Can humans live without eating food, just by drinking water? How long can we survive just by drinking water everyday?
It is tragic, but apparently Killer whales and Dolphins can commit suicide too (e.g. here)... This suggests they can become depressed. I wondered whether they were "clinically" depressed like many ...
Both elephants and humans perform rituals when deaths occur. However, I do not see any evolutionary benefit of this. The rituals take time, which apparently could be better spent hunting, foraging, ...