Free Radicals - Is That Really the Cause of Aging?

The mitochondral reactive oxygen species theory. We often hear about free radicals being somthing that causes agent. But actually, with hindsight, it makes a lot of sense because life has been dealing with the consequences of free radicals for billions of years. The idea that all species have a fixed number of heart beats is one of my favorite old theories. And if you work through your 60s and 70s well, both of those come out at about half a billion beats. Where animals like gallapagus tortoise can live to 100 or even 200 years after they've got their first heart beat.