Strictly Paleo

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Purpose - Paleo diets are in vogue these days.  Always wanting to be “in with the in-crowd”, and needing to lose a few pounds, I’m giving it a try and have the following observations to share.  This dovetails nicely with my earlier posts regarding populations of the genus Homo during the Paleolithic era, especially what they ate.  Accordingly, I’ll start by putting the modern conception of a Paleo diet in proper context.

Background - Anthropologists apply the term human to all fossil members of the genus Homo, commonly called hominids or hominins.  All humans alive today (except maybe Bigfoot) belong specifically to the lineage called Anatomically Modern Homo sapiens, with our characteristic chins and flat faces without prominent brow ridges.  Before about 180,000 years ago (180ka), the fossil record includes our presumed ancestors, so-called archaic Homo sapiens, who had a vestigial brow ridge, parabolic dental arcade and other cranial features inherited from their presumed ancestors, Homo erectus:

Homo erectus lived from over a million years ago (earliest specimen 1.9ma), until about 400ka, after which they evolved into, and were displaced by, Neandertals in Eurasia and archaic Homo sapiens in Africa. Homo erectus perfected the art of creating cutting tools from select stone materials.  With their wooden spears, and their ability to run long distances, they were highly capable, pursuit predators.  Their stone tools enabled them to butcher large animals and carry the spoils back to their encampments.  Armed with sharp sticks and working in teams, they easily fended off competing predators and scavengers.  Homo erectus fossils are almost as large as modern humans, one complete skeleton is 5’ 8” tall, but very thin, as befits a long distance runner. 

They were the first hominids to leave Africa, about 1.8ma, traveling across Asia all the way to modern China and Indonesia, chasing herds of large herbivores.  They stuck to the lower latitudes, below about 35 degrees North, because they needed direct sunlight to make vitamin D.  They lived primarily off the meat of their prey and a variety of vegetable foods.  In many parts of their range, fruits or berries were available at least part of the year, along with selected tree nuts and leafy foods, plus roots, tubers and bulbs, which paleo-anthropologists call underground storage organs (USOs).

No later than 800ka, and possibly much earlier, Homo erectus and their close relatives were controlling fire and presumably cooking their food.  The evidence includes ancient hearths, circular stone enclosures with ashes inside.  Sometimes stone tool fragments and animal bones are nearby.  They had long since been successful predators, following herds of grass eaters and gathering fruits and vegetable matter along the way.  Once they began roasting them over open fires, the meat, marrow, nuts and various USOs these hominids foraged, became much more digestible.  Various parasites and pathogens were also neatly eliminated from the otherwise raw meat.  Meat dried and cured with smoke could be kept for long periods in cooler climates.

Analysis of fossil skulls from this 800ka period indicates sufficient brain power in the cranial regions associated with speech.  That, plus their millions of years of natural selection as social predators, strongly suggests a language capability beyond any of the vocalizations made by other animals.  There is also evidence Homo erectus throats were adapted for speech, but not as well as anatomically modern human (AMH) throats are.  The capability to make predicate statements would have been extremely useful, perhaps necessary, in sharing plans for a hunt or other complex group activities.  

If we follow the fossil evidence, from these early Paleolithic foraging societies, down to our earliest anatomically modern Homo sapiens at 180ka, anthropologists have demonstrated how natural selection changed the shape and function of human heads.  With less need to chew raw meat and fibrous tubers and more need to speak clearly with a large vocabulary, humans evolved from having distinctly ape-like heads with powerful projecting jaws and about 600cc of brain matter, to our familiar modern human heads with their peculiar flat faces and 1150cc brains.  

People in Paleolithic times were mobile, with no fixed place of abode.  Needless to say, they got plenty of exercise.  Some lived in caves during cold seasons, but generally they were on the move, following their grass-eating prey.  That’s why the primary external parasites on humans are lice rather than fleas.  Our ancestors didn’t consistently sleep in the same nest long enough for fleas to complete their life cycle, about 2 months, depending on conditions.

If you look at yourself in the mirror, through the eyes of an anthropologist, you can see a small mouth with teeth adapted to biting and chewing cooked food rather than ripping through raw skin and flesh, and a prominent chin to support the lower front row in that new role.  The small nose reflects a shift from smelling distant prey, to tasting our food.  The ears are fixed in a position ideal for hearing speech.  The large stereoscopic eyes are necessary for tracking down herbivores in open country.  Vision is our primary sense, followed by hearing, with smell a distant third.  

From 230ka down to about 100ka, Homo sapiens lived exclusively in tropical Africa and perhaps the Levant.  After 100ka, AMHs expanded their range throughout the Eurasian continent and eventually to the New World.  Except for a brief warm spell about 100ka, this was a time of low sea levels, huge deserts and a relatively cold global climate.  

Thus, between about 800ka, when humans began cooking their food, down to anatomically modern people at 10ka, our bodies, including digestion and metabolism, were adapted through natural selection to this foraging lifestyle and a diet of cooked food.  Our current skeletal structure, omnivorous digestive system and metabolism were about right for the varied ecosystems the population occupied: usually open savannahs with large herds of hoofed, grass-eating animals to eat and scattered pockets of forest with available fruits and nuts.  

