Why do dogs love bones?
Scientists from the National University of Columbia have created a canine “family tree” piecing together the relationships between over 300 species of dog. Dr Joao Munoz-Doran presented his findings at the First Joint Congress for Evolutionary Biology in Ottawa, Canada.
Around eight million years ago, ancient canines adopted pack-living in order to hunt larger prey. Researchers believe the resulting evolution of their jaws gradually turned the ancestors of modern wolves, and ultimately our own dogs, into ‘hypercarnivores’ (an animal which eats more than 70 per cent meat).
Dr Munoz-Doran explained: "Eight million years ago was when [less forested, more] open habitats were spreading through Asia, Europe and North America. And when there are open habitats, the big prey group together. So there will be more eyes watching for a predator."
The only way that dogs roaming the open plains could snatch very large prey from a herd was to work together.
The researcher added: "After many generations of this grouping behaviour, there are new selective pressures on their [skull shape]." This pressure meant that animals with larger teeth and stronger jaws were more likely to succeed in hunting, and to survive to pass on their large-toothed, strong-jawed genes to the next generation. Over time, they became adapted to be 'hypercarnivorous.”
The researcher pointed out, that domestic dogs, therefore, have "very good evolutionary reasons to enjoy chewing a bone".
Veterinary practices are being urged to help owners safely dispose of any unused and expired pet medicines - not just antibiotics - during November's Animal Medicines Amnesty. 
