This document discusses feral children and the critical period hypothesis of language acquisition. It defines feral children as those who have lived in isolation from human contact and language from a very young age. It presents several cases of feral children who were isolated, confined, or raised by animals. These cases provide mixed evidence for the critical period hypothesis, which proposes a sensitive period for language acquisition between ages 2-12. Some feral children acquired language abilities after being found, while others did not.