When it comes to animals, even tiny differences are a big deal

I’ve been struck over the past year by just how tricky it is to conceive of important differences between individuals within the same species.

We have come to terms with the notion that beasts from octopuses and grouper fish, to crows, chickens and parrots, chimps, cows and horses can deceive, or feel pain, grief, terror and joy.

And we also recognise that there are individual species that show consistent differences in how they conduct themselves, from brave to shy, lazy to active, curious to phlegmatic, rambunctious to timid.

But beyond that there is a world of individual variation in…