The monkeys at the clinic are the cutest – the Spider Monkey learns everything it needs to know about being a Spider Monkey from its mom. When Spider Monkeys are hunted and their mothers killed they can no longer learn how to survive in the wild.
Although quite intelligent these monkeys have little to no instinct. Instinct, is usually the main factor determining whether an animal can be released into the wilderness. When these monkeys arrive at a clinic like Proyecto Asis they grow accustomed to human behavior and cannot be placed in the wilderness again because they’d likely treat a predator the way they do a human.