Reply to Bredberg and Bredberg: Do some individuals age more slowly than others?

Bredberg and Bredberg (1) suggest that some individuals age more slowly than others and that this accounts for the leveling off of death rates after age 100 y. They make this claim in a letter responding to Vaupel et al. (2). Bredberg and Bredberg (1) vaguely describe their mathematical model without specifying formulas. Apparently, their model is based on q ( x − 70 , b ) = a e b ( x − 70 ) , where x ≥ 70 is age and q ( x − 70 , b ) is the annual probability of death at ages 70+ y for an individual with aging rate b … [↵][1]1To whom correspondence may be addressed. Email: jamesw.vaupel{at}gmail.com. [1]: #xref-corresp-1-1