He acquired all sorts of magic powers by means of which he extended his life-span.
As to the life-span itself there is reason to suppose that it is meant to be more regular than man allows it to become.
That's where the men astern would find use for the life-span.
Now, of course, shortened working hours and medical advances have equalized the life-span.
life span n.
The average or maximum length of time an organism, a material, or an object can be expected to survive or last.