There’s a wonderful cartoon by Gary Larson where a penguin, standing amid a throng of virtually identical birds, sings, “I gotta be me! Oh, I just gotta be me…” As ever, Larson’s The Far Side captures the humorous side of a real natural dilemma. Social animals spend time in large groups, but they still have to tell the difference between individuals so they can recognise mates, young, leaders and rivals. As the groups get larger, so does the scope of this challenge, and some species meet it by evolving individuality. As groups get bigger, their members become more distinctive.

Kimberly Pollard and Daniel Blumstein from the University of California, Los Angeles studied different species of ground squirrels, each with a different