Implications for a healthy diet - So what does all this history imply for the paleo diet us moderns are experimenting with?  Why would a diet modeled after Paleolithic humans at their finest, be any better than Taco Time, Burger King, or a big bowl of packaged macaroni and cheese?  The basic proposition of Paleo diet proponents is that through natural selection the modern human organism has evolved to perfectly subsist on those foods our ancestors ate during the period from 800ka down to about 10ka, when agriculture and animal husbandry began to be commonly practiced.  

The idea is, our bodies thrive best on a well-rounded diet, consisting of certain kinds of foodstuffs, in certain proportions, similar to what was available to humans for most of the last million years.  The most recent 10,000 years is not enough time for the evolutionary process to significantly adapt human populations to their radically different diet as agriculturists and pastoralists.  Obviously some adaptation has occurred and natural selection has begun to remove genotypes which are intolerant to sucrose, lactose and gluten, but the net effect is small compared to a million years of adaptation to subsisting on typical foraged foods cooked over open fires.  

Granted, most modern humans are alive and kicking despite the predominant role of sugar and cereal grain products in their diets.  It’s a testament to how adaptable humans are to changed conditions; but how many of our widespread chronic health problems, obesity for example, are rooted in our over-dependence on sugar, cereal grains and milk products? 

Do physically fit people who adhere to a Paleo diet have better long-term health outcomes than comparable groups who follow a traditional, government approved diet?  Time will tell, perhaps with some help from future scientific studies, but in the meantime I’m giving it a try based on its logical merits.  One thing is for sure, regardless of the presumed benefits of a Paleo-like diet, the world’s current population is utterly dependent on direct consumption of cereal grains. Without them, famine will surely result.

Let’s briefly examine the eating habits of the typical anatomically modern human in the late Paleolithic period, 20 to 30ka.  That representative time period accounts for the full extent of the long evolutionary process described above.  It must include people living in various ecosystems around the globe, therefore any generalizing has its limitations.  As a rule though, Paleolithic people placed the highest value on animal protein, primarily big game but also rodents, birds, fish, reptiles, etc.  This has been confirmed by chemical analysis of fossil teeth and remnants of plaque.

Anatomically modern humans (AMHs) are omnivores, shaped by the tropical African environment they were confined to until a mere 100ka.  As such, we cannot subsist exclusively on lean meat of the kind produced by most wild animals - too much protein, not enough calories.  Accordingly, Paleolithic people went out of their way to crack open large bones for the fatty marrow.  Animal fat is very dense in usable calories, so they didn’t need very much - more in cold seasons, less in the warm.  They also gathered edible fruits, nuts and USOs, plus fish and small game.  Under the best circumstances, they partook of a balanced diet consisting of predominantly animal meat and fat for proteins and calories, supplemented with a variety of vegetable matter for additional calories and proteins, plus essential vitamins, minerals and fiber.  

Why the preference for meat?  Undoubtedly because animal tissue, with its lipids (fats) is a more concentrated source of energy for an omnivore than almost any vegetable matter.  High quality meat also provides a complete set of amino acids (proteins) needed by our bodies.  While some plant materials like nuts contain proteins, multiple plants usually need to be combined to make up the complete set of amino acids needed by humans.  Following the herds and primarily subsisting on their meat and fat was the only practical way for our species to thrive, expand their range and become the premier apex predator on the planet.  

The USOs our ancestors ate contained starches, and during times when animal prey was not available in sufficient quantity, people made do with larger quantities of whatever vegetable matter could be found, however, over a successful Paleolithic lifetime, the flesh of animals was the primary source of protein and calories. Interestingly, the ability to make nets and hooks to routinely catch fish came relatively late in Paleolithic times, after AMHs left Africa about 40ka.  Fish, lichens and animals that eat them (e.g., reindeer and marine mammals) are rich in vitamin D.  Incorporating these animals into their diets enabled humans to move into parts of Eurasia north of latitude 50 (called the vitamin D line by paleo-anthropologists)

The modern era - This million-year-long dependence on animal flesh came to a relatively sudden end for Homo sapiens with the advent of agriculture and pastoralism (herding domesticated animals).  Irrigation agriculture in particular, starting about 8ka in major Asian river deltas, resulted in rapid population grown in affected regions, with in turn produced cities, roads, priests, ruling families, etc.  The majority of people living in these agricultural zones, and thereby the majority of the human species at the time, subsisted on a diet based largely on the cereal grains they grew.  Wheat, barley and rice were plentiful, but animal products were relatively scarce and expensive.  Subsistence farmers could raise their own animals, especially cows and goats for milk, since they lived in a fixed place, but most of their calories typically came from starchy grains.  

This pattern has continued down to this day.  Meat may be more plentiful in general today, but most people and especially the poor, get the bulk of their calories from starches and sugars.  In fact, red meat and animal fat is widely discredited by modern medical authorities as harmful to our health and long life.  Someday, perhaps 100k years hence, Homo sapiens will become perfectly adapted to an agricultural diet of cereal grains, but in the meantime, we are programmed from birth to subsist on the same foodstuffs our Paleolithic ancestors did.

