Tuesday, November 4, 2014

The Longevity Deception (part 2 of 5)

Part 1

2. Is a grain based diet superior?

Even corrected for infant mortality, the mean, median, and mode lifespans reported for hunter-gatherers are still lower than those reported for modern industrialized societies where life expectancies of 70-80 are the norm.

Does that mean that the people eating the Paleo diet of meat, fish, fruits, nuts and vegetables can expect to die by 50, while those eating whole grain bread, pasta, cakes, pies, corn syrup and little or no red meat will live to be a ripe old age? And does it mean that industrialism, with its crowding, pollution, hectic work schedules, sedentary lifestyles and chronic stress has actually extended our lifespans?

Not so much.

It's best to compare hunter-gatherers with contemporary populations of agriculturalists living in the same area. It's also useful to compare populations in the same location over time during the transition between the Paleolithic hunter-gatherer lifestyle and the Neolithic lifestyle of weeding, hoeing and plowing, with grains and legumes as the staple foods with little or no meat.

In fact, this has been done. In a landmark study, skeletons in the Mediterranean region were compared over time. The results are summarized in this chart:


You can see that overall lifespans did not change all that much until sometime in the twentieth century, only a few generations ago. There is an increase in the classical period, but for the most part life expectancies (including infant mortality, remember) were on the order of 35-40 years. That's consistent with what we saw last time where life expectancy in 1800's Sweden (where extensive records were first kept) was only 32 years, and that the mode age of death in England and Wales was zero years in 1964. In fact, during the transition to agriculture in the Neolithic period, life expectancies went down, not up.

So when you hear that "hunter-gatherers only lived to be forty," you should note that before the twentieth century, so did everyone else.

Clearly the Neolithic grain-based diet had no effect on living standards for the thousands of years since the transition to agriculture. What it did impact, however was health. The heights of farmers declined significantly, as did their pelvic inlet depth (meaning more painful pregnancies and more women dying in childbirth). Other studies have shown that agricultural populations had much worse oral health and more dental caries (cavities & rotting teeth):
Prehistoric humans didn't have toothbrushes. They didn't have floss or toothpaste, and they certainly didn't have Listerine. Yet somehow, their mouths were a lot healthier than ours are today.

"Hunter-gatherers had really good teeth," says Alan Cooper, director of the Australian Centre for Ancient DNA. "[But] as soon as you get to farming populations, you see this massive change. Huge amounts of gum disease. And cavities start cropping up."

And thousands of years later, we're still waging, and often losing, our war against oral disease. Our changing diets are largely to blame…
Ancient Chompers Were Healthier Than Ours (NPR)

This is consistent with eating grains, because saliva converts the grains to simple sugars which cause tooth decay. Also, things like arthritis and other degenerative diseases become more common, probably because of the repetitive, back-breaking labor required to practice agriculture. If Paleo diet advocates are correct, however, a grain-based diet also encourages inflammation, which has the same effect. Here's obesity researcher Stephan Guyenet:
"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."

Dr. Spencer Wells, a geneticist and the National Geographic Explorer in Residence, discussed the study above in his 2010 book Pandora's Seed (emphasis mine):
One of the great myths surrounding the development of human culture over the past 10,000 years is that things got progressively better as we moved from our hunter-gatherer existence to the sublimely elevated state in which we live today. Most people assume that the lives of our distant ancestors were, to quote Thomas Hobbes, "solitary, poor, nasty, brutish, and short." When agriculture and government came along...their obvious superiority was clear, and after that people's lives improved immeasurably. The explosion in the size of the human population after 10,000 years ago is assumed to be merely the numerical manifestation of the positive impact of growing our own food, the benefits of a new lifestyle writ in the expanding number of happy farmers. In fact, nothing could be further from the truth.

In a classic paper published in 1984, he anthropologist J. Lawrence Angel analyzed the skeletal remains of people living in the eastern Mediterranean before and after the transition to agriculture. He examined several pairs of the skeletons of many individuals from each time period, focusing on the teeth (which allow an estimate of the person's age at death), as well as height and something called "pelvic inlet depth index," both of which are measures of how healthy the person was. When he tabulated the data he saw a surprising pattern.

