"Once damaged, these hairs never grow back. You have around 3,500, and that is all you'll have throughout your entire life...

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. Each human is a ...

The human body is a machine whose many parts – from the microscopic details of our cells to our limbs, eyes, liver and brain – have been assembled in fits and starts over the four billion years of our ...

The world is such a fragile place. At any time, a building might fall apart, industries could collapse and it’s entirely possible for Beyoncé to release a mediocre album. The world itself will ...

Functions of the human body explained with special emphasis on the senses of sight and hearing and the individual's responsibility to care for the house lived in. This film was part of Wonder series, ...