Industrial countries in general, and victims of British colonialism in particular, including the US, have been the targets of massive pro-protein propaganda. How this started is unknown, just as how the human species first began eating animal flesh is forever unknowable, but perhaps the Commoners' blood-lust was exacerbated by the fact that in the Good Old Days, the Kings prohibited the peasants from hunting the "best" animals, and so the peasants, as usual when denied something, reacted by wanting it even more. Other examples include the prohibition of alcohol, marihuana, and other 'recreational' drugs. Thus, eating large quantities of animal flesh became a status symbol, a symbol of conspicuous affluence, success, and wealth, just as being overweight currently is in some cultures. TV commercial time is saturated with ads for tobacco (until recently), animal burgers, chicken parts, dairy products, alcohol, junk food, and their resulting need for "remedies": toxic patent "medicines", all of which have a devastating effect on human health and longevity. Ads for healthful foods, such as fruits and vegetables, are virtually nonexistent. Obviously, items that destroy health must have a much higher profit margin than healthful items to support this blitz of advertising. (The average 30-second ad on prime time cost $300,000 - $500,000 to run, exclusive of production costs.)
Even "vegetarians" bring a protein lust with them into their new lifestyle -- the legacy of decades of conditioning by the advertising industry. They are continually asked: "Where do you get your protein??" Well, how much protein does the human need, anyway??
The easiest way to understand what our true needs for protein are is to consider the human baby. Protein is used for construction and maintenance of tissue; it is not used for energy, except under extreme emergency conditions. The human infant is growing new tissue at the most rapid rate of its entire life; therefore, its protein needs are at the maximum of its entire life! What does Nature provide for its protein needs?? Human milk is a liquid with a protein content of ~1%. Yes, 1% of our total diet is enough protein to support the most rapid growth rate, and the highest protein needs of our entire life! Upon reaching adult size, protein intake is necessary only to support maintenance, not additional growth; therefore, adult protein needs are even less! In fact, current RDA's indicate that the adult human needs ~1/3 of the protein of the infant; thus, the adult needs 1/3% of its overall diet as protein. This can be adequately supplied with fruits and vegetables, as shown in the chart below, without resorting to concentrated sources: nuts/seeds, "seed cheese", beans, tofu, miso, "texturized vegetable protein" (TVP), etc.
How does orthodox "nutritional science", with its massive funding by the food processing cartels, come up with its recommendations for recommended daily allowances (RDA's), specifically for protein??
One method claimed to evaluate the "quality" of protein is called the "Protein Efficiency Ratio (PER) and is defined as the weight gain of a growing animal divided by its protein intake. Although it is a proximate measure of protein quality when conducted under specific conditions, it has been criticized because only the amount of protein consumed above maintenance is used for growth. Furthermore, the PER varies with food intake. This ratio finds use with small animals, and has been employed also in infant studies."  A little bit of thinking shows the fallacies here. First of all, results based on studies of animals other than human offer very little, or no, useful information that can be applied to the human species, because the biochemistry and dietary needs of different species are quite different. Rat nutrition simply does NOT apply to humans any more than the research on the effects of LSD on spiders could be extrapolated to humans. This kind of "research" may generate lucrative grants for universities, and produce numerous PhD's, but it is useless for any understanding of real human dietary issues.
Further, when one considers weight gain, it does NOT relate to optimum health whatsoever. The one who gets the fattest, quickest is the healthiest? Nonsense. Conversely, obesity is known to be quite detrimental to health, so why should rapid weight gain be equated to dietary usefulness? Cow's milk, since it is designed for an animal that gains ~1000 pounds in its first year WILL produce more rapid growth in the human infant (that is supposed to grow ~13 pounds in the first year) than human milk, because its concentrations of protein and calcium are about 3-4 times that of human milk, casein is 7 times that of human milk, minerals are 3.4 times as much, and bovine growth hormones causing the cow's rapid growth are present. Obviously, over-feeding any organism by a factor of 4 or more WILL produce rapid "growth", i.e., obesity, but no intelligent person could possibly consider this as healthy growth, or as any indication of the "superior" nutritive quality of bovine beverage over human milk for human infants.
Indeed, the cow-fed human baby is always grotesquely obese, lethargic, ill tempered, plagued by rashes, suffers constant digestive problems, cries a lot, slow to learn, and smelly. The PER concept is a holdover from the post-WWII mentality of mindless consumerism: more, more, more is always better, better, better. The PER concept, and other orthodox nutritional dogma based on similarly flawed "logic", has led to this society consuming enormous amounts of indigestible proteins and other "foods" which cannot be properly digested and used by the body. Thus, large quantities of these materials are stored in the body as partially-digested material and toxins that the body tries to eliminate by such grossly misunderstood phenomena as "colds" and "flus". The body's efforts to eliminate these stored toxins are misinterpreted as "disease", and highly poisonous pharmaceuticals are used to suppress the body's efforts at self-cleansing and self-healing. More detailed analysis of this deleterious process of interfering with natural bodily cleansing processes, and a simple technique of permanently eliminating "colds", "flus", and "allergies" from one's life, are given in the present author's article: Beyond Vegetarianism: How To Permanently Eliminate "Colds/Flus" by Simple Dietary Change.
This erroneous way of looking at reality, considering ONLY quantity while always ignoring quality, has led exactly to the global ecological disasters that currently threaten the continued existence of all Life on this planet. There are QUANTITATIVE and QUALITATIVE aspects to all situations, concepts, and practices; both must be fully considered, otherwise, misunderstanding and disaster are inevitable.
