I agree, this is one of the biggest flaws with this line of reasoning. However, it does say something (although it's unclear what it means for us) that some of

I agree, this is one of the biggest flaws with this line of reasoning. However, it does say something (although it's unclear what it means for us) that some of those cultures had less incidence of the diseases commonly associated with old age compared with nearby similar cultures that ate less or no meat.