The average longevity of male Paleolithic hunter-gatherers was 35.4 years, and that of females was 30.0. Women's shorter life spans were a result of complications due to childbirth, and the pattern of greater male life span has been reversed only in the past century as advances in medicine have led to healthier deliveries. Note, though, that as the population made the transition to agriculture during the Neolithic period, and particularly the Late Neolithic, when the transition was complete, the longevity for both men and women decreased significantly, to 33.1 years for men and 29.2 for women. More strikingly, the measures of health decrease dramatically. Male height drops from nearly five foot ten in the Paleolithic to approximately five-three in the Late Neolithic, and the pelvic index drops by 22 percent. People were not only dying younger, they were dying sicker. Although it is possible that this may be an artifact having to do with the particular populations studied by Angel, similar patterns have been seen in the Americas. Overall, the data shows that the transition to agricultural lifestyle made people less healthy.

Surely for it to have resulted in such a massive explosion in human population, agriculture must have been a huge benefit to humanity. How can we explain the massive increase in human population and the dominance of agriculture, which has pretty much completely replaced hunting and gathering in every inhabited corner of the world, when it actually didn't improve people's lives? It is only in the twentieth century that we see a significant increase in longevity, and even then the pelvic index is still lower than that of our Paleolithic ancestors. Looking critically at the numbers in Table I, an evolutionary biologist would say that hunter-gatherers had an overall 22 percent health advantage over Neolithic agriculturalists, which should have allowed them to win hands down in the game of natural selection. Why did they lose? pp. 22-24
In the classic work in this genre, The Food Crisis in Prehistory, anthropologist Mark Nathan Cohen writes:
"Prior to about 1960, hunting and gathering groups were commonly pictured as existing near starvation, struggling to constantly find adequate food resources. According to standard reconstructions of the period, the advantages of agriculture over hunting and gathering in improving the quality and reliability of the diet, reducing labor costs in the food quest, and providing leisure time were sufficient (and sufficiently obvious to recipient populations) to make acceptance of agricultural technology automatic once the concept was perceived. This model was an attractive one. Western science is imbued with a sense of its own progress; with a deeply rooted belief in the superiority of Western man; and with an abiding belief in the sanctity of hard work, particularly work with the soil. Descriptions of nonwestern (and largely nonwhite) populations tended strongly to emphasize the backwardness of their life-styles and the poverty of their existence."
"An increasing number of studies of contemporary hunting and gathering populations, however, have tended to challenge these traditional assumptions. Although the sample of contemporary hunting groups is small, and although very few good quantitative scientific studies have been done, a good deal of evidence is accumulating which suggests rather uniformly that the diet of hunting and gathering populations (outside the Arctic) may be calorically quite adequate, and at the same time richer in food variety, vitamins, minerals, and above all protein, than that of agriculturalists. These recent studies also suggest that hunting and gathering involves activities widely preferred to those of agriculture and provides foods widely preferred for consumption to the main agricultural staples--grains and tubers; that the food supply of hunters and gatherers may be more reliable than that provided by agriculture; and that it may be obtained with as little, or significantly less, labor than is necessary for agricultural production."

