According to Buddhism, there are two main causes of long life . The substantial cause is our past karmic actions and the imprints deposited carried over into this present life.The supportive or environmental cause depend on our accumulation or depletion of merits.
Besides the above, genetics,the physical environment, the natural laws of nature and the whole body of scientific laws such as physics, chemistry etc are also contributory factors.
We know we can prolong life through the intervention of medical advancement and technology which can protect us from external agents of harm such as germs, diseases, deadly insects and wild animals , natural disasters etc, with varying degree of success.
I think it is perhaps more exciting and meaningful to relabel the topic ' Practicing Buddhism results in Happier and more Useful Life ? After all that is the purpose of life. Without it , longevity is not such a big deal and no meaning.