i love that logic. base your diet around what was eaten by people who were lucky to reach 20 and ate whatever they could to avoid starvation.
Is your logic based on thinking our DNA and genes change rapidly within 50 years? They don't. They're very slow to change. The reason why processed vegetable oils introduced in 50s or 60s are bad for you, margarine far worse than butter, etc.
Life expectancy was lower for various reasons. They didn't exactly have healthcare back then. And maybe sometimes they even had to eat rotten meat in an effort to survive but not by choice and not always.
They ate greens, other veggies, fruits (were far less sweet), nuts & seeds, wild grains, insects, wild caught fish and wild game.
All proven to be healthy now. (Even insects are considered a superior source of protein, just not every culture eats them now.)
Heart disease, diabetes and others are modern diseases.
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I shouldn't say wild game has been proven to be healthy. It's way healthier than factory-raised meat (far superior omega 3 to 6 ratio, far less toxins or toxin free), which are quite unhealthy. But we don't know if we can consume them all the time or limit them like conventional meat or if wild red meat is also type II carcinogenic.