Bartke's work in this area originated 10 years ago, when he began studying mice that have too much of the hormone. These mice, created at Ohio University, have DNA altered to include genes for human or bovine growth hormone. SIUC research on the mice, which was funded by the U.S. Department of Agriculture and the National Institutes of Health, was aimed at investigating the effects of high growth hormone levels on fertility. But it also revealed evidence of major effects on aging. Bartke and his collaborators found that the transgenic mice show many signs of premature aging and live less than half as long as their normal counterparts.
People find something that shortens life inherently less intriguing than something that prolongs it.
He suspects that the developmental effect limiting body size is probably the key factor in prolonging life. Small breeds of dogs and horses live longer than larger breeds, he says, and there is also some work that suggests short people tend to outlast tall ones. One researcher has found differences in life span between people in northern and southern Europe, who differ in average height. There are stronger studies with more compelling evidence, yet even those are open to varying interpretations. Lots of information that can help us understand human biology can come from an understanding of species different from us.