In a scene from Star Wars: The Emprie Strikes Back, Darth vader cuts off Luke Skywalkers right hand. Afterwards, Luke receives a robotic replacement hand that is as good as new. 

Researchers think that looking at how quickly a person's pupil dilates when taking cognitive tests could predict if a person is at an increased risk for Alzheimer's disease, even before any obvious symptoms show up. 

Humans voluntarily choose some of our actions, but others are automatic. Scientists want to know whether animal behaviors are automatically triggered by environmental situations, or whether animals sometimes choose their behaviors just like humans do.

When people are hungry, this hunger sometimes turns into anger. This mental state is known as "hangry," and could be caused by the stress of the morning mixed with hunger.