Super strong chompers, more than twice as tough as ours, let sea otters crunch through the shells of crabs and clams, scientists report in the journal Biology Letters.
Biologists and archaeologists from Kuwait, Germany and the United States examined the Hunter-Schreger bands, the enamel structure that prevents chips in teeth. Compared with humans, otters' bands were more common, making the teeth less prone to chipping. In fact, the bands in the otters' pearly whites resembled the teeth of an early human ancestor who subsided on nuts and hard fruit.
It's tough to get a sense of exactly what our ancestors ate - but looking at chips and wear on fossilized molars of Paranthropus boisei, a hominin found in eastern Africa, indicates they consumed small, solid items. Because otter teeth are easier to examine than fossilized molars - and we know the otter diet contains lots of hard items - the archeologists could use the marine mammals as toothy stand-ins for long-lost apes.