Scientists at the University have found that mice and rats have evolved to gnaw with their front teeth and chew with their back teeth more successfully than rodents that ’specialise’ in one or other of these biting mechanisms.
Researchers designed a computer model to simulate the bite of rats to understand whether their skull shape or muscle arrangement was a major factor in their evolutionary success and global dominance, making them one of the most common pest species in the world.
Research has already shown that rats and mice can both chew and gnaw, whereas other rodents, such as squirrels, specialise in gnawing, and some, like guinea pigs, specialise in chewing. To understand whether the rat’s ability to do both made its bite more effective, the Liverpool team took the anatomical features of rats, squirrels and guinea pigs and fed them into a computer model to simulate the different biting mechanisms.
They also created virtual animals with a rat skull and squirrel muscles, for example, to investigate whether it was adaptations of the skull or jaw muscles that gave rats their biting abilities. The findings, published in the journal PLoS ONE , showed that it is the rat’s muscles that increase bite efficiency, allowing it to gnaw and chew with more success than species that specialise in just one of these methods.
Nathan Jeffery , from the University’s Institute of Ageing and Chronic Disease , said: "Mice and rats belong to a group of rodents called the myomorphs, which are amongst the most successful of all mammals. With over 1000 species, comprising nearly a quarter of all known mammal species, they live in a wide variety of habitats on every continent, except Antarctica.”†