Check out this line from the article, referring to men living on the island of Crete:

"Middle-aged men there now walk less than 1.5 miles a day; in the 1960s, they walked an average 8 miles a day."

That's really interesting. What a change in activity levels, from an average of 8 miles a day to less than 1.5, and that's just in walking. There have probably been similar decreases in other phases of their lives. The dietary changes must have an effect, of course, but much of the effect must be from the change in lifestyles.