Essentially, dogs bury bones for the same reason squirrels bury nuts: as a hedge against the lean times.

Essentially, dogs bury bones for the same reason squirrels bury nuts: as a hedge against the lean times. Not that the typical dog has to worry about where his next meal will come from, but his wild ancestors figured out a long time ago that when food is easy to come by, it's a good idea to put some aside --- kind of like setting up a savings account that can be drawn on in an emergency. This behavior is called"caching," and it's common among wolves and certain species of foxes as well as dogs. (When I find it necessary to feed my dogs in their travel crates during hunting trips, my English setter female will "cache" any leftovers by very carefully covering her bowl with a layer of straw.)

My impression, though, judging by the prevalence of the theme in the popular art, literature, and film (including cartoons) of the early and mid-20th century, is that dogs aren't burying bones the way they used to. Not that they're any less interested; the more likely explanation is that they're simply not getting the opportunity, the veterinary profession having done a pretty thorough job educating dog owners about the consequences of a shard of bone lodging in their pet's digestive tract. The jaws of the average dog, after all, can generate several hundred pounds per square inch of crushing force, more than enough to splinter even the toughest beef bone.