If you only looked at mammals, you could reasonably believe that the chisellers have inherited the earth. Of all the various species of mammals, forty percent are rodents. Rats, mice, squirrels, guinea pigs… all of them have the same modus operandi. They gnaw their way into their food with self-sharpening chisel-like teeth.

Whether tiny gerbil or huge capybara, rodents eat with the same special teeth. The upper and lower jaws each have a single pair of incisors that grow continuously through their lives. The front of each tooth is made from hard enamel, while the back is made of soft dentine. As the rodent gnaws, the incisors scrape at each other, and the dentine wears away faster than the enamel. This