While it is undoubtedly and indisputably true that a meat-based diet is far healthier than any diet lacking meat or animal products, you'd need a much larger sample size to make this case. Different people age biologically at different rates, based not only on their own genetics but on environmental factors as well. It's the same as the old Jack Lalanne vs. Frank Sinatra comparison. Sinatra likely had much better genes despite his terrible habits while Jack Lalanne had terrible genes but forestalled a much earlier death by vigorous exercise.