Studies conducted in the s showed that most left-handers have the same left-hemispheric brain specialization for language typical of all humans--only a portion of left-handers have different patterns of language specialization. So the bottom line is, we have a good general idea of the causes of right-handedness in human populations, but we have yet to work out the precise details, including why the direction is right instead of left.
Do other primates show a similar tendency to favor one hand over the other? The second question do non-human primates show handedness is currently a controversial one. It is important to note the difference between an individual animal being left- or right-handed, and most of the animals in an entire population being either left- or right-handed.
It is not unusual for individual animals to show a preferential use of one hand over the other, to develop an individual hand preference. But there is no consensus among researchers that any non-human species shows the same species-level handedness found in humans. There are a few researchers who argue for this, but most of these work with animals in laboratory or captive settings, performing manual tasks that are very different from how animals use their hands in the wild. In addition to studying handedness in humans, I have also studied hand usage in mountain gorillas in Rwanda as well as chimpanzees, red colobus monkeys, redtail monkeys and grey-cheeked mangabeys in Uganda.
My own research shows that individual monkeys and apes often develop individual preferences both left and right for manual tasks, but I have found no evidence for population-level handedness, as seen in humans. In an earlier study , researchers noted striations on the front side of teeth belonging to European Neanderthals.
They hypothesised that these marks were made when material was held in one hand and gripped between the front teeth and worked by the other hand with a stone tool, with the stone tool occasionally striking these teeth. These actions were replicated during experiments in which participants wore mouthguards.
The results indicated that right-slanting striations are made on teeth when material is pulled with the left hand and struck with the right hand. Right-slanting striations are therefore a good indicator of right handedness. The subject of the new study — an ancient upper jawbone — provides the oldest evidence for right-handedness known in our genus Homo.
The jaw was identified at Olduvai Gorge in the Serengeti Plain, which has yielded some of the earliest archaeological traces in the world. The authors of the study noted a number of striations on the front side of the teeth. Take heart! According to a paper in the journal Psychological Bulletin , "there is remarkably little evidence for any association of left-handedness with deficit, as has often been suggested". In fact, some research shows that left-handed folks might even have an easier time recovering from brain damage.
And their left hand seems to have the advantage of surprise in a fight, which means they can be better at combat sports. All of which suggests there are advantages to breaking from the norm. Share this story on Facebook. Body Matters Evolution. Evolution: Why are most of us right-handed? Share using Email. Left-handedness has been falsely linked to evil, perversion and criminality. But as the scientific view of left-handedness as a pathology has lost momentum, so too have claims that left-handers are, on average, more creative or more intelligent.
It may have to do with resilience. A lifetime of being seen as different — and dealing with such indignities as right-handed scissors — may make southpaws more adaptive, though we have yet to turn up hard evidence. To go any further is risky.
Register or Log In. The Magazine Shop. Login Register Stay Curious Subscribe. The Sciences. Marianocecowski via wikimedia. Newsletter Sign up for our email newsletter for the latest science news. Sign Up. Researchers can determine handedness in hominins by the dominant direction of teeth striations from individual fossil remains going back as far as Homo habilis, the first member of our genus. Drawing: Jay Smith.
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