Handedness in captive bonobos (Pan paniscus).
ABSTRACT Species level right-handedness is often considered to be unique to humans. Handedness is held to be interrelated to our language ability and has been used as a means of tracing the evolution of language. Here we examine handedness in 3 captive groups of bonobos (Pan paniscus) comprising 22 individuals. We found no evidence for species level handedness. Conclusions that can be drawn from these findings are: (1) species level handedness evolved after the divergence of the Pan and Homo lineages; (2) inconsistent preferences may represent precursors to human handedness, and (3) Pan may have language abilities but these cannot be measured using handedness.
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ABSTRACT: Handedness is a product of brain specialization, which in turn seems to be responsible for the higher cognitive capabilities of humans, such as language and technology. Handedness in living humans is well established and shows the highest degree of manual specialization. Studies on hand laterality in nonhuman primates, particularly in chimpanzees, remain a matter of controversy as results tend to vary depending on factors such as the tasks performed and the environment in which the individuals live. Studies in several disciplines have attempted to determine where in the course of human evolution handedness established itself, with evidence collected from sources such as paleoneurological analyses, stone tool flaking, zooarchaeological studies and dental wear analyses, the last one of which have proven the most reliable source of information. Here we report an experimental and paleoanthropological study on hand laterality of a sample of 28 hominids from Sima de los Huesos (Atapuerca, Spain), dated at about 500,000 years ago, and compare our results with dental microwear analysis in other fossil samples such as that from Krapina (Croatia), as well as modern traditional societies. Our results indicate that European Middle Pleistocene Homo heidelbergensis was already as right-handed as modern populations.Evolution and Human Behavior 09/2009; 30(5):369-376. DOI:10.1016/j.evolhumbehav.2009.03.001 · 2.87 Impact Factor
Animal Behaviour 11/2008; 76(5):1749-1760. DOI:10.1016/j.anbehav.2008.05.026 · 3.07 Impact Factor
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ABSTRACT: Within the evolutionary framework about the origin of human handedness and hemispheric specialization for language, the question of expression of population-level manual biases in nonhuman primates and their potential continuities with humans remains controversial. Nevertheless, there is a growing body of evidence showing consistent population-level handedness particularly for complex manual behaviors in both monkeys and apes. In the present article, within a large comparative approach among primates, we will review our contribution to the field and the handedness literature related to two particular sophisticated manual behaviors regarding their potential and specific implications for the origins of hemispheric specialization in humans: bimanual coordinated actions and gestural communication. Whereas bimanual coordinated actions seem to elicit predominance of left-handedness in arboreal primates and of right-handedness in terrestrial primates, all handedness studies that have investigated gestural communication in several primate species have reported stronger degree of population-level right-handedness compared to noncommunicative actions. Communicative gestures and bimanual actions seem to affect differently manual asymmetries in both human and nonhuman primates and to be related to different lateralized brain substrates. We will discuss (1) how the data of hand preferences for bimanual coordinated actions highlight the role of ecological factors in the evolution of handedness and provide additional support the postural origin theory of handedness proposed by MacNeilage [MacNeilage . Present status of the postural origins theory. In W. D. Hopkins (Ed.), The evolution of hemispheric specialization in primates (pp. 59-91). London: Elsevier/Academic Press] and (2) the hypothesis that the emergence of gestural communication might have affected lateralization in our ancestor and may constitute the precursors of the hemispheric specialization for language. © 2013 Wiley Periodicals, Inc. Dev Psychobiol 55: 637-650, 2013.Developmental Psychobiology 09/2013; 55(6):637-50. DOI:10.1002/dev.21150 · 3.16 Impact Factor