eKatherine, not sure I share your theory of our ancestors when you take into account the life expectancy a century or two ago and now. Old age to them was 50-60 years. Clearly they worked harder or had far more exercise so what other than what they ate could cause that?
i may be wrong but i think she is talking about 'primitive/cave man'
they lived a somewhat riskier life and although generally very healthy they were highly likely to get killed by each other, wild animals, accidents and infections.
once we started eating grain and cultivated crops mankinds health declined but the population grew hugely