Mammoths spent much of their lives chewing tough, abrasive vegetation, and ordinary teeth simply wouldn't have lasted very long. Instead, their molars were made from a series of hard enamel plates packed together into a huge grinding surface, ready to grind up dinner!
As it chewed, the plates wore down at different rates, creating these ridges that would allow them to grind up dinner.
But perhaps the cleverest part was what happened when a tooth eventually wore out. Rather than growing replacement teeth upwards from underneath like ours, mammoth molars developed towards the back of the jaw and gradually moved forwards, pushing the old worn tooth out.
A mammoth only went through six sets of these molars during its lifetime. Once the final set became badly worn, there was nothing left to replace them, which could eventually leave an elderly mammoth struggling to eat enough food.
It's an incredible amount of evolutionary 'engineering' hidden inside something as seemingly simple as a tooth.
Fun fact: Palaeontologists can estimate a mammoth's age from its teeth. Mammoths had six successive sets of molars, which became larger as the animal grew, with more or the enamel plates, and their pattern of eruption and wear provides clues to how old the mammoth was when it died.
