re: Limits to human life span
The last statistics for the chances of being murdered in ones life time were I believe 1 in 165.
That doesn't count things like the woman who died because she slapped a mosquito and got a rare virus in her blood as a result she died, or joggers who are apparently in good health who drop dead of heat attacks.
Then theres the guy who survived going over Niagra falls who slipped on an orange peel and died.