"In fact we have gone through a rather abrupt reversal in the literature to a point where hunting and gathering is seen, somewhat uncritically perhaps, as a superior mode of life. We may be overemphasizing the quality of the hunting life now, just as previously we overemphasized its poverty. Cowgill (1975b) has warned that the hunting existence may not have been as stress-free as we now commonly picture it. Similarly Hayden (1975), citing Bartholomew and Birdsell (1953) warns that the economic well-being of a community may be more accurately measured in its reaction to periodic stress years than its reaction to normal periods of plenty...On the other hand, there is no evidence to suggest that such stress periods are more frequent among hunter-gatherers than among farmers, and there is both logical and empirical argument to suggest, on the contrary, that periodic stress is more often a function of farming. Thus, despite warnings about the contemporary "bandwagon" emphasis on the quality of life among hunters, a certain optimism about their condition seems to be warranted." pp. 27-28
He concludes:
"I think that the inference can safely be made that prehistoric hunters, like their modern counterparts, enjoyed adequate, high quality diets, good nutritional standards, reliable, well-buffered food supplies, and abundant leisure. Since contemporary hunting and gathering groups appear to fare at least as well as, and in most cases better than, their agricultural neighbors, who have the benefit of highly evolved crop plants and time-tested cultivating techniques, we may safely assume that the Pleistocene hunters and gatherers would have fared at least as favorably when compared with early agricultural pioneers, who had not yet perfected either their cultivating techniques of their cultigens."
"This in turn creates a new problem in the interpretation of agricultural origins. If agriculture provided neither better diet, nor greater dietary reliability, nor greater ease in the food quest; if it did not of itself confer the capability of sedentism, but conversely provided a poorer diet, less reliably, at equal or greater labor costs; why did anyone become a farmer? According to Lee (1968), Bushmen, who like other contemporary hunting and gathering groups know all about planting seeds, argue that this would be foolish since there is so much wild food available to harvest." p. 39
The answer that most anthropologists and archaeologists give is that population pressures meant that more food needed to be produced per unit of land, and large-scale irrigation agriculture was the only way to accomplish this. The thinking is that a dramatic climate shift occurred about 10-12,000 years ago due to climate change. This led to traditional food sources drying up. Humans had already overhunted many large game animals to extinction by this time period, and the climate crisis made things even worse. 

Humans reacted by abandoning a nomadic lifestyle and settling down in agricultural communities where they grew domesticated crops and bred domesticated herd animals for slaughter instead of hunting them. Sedentism, in turn, led to larger populations, since you no longer had to move from place to place and could wean children earlier. These larger populations led to a need to grow even more food per acre, leading to a vicious circle of larger populations requiring ever larger food supplies, a circle we are still living out today!

In addition, these larger populations led to overcrowding, disease, and violence. To quell the violence, early kings instituted laws to control people, backed by powerful militaries and organized priesthoods. They began taxing their citizens and requiring compulsory military service. Because expanding populations needed more land to grow grain crops, military conflicts over land became commonplace. Because of stored surpluses, large scale military campaigns could now be conducted instead of small, intermittent skirmishes, and the first empires were formed. Because farming was so awful, slavery was instituted to make the losers in these conflicts a permanent underclass who did all the work. These slaves were kept alive with a diet of grains, which has been the primary food for the poor ever since.

Writer Richard Manning aptly summarizes the evidence in his outstanding book, Against The Grain:
We have seen that agriculture in fact arose from abundance. More important, wealth, as distinct from abundance, is one of those dichotomous ideas only understood in the presence of its opposite - poverty. If we are to seek ways in which humans differ from all other species, this dichotomy would lead the list. This is not to say that hunter-gatherers did not experience need, hard times, even starvation, just as all other animals do. We would be hard-pressed, however, to find communities of any social animal except modern humans in which an individual in the community has access to fifty, a hundred, a thousand times, or even twice as many resources as another. Yet such communities are the rule among post-agricultural humans.
Much has been made of the creative forces that agriculture unleashed, and this is fair enough. Art, libraries, and literacy, are all agriculture’s legacy. But around the world, the first agricultural towns are marked by mounds, pyramids, temples, ziggurats, and great walls, all monuments reaching for the sky, the better to elevate the potentates in command of the construction. In each case, their command was a demonstration of enormous control over a huge force of stoop labor, often organized in one of civilization's favorite institutions: slavery. The monuments are a clear indication that, for a lot of people, life did not get better under agriculture, an observation particularly pronounced in Central America. There, the long steps leading to the pyramids' tops are blood-stained, the elevation having been used for human sacrifice and the dramatic flinging of the victim down the long, steep steps.

