Rats could grow as big as sheep in the future, experts have warned (Picture: Alamy)

Rats of the future could grow to the size of sheep or even bigger as they evolve, experts have warned.

Super-adaptable rodents could take advantage of larger mammals becoming extinct.

In time, rats could grow to be the size of the capybara, the world’s largest rodent which can reach 80kg (12st).

‘Animals will evolve, over time, into whatever designs will enable them to survive and to produce offspring,’ said geologist Dr Jan Zalasiewicz, from the University of Leicester.


‘Given enough time, rats could probably grow to be at least as large as the capybara, the world’s largest rodent, that lives today [and] can reach 80kg.



‘If the ecospace was sufficiently empty, then they could get larger still.’

The largest extinct rodent known, Josephoartegasia monesi, which lived three million years ago, was larger than a bull and weighed over a ton.

A hint of the nightmare to come can be seen on ‘rat islands’ – isolated regions where rats introduced by humans have quickly risen to become the dominant species, according to Dr Zalasiewicz.

‘So there will be future thin rats, future fat rats, slow and heavy rats, fast and ferocious rats, probably future aquatic rats – the list goes on,’ he added.