DALLAS -- There is some substance to the old Air Force legend that 'top guns' have fewer sons, apparently because of their exposure to high gravity forces, a geneticist has discovered.
A group of Air Force 'top gun' pilots and U.S. astronauts produced 60 percent daughters to 40 percent sons, compared with the normal 50-50 ratio in the general population, apparently because the high G forces the men were subjected to during flights had some effect on their X and Y chromosomes, the research showed.
Dr. Bertis Little, an assistant professor of obstetrics and gynecology at the University of Texas Southwestern Medical Center at Dallas, published his findings recently in 'Aviation, Space, and Environmental Medicine.'
Little said he became interested in exploring the 'top gun myth' while on the faculty of the University of Texas at Austin.
While he and his wife, Lori, were briefly 'iced in' with their relatives in the Austin Hill Country, Little's father-in-law, retired Air Force Col. Cecil H. Rigsby mentioned the 'top gun myth.'
When the two men began looking in Rigsby's old war-college annual, checking for girls vs. boys in the pilots' offspring, they found an apparent basis for the legend and Little decided to pursue the study seriously.
Little's data were taken from published biographies of pilots attending the Air War College at Maxwell Air Force Base in Alabama in 1965 and of the U.S. astronauts.
Formal results indicated a low-G exposure group comprised of 220 officers and non-fighter pilots had about 50 percent male offspring, while the high-G group of 62 fighter pilots and astronauts had 38 percent and 43 percent males, respectively.
Little acknowledged his study does not prove that exposure to high G-force caused the drop in the number of male offspring, but added, 'It does suggest an association between the high-G exposure and reduced male to female ratio.'
Little is currently carrying his research one step further by working with mice that have been used in NASA-financed studies under conditions similar to high-G force exposure.
Working with a control group of mice, Little is doing a study in which he is trying to identify which mice have been 'flying' at high G in a centrifuge by analyzing the X and Y chromosomes in their sperm counts.
'More pilots are flying more types of aircraft at higher speed every day,' he said. 'Also, as technology takes us beyond the face of the Earth at great speeds, effects on physiology and reproduction will become increasingly important.'
Furthermore, Little said, while a few studies have been done on male fertility, nothing has been investigated about the effects on women of flying for long times, at high speeds and at high altitudes.