In his book Oxygen, Nick Lane argues that most age related diseases are a function of cumulative oxidative stress, particularly in the mitochodria. He suggests

In his book Oxygen, Nick Lane argues that most age related diseases are a function of cumulative oxidative stress, particularly in the mitochodria. He suggests that vigorous exercise is actually more stressful than lower intensity exercise, as well as the effects of calorie restriction etc on how the body handles the longevity vs reproduction balance. I think this may have a part to play in hunter gatherer societies, which were calorie restricted, and also relaxing most of the day :)