Final answer:
Metabolic engineering in mice related to the free radical theory of aging encompasses reducing or increasing oxidative damage to study its effects on lifespan, with calorie restriction shown to extend longevity in some lab animals.
Step-by-step explanation:
The type of metabolic engineering with mice that provided evidence in support of the free radical theory of aging involved manipulation of oxidative damage levels. Studies have indicated that by reducing oxidative damage, a longer lifespan can be achieved in organisms like yeast, worms, and fruit flies. Conversely, increased oxidative damage can shorten the lifespan of mice. For example, calorie-restriction, which reduces caloric intake, has been demonstrated to increase lifespan in laboratory animals, possibly by reducing oxidative stress. However, results in primates have been inconclusive. These investigations into reactive oxygen species and aging suggest a correlation, though the exact mechanisms and implications for humans are still being explored and require further research.