[JeffSnazz]

> This is a fable.

No, it's a myth, or even better, a common misconception. A fable is a morality story.

[strken]

It's closer to a misleading truth or a fallacy. Life expectancy really was that low, but it was driven by child mortality, so knowing the mean life expectancy doesn't give an accurate picture of life expectancy upon joining the army in one's late teens.

[s1artibartfast]

To be argumentative, perhaps Romans living to 40 is a common misconception because it is a morality story about the superiority of modern humans