Monday, September 19, 2011

Hand preferences for coordinated bimanual actions in 777 great apes: Implications for the evolution on handedness in Hominins

Population-level Right handedness is a universal trait of humans. In this article from the Journal of Human Evolution, researchers present an assessment of handedness in four great ape species. After conducting the TUBE test that requires bimanual actions on numerous samples of these different species, results showed that chimpanzees, bonobos, and gorillas all showed population-level right handedness, whereas orangutans showed population-level left handedness. Findings from this experiment were meant to be compared to the results from a similar 2003 experiment by Hopkins et al which used smaller population sizes and therefore produced potentially inaccurate data.

In this experiment, researchers considered many factors such as the influence of age, sex, and human rearing on species' hand preference, concluding age to be the only relevant factor in certain species. Additionally, there seems to be a focus on compiling accurate data for chimpanzees as man's closest nonhuman primate relative. The authors make a note that the lateralization of handedness is linked to language lateralization in humans, which suggests linked evolution. With this in mind, results from this experiment could shed more light on human-primate divergence.

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