Aristotle once questioned what separates humans from animals. He decided it’s not language or reason. It’s laughter. Aristotle wrote that the moment when a baby first laughs is when the child becomes fully human. According to historian Barry Sanders, Aristotle believed that “At that point, the creature moves from being a human into a human being.”
Throughout history, there have been stories of animals committing suicide. Two thousand years ago, Aristotle wrote about a horse that was so ashamed after unknowingly mating with his own mother, that he killed himself. While these types of stories sound improbable, there are cases where animals kill themselves, and no one knows why.