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.
"Chapelain and colleagues (Chapelain & Hogervorst, 2009; Chapelain et al., 2011) have examined handedness for the TUBE task, and contrary to chimpanzees (Hopkins et al., 2004; Llorente et al., 2010), they reported no evidence of populationlevel right handedness in the bonobos (see also Hopkins et al., 2011). There are also reports of a lack of population-level handedness for manual gestures in bonobos by several authors (Hopkins & de Waal, 1995; Shafer, 1997; Harrison & Nystrom, 2008), which also contradicts reports in captive chimpanzees (Hopkins et al., 2005a), though methods of handedness assessment may explain some of these differences (Hopkins et al., 2012). Whether these purported species differences reflect methodological factors or are true differences is not clear because the approaches to the assessment of handedness have varied between studies. "
[Show abstract][Hide abstract] ABSTRACT: The evolutionary origins of human right-handedness remain poorly understood. Some have hypothesized that tool use served as an important preadaptation for the eventual evolution of population-level right-handedness. In contrast, others have suggested that complex gestural and vocal communication served as prerequisite for the evolution of human right-handedness. In this study, we tested these competing hypotheses by comparing the handedness of bonobos and chimpanzees, two closely related species of Pan, on three different measures of hand use including simple reaching, manual gestures and coordinated bimanual actions. Chimpanzees are well known for their tool using abilities whereas bonobos rarely use tools in the wild. In contrast, many have suggested that bonobos have a more flexible gestural and vocal communication system than chimpanzees. The overall results showed that chimpanzees were significantly more right-handed than bonobos for all three measures suggesting that adaptations for tool use rather than communication may have led to the emergence of human right-handedness. We further show that species differences in handedness may be linked to variation in the size and asymmetry of the motor-hand area of the precentral gyrus. The results are discussed within the context of evolutionary theories of handedness, as well as some limitations in the approach to handedness measurement in nonhuman primates.
"In addition to expanding the previous study on handedness in great apes, the second aim of this study was to include data from bonobos for comparison to the other great apes. There have been relatively few studies of handedness in bonobos compared to other great apes (Hopkins and De Waal, 1995; Shafer, 1997; Harrison and Nystrom, 2008), and recent reports of hand preference in bonobos using the TUBE task have failed to detect populationlevel biases in this species (Chapelain and Hogervorst, 2009; Chapelain et al., in press). Thus, we aimed to obtain a new set of handedness data for comparison to these recent reports. "
[Show abstract][Hide abstract] ABSTRACT: Whether or not nonhuman primates exhibit population-level handedness remains a topic of considerable scientific debate. Here, we examined handedness for coordinated bimanual actions in a sample of 777 great apes including chimpanzees, bonobos, gorillas, and orangutans. We found population-level right-handedness in chimpanzees, bonobos and gorillas, but left-handedness in orangutans. Directional biases in handedness were consistent across independent samples of apes within each genus. We suggest that, contrary to previous claims, population-level handedness is evident in great apes but differs among species as a result of ecological adaptations associated with posture and locomotion. We further suggest that historical views of nonhuman primate handedness have been too anthropocentric, and we advocate for a larger evolutionary framework for the consideration of handedness and other aspects of hemispheric specialization among primates.
Journal of Human Evolution 02/2011; 60(5):605-11. DOI:10.1016/j.jhevol.2010.12.008 · 3.73 Impact Factor
"There are some exceptions to this in primates as reviewed by Papademetriou et al. (2005), but consistent, species-wide righthandedness is not found outside Homo. After surveying studies of chimpanzees and bonobos, Harrison and Nystrom (2008:266) concluded " that amongst extant apes species level handedness is unique to humans. " Hand preference in the living humans is measured by direct observation of manipulation or analysis of writing patterns, and, while not as straightforward as sometimes presumed (Faurie & Raymond, 2003), worldwide patterns are consistent. "
[Show abstract][Hide abstract] ABSTRACT: Seven Vindija (Croatia) Neandertal teeth, dated about 32,000 years ago, were analyzed to determine patterning of scratches on the anterior teeth. Oblique scratches exclusively on the labial faces of incisors and canines represent a distinctive pattern, characteristic of hand directed, non-masticatory activities. At Vindija and elsewhere these scratches reveal activities, which were performed primarily with the right hand. The late Neandertals from Vindija, combined with other studies, show that European Neandertals were predominately right-handed with a ratio 15:2 (88.2%), a frequency similar to living people. Studies of teeth from Atapuerca extend this modern ratio to more than 500,000 years ago and increase the frequency of right- handers in the European fossil record to almost 94%. Species-wide, preferential right-handedness is a defining feature of modern Homo sapiens, tied to brain laterality and language with the 9:1 ratio of right- to left- handers - a reflection of the link between left hemispheric dominance and language. Up-to-date behavioral and anatomical studies of Neandertal fossils and the recent discovery of their possession of the FOXP2 gene indicate Neandertals (and, very likely, their European ancestors) had linguistic capacities similar to living humans.
Journal of anthropological sciences 01/2010; 88:113-27. · 1.70 Impact Factor
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