A tiger walks the same worn groove along the edge of its exhibit, like a broken record. A parrot methodically plucks out its own feathers until bare skin shows through. To a casual visitor, these can ...

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. Giant pandas living ...

You can't prove normality, and its definitions are constantly updated The problem in mental health is you can’t prove you are normal, but for some reason, many seek to prove you are abnormal as a good ...