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Title: Mosaic evolution in hominin evolution and the case of Neandertals and modern humans
Authors: Arsuaga, Juan Luis
Martinón-Torres, María
Keywords: Speciation;Mosaic evolution;Anagenetic;Cladogenetic;Accretion;Neandertals
Issue Date: 2018
Publisher: International Union for Prehistoric and Protohistoric Sciences (IUPPS)
Citation: XVIII World UISPP Congress, 2018
Abstract: Reconstructing patterns of evolution is a central issue in paleoanthropology ever since Darwin (Arsuaga, 2010). Concerning the shape of the hominin phylogenetic tree, there are two possible geometries: basically linear (called anagenetic) or primarily branching (called cladogenetic). They correspond to two of the three classic modes of evolution defined by G.G. Simpson (1944): phyletic evolution and speciation. Concerning the tempo, speciation can be slow or fast. Supporters of Punctuated Equilibrium Theory favor a rapid speciation event followed by a long period of evolutionary stasis as predominant in evolution. On the contrary, phyletic evolution is generally considered gradual (and called “phyletic gradualism” by punctuationists). Traditionally, neo-Darwinism tends to favor anagenesis as the main mode, and evolution is envisioned as a slow accumulation of changes in the alele frequencies of the populations. If we substitute characters for genes, and character states (traits) for aleles, the neo-Darwinian definition of evolution used in population genetics (“accumulative slow changes in the alele frequencies of the populations”) would translate into “accumulative slow changes in the frequencies of the character states of the populations”. The “accretion model” posited for the origin of the Neandertals seems to correspond to this phyletic mode of evolution (Dean et al., 1998; Hublin, 1998). The first ‘missing link' discovered in human paleontology was the Taung Child and resulted in an unexpected mosaic of apish and human traits. To everybody's surprise, bipedalism came earlier that encephalization in hominin evolution. As it happened in Darwin´s times with Archaeopteryx, the “missing links” seem to be “mosaic links” with combinations of primitive and derived traits that are almost impossible to predict. Almost one century later, it seems that evolution of Neandertals (Arsuaga et al., 2014; 2015; Dennell et al., 2011; Martinón-Torres et al., 2012) and modern humans (Hublin et al., 2017) has also been mosaic-like, with changes in the face and the masticatory apparatus and teeth preceding brain expansion. Does this mean that mosaic evolution is preponderant in hominin evolution?.
Type: Presentation
Appears in Collections:Congresos, encuentros científicos y estancias de investigación

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