A Question About Prehistoric Humans

I have a question ... for anyone ... because it looks like many of you know more about prehistoric man than I do.

I looked up the average lifespan for some older humans (I don't know prehistoric designations, but this chart said Neanderthal, Upper Paleolithic, Neolithic):
Wikipedia: Life Expectancy

It looks like they died young, in their 20s. So, my question is ... Is the diet that sustained a human up to their 20s tens of thousands of years ago the same diet that can sustain a human into their 80s today?
________The photo is from a story in the Daily Mail. It's a reconstruction of a person called Thea. Her remains were found in 1937, in Sicily. She was thought to have lived 14,000 years ago.