at a newly opened zoo in Kansas City about 30 years ago, I WATCHED as a teenage boy fed a 600lb. male silverback gorilla Hershey's Kisses! The gorilla would very carefully peel the foil off and eat the candy, then reach for another one. You can imagine what might have happened if the kid had teased the animal.......but this was not the worst problem...Gorillas, etc., can catch human diseases, and need to be behind a protective barrier for the gorillas sake!.....And to add to the list, in the rear of the cages, for access by the keepers, there was a lever to unlock the cage--which was within reach of a clever gorilla who was willing to strech a bit!...Needless to say, these situations were corrected after a while...but...

(my guide on the trip was a professional zookeeper who had inside info from other zookeepers)