This lifespan issue has intrigued me for years. Every now and then, I spend some time looking up online mini-biographies of famous ancients, and have been interested to note that many of them lived well into their 80s. I've seen nary a mention of this being unusual -- not even a "ripe old age" comment.
The author of this article explains in very simple terms why the numbers seem to support the "miracle of modern medicine" myth; it's simply another example of lying with statistics.
Once again, we are reminded that it's the Lord who determines our individual lifespans. "And in Your book they all were written, the days fashioned for me, when as yet there were none of them" (Psalm 139).
Whether we die of cancer or heart disease, childbirth or infection, we're going to die at precisely the moment He has ordained for us; the only important question is where we will be spending eternity. Thanks be to God, that's one thing we can control, simply by repenting and trusting in Christ.