There's also a documentary called Project Nim. It's about an experiment in the 70s where they decide to bring up a monkey as a baby or a chimp. And these bunch of hippies basically decide to rear it and see if they can teach it language. But all it's doing is repeating the process it needs to do in order to get its treat. So it's not really communicating, it's just learned this pattern that it has to do to get the food. As it gets bigger, it becomes more and more unruly. They have to put it into sort of monkey care. 15 years later, she goes back to see it and it recognises her immediately. She