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What is color blindness and how it was discovered?

There is an opinion that the distant ancestors saw the world in black and white colors. Then in the process of evolution the sensation of light became divided into yellow and blue. After some time, yellow split into red and green.

Cases of color blindness and decreased sensitivity to certain colors in some people is a return to the physiological properties of our ancestors.

There are three types of color blindness: red (Protanopia), green (deuteranopia) and, more rarely, to the blue color (tritanopia).

Test for blindness to red
People with Protanopia
't see number 37
Test for blindness to green
People with deuteranopia
't see number 49
The test is blind to blue
People with Tritan
you will not see the number 56


The artist's painting with color blindness
To the left is a reproduction of a painting by artist Bogdanov "Waiting".
To the right is a copy of this reproduction, the artist with color blindness to red color.
Drawings from the collection of Professor E. B. Rabkin

For the first time this phenomenon was studied and described in 1794, the English scientist John Dalton (1766-1844), and from experience he himself suffered from this defect.

To 24 years, Dalton didn't even know that he has impaired vision, until you became interested in 1790 botany. Then it was discovered that it is difficult to understand Botanical monographs and determinants. When the text was talking about the white or yellow flowers, he experienced no difficulty, but if the flowers were described as purple, pink or dark red, they all seemed to Dalton indistinguishable from the blue.

At first he thought it was confusion in the classification of colors, and not enough of his own view. But then he noticed that the flower that day by the light of the sun, he saw the sky blue, light candles became for him a dark red. Dalton turned to the others, but no one noticed this strange transformation, except his brother. Thus, Dalton guessed that his vision is something wrong and that this problem is inherited. The Dalton were three brothers and a sister, two brothers suffered from zwetsloot on red.

Dalton suffered from a rare form of color blindness - deuteranopia, in which the eye does not detect light medium wavelengths. In addition to the purple and blue colors he was able to recognize only one - yellow. He described it as: "That part of the picture, which others call it red, it seems to me as if a shadow or just poorly lit. Orange, green and yellow seem to be shades of the same color, from intense to pale yellow.

Dalton decided that in his eyes there was any blue light filter. He bequeathed after his death to retrieve his eyes to see whether painted in a bluish color of the vitreous body. The scientist will was executed, but his eyes were not detected nothing special or unusual.

Eye Dalton preserved in alcohol in the Manchester literary and philosophical society, and in our time, in 1995, genetics have identified and examined DNA from the retina. As expected, it was found genes for colorblindness.

John Dalton
John Dalton

The study by Dalton's own illness was so precise and accurate that the term "color blindness" is firmly entrenched in this disease, and in our time, every schoolboy is familiar with the term "colorblind", even if not until the end is what he means.

Did you know that...

English provincial teacher-taught chemist, meteorologist and scientist John Dalton was one of the most famous and respected scientists of his time. Today his name we are more known under the name of defect of vision - blindness, which was named in his honor as the discoverer and researcher of this phenomenon. But in their time, Dalton was widely known thanks to many innovative works in various fields of knowledge. He discovered the law of partial pressures (Dalton's law), the law of the uniform expansion of gases when heated, the law of solubility of gases in liquids (Henry's law-Dalton), the law of multiple relations. Dalton discovered the phenomenon of polymerization (for example, ethylene and butylene), introduced the concept of "atomic weight", first calculate the atomic weight (mass) of a number of elements and was the first table of relative atomic weights, thus laying the basis of the atomic theory of the structure of matter.

The merits of Dalton were recognized. He was a Professor at Manchester College, Oxford University, member of the French Academy of Sciences (1816), President of the Manchester literary and philosophical society, a member of the London Royal society and the Royal society of Edinburgh.

 


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2013-04-10 21:43:07
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