Each chimp was tested in three different postures: for the first, they were allowed to hold the tube and all sat down to extract the food for the second, the tube was suspended vertically above head-height but within a short distance of a wall, so they could support themselves with one hand while standing bipedally, and finally, the tube was suspended above head-height but away from the wall, so the chimps had to stand unsupported (Braccini et al. therefore set up an experiment in which a number of chimps (of whom 15 were ambidextrous, 15 right-handed and 16 left-handed according to previous research) were given sticks to access peanut butter in the middle of plastic tubes. ![]() ![]() In fact, these authors, publishing in the current issue of the Journal of Human Evolution, argue that much more research into handedness in the apes is needed to establish whether the human predominance of the right side of the body is an extension of a trait present in the last common ancestor or a uniquely human character.īraccini et al. Laterality is reduced (with many individuals being ambidextrous), and although the results of early research are inconclusive, there is no demonstrable preference for being right-handed over being left-handed (Braccini et al. In chimpanzees and other apes, though, the situation is different. In humans, who are (mostly) right-handed, the left side of the brain, which is the side associated with language, is therefore dominant. Handedness is a manifestation of laterality - having a behaviourally dominant side or limb - and may be related to the relative dominance of the two halves of the brain. Yet the fact remains, over 90% of humans are right handed, and strongly so - there are proportionally few left-handed individuals and very few ambidextrous ones. ![]() Of the many mysteries surrounding human evolution, the question of why humans, alone out of all the apes, display a strong tendency towards being right-handed is perhaps less well known than uncertainties about our locomotion, brain size and cultural capacity.
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