Susceptibility seems to be the key, and there's no way to know that beforehand at present. Obviously, there are people who die at advanced ages even by today's standards who do the things that are supposed to shorten life -- cigarettes, red meat, alcohol. My dad was certainly a meat eater and he lasted 89 years and some months, and liked gin martinis into his 80's and smoked pipes and cigars most of his teens and adulthood. Still, you have to respect the statistics that say people who do these things, as a group, don't live as long. I think people who grow up eating mostly vegetables train their bodies, as some people who go vegetarian later carefully do. People can get in bad trouble doing vegetarian diets even with good advice. The species as a whole is omnivorous, so no meat means educated substitutions. You have to have proteins and fats another way.