Wolves and foxes are closely related and share many of the same characteristics.
But look at their eyes – where wolves have rounded pupils like humans, foxes instead have a thin vertical line.
But it isn’t just canines –across the animal kingdom, pupils come in all shapes and sizes. So why the differences?
It’s a question that has long interested scientists working on vision and optics. In a new study published in the journal Science Advances, colleagues from Durham, Berkeley and I explain why these pupil shapes have developed.