Evolução do gênero Homo

segunda-feira, setembro 20, 2010

Evolution of the Genus Homo

Annual Review of Earth and Planetary Sciences
Vol. 37: 67-92 (Volume publication date May 2009)

First published online as a Review in Advance on January 26, 2009

Ian Tattersall1 and Jeffrey H. Schwartz2

1Department of Anthropology, American Museum of Natural History, New York, NY 10024-5192; email: iant@amnh.org

2Departments of Anthropology and History and Philosophy of Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15260; email: jhs@pitt.edu


Definition of the genus Homo is almost as fraught as the definition of Homo sapiens. We look at the evidence for “early Homo,” finding little morphological basis for extending our genus to any of the 2.5–1.6-myr-old fossil forms assigned to “early Homo” or Homo habilis/rudolfensis. We also point to heterogeneity among “early African Homo erectus,” and the lack of apomorphies linking these fossils to the Asian Homo erectus group, a cohesive regional clade that shows some internal variation, including brain size increase over time. The first truly cosmopolitan Homo species is Homo heidelbergensis, known from Africa, Europe, and China following 600 kyr ago. One species sympatric with it included the >500-kyr-old Sima de los Huesos fossils from Spain, clearly distinct from Homo heidelbergensis and the oldest hominids assignable to the clade additionally containing Homo neanderthalensis. This clade also shows evidence of brain size expansion with time; but although Homo neanderthalensis had a large brain, it left no unequivocal evidence of the symbolic consciousness that makes our species unique. Homo sapiens clearly originated in Africa, where it existed as a physical entity before it began (also in that continent) to show the first stirrings of symbolism. Most likely, the biological underpinnings of symbolic consciousness were exaptively acquired in the radical developmental reorganization that gave rise to the highly characteristic osteological structure of Homo sapiens, but lay fallow for tens of thousands of years before being “discovered” by a cultural stimulus, plausibly the invention of language.


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