Good idea (this darkening of the background). But, the "emphasized shadow" should be applied more gradually, in order to not be perceived as a "trick" (chimp's left leg!). And then again, the photo which is already "lacking a story" (apart from the expression of the chimp's face - the animal is obviously frightened - but from what? Where are the predators?etc. - spectators could ask themselves) would suffer from losing the "substance"... So, any kind of image detail (fence, ropes, grass, wooden structures... can at least add a certain weight, suggesting, like in the original photo that we are looking at a chimp in some zoo...