Pupula duplex - commonly called double pupil - is a rare medical condition, in which one's eye or eyes has two pupils.

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Men’s noses are 10% larger than female's.

Males generally have leaner muscles and need more oxygen for muscle growth and maintenance—and larger noses mean more oxygen can be breathed. A new study found that the difference in nose size between males and females of European descent starts showing in early puberty, when 95% of body weight gain in males comes from fat-free mass, compared to 85% in females.

Watch as a neurosurgeon opens up a patient's skull and clears the clotted blood from the surface of her brain. We probably don't have to tell you that this is extremely graphic footage, but - you've been warned.

Have you ever chillaxed (chilling and relaxing ) under the sun, cloud watching, and all of a sudden noticed transparent blobs floating around? Did you know what these things were? I know I didn't until I saw this:

What sets Homo sapiens apart from other animals? Among other things, our chins do. That piece of bone sticking out from your jaw is somewhat of a mystery - one that's inspired a diversity of wild theories to explain its purpose, according to a paper published this month in Evolutionary Anthropology.

The author of the paper dismisses a number of these explanations, such as the possibility that the chin serves as a sexual signal (such traits usually only appear in one sex - like the mane of a male lion). Another proposal is that the chin acts to protect your throat - an idea the paper's author also shoots down, because for this to be a substantial advantage, humans would have to be constantly punching each other in the face.

So the mystery rem ...

With up to one million hairs per square inch of its body, the sea otter has the densest fur in the animal kingdom. (To put this in perspective, you’ve probably only got 100,000 hairs or less on your whole head!) Together with a huge lung capacity, this makes these water-loving creatures extremely buoyant. The pups are born so buoyant, they're incapable of diving underwater, and are often left bobbing on the surface in a sea kelp bed while their mothers hunt for food nearby.

A viscous fluid made out of citrate and water is what gives our bones flexibility. The gooey fluid is trapped between the tiny crystals of calcium phosphate that form our bones, absorbing shocks and allowing movement. Without this fluid the crystals fuse together and become less flexible and brittle.