Is there any more charismatic animal than the much maligned koala? Said to "defy evolution", they sleep 20 hours a day, survive solely on eucalyptus leaves - a food source not only nutritionally poor but indeed toxic - and famously don't recognise that food source detached from a tree. And yet, they have not only survived but thrived for more than 25 million years, outcompeting faster, stronger and smarter animals. How is such a thing possible? Koalas are hyper-specialised to a very specific nic...