Individuals with a genetic predisposition to diseases like cancer or heart disease may be less likely to survive into old age.

“in large-scale populations what you see is that the people who had genetic propensity for cancer heart disease etc vanished from the population as a population age so if you would have been susceptible to let's say over consuming meat actually causing heart disease and cancer in you you wouldn't be around when you were 90 when they were looking at 90 year old population”