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Why we see what we see. Evolution theory explains many things, but one thing never explained to the satisfaction of CAS Professor of Physics Kenneth Brecher is why almost every creature on earth sees visible light, as opposed to other frequencies in the spectrum.

"The standard school of thought is that since most of our sun's radiation is in the form of visible light, rather than infrared or ultraviolet, our eyes evolved to tune in that range of wavelengths," says Brecher.

In exploring this conventional wisdom, however, Brecher found that most of the sun's radiation is actually in the infrared band. As those who have tried on night vision goggles know, all warm-blooded creatures give off infrared radiation. "This kind of vision would be very helpful to creatures that hunt, allowing them to pinpoint their prey, especially in dim light," notes Brecher.

A more effective way to locate prey would be an enormous evolutionary advantage, and this brought Brecher back to the question: why do most eyes process only a small part of the spectrum?

"Our vision relies on a substance in the retina, rhodopsin, which absorbs and converts photons into a chemical that triggers the sensation of vision in the brain," Brecher explains. "There just may be no chemical processes that allows our eyes to respond to infrared." Why this mechanism never evolved is another question, he adds, noting that even plants absorb solar energy from only a small part of the spectrum.

Brecher presented his findings at a January 1999 meeting of the American Astronomical Society; an account also appeared in the Boston Globe on January 25, 1999.

Exploring a medical mystery. Some residents of South Boston have suspected for a while that there are an abnormally high number of cases of lupus and scleroderma in their neighborhood. State health officials would expect to see 13 to 15 cases of lupus and about 6 cases of scleroderma in an area the size of South Boston, but more than twice that number have been reported recently.

Dr. Joseph Korn, MED professor of medicine and director of the Arthritis Center, is working with residents and state officials to launch a comprehensive study to determine what the problem might be. After being alerted by some residents of South Boston and some who have moved away, Korn and Suzanne Condon from the Massachusetts Department of Public Health agreed to investigate the situation.

"We seem to be seeing more cases of these conditions among current and former residents," says Korn. "The study will help us determine if the two conditions are genuinely present in abnormal numbers."

Lupus and scleroderma are autoimmune disorders in which the body's own connective tissues are attacked by the immune system. Both illnesses affect women more than men and currently have no cure.

"We're in a unique position to conduct this work," says Korn, "as the BU Medical Center is a national leader in research and treatment for scleroderma."

"Research Briefs" is written by Joan Schwartz in the Office of the Provost. To read more about BU research, visit


15 May 2003
Boston University
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