Biomedical researcher Leonard Hayflick passed away recently.
He has discovered that normal somatic cells can divide (and thus reproduce) only a certain number of times.
He has discovered that cell division in somatic (non-reproductive) cells stopped after roughly 40-60 times.
This means that there is an in-built cellular clock in the human body (and that of other organisms) which determines how long one can live.
This “ultimate Hayflick limit”, is around 125 years for humans, beyond which no amount of diet, exercise, or even genetic tweaking against diseases can extend the human lifespan.