Genética quantitativa evolutiva e o tamanho do cérebro em Homo floresiensis
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Data
2007-06
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Editor
Museu de Arqueologia do Xingó
Resumo
In 2004, a new species of the genus Homo (H. floresiensis) from
Late Pleistocene of Indonesia (Flores Island) was described based on
parts of an adult female skeleton about 1 meter tall and brain size about
400 cm3. The new species was interpreted as a case on miniaturization
of body and brain sizes due to occupation of an island habitat (the "island
rule"). Although there is some discussion about the identification of the
material (some argue that it belongs to a microcephalus H. sapiens),
some recent studies on brain anatomy validated the material as a real
new species. In this paper we applied quantitative evolutionary genetic
models to evaluate reduction in brain size of H. floresiensis from an
ancestor H. erectus population under island rule, assuming various times
for divergence between these species. Under the most conservative
scenario (about 100,000 years of divergence, or 10,000 generations),
brain size evolved at 9.16 darwins, with an intensity of selection
equivalent to 0.096% of selective mortality. Evolutionary rates similar
to those calculated for phenotypic evolution in post-Pleistocene mammals
were observed when assuming divergence times about 250.000 years.
Thus, brain size reduction in H. floresiensis under island rule would be
plausible, even in a very conservative scenario of recent divergence
between the species and its ancestor.
Descrição
Palavras-chave
Homo floresiensis, Seleção natural, Tamanho cerebral, Regra das ilhas, Genética evolutiva, Taxas de evolução
Citação
DINIZ FILHO, José Alexandre Felizola. Genética quantitativa evolutiva e o tamanho do cérebro em Homo floresiensis. Canindé, Aracaju, n. 9, p. 157-168, jun. 2007.