Thanks to a dingo pup found close to death on a lonely outback track, scientists may get the first opportunity to test one of Charles Darwin's most challenging hypotheses.

Sandy and her two siblings were three weeks old when they were rescued near the Strzelecki Track in central Australia by Barry and Lyn Eggleton in 2014.

The holidaymakers nearly ran over two of the pups huddled on the road. They found a third nearby, but no sign of their mother or a den.

The dingoes were tiny - all three could fit in Mr Eggleton's hand. They were dehydrated and covered in parasites. With the help of vets, the couple nursed them back to health and raised them.