Its true, too much animal fat, combined with little or no exercise, will eventually result in arterial sclerosis, the main killer of old-age men in industrialized societies.  The Paleo diet proposition is, a balanced diet with most protein and calories coming animal products, supplemented by nuts, fruits and vegetables, and modest amounts of starchy foods, is more conducive to good health and long life than a diet of equal calories based primarily on milk, sugar and cereal grains.  

Paleolithic people were not fat.  The meat they subsisted on was often scarce, with periods of want between kills.  They had to run long distances to catch big game, many of which would put up a fight or escape.  In general humans had to work hard to scratch a living from the land.  So as we attempt to duplicate the main elements of their diet, we must restrain ourselves from overeating, or our attempts at weight control will fail.  Gorging on fat meat and roast potatoes every day will do it to you just as quickly as excessive amounts of bread, pasta and cheese.  Gluttony and sloth lead to the same results regardless of one’s diet.  Count your calories and stay thin.  

My Paleo diet - Specifically, how has my diet changed, now that I subscribe to the Paleo diet proposition?  For starters, I’ve eliminated most dairy products from my daily intake, leaving only a little cream for my coffee.  Same with sweets, except for a teaspoon of maple syrup in my coffee and 5 grams of sugar in an occasional nut bar.  The fruit I eat has fructose, but that doesn’t amount to much.  

I’ve also quit eating the usual baked goods made from grain flour.  No bread, pasta, pastries, tortillas, rice or snack foods made from same.  For my main meal, I do eat fingerling potatoes and occasionally whole kernel corn and black beans.  The potatoes are arguably similar to the starchy USOs our ancestors supplemented their meat with.  Whole maize and legumes are not strictly Paleo, but they are nevertheless healthy, unprocessed plant foods.  

The fact is, most everything we eat, including meat, comes from genetically modified organisms, modified by humans long ago through selective breeding.  A strict paleo diet therefore would have us combing the countryside for road kill and wild tubers.  Think of Euell Gibbons.  Since most of us are unwilling to go that far, and we don’t have the opportunity to chase herds of big game across the prairie, a modified diet of foods from the supermarket, with reasonable proportions of meat, fat and vegetable matter is just as good at the real thing.  

What are the right proportions?  I don’t know for sure and I’m still learning, but in my case, besides meat and animal fat, I still get some calories from starchy and sweet foodstuffs.  As mentioned above, I’ve cut back the sugar to small amounts in my coffee, condiments and of course the fruits I eat.  I’ve also cut back on starches to modest amounts by focusing on fingerling potatoes.  It seems easier to restrict one’s starch intake by adding one little potato to your meat dish.  The end result satisfies our hunger feelings as much as a larger meal of mostly starchy foods, and does it with fewer calories.  

Occasional inputs of whole maize and legumes seem beneficial, in spite of their agricultural origins.  At least they are macrobiotic, i.e., whole from the plant without processing.  Small potatoes may be more nutritious for the human organism than cereal grain products, I’ll take that on faith, but surely the most important benefit of removing the latter from our diets, is a reduction in the proportion of starchy foods in our total daily intake of calories.  

My objective is not to reject the agriculture and animal husbandry revolutions, but rather to forage from their cornucopia of natural products, selecting those foodstuffs our Paleolithic ancestors would partake if they were here with us. – CW

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Appendix - Here is a typical daily intake for me, when I’m at my best, including a total of 3 cups of coffee, 2 of them decaf, plus frequent 12 oz glasses of tap water at room temperature

• o   First light – Generous helping of wheat bran, psyllium husk, nutritional yeast, lecithin, Spirulina, Flaxseed oil and cod liver oil – mixed with 16 oz of warm water and downed in one long draught. 

• o   Mid-morning breakfast - One small organic banana, a Mandarin orange and a raw carrot

• o   Early afternoon lunch – A modest portion of eggs, beef, or pork, including the pre-cooked, frozen varieties, and a fingerling potato either roasted (in batches) or stewed with the meat.  Chili sauce, etc. as condiments

• o   Early evening dinner – A large lettuce salad with a variety of fibrous vegetables, topped with dressing made with avocado oil, olive oil and white vinegar, with packaged “Italian” mix.

By controlling the size of these portions, you can keep the whole day’s intake under 1000 calories if necessary, while getting everything needed in the way of nutrition, Paleo style.

Its also relatively easy to maintain your paleo diet when visiting a restaurant, particularly Asian cuisine.  Order meat and vegetables, bacon and eggs, or soup and salad.  If you must have some starchy calories, order a side of potatoes and don’t finish it.

PS:  Beware of gout, a painful condition of the foot that lasts for weeks and is only eliminated and prevented by a change in diet.  Gout is caused by accumulation of urea in the blood, which in turn is caused by eating foods high in purine.  The number one contributor is beef, followed by certain other meats and shellfish.  Treatment for gout consists of eating only eggs and cheese for protein until symptoms cease, then limiting your intake of meat to that which is necessary for optimum health and fitness.  Bummer