Tuesday, August 5, 2008

Life Expectancy and Growth of Paleolithic vs. Neolithic Humans

If paleolithic people were healthier than us due to their hunter-gatherer lifestyle, why did they have a shorter life expectancy than we do today? I was just reminded by Scott over at Modern Forager about some data on paleolithic (pre-agriculture) vs. neolithic (post-agriculture) life expectancy and growth characteristics. Here's a link to the table, which is derived from an article in the text Paleopathology at the Origins of Agriculture.

The reason the table is so interesting is it allows us to ask the right question. Instead of "why did paleolithic people have a shorter life expectancy than we do today?", we should ask "how did the life expectancy of paleolithic people compare to that of pre-industrial neolithic people?" That's what will allow us to tease the effects of lifestyle apart from the effects of modern medicine.

The data come from age estimates of skeletons from various archaeological sites representing a variety of time periods in the Mediterranean region. Paleolithic skeletons indicated a life expectancy of 35.4 years for men and 30.0 years for women, which includes a high rate of infant mortality. This is consistent with data from the Inuit that I posted a while back (life expectancy excluding infant mortality = 43.5 years). With modest fluctuations, the life expectancy of humans in this Mediterranean region remained similar from paleolithic times until the last century. I suspect the paleolithic people died most often from warfare, accidents and infectious disease, while the neolithic people died mostly from chronic disease, and infectious diseases that evolved along with the domestication of animals (zoonotic diseases). But I'm just speculating based on what I know about modern populations, so you can take that at face value.

The most interesting part of the table is actually not the life expectancy data. It also contains numbers for average stature and pelvic inlet depth. These are both markers of nutritional status during development. Pelvic inlet depth is a measure of the size of the pelvic canal through which a baby would pass during birth. It can be measured in men and women, but obviously its implications for birth only apply to women. As you can see in the table, stature and pelvic inlet depth declined quite a bit with the adoption of agriculture, and still have not reached paleolithic levels to this day.

The idea that a grain-based diet interferes with normal skeletal development isn't new. It's well-accepted in the field of archaeology that the adoption of grains coincided with a shortening of stature, thinner bones and crooked, cavity-ridden teeth. This fact is so well accepted that these sorts of skeletal changes are sometimes used as evidence that grains were adopted in a particular region historically. Weston Price saw similar changes in the populations he studied, as they transitioned from traditional diets to processed-food diets rich in white wheat flour, sweets and other processed foods.

The change in pelvic inlet depth is also very telling. Modern childbirth is so difficult, it makes you wonder why our bodies have evolved to make it so drawn-out and lethal. Without the aid of modern medicine, many of the women who now get C-sections and other birth interventions would not make it. My feeling is that we didn't evolve to make childbirth so lethal. It's more difficult in modern times, at least partially because we have a narrower pelvic inlet than our ancestors. Another thing Weston Price commented on was the relative ease of childbirth in many of the traditional societies he visited. Here's an exerpt from Nutrition and Physical Degeneration:
A similar impressive comment was made to me by Dr. Romig, the superintendent of the government hospital for Eskimos and Indians at Anchorage, Alaska. He stated that in his thirty-six years among the Eskimos, he had never been able to arrive in time to see a normal birth by a primitive Eskimo woman. But conditions have changed materially with the new generation of Eskimo girls, born after their parents began to use foods of modern civilization. Many of them are carried to his hospital after they had been in labor for several days. One Eskimo woman who had married twice, her last husband being a white man, reported to Dr. Romig and myself that she had given birth to twenty-six children and that several of them had been born during the night and that she had not bothered to waken her husband, but had introduced him to the new baby in the morning.
Now that's what I call fertility!

17 comments:

AA said...

The Old Testament mentions the travails of childbirth as one of the curses inflicted on women after the fall. It seems the bad effects of leaving the Garden of Eden (Hunter Gatherer world) and having to “earn thy bread by the sweat of thy brow” (agriculturalism) was noticed long ago. I’ve often thought that the Garden of Eden story was an allegory for the transition from wild man to civilized man. The ancients knew that this path was cursed.

Stephan said...

AA,

Interesting point. I wonder if that concept was passed on from early agriculturalists who saw the effects of their new lifestyle. The old testament is from about 3,000 years ago, so maybe the authors still had an oral history of the paleolithic/neolithic transition.

reid said...

The dietary and physiological factors could also be partly why the use of midwives are less common these days (in addition to the long lingering cultural aftermath of the witch hunts which stemmed from superstition, psychological repression and class/gender oppression).

Josephine said...

This is really really interesting stuff.

Alexandre Costa said...

Yeah really interesting and it goes along with this book's whole idea: The Last Hours of Ancient Sunlight
recommend it

bunkhabit said...

The story of Cain and Abel (Agricultural Revolution) (AA's "transition from wild man to civilized man") is retold in the philosophical novel "Ishmael" by Daniel Quinn (1992).

bunkhabit said...

The story of Cain and Abel (agricultural revolution) (AA's "transition from wild man to civilized man") is retold in the philosophical novel "Ishmael" by Daniel Quinn (1992).

gwarm said...

Fertility... what do you assess about this theory ... people always say 'eat for fertility' for the best diet but there is this 'pleiotropy theory of aging':
"This system is highly likely to remain the way it has evolved
because of the antagonistic pleiotropy theory of aging, which asserts
that selection for early reproductive success permits deleterious
effects on fitness in later life because genes that are operative during
development are also operative in later life, but exert different effects
on health.26 Indeed, because the lack of negative feedback ensures
maintenance of the drive to procreation mediated by testosterone,
the present evolutionary state (without a mechanism of limiting
free T) may already represent the desirable ultimate of evolution as
far as propagation of the species is concerned."
(text is from 'acne and cancer.pdf': http://robbwolf.com/2011/09/13/the-paleo-solution-episode-97/#comment-47146)

Philo Logia said...

