Rats the size of sheep are in horror movies. However, scientists say giant rats could be real in the future. They could weigh 80kg. Rats are now all over the Earth. They are the strongest animals in many places. They travel on ships and move to places that never had rats before. Larger animals are becoming extinct, so fewer animals can kill rats. Researcher Dr Jan Zalasiewicz said rats might grow to become the world's largest rodent.

Dr Zalasiewicz said humans spread rats around the world. They adapted well to their new environments. He said the future would have thin rats, fat rats, slow ones, fast ones, and heavy ones. There might also be water rats. After the dinosaurs, many small animals grew bigger. The same thing could happen with rats if there were no animals left that kill them. They might make other species extinct. A big question is what humans would do about giant rats.