We evolved to eat everything that moved, but possibly mostly small animals
As a result, 'meat' for our distant ancestors, was anything that moved - birds, rodents, lizards, turtles, grubs, animals of all kinds. Africa has one of the largest and most diverse number of species of birds of any continent. Bird meat is invariably tough (except for nestlings). As is wild herbivore meat (new borns aside), except for the choice muscle groups and the organs. Hunting large animals brought prestige - and therefore was important only for males - but was not an efficient use of time. Capturing lizards and other small game was more likely to be successful (small rodents can be dug from burrows, for example), but it did not bring the 'kudos' of a large shareable food resource. Once a large animal is killed, it's carcass is regarded, even by todays hunter gatherer societies, as a variably valuable resource. The internal organs, especially the liver, were of the highest value. The more choice and easily transportable muscle meats were next in value, and the tougher and more bony parts (bone is very heavy to carry) were least valued. Those lower down the socail hierachy (in some hunter gather societies) got the least valued parts of the carcass.

So 'meat' for the greatest part of our evolutionary history has quite possibly meant small animals, birds, grubs, with only intermittent  meals of the wild animal equivalent of our domestic beef steak.

The very fine bones of frogs and mice, lizards, and other small creatures were probably eaten - especially the rib cage. Our ancestors probably consumed far more calcium than we do (especially when the calcium content of tree seeds is also taken into account).
 

We eat only four animals now, and no small ones, although our genes are unchanged
Today, 'meat' for us means virtually four animals - an animal so familiar it has no common name, the 'cattle beast'; the sheep; the pig; and the domestic fowl ('chicken'). Most of us will rarely eat any other kind of animal in our lifetime, and especially not lizards, frogs, grubs, rodents, snakes, turtles, or other small animals that were our species' normal daily food for almost all our evolutionary history up to the present!

Now, the word 'meat' has come to mean muscles, not internal organs. In a wonderful cultural 'flip flop', that which was once prized, the internal organs, are now called 'offal'. And in many households in the West the internal organs are now called "ugh" or "yuck". Muscle meat by itself may raise levels of an amino acid called 'homocysteine' in the blood, and high levels of homocysteine have been associated with tendency to heart disease. But folic acid and B vitamins have been found to prevent elevated homocysteine levels. The liver is an excellent source of folic acid. So eating of the whole animal keeps the balance of health. Folic acid is also high in some green vegetables, particularly spinach. Meat and vegetables go together.

These notes are a look at the animals we eat, but from a hunter-gatherer evolutionary perspective. It is not so much a 'guide to' as a 'guided tour' of what we evolved to eat, and what we now eat due to urbanisation.  The guide is divided into two parts.

First, the animals whose bodies we eat regularly, or on occasion. We eat such a narrow range of animals trially because of cultural conditioning, because of the industro/heirachical urbanisation of our Western society, and because some wild animals are extremely difficult to domesticate.

Second, those animals whose bodies a Western person is unlikely to eat in their lifetime -  a normal human food, perhaps eaten by many people, but screened out by Western cultural conditioning.(note: the second part is on hold at the moment).

"[Affluent populations] habitually consume a diet that was unknown to the human species a mere ten generations ago. Compared with the diet that fuelled human evolution, the so called "affluent" diet of today has twice the amount of fat, a much higher ratio of saturated to unsaturated fatty acids, a third of the former daily fibre intake, much more sugar and sodium, fewer complex carbohydrates, and a reduced intake of micro nutrients. World - wide, the adoption of this diet has been accompanied by a major increase in coronary heart disease, stroke, various cancers, diabetes and other chronic diseases"
- 'Conquering Suffering, Enriching Humanity, The World Health Report' - WHO, Geneva 1997.

Yes, you and I have the same genes as our ancestors of ten generation and more ago, but we no longer eat naturally. To cap it, we are exposed to a very great number of chemicals that did not exist on earth ten generations ago. Their long term effect, singly or acting together, cannot ethically be established with any degree of certainty. There is some evidence that naturally occuring anti oxidants in food help to dampen down the effects of the foreign chemical agent we are unwittingly exposed to. Ironically, we have never had such a low intake of anti oxidant containing food in all our evolutionary history, we have never had a time when vitamin and mineral intake was so low. At a time when we need a 'natural diet' most, it is least available - and least likely to be a practical option in our current way of life.

