Researchers report another longevity gene: "Scientists have previously found mutations that extend fruit fly lifespan, but this group of genes is distinct because it acts specifically in muscles. The findings could help doctors better understand and treat muscle degeneration in human aging. [Researchers] started investigating a pair of genes called "p38 MAP kinase" in fruit flies with the expectation that they could play a role in learning and memory. Along the way, they discovered that mutations in these genes speed up the process of aging and make the flies more sensitive to oxidative stress. ... It was really just dumb luck, because we found a mutant that had almost completely lost gene activity, but had enough activity to be born. ... If both genes are defective in the same fly, the flies die very early. ... The experiment that made us nervous was when we asked whether having more p38 could increase lifespan. You can make flies sick and shorten their lives in a hundred different ways easily, but finding one gene that makes a big change in lifespan is more significant. ... Fruit flies normally live about fifty days in [this] laboratory, depending on temperature and conditions. Some strains of fly that overproduce p38 MAP kinase live on average about 75 days, 50 percent longer than regular flies ... For this effect, it is sufficient that p38 is overproduced in muscles only. ... a protein that protects cells against oxidative stress that is found in mitochondria, superoxide dismutase (MnSOD), is responsible for at least some of p38 MAP kinase's effects on aging." That last point makes this look rather like the mouse studies in which life span was extended by genetic engineering to boost levels of natural antioxidants present in the mitochondria.