The Australian quokka, part of the kangaroo family, is the happiest animal on earth. At least, that’s how it appears. Once described by a Dutch sea captain as ‘a kind of rat as big as a common cat’, the furry creatures always wear a cheeky grin – even when asleep… Scientists still don’t understand why the quokkas are always smiling but they put it down to an ‘accident of evolution’. That can make it pretty hard to judge their character. Quokkas bite dozens of people each year on Rottnest Island off Western Australia (their primary home), normally when snatching food. Who knew that appearances could be so deceptive?