Hydrolic production
An important nutritional disadvantage of total specialization on crop farming was the disappearance of meat from the peasant diet. Human energy is supplied mainly by the carbohydrates in food, and we have seen that the coming of agriculture meant unprecedented supplies of carbohydrate food from the grains of cereal crops or, in some regions, from starchy tuber crops. But man also needs proiein for growing and maintaining the structure of his body; and for this purpose various kinds of protein, having different combinations of component substances called amino acids, are required in correct balance. Animal food is a good protein source, and the efficient Mesolithic hunters were adequately supplied. The new large populations based on Neolithic agriculture needed to make up their protein partly from their small herds of farm animals and partly from crops. Protein makes up only 6-14 per cent of cereal grains, and an exclusively cereal diet is liable to cause protein deficiency.
A solution to this problem came about through growing legumes. Legume grains (various peas and beans, groundnuts, and other crops) have a protein content of 17-25 per cent (38 per cent in the useful soy-bean of the Far East). This high protein content is probably related to their special capacity for obtaining nitrogen (the crucial element in protein), which, as we have seen, comes in so useful for conserving soil fertility, and makes them invaluable as green manures. Moreover, cereal proteins are short of some amino acids (such as lysine) but well supplied with others (such as methionine), while legume proteins are rich in the former and poor in the latter. When maize (cereal) and cow-peas (legumes) in different ratios are fed to young rats, it is found that a 50-50 combination gives the best protein balance; for man, too, the cereal-legume combination provides a balanced protein diet without meat.
When cereal crop agriculture began, it was accompanied in every continent by the growing of legumes. Lentil beans were grown at Halicar in Turkey in the sixth millennium b.c. They were especially common in ancient Egypt, where lentil soup preparation is the subject of a fresco from the reign of Rameses III (late second millennium b.c.). The scale of lentil production in Egypt under the Romans was impressive. When an already ancient Egyptian granite obelisk was shipped to Rome as a souvenir for the Emperor Caligula (early first century a.d.), tons of lentils were used as packing. Remains of peas have been found in a Swiss Neolithic village of the fifth millennium b.c., and broad beans in another Swiss site of the second millennium B.C. Remains of kidney beans dating from 4000 b.c. or earlier occur in caves in Mexico, and kidney beans, lima beans, and a jar of ground-nuts have been found in Peruvian tombs. Manuals on how to grow soy- beans were among the earliest Chinese books (second millennium b.c.).
In due course, all these crops were spread far and wide, and lentils, broad beans, and kidney beans are now almost world-wide.
It seems to have been realized very early that legumes were a food substitute for meat. The first recorded nutritional experiment is described, with admirable scientific precision, in the Book of Daniel. At the end of the seventh century b.c., Nebuchadnezzar, the Chaldean king of Iraq, sacked Jerusalem and carried off most of the Hebrew upper classes to Babylon. The most promising children he decided to bring up in his palace, to be trained into competent Babylonian bureaucrats. He instructed his chief eunuch, Ashpenaz, to feed them for three years from the royal table, after which he intended to inspect their health and educational progress. Among these young students was the prophet Daniel. He realized that the planned diet would include meat that was not kosher (not permitted by the laws of Moses, because not prepared in the Hebrew way); and he asked Ashpenaz, who liked him, if the Hebrew children could be excused. The official objected that if they did not eat the fine nutritious meats they would be less healthy-looking than the other palace children by the time of the king's inspection: "Then shall ye make me endanger my head to the king." The intelligent young Hebrew persuaded Melzar, a subordinate eunuch in charge of catering, to let the Hebrew children live on beans and water for ten days, and observe the result. "And at the end of ten days, their countenances appeared fairer and fatter in flesh than all the children which did eat the portion of the king's meat." So Daniel and his friends were allowed to stick to their leguminous diet.
The royal table of Babylon was certainly supplied with plenty of meat. On account of its scarcity, what meat there was in the hydraulic societies found its way to the larders of the king and the top officials of the bureaucracy. Meat became, and has remained, one of the most universal status symbols in human civilization. In later history influenced by Europe, meat became associated with wealth in money. The Greeks (in the fifth century b.c.) described a new-rich self-made man thus: "now he doesn't like lentils any more." An FAO survey made in a.d. 1964 shows that meat goes with higher incomes today, not only as between individuals but also as between the more and less developed nations (see map). The average New Zealander gets 2-| ounces of actual animal protein per day, the average Indian j ounce. In the U.S.A., animal protein makes up 70 per cent of all the protein in the nation's diet; in India it makes up only 12 per cent. Peasants of the dry belt, today as for so many millennia in the past, must make up most or all of their protein from cereal and legume crops.