We know from their remains that the farmers were smaller, the result of deprivation and abuse. The women, especially, were smaller. The physiques that make up a modern women's soccer or basketball team were simply unheard of among agricultural peoples, from farming's beginnings to only very recent times. On average, we moderns (and only those of us in the richest parts of the world) are just beginning to regain the stature that we had as hunter-gatherers, who throughout time were on average as tall as North Americans are today.

Part of this decline stems from poor diet, especially for those who provided the stoop labor. Some of it is inherent in sedentism. Almost every locale's soil and water are deficient in one mineral or another, a fact that was not a problem for nomadic hunter-gatherers. By moving about and taking food from a variety of niches, they balanced one locale's deficiencies against another's excess. This is also true for the early sedentary cities that relied on seafood. They didn't move, but the fish did, bringing with them minerals from a wide variety of places.

More important, however, grain's availability as a cheap and easily stored package of carbohydrates made it the food of the poor. It allowed one to carry baskets of dirt day after day, but its lack of nutritional balance left people malnourished and stunted. The complex carbohydrates of grains are almost instantly reduced to sugars by digestion, sometimes simply from being chewed. The skeletal record of farming peoples shows this as tooth decay, an ailment nonexistent among contemporary hunter-gatherers.

That same grain, however, could be ground to soft, energy-rich gruels that had been unavailable to previous peoples, one of the more significant changes. The pelvises from female skeletons show evidence of having delivered more children than their counterparts in the wild. The availability of soft foods meant children could be weaned earlier--at one year instead of four. Women could them turn out the masses of children that would grow up to build pyramids and mounds.

The baseline against which these deformities and rotten teeth are measured is just as clear. For instance, paleoanthropologists who have studied skeletal remains of hunter-gatherers living in the diverse and productive systems of what is now central California found them "so healthy it is somewhat discouraging to work with them." As many societies turned to agriculture in the early days, they did so only to supplement or stabilize a basic existence of hunting and gathering. Among these people, paleoanthropologists found few of the difficulties associated with people who are exclusively agricultural.

The marks of agriculture on subsequent groups, however, are unmistakable. In his book The Day Before America, William H. MacLeish summarizes a record of a group in the Ohio River valley: "Almost one-fifth of the Fort Ancient settlement dies during weaning. Infants suffer growth arrests indicating that at birth their mothers were undernourished and unable to nurse well. One out of a hundred individuals lives beyond fifty. Teeth rot. Iron deficiency anemia is widespread, as is an infection produced by treponemata" (a genus of bacteria that causes yaws and syphilis).

The inclusion of communicable diseases is significant and consistent with the record worldwide. Sedentary people were often packed into dense, stable villages where diseases could get a foothold, particularly those diseases related to sanitation, like cholera and tuberculosis. Just as important, the early farmers domesticated livestock, which became sources of many of our major infectious diseases, like smallpox, influenza, measles, and the plague.

Summarizing evidence from around the world, researcher Mark Cohen ticks off a list of diseases and conditions evident in skeletal and fecal remains of early farmers but absent in hunter-gatherers. The list includes malnutrition, osteomyelitis and periostitis (bone infections), intestinal parasites, yaws, syphilis, leprosy, tuberculosis, anemia (from poor diet as well as from hookworms), rickets in children, osteomalacia in adults, retarded childhood growth, and short stature among adults.
Such ills were obviously hard on the individual, as were the slavery, poverty, and oppression agriculture seems to have brought with it...
We were forced by historical circumstances beyond our control to give up our hunter-gatherer diets and lifestyle; there was nothing superior at all about an agricultural diet based around grains and legumes. It made us less healthy as documented by skeletal evidence. It also forced us to work more, not less. With that change in lifestyle came organized religion, centralized government, kings and priests, laws and courts, slavery, poverty, serfdom, taxes, police, prisons, money, militaries, pollution and large-scale wars.

Surveying the literature for Discover Magazine in 1990, Jared Diamond famously questioned whether it was "the worst mistake in the history of the human race."

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