Euegene stated what may be a revealing observation about Jao's hostile behavior.
Eugene said something like "every time the weather is overcast, Jao gets..." I can't remember the exact last word, but it meant cranky, hostile, etc.
SENIOR CITIZEN: Jao is a staggering 44 years old, which could make him eligible for AARP (American Association for Retired Primates) if converted to human years.
SENIOR CITIZEN WITH BRITTLE BONES: When Jao was isolated, caged, abused, neglected and rarely fed for all those years, what if he rarely or never got milk or calcium/vitamin D?
And what if that lack of bone-building mineral during his growing years affected Jao's old bones and joints like it does humans, making them brittle with loss of bone density, causing arthritis and pain, especially with certain weather changes?
And, since overcast weather means increased humidity and joint pain in human arthritic joints, is there a chance that Jao is suffering the same?
Try watching Jao very very closely when he walks, for signs he's leaning to one side or walking in pain. It's hard to tell for me as a layperson, as I have zero professional or historical experience for comparison.
Unless it's already proven that primates are incapable of developing joint disease, it might be worth it to sedate Jao for an MRI or bone-density scan, plus take blood work for arthritis antibodies.
If results are positive, there are treatments to consider that may help ease his discomfort.
If results are negative, then at least staff would know it's not that particular physicial issue causing his crankiness.
Of course, I don't assume physical illness could explain all of Jao's unhappy behavior, as he's elderly and enduring some serious stressors with social changes right now.
It could be that Jao is just a cranky old man; every neighborhood has one. You know, the man who is never happy and yells at kids when they touch his yard.
However, Eugene's comment about Jao's behavior change during certain weather conditions kinda jumped out as a possible clue to his attitude change.
Good thoughts, Pink! I know I ache on dreary days ... both physically if it's damp and with SAD (Seasonal Affective Disorder) if it's dark and icky (especially in the winter with lack of sunlight). Good pick-up ... I wonder if these ideas can get to Chimp Eden?