The sources of fat and the kinds of fat we have today are completely different to those of our evolutionary history
As the World Health Organisation Report points out, we have a much higher ratio of saturated to unsaturated fatty acids in our diet now. But it is a little misleading. The implication is that we are eating too much saturated fat. This is certainly true in absolute terms (we overeat). But  there are actually two significant points to be aware of-

First, we eat too much. We regularly overeat. Whether fat or carbohydrate, calories in excess of those needed to burn for energy are stored as fat. Carbohydrates (pasta, bread, potatoes - any carbohydrate, natural or not) in excess of our needs for energy are converted to fat. Worth repeating. Excess carbohydrates are stored as fat.

Animal fat in itself is a normal food for the human animal. It is a normal food and has been for countless millenia. Animal fat in itself is not dangerous. But large wild animals were only fat at certain times of year. Their muscle meats contained only about 4% fat. But no part of the carcass was left uneaten, including the fat stores. But on balance, in evolutionary terms, we did not regularly eat 'a lot' of fat. Let's be clear. Excess calories - from any source - are dangerous. Very dangerous.

Second, we have been eating saturated animal fat for all of our evolutionary history. Organ meats - especially brains - and nuts, seeds, and green leafy plants provide the small amounts of essential polyunsaturated fatty acids our bodies aren't able to manufacture. Saturated fats are evolutionarily natural, whether derived directly from animal fat, or whether the body has to construct its saturated fats from the nuts, tubers, and seeds that it eats. We ate the marrow of the larger bones- indeed, some scientists believe nutrient rich marrow was a key factor in providing the very dense nutrients needed to build a baby with a very large and nutrient demanding brain. Marrow contains about 75% of its fat as monounsaturated fats.

But what we have almost never ever eaten before in our evolutionary history are 'hydrogenated' fats. These are industrially extracted vegetable oils that are made solid and stable through an industrial/chemical process called hydrogenation. Tiny amounts occur naturally in the stomachs of grass fed cows. They are excellent for deep frying and for baked goods. They are stable, cheap, and ideally suited to industrial food production. But large scale industrial hydrogenated vegetable fats did not exist ten generations ago, or at any time in our evolutionary history, and there is some evidence that, in the quantities currently consumed in the West, they have a role in the development of cardiovascular disease.

The animals whose bodies we eat are either herbivores (cattle beasts and sheep) or more or less omnivores (pigs, chickens).
The kinds of fats in their bodies to the greater degree reflect the kinds of fats the animals themselves eat. Only grass fed domestic animals have a 'fat profile' fairly similar to wild herbivores. When animals are fed supplements of grains or compounded feeds derived from a wide variety of plant and animal products and by-products, their body fat tends to reflect the fats present in the grains and feeds they are fed.

For example, pigs in America are fed primarily a soya bean/maize based feed. Their back fat, typical of the fat on pork chops, for example, has around 39-43% oleic acid and 19- 23% palmitic acid. Adding sunflower oil (higher in monounsaturated fats, particularly oleic acid) to the standard feed increases the oleic acid component of the fat to about 60% and reduces the (somewhat undesirable) palmitic acid to 17%. Making ground up whole sunflower seeds of a 'high oleic' type a major part of the standard soya/maize feed changed the oleic acid content of the back fat to about 67% (olive oil, by way of comparison, is about 72% oleic acids), and the palmitic down to 12%. Pigs are omnivores (as we are), not grass eaters (ruminants) . Therefore their fat profile reflects the kinds of fats they are fed. Our body fat profile also reflects the kinds of fats we eat, and in part, the kinds of fats the pigs we eat, eat!
 
Cattle, on the other hand, as grass eaters for most of their lives, are much less affected by 'finishing' on meal; but are nevertheless still affected.

