National Geographic : 1997 Nov
days. Field mice typically live three years. Ger bils six years. Mountain goats, 14. Dolphins, 25. African elephants, 48. A pattern emerges, with smaller species generally living shorter lives than bigger ones. Do these smaller species have faster running programs, or are they more prone to wear and tear? One way to find out, Finch says, is to study the exceptions-such as species that are small but nevertheless long-lived-and see what sets them apart from their peers. Something like turtles. MANY SPECIES of turtles and tortoises live a long time for their size. Some freshwater turtles survive 50 years or more, and Galapagos tortoises sometimes exceed 100. But they are of particular interest to gerontologists because they show virtually no signs of aging throughout their lives. They don't get disabled, weak, or fat, and most stay fertile and keep laying eggs until they die. In many respects they are models for how people would like to age: Stay healthy AGING-NEW ANSWERS TO OLD QUESTIONS Longer, healthier lives could result from knowledge gained in laboratories. At the University of Wisconsin-Madison an x-ray scan of a rhesus monkey, shown in a time exposure, will reveal the effects of a calori cally restricted diet on the body. Severe calorie cuts have lengthened the life span of mice by 50 percent. Genetically altered to produce an abundance of antioxidants, a fruit fly at Southern Methodist University will live 30 percent longer than normal.