Our life expectancy has actually been increasing steadily since the mid-19th century, and there is every reason to believe that this trend will continue for a while yet. So we really are living longer and longer. And, in fact, it is not the case that unhealthy lifestyles are generally on the increase. Nowadays, the average person is more informed and eats more healthily; our healthcare is far better, hygiene standards have improved, and the water we drink is safer than ever before. In the past, increased life expectancy was primarily attributed to a decline in infant mortality, but today the above-mentioned factors are much more relevant.
This question was answered by Dr Andreas Edel of the Max Planck Institute for Demographic Research.