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The Biodesign Institute at Arizona State University
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DNA Travelogue (article on Tishkoff's research)
Publication Date: Fall 2004
Men often “see red” when angry. Actually, women might see red much better than men. Other colors, too. No matter what the emotion of the moment. Stereotypes about the superior color sense of women may be rooted in genetics. New research suggests that natural genetic selection often gives women the ability to better discriminate between colors.
Brian Verrelli is a researcher with the Biodesign Institute at Arizona State University. He and Sarah Tishkoff of the University of Maryland studied the gene that allows people to perceive the color red. The scientists found that the gene has maintained an unusual amount of variation that is about three times that of other genes. Their results were published this year in the American Journal of Human Genetics.
The scientists think that enhanced color perception was important to women in prehistoric times. While men were out hunting meat, women were busy gathering fruits and nuts. Good color vision would have allowed them to better distinguish among fruits, foliage, and insects.
Verrelli explains that variation in the “red” gene is created via the exchange of genetic material with a gene “next door.” That gene detects the color green. The red gene is found only on the X-chromosome. Because women have two X-chromosomes, they can receive one chromosome with the typical configuration of the red vision gene while the other chromosome receives a slight variation. The combination of a normal and variant gene occurs in about 40 percent of all women. This combination may give those women a broader spectrum of color vision in the red-orange range.
By contrast, men have one X-chromosome. If they receive any variation in the single red gene, it usually reduces their ability to distinguish between red and green. While the common term used is “color blind,” the ASU scientist says that “color vision deficiency” is a more accurate description. About 8 percent of all men have a color vision deficiency. That number caught Verrelli’s attention.
“Most detrimental conditions caused by a genetic variation affect a tiny fraction of one percent of the population,” Verrelli explains. “The fact that color-blindness was so common suggested an important mitigating advantage.”
Humans see color because we have the ability to distinguish red, green, and blue. The combination of these three colors forms the basis for all the colors we see. Other creatures use different color vision systems. By studying these distinctions, scientists might better understand how and when life forms. Life Science: Genetics | Health & Medical: Human Physiology