Answering the Important Questions: No, We Don't Live Longer Than Our Ancestors

    I have occasionally come across people that believe our greater life expectancy today is due to our having longer life spans (with some even using this as "evidence" of evolution). But that is not true: our life spans appear no greater than in the past, it is just that more of us survive accident and disease to live to old age. Get Pocket has republished an article from BBC Future entitled, "Do We Really Live Longer Than Our Ancestors?" that explains the issue. An excerpt:

    In fact, while medical advancements have improved many aspects of healthcare, the assumption that human life span has increased dramatically over centuries or millennia is misleading.

    Overall life expectancy, which is the statistic reflected in reports like those above, hasn’t increased so much because we’re living far longer than we used to as a species. It’s increased because more of us, as individuals, are making it that far.

    “There is a basic distinction between life expectancy and life span,” says Stanford University historian Walter Scheidel, a leading scholar of ancient Roman demography. “The life span of humans – opposed to life expectancy, which is a statistical construct – hasn’t really changed much at all, as far as I can tell.”

    Life expectancy is an average. If you have two children, and one dies before their first birthday but the other lives to the age of 70, their average life expectancy is 35.

    That’s mathematically correct – and it certainly tells us something about the circumstances in which the children were raised. But it doesn’t give us the full picture. It also becomes especially problematic when looking at eras, or in regions, where there are high levels of infant mortality. Most of human history has been blighted by poor survival rates among children, and that continues in various countries today. 

    This averaging-out, however, is why it’s commonly said that ancient Greeks and Romans, for example, lived to just 30 or 35. But was that really the case for people who survived the fragile period of childhood, and did it mean that a 35-year-old was truly considered ‘old’?

    If one’s thirties were a decrepit old age, ancient writers and politicians don’t seem to have got the message. In the early 7th Century BC, the Greek poet Hesiod wrote that a man should marry “when you are not much less than 30, and not much more.” Meanwhile, ancient Rome’s ‘cursus honorum’ – the sequence of political offices that an ambitious young man would undertake – didn’t even allow a young man to stand for his first office, that of quaestor, until the age of 30 (under Emperor Augustus, this was later lowered to 25; Augustus himself died at 75). To be consul, you had to be 43 – eight years older than the US’s minimum age limit of 35 to hold a presidency.