Tool behavior and the origins of laterality
1980; Elsevier BV; Volume: 9; Issue: 6 Linguagem: Inglês
10.1016/0047-2484(80)90002-0
ISSN1095-8606
Autores Tópico(s)Paleontology and Evolutionary Biology
ResumoThe cerebral cortex of modern humans is exceptional in that it is characterized by certain functional asymmetries for which no clear homologue is known in the non-human primates. These asymmetries consist at least in part in the presence in the left cerebral hemisphere of certain mechanisms which mediate language as well as skilled manual activity. Right-handedness is the most obvious overt manifestation of this cerebral asymmetry. It is argued in this paper that the lateralized representation of these mechanisms is an evolutionary consequence of the requirement for asymmetric employment of the forelimbs in the making and using of tools during hominid evolution. The adaptiveness of such an asymmetric arrangement is shown to follow from a few assumptions pertaining to brain organization and evolution. The colateralization of language mechanisms in modern humans to the left hemisphere is held to be a consequence of the coupling of these linguistic mechanisms to the motoric mechanisms already lateralized to the left hemisphere at an earlier point in hominid evolution. Finally, it is argued that this explanation of the evolution of laterality is more parsimonious in relation to known facts about human evolution than competing hypotheses.
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