Thaindian News

London, April 29 (IANS) 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, a new study reveals.

Researchers at the University of Liverpool 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.

Researches have 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, the journal Public Library of Science ONE reports.

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, according to a Liverpool statement.

Nathan Jeffery, from the Liverpool 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.”

Philip Cox, study co-author, added, “Since the Eocene era, approximately 56 to 34 million years ago, rodents have been adapting their skulls and jaw muscles in what we might call an evolutionary race.”

The researchers 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 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.