[ExI] Half of everyone who ever reached 65 are alive now?

[Max More]

In this modestly interesting article...

The shock of the old: Welcome to the elderly age
http://www.newscientist.com/article/mg20627550.100-the-shock-of-the-old-welcome-to-the-elderly-age.html

...the following claim is made:

"Of all the people in human history who ever reached the age of 65, 
half are alive now."

This sounds a bit like (but less implausible) the claim that more 
people are alive today than the total number of people who ever lived 
in the past. The latter claim turns out to be extremely far from the 
truth. I haven't tried to calculate the numbers for this more modest 
65+ claim, but it seems dubious. For instance, I suspect the author 
is using the life expectancy of past ages (say 30) and treating that 
as the age at which practically everyone died. In reality, even when 
life expectancy at birth was very low, that was substantially due to 
high infant mortality. Some people surely did live to 65. A small 
percentage than today, to be sure, but I find it implausible that the 
65+s of all of human history don't exceed those today.

But I may be wrong. Anyone know of any other analyses of this?

Max