny node reconstruction geometric morphometrics morphospace European Pleistocene
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