Lips Are Red Because...
Your lips are red because there are many blood vessels around the lip area and because the skin on your top and bottom lip is very thin the color from these blood vessels is seen through to the surface of the lips, making them appear red. This also explains the reason why your lips turn blue in cold weather.
The cold air makes the blood vessels in your skin tighten and contract, forcing the blood to go deeper into your body to hold in the warmth. This makes your skin look paler and your lips look blue, it's been known as sign that you need to be warmed up for thousands of years. This is one possible explantion for why we find lips so attractive, we think of red lucious lips as a sign of warmth, good health and invitation.
This redness of the lips has been artificially created through lipstick since Mesopotamian times, over 5000 years ago.