Many animals have a hand preference. However, that preference is normally evenly split within a species. Humans are weird because most of us (~90%) prefer our right hands. New research into cats is shedding light on why that may be the case1.
It turns out cats also have a hand preference. Like most animals, their hand preference is fairly even. In this case by sex, with female cats preferring their right paws. That, by itself, isn’t unusual. Sexual differences in hand preference are also present in dogs1.
However, in most cases, a sexual split seems to be hormonal. When those hormones are changed by neutering the dog, paw preferences also stop being split by sex. Cats, on the other hand, retain those paw preferences. For the first time, they provide evidence that something else is at work here1.
What could it be? And what implications does it have for our evolution?
At this point you may be wondering why these researchers behind this discovery picked cats, of all animals, to study hand preference in.
A big part of the reason was that they were curious about spontaneous behaviour. Often, studies into animal hand preference involve putting them in unusual situations to try and force them to pick a hand. Cats on the other hand, with their constant climbing, playing, and interacting with objects, provide a great chance to study hand preference in a “natural” way1.
However, I suspect a part of it was because they wanted an excuse to play with a bunch of cats. Which was essentially what the experiment was. They watched 44 cats climbing, stepping, and interacting with food dispensers to see which paw each preferred1.
As I gave away earlier, the results of this experiment revealed a sex bias in cat hand preference. 1/3 of them were ambidextrous, but amongst the cats that did have a preference, it was split 50/50. That split was right down sex lines, with females preferring their right paw and males preferring the other one1.
Which again, isn’t that unusual. Dogs and horses also show a similar split down sex lines (once ambidextrous animals are taken into account).
However, in dogs, the sex difference went away when neutered animals were tested. This led most to infer that sex differences in hand preference had a hormonal cause. However, all the cats in this study were neutered and the difference still remains1. Clearly, this is more complicated than we thought.
Of course, the cats, being assholes like all cats, weren’t done pooping over our theories.
Another popular explanation is that handedness is linked to the complexity of the action been done. This has been seen in chimps, where they’re more likely to show a hand preference for more complicated activities. Interestingly, most seem to prefer the right hand in those situations, just like humans. Coincidence?.
But then the cats came along and ruined everything. As the chart above shows, hand preference was fairly evenly split amongst all activities1. Including the most complicated one they performed (“food reach”), where they had to manipulate a feeder to get food.
So now we know so much about cats, what have we learnt about human evolution?
Well, we’ve not gained any new knowledge really. Most of the cat behaviour has precedent in other species. But what this research does do is challenge several hypotheses we had about why handedness might develop. Clearly, simply pointing to hormones or activity complexity isn’t enough.
It’s like our hypotheses were a glass perched too close to the edge of a table and a cat knocked it off. Except clearly, our hypotheses were flawed, so we should be grateful that they’re being challenged by cats.
So I guess a better analogy would be a cat breaking our hypothesis-glass, except it was ugly and really did need to be destroyed. They did us a favour really.
- McDowell, L.J., Wells, D.L. and Hepper, P.G., 2018. Lateralization of spontaneous behaviours in the domestic cat, Felis silvestris. Animal Behaviour, 135, pp.37-43.