Another way orthodox nutritional pseudoscience uses to determine protein "needs" is called the Nitrogen Balance method. Since nitrogen is part of the amino group [-NH2] in the amino acids from which all proteins are made, and since nitrogen is much easier to quantify in the lab than complex proteins, the theory is that one should consume enough protein (measured as nitrogen) so that the amount eaten equals the amount excreted. (This is similar to the nonsensical Gatorade philosophy: eat your excretions.) Therefore, when in "nitrogen balance", there are no net gains or net losses of nitrogen and one's tissues are claimed to be maintained ideally. To determine one's protein status, they place people on a reduced-protein, or protein-free, diet and then measure the nitrogen excreted over a few days and then assume that since this represents the amount of protein lost, it also represents the amount one should have eaten over the same time period in order to maintain a steady weight. Simple and obvious; right? Wrong! Unfortunately, orthodox nutritionists do not know that enormous amounts of protein-based mucus and toxins are stored in the average high-protein meat/egg/dairy cooked-food eaters' body, or that putting them on what is essentially a fast will trigger a self-cleansing process that will cause large amounts of nitrogen-rich mucus and toxins to be eliminated from the body. As a result of these inadvertently-accelerated excretions, the protein needs of the human being are grossly overestimated.
Anyone with any serious personal experience with dietary change, or especially fasting, knows that enormous quantities of debris are eliminated with any positive changes in diet, and that these eliminations are highly accelerated during a fast. (A fast is consuming only water, and taking enemas to help clean the colon of waste material to prevent severe autointoxication.) In addition, large quantities of mucus are eliminated at first; and as the body cleans itself, the mucus excretions will slow markedly. Since the nutritional "Nitrogen Balance" experiments generally do not last long enough for the body to become clean enough to allow determination of its true protein needs, as evidenced by a constant, not exponentially decreasing, nitrogen loss, the amounts estimated by this method are far in excess of our true needs.
With regard to protein requirements, Albanese and Orto  admit that although "The study of human protein requirements has engaged the interest of scientists for scores of years ... definitive requirements have not been established to the satisfaction of many." They lament that the Nitrogen Balance method "has frequently been studied, but this actually seems to be a rather unreliable indicator of satisfactory protein intake." Further, "the quantities of protein necessary to maintain nitrogen equilibrium vary according to the nutritional status of the subject. When the protein stores were exhausted even small amounts of absorbed N(itrogen) were sufficient to produce a positive N-balance. Likewise it was found that, in patients on rice diets, nitrogen equilibrium could be maintained with small quantities of protein -- quantities which would not seem to be conducive to good health." "... the sum of all present data, including the National Research Council's recommended daily allowances, 'represent little more than intelligent guesswork as to the quantities of protein which will amply cover man's needs.'" 
"The effect of total starvation (i.e., real fasting) on nitrogen excretion has been studied several times. One report shows that a voluntarily starving healthy woman excreted during the first few days of starvation an average of 6 to 8 grams of nitrogen, and then in the next days, up to the 26th day, 4.26 gm, and still later 2 to 3 gm daily. ... The progressive reduction of nitrogen excretion, as seen in starvation, semi-starvation, or protein-free diets, occurs not only because the easily available protein fractions of the body are progressively exhausted but probably because of adaptation to the low food intake or low protein supply."  Strangely, if the body really did adapt to this reduced protein intake, higher intake is obviously not necessary. If, for example above the 2-3 gm/day represents the body's true protein needs, after excess protein-based waste material was eliminated, then the daily protein needs would be: P=N x 6.25, = 2.5 x 6.25 = 15.6 grams/day, considerably less than the RDA's "intelligent guesswork" of 64 grams/day for a woman. This amount could be supplied by about 3 pounds of fruits and vegetables.
Significantly, Albanese and Orto admit that "efficiency of protein utilization is diminished when caloric intake is low or protein intake excessive".  This is additional evidence that a high-protein diet is wasteful and self-defeating. As one gains personal experience with a low-protein, plant-based diet, one comes to understand that concentrated proteins, i.e., those greater than about 1%, cannot be digested properly, and that one is much healthier with proteins supplied by fruits and vegetables than attempting to get 'sufficient' protein through concentrated sources, such as nuts/seeds, beans, legumes, etc.
A very shocking conclusion, at least to those conditioned by the Cowboy Culture to believe we need lots of protein, is revealed by the official RDA's and the application of a little 6th grade arithmetic. Typical values for protein and energy RDA's are given below. The 4th and 6th columns, however, are the RDA's/lb of bodyweight, as this information is imperative to produce meaningful comparisons for people of different weights. By intentionally omitting this simple and quite necessary calculation, the 'authorities' give the obviously mistaken impression that protein and calorie needs increase as we grow; however, exactly the opposite is true. The truth is that the adult human needs about 1/3 of the protein and 1/4 the calories, on a pound-for-pound basis, as it needed during infancy! This is readily supplied by fruits and vegetables.
|Infants and children|
PROTEIN CONTENT OF FOODS
and stomach commodities
NOTE: % protein is expressed as weight
(i.e. grams protein/100 grams "food")
NOTE: the following items have far too much protein for the human to digest properly, and therefore are not recommended for consumption, but are included for numerical comparison.
More: John Coleman on protein.
1 Goodhart and Shils, Modern Nutrition in Health and Disease, Lea and Febiger, 5th ed, 1973