I don't believe there is "reverse underwriting" for annuities. I suspect that when the insurance companies price annuities, they price in some "adverse selection" by assuming these are more likely to be purchased by healthy people with family history of longevity.
The primary drivers of the payout you receive are your age and the prevailing long-term interest rates at the time. Annuities are priced to yield the same way high-grade long term bonds are: the lower interest rates are when you buy the annuity, the lower the monthly payout.
"Hey, for every ten dollars, that's another hour that I have to be in the work place. That's an hour of my life. And my life is a very finite thing. I have only 'x' number of hours left before I'm dead. So how do I want to use these hours of my life? Do I want to use them just spending it on more crap and more stuff, or do I want to start getting a handle on it and using my life more intelligently?" -- Joe Dominguez (1938 - 1997)