The decades that make up a typical human lifespan can seem like vast stretches of time to us. But to the forces of evolution, they are mere temporary blips. Common wisdom has it that evolution occurs over geological timescales – thousands and millions of years. As such, evolutionary biology takes a lot of criticism for being a ‘descriptive science’, being less open than other fields to that fundamental aspect of science – experimentation. Though there are exceptions, those who study evolution must mostly be content to observe snapshots of life, either present or entombed in rock, and make inferences from there.

But this isn’t always so. Occasionally, evolution happens at astonishingly fast rates, as epitomised by the case of the