http://joshmitteldorf.scienceblog.com/2015/04/29/large-new-survey-tracks-telomere-length-and-mortality/
Conclusion: This demonstrates that age is the biggest factor in mortality, and telomere length has a strong effect, independent of age. All the health variables together are a small factor compared to age and telomere length.
Short telomeres are not just a marker but a major cause of mortality.
Evolution has turned telomerase off such that short telomeres substantially affect our life span. Turning telomerase on would not have cost anything, but that is not what evolution has done.
So the theory is wrong that says evolution has already made our life spans as long as possible. Evolution has arranged for us to age and die “on purpose”. Withholding telomerase is part of an evolved death program.