Mimicry plays an important role in social interaction.
Cues like sneezing, laughing, crying and yawning may be ways of creating strong social bonds within a group. If it were, we might have wings instead of wisdom teeth.
Most cells in our bodies sport hair-like organelles called cilia that help out with a variety of functions, from digestion to hearing.
In the nose, cilia help to drain mucus from the nasal cavity down to the throat.
Long ago, they served as a useful third set of meat-mashing molars.
But as our brains grew our jawbone structure changed, leaving us with expensively overcrowded mouths.
All skin, without coloring, would appear creamy white. These four hues mix in different proportions to create the skin colors of all the peoples of Earth.
Lastly, sepia-toned melanin, created in response to ultraviolet rays, appears black in large amounts.