Some degree of gum recession can happen as people age. can this also be the situation with bone loss without the presence of periodontal disease?

Yes: With periodontal disease, often the bone tissue recedes and the gum tissue stays becomes inflamed and swells. The difference in height of the gum and bone tissues creates a pocket than exacerbates the disease progression.

Bone loss: Bone loss is associated with gum loss, they go hand in hand. Most perio is due to bacteria (better hygiene) but can be increased by trauma, smoking, systemic disease, nastier bacteria, meds, etc. The biggest reason we get more loss with age (besides disease and inability to clean) is we have more time to be exposed to the above bad habits. I have seen 80 year olds with all their teeth. See a dds.

Yes: That's the only way you get gum recession, is that the bone has to go too. And most people don't realize that. If your gums are receeding, then you know for sure that the bone underneath is also going away. This can happen with aggressive brushing, or people that clench and grind their teeth. Also, some people have receeding gums and we just can't find a cause.

No: By definition, one of the diagnostic indicators of gum disease is "bone lose". So if you have bone lose and any additional combinations of issues like recession, bleeding gums, mobile teeth, etc...You have some type of gum disease. You could also just have bone lose (radiographically) and i'd seek professional dental care!