Why doesn’t that bear have osteoporosis?

The parathyroid theory is interesting. I would imagine that bears also have less chronic stress than humans do, and therefore have less cortisol pumping through their systems at all times of the day. No doubt that high cortisol levels deplete bone mass. We know that corticosteroid drugs deplete bone mass too.

I would bet that if physicians regularly ordered circadian saliva tests in order to measure cortisol levels as well as rhythm, they would notice that high levels and/or faulty rhythm are associated with not only osteoporosis, but also many other serious health issues. Lower the systemic stress (physiological and psychological) and we plug the bone drain. We are a society in chronic stress, and that is wreaking havoc with our health.