The Lifespan of our Hunter-Gatherer Ancestors

I talk about paleo eating a lot.  During my workday as a personal trainer and a nutrition consultant it is not unusual to have 3 or 4 (if not more) separate conversations on the topic.  I'm not surprised with the amount of skepticism I run into.  I can’t help but think it is because of all the misleading “certainties” we hear about diet -- by-the-way, coffee is good for you again.  Or maybe it’s because of the numerous diets that offer as many stories of failure as success. In fact, just this morning one of the gym’s TVs broadcast the “Best Diets of 2012”. They were listing the top 4 weight loss diets, top commercial diet and their vote for top “overall” diet.  One finishes the TV segment less informed and more skeptical.

The paleo diet has its share of red flags.  Two of my favorite challenges were brought up in the comment section of my last post: “Don't we have to worry about cholesterol and clogging of the arteries? Plus our life span is much longer than our hunter gather ancestors. Life spans have increased with farming.” – Anonymous. 

These are the two most frequent challenges to paleo. Understandably, the medical community has held this theory for over a generation. My short response is NO to cholesterol concerns, and lifespan concerns are misplaced. Cholesterol is a big topic, and much more controversial.  I will come back to that in a later post.  For now I want to move past the idea that our ancient ancestors lived short lives.

The Lifespan of our Hunter-Gatherer Ancestors

We’ve been told (by whom I’m not sure) that the hunter-gatherers lived a very short, brutal life - I’ve heard averages from 25 to 35 years.  Ok, but let me first get some obvious counter-arguments out of the way.  For one, infant mortality rates were higher(pdf), skewing the mean.  Also, our ancestors didn’t have the safety net of a hospital under them if they happened to fall and break a bone, often leading to infection and death.  So you can easily make the argument that if our ancestors had the luxury of the modern medical system, their average age might have been significantly higher than what we think it was.  It’s a solid rebuttal to the often-stated lifespan argument.  I could end this post here, but I’m not satisfied with speculating on the “what ifs”.  Instead, I’d like to back up and reevaluate how it came to be determined that 30 years was the average age of death in early man.

Forensic anthropologists determine the age of death by studying the bones of the deceased.  It is a seemingly accurate science with a small margin for error up to a certain age.  Teeth can accurately determine one’s age up to about 21 years old.  Ectocranial sutures (seams of the bones on the skull) can provide an estimated age of up to 35 years old.  Epiphyseal fusion (closing of the growth plates at the ends of long bones and clavicle) only tells us up to about 28 years.  But beyond that, the best estimate for age is by looking at the bone mineral density or pubic synphyseal face of the bone.  So basically beyond the age of 35 there is no real solid way of determining age except by looking at the assumed wear and tear of a bone. 

Now, I don’t doubt the accuracy of age prediction in forensic anthropology for modern bones,  but I seriously doubt the accuracy when looking at the bones of our hunter-gatherers, and here is why:

Bone growth and density is influenced by many environmental factors.  Environmental factors include “anything that the organism interacts with,” and as far as bone health goes - diet, activity level, and micronutrient intake are some of the big factors.
Read more: http://www.webmd.com/osteoporosis/features/building-stronger-bones

We’re talking about a people that ate only whole, organic foods that were grown or fed off rich, nutrient earth.  A people that breathed clean air, and drank clean water, who stayed active throughout the day, moved heavy things (resistance training), and got plenty of sunlight (vitamin D).  In other words, we’re talking about an environment that had all the right ingredients for strong, dense bones.  I’m likely to believe that even if a modern man dedicated his life to bone health, chances are he would still not reach the same level of bone health of our early ancestors. 

Now, I’m going out on a limb here, but with this knowledge, wouldn’t you agree that it’d be very likely for 40, 50, or maybe even 60 or 70 year old caveman to have the bones of our average modern 30 year old?

Let me know what you think!