On the other hand

I’m curious about left-handedness because I’m a lefty. Last night I wondered whether there were right- and left-handed primates. According to my AI-assisted search of the web, yes.

Whereas approximately 10% of humans are left-handed, about 25% of gorillas and 30-35% of chimps are. Perhaps that’s because they don’t smack each other with rulers when they use the “wrong” hand. Furthermore, ambidexterity is more common in primates, with some showing no hand preference at all.

One on the ways researchers determine the handedness of primates is by putting a treat in a tube. The primate needs to hold the tube with one hand while retrieving the treat with the other.

I tend to use different hands for different tasks. For example, I throw a baseball with my left hand but bat right-handed. I also bowl and play guitar (badly) right-handed. And since my mother told me life would be easier if I learned to use scissors with my right hand, that’s what I do. And I’m not the only southpaw with some degree of ambidexterity. Most of us have needed to adapt to the right-handed world of humans, or our brains are wired in a way that makes dominant handedness less of an issue. Some of us use whichever hand is…handy.

I also learned from my late night research that left-handedness occurs to a slightly higher degree among neurodivergent populations. About 28% of autistic people, 14.5% of those with developmental coordination disorder, and 27.5% of those with ADHD are likely to be left- or mixed-handed.

And although the reasons for the connections are unknown, left-handed people have a slightly greater incidence of immune diseases, migraines, breast cancer, cardiovascular disease and inflammatory bowel diseases. I haven’t had a problem with any of those (yet) but maybe I should worry that 40% of those with schizophrenia or schizoaffective disorder are left-handed.