For practical purposes, the end result is that 'corn fed' or 'feedlot' finished cattle have, relative to grass fed animals, more of one kind of 'fatty acid' (type of fat), namely 'omega 6' fatty acids, and less of another kind, 'omega 3', than they would if they had been totally grass fed until the day of slaughter. (Corn/maize and soybeans, common ingredients in animal feeds, are particularly high in 'omega-6' fats.) Feedlot cattle may have almost no 'omega-3' in their fat after 196 days in the feedlot - whereas grass fed animals have about 7%. Some wild game has about 4%. We need both 'omega-6' and 'omega-3' fats, they are vital to many bodily processes. But we need them in the right amounts and the right ratio of one to the other.

Currently, it is thought that the ratio of 'omega 6 fatty acids' to 'omega-3' should be 4 of 'omega-6' to1 of 'omega-3'. A more evolutionarily appropriate ratio of these two essential fatty acids has been linked to a greatly reduced risk of breast cancer and coronary heart disease. The average ratio in the USA today is around 17 'omega-6' to 1 'omega-3'. But grain fed beef consumption is responsible for only a very small part of the skewing of this ratio ( recent research has shown that cattle fed with a particular variety of corn/ zea mais bred to be high in corn oil give meat with a very high 'marbling score' and more likelihood of being graded 'US choice'. If 'natural corn' is replaced with 'high oil corn' to get better prices, there may be a further increase in omega - 6 fatty acids in US beef, altho' compared to some urban/processed food dietary loadings, it would still be relatively unimportant. Interestingly, steers fed a diet with high levels of soya bean oil increased their percentage of desirable monosaturated fats, whereas bulls on the same diet, increased their polyunsaturated fats ).

Interestingly, one form of omega-6 linoleic acid, 'conjugated linoleic acid', found primarily in grass fed meat (and beef has the second highest amount in it's fat of any domestic animal) and cheese, has recently been found to help prevent the onset of 'adult' or 'noninsulin-dependent' diabetes. Tests showed it also has the effect of reducing body fat - at least in laboratory rats! (The amount in a 'normal' daily serving meat or cheese is only about a quarter of the amount needed to produce these effects.)

In addition, natural, grass fed beef has a higher anti oxidant capacity than feedlot beef, which means the grass fed meat cuts retain their red color longer. In fact, it is proposed to add vitamin E (the alpha tocopherol form) to feedlot fed cattles diet to bring the shelf life of the meat up to match that of meat from grass fed animals.

You might have  inferred that the World Health Organisation is suggesting we ought to eat MORE  'unsaturated fatty acids', such as various vegetable oils. In fact, in evolutionary terms, we probably ate far fewer omega 6 unsaturated fatty acids than we do today, and more omega 3. Leaving aside being informed on safety issues, it is more important to eat meat, especially organ meat, than to be fixated on the particular pattern of fatty acids in the animals' fat. In orders of magnitude, far greater benefit can be had by getting regular excercise, selecting natural food over processed food, and substituting fresh monounsaturated oils such as olive oil for high 'omega-6' vegetable oils. The unaturally low omega three part of the modern diet can be bumped up by eating omega three rich fish such as sardines, or, if you object to 'sardine breath', taking omega three supplements regularly.

Even if we compensate for the unnaturally high 'omega-6' component of the modern diet by taking additional omega-3 fats, the omega-3 oils must still have saturated animal fat present in order to make possible the protective anti-thrombitic metabolic process.

We sedentary Westerners need to reduce fat and carbohydrate intake, eat whole foods, and avoid processed foods
Today, I believe we need to reduce our overall saturated fat intake by reducing our intake of industrial saturated fats, but still take animal fat commensurate with our energy needs (or substitute whole grains, nuts, and tubers so our bodies can make it's own saturated fat). For most sedentary urbanites, that means reducing animal fat intake as well. We need to obtain our essential polyunsaturated fats from whole natural sources, such as organ meats, nuts, seeds, and leafy green vegetables. We need to reduced the excessive amount of omega 6 fats we eat by substituting monounsaturated oils (such as olive oil) for high omega 6 oils (such as soya). We need to eat more omega 3 containing foods (such as fish) or take omega 3 supplements. This in itself will tend toward restoring a more evolutionarily natural balance. The easiest 'way' overall is to eat natural foods - including  animals of all kinds - in amounts that leave very little room for highly processed foods.

