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hat is color blindness? A color festival. No. Color blindness or color deficiency is a vision problem. Now, our eyes have light sensitive cells called rods and cones. Can I put ice cream on these cones? You are just unbelievable. Rods are responsible for black and white vision. They do not detect color. Whereas, cones detect color. There are three types of cones. One cone perceives red light, another perceives green and the third perceives blue. Together, these cones help us to see the whole spectrum of colors. Now in some cases, when one or more types of cones do not work properly, it causes color blindness. People with such deficiency have difficulty in distinguishing between certain colors or shades. For example, in red-green color blindness, the apple tree may appear like this.

Normally, male squirrel monkeys can't distinguish between red and green hues-they're what is called color-blind in humans. The South American Saimiri genus lacks a gene that allows color-sensitive cells in the eye, called cones, to differentiate red and green from gray. To these animals, other colors, such as blue, brown and orange, appear faded. But Sam was one of two males in the experimental group of a groundbreaking 2009 ophthalmological study conducted at the Washington National Primate Research Center in Seattle. Husband-and-wife vision researchers Jay and Maureen Neitz injected a viral vector behind the retinas, the part of the eye that responds to color, of Sam and his simian lab partner, Dalton. The virus contained the genetic code in human eyes for red pigment, giving the monkeys an extra class of cone photoreceptor.

When babies are born, their eyes and hair are one color, but change within the first few years of their life! Why do hair and eye colors change? Trace explains the process of inheriting certain traits from your parents, and discusses why the colors change!

We see color because of specialized light-sensing cells in our eyes called cones. One type, L-cones, sees the reds of strawberries and fire trucks; M-cones detect green leaves, and S-cones let us know the sky is blue. But vision scientists have now discovered that not all cones sense color (see video).

SciShow explains the genetics -- and physics -- behind why blue eyes are blue, and what the future may be for the trait. Spoiler alert: Blue eyes aren't really blue! SciShow explains!

Links to teacher's guide for October articles Eating with your eyes: The Chemistry of Food Colorings Tooth Decay: A Delicate Balance Probiotics: Good bactria good health Dirt? Who needs it? How hydroponics is poised to change the world Light in the cellar of the sea

Your mother's DNA may have determined your eye color, but some traits that you thought came from her may instead have come from the DNA of bacteria she passed on to you soon after birth, a new study finds. The study found that a mother mouse can pass along to her offspring a susceptibility to intestinal disorders, such as inflammatory bowel disease, by way of a gut-residing bacterium called Sutterella, the researchers reported in the journal Nature on Feb. 16.