Sex at Dawn

Exploring the evolutionary origins of modern sexuality.

Christopher Ryan, Ph.D. is co-author of Sex at Dawn: The Prehistoric Origins of Modern Sexuality (HarperCollins 2010). See full bio

April 30, 2009, Aging

How Old was "Old" 20,000 Years Ago?

35 was never old – not even 20,000 years ago.

This post is a response to The Testosterone Curse (Part 1) by Leon F. Seltzer, Ph.D.

Leon F. Seltzer recently posted an interesting essay about some of the troubles with testosterone. It's well worth reading, if you missed it. But even Dr. Seltzer (with two Ph.D.s!) is misinformed about human life span in prehistory (a subject we get into at some depth in our soon-to-be-released book). He writes:

Many centuries ago, when our life span was far shorter than it is today, it made good evolutionary sense for us to be ready to conceive as soon as we physically could …. Back then, prior to modern medicine, life was extremely fragile; and so it was clearly adaptive to be able to do "deliver" babies (as, well, "replacements") as promptly as possible.

While this argument may seem to make perfect sense – and represents conventional wisdom on the subject of prehistoric longevity – it's simply wrong that the human "life span" was much shorter then than it is now. "Average longevity" was shorter, but that's something else.

Average longevity is calculated by taking the age of death of all the skeletons archaeologists find and averaging them out. There are lots of problems with this method, including the fact that once the wisdom teeth stop growing (around age 35), it's very hard to tell how old someone was when they died 25,000 years ago. The other problem is that for various reasons, a lot of babies died. So the average age of death normally cited (25 or 30) is based on a misleading calculation using suspect data.

In fact, as we detail in the book, once they got through infancy, most people in prehistory lived well into their 60s and even 70s, as foragers do today.

Remember, it's the Old Testament that says man's allotted time on Earth is "three score and ten" (=70). There was no "modern medicine" available to the people who came up with that number!