Did you ever notice that apes, are just quadrupedal humans? Well a scientist by the name of Maurice K. Temerlin adopted an ape in the early stages of its life, and raised it like a human.
This was a science experiment of sorts, to see how close exactly apes are to humans, but after being attached to it (they named it Lucy) for so long, the ape began to act up. After a long, and heartbreaking story, it was most likely Lucy's humanization that brought her to her end.
I feel that this was a very beneficial experiment, but I also feel that it wasn't properly carried out. An ape is an ape, and we should keep it that way, and the way that Lucy died saddens me. And it was all because she was so used to being around humans so much. Lucy did teach us a LOT about how chimpanzes can be so much like humans, and it definitely proves that we came from a common ancestor, but it also taught us that animals like that, who are wild and free, can be socialized and civilized, the story that Maurice Temerlin told were incredible, and really gave me insight on how close we actually are to some animals.