Part one looks at the very narrow range of meat we eat in the Western industrialised city based world.

Part two will look at animal meat eaten regularly or occasionally in other parts of the world, but which we will either never or rarely, eat. (under construction, it might hopefully, all things being equal, appear in 2006 or sooner or later. Or not.)

Links
Wild animals in North Africa 2.5 million years ago  JJJJ While the scientists have not found (?yet) evidence of the evolving human in North Africa at this date, this site gives a fascinating insight into the animals, including shoreline animals, present in North Africa at this time, helping build a mental picture of the environment and faunal of our evolutionary past.

The destruction of Botswanan natural meat animals JJJJJ in the interests of cattle farming. A documentation of the tragic and outrageous destruction of the delicate Botswana Kalahari ecosystem ostensably to control cattle disease. So meat can be exported to the west...An indictment on the human species.
URL:  http://www.stud.unit.no/~skjetnep/owls/fences/index.html

USDA Nutrient Database for Standard Reference
http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl

Table 2. Systematic and common names for fatty acids - this table is in the lipids paragraph of the Nutrients section and gives the name of the fatty acid which appears in the database as a number, such as 18:3. It gives the chemists 'systematic' name, and the 'common' name of the most common form of the fatty acid. The high visibility 'omega-3' fatty acids are:
20:5 eicosapentaenoic (EPA); the very important 22:6 docosahexaenoic (DHA) and 18:3* octadecatrienoic (linolenic acid in its alpha form, alpha linolenic acid, ALA).
*NOTE: when a fatty acid is designated '18:3' the database does not distinguish between alpha (18:3n-3 ), an omega-3 essential fatty acid, and gamma (gamma linolenic acid GLA, 18:3n-6), an omega-6 essential fatty acid (a particularly important omega-6 fatty acid).
The 18:3 data may sometimes be a combined value of alpha and gamma forms (isomers). Usually, one of the isomers will be the most common and is "often" used as a "convenient way to identify the fatty acid."
http://www.nal.usda.gov/fnic/foodcomp/Data/SR13/sr13_doc.htm#Nutrients

The Grassfed Meat Page. JJJJ An easy to read summary of the nutritional profile of grassfed versus grain finished meat with particular reference to USA. It discusses the relative fat contents of meat produced under the two production systems, relative differences in Omega-3 content and CLA content, and what that may mean to health.
http://www.eatwild.com/benefits.html

Grassfed versus grainfed meat JJJJ A Texas cattleman's lucid and pointed musings on the scientific studies into the omega-3: omega-6 ratio in the modern diet, with special reference to his own cattle.
http://www.texasgrassfedbeef.com/id31.htm

Economics and Culture of Grain Finishing versus Grassfed Cattle. JJJ From the same cattleman. An insiders view.
http://www.texasgrassfedbeef.com/id29.htm

Animal fat JJJJ A discussion of the fat in animal carcases, specifically marbling fat (intramuscular adipose tissue), the origin and nature of fat (adipose) cells and deposits, fat distribution between muscles, within muscles, around the guts, and under the skin, and more!
http://www.aps.uoguelph.ca/~swatland/ch2_4.htm

The animals in Europe in the time of Homo erectus - a page at the Boxgrove site listing the small and large animals available to hominids in western Europe 500, 000 years ago. Note the relative numbers of small animals.

The author rejects any responsibility for any decisions about life, diet, or anything else other than his own. Any action you take after reading the material here is solely your responsibility - seek advice from others, read critically and widely, don't accept everything you read here. You have been warned! Question everything.

Form your own opinion on these matters after reading widely and consulting appropriate professional advice, including advice of medical practitioners and professional nutritionists.