I've just spent the morning studying Paleo vs. Neo in regards to stature. I specualte alongside you that deaths were trauma-induced causing the life expectancy to be much shorter. I'm sure there are numerous times many of us would have died already had we not the access to technology that we do now.
Interesting summary of information, I especially enjoyed the tidbit about the Eskimo women birthing so naturally. It reminds me of a documentary I watched recently called Orgasmic Birth, but that is another topic :]

Cheers!

me said...

Old Testament is 3000 yrs old? Try 5000 years. Also, while I agree paleo is the way we should eat for optimal health, the bible states man is to work or toil by the sweat of his brow. it does not mention bread. And G-d didn't dole that out, he just told them what they got themselves in to by not obeying. Also, in obedience and Eden, they didnt eat grain. They ate fruit and while not mentioned specifically, I assume meat from the kids sacrifices. Paleo :)

healthy said...

Paleolithic man lived healthy in their 90's. However their bones look like bones of people in their 30's by today's classification. So it confuses our findings.

XXYGuru said...

"why did paleolithic people have a shorter life expectancy than we do today?", we should ask "how did the life expectancy of paleolithic people compare to that of pre-industrial neolithic people?"

So rather than answer the question you change the question and answer that, I'd rather you answer the question!

How about I'll answer for you. Paleolithic people lived less long than us because diet isn't the determining factor as to why we live longer, but a range of lifestyle differences including better health care, modern medicine, scientific advances, better clothing, warmer homes.

DB said...

I think the "paleo" diet is overrated as well. We can only speculate on their health and we know that most died young for whatever reason. On the other hand, we have real life, modern day, evidence-based research on living people that gives the best chance to keep you plenty healthy and vibrant. Its called the Blue Zone diet. But really its diet and lifestyle: plant based diet, including beans (legumes are commonly consumed in blue zones), strong family bonds, social engagement and consistent physical activity. So, there you go.

YL W said...

I think OP made too many speculations with too little proven supports.

The Eskimo (Inuit, you don't call them Eskimo nowadays) women example of difficulty in childbirth isn't unique to a hunter/gatherer society transitioning into modern time. The same things happen in agricultural to modern transition.

Where I came from, the population half a century ago was mostly farmers and according to my mom, women back then had rather easy time giving birth, albeit with a much higher birth fatality rate. With agri population dwindling to less than 10%, yes, you see a lot women now have to do c-sec (both my sister and sister-in law) when giving birth. The difference is the active vs. non-active life style. I doubt nutrition plays much in it.

And, I think birth fatality rate in neolithic era is probably as high as in paeleo era. The life expectancy after adolescence in either times probably didn't differ in any way significant, from some of the info I read. And wars have happened in most part of human "history", not exclusive to paeleo/agri societies (really, there were too many speculations). Paeleo ancestors might be as healthy as neo ones. But to say the paeleo old men were healthier, that's comparing apples to oranges. With the help of modern medicine, a lot of guys get to live to a very old age, with diseases and there was no such men to survive in paeleo time for a legit comparison. But you wouldn't compare the modern healthy old guys to their paeleo counterpart.

Just my 2 cents.

Mary F said...

I don't understand how a judgement can be formed about life expectancy vs diet this far back. How is it possible to know exactly the proportion of protein vs vegetables vs cereals vs fruit eaten by paleolithic vs neolithic humans? If you read the results of the 'China Study' a max of 10% protein is adequate and beyond that is more likely to support cancer growth. A significantly higher vegetarian diet is healthiest. Cancer research UK says the haem in red meat is an irritant and raises the risk of cancer of the gut, but ancients wouldn't be aware of this, they'd have died before these diseases were that noticable. Or could they have died because this diet was high protein. Neanderthals lived in Northern Europe between ice age fluctuations, may have mixed wiht Homo Sapian had a high protein diet and died out ?

Mary F said...

also "Several worldwide surveys document that the countries with highest animal protein intakes are those with highest hip fracture rates. The proposed explanation of this relationship between animal protein and hip fracture incidence relates to the fact that animal protein is rich in acid-forming, sulfur-containing amino acids and low in base-forming precursors (such as vegetable sources of potassium citrate). Further, the contemporary cultures consuming a high animal protein diet also tend to under-consume vegetables, fruits, nuts and seeds, food high in base-forming precursors. This combination contributes to chronic low-grade metabolic acidosis and subsequent bone weakening. The growing body of literature documenting the association between chronic, low-grade metabolic acidosis and bone loss bolsters the argument that high dietary protein, if not balanced with high base-forming precursor intake, can have a detrimental impact on bone."

This suggests that post ice age cultures who were eating primarily meat protein diets would have suffered significant bone corruption of some form .

http://www.betterbones.com/bonenutrition/protein/benefits.aspx

Walt said...

Well this is all great stuff.
I'd just like to mention that without the addition of agriculture human population(s)couldn't/wouldn't be so large nor sustainable.
As we often heard in school, we can feed more people from food groups lower on the food chain than we can from food sources higher on the food chain.
I wonder if socioeconomic factors are more important [see NY Times article from 3/24/14 "Who Lives Longest"
Just gets me the hype about the Paleo Diet; you have to be able to aford it.
Maybe the simplest thing is to cut out the refined sugars and refined salt which I believe the Paleo diet does do.
Anyway, is this time of GMO foods maybe giving up commercially grown grain products it's the way to go. Take care, all.