New Views on Immigration. Politics Culled from Palestinian’s Study of Flies

Long rows of milk bottles swarming with flies, ranked on the shelves of a laboratory at the Hebrew University, are providing data today for a new scientific view of historic, political and sociological events.

From the bottled flies, Professor F.S. Bodenheimer has drawn far-reaching inferences about such phenomena as liberalism and conservatism, democracy, fascism and communism, rising and falling birth rates, longevity, fertility and other matters of major social and political importance.

One of his conclusions, of great significance to human affairs, is that the population of any region will reach the same level, no matter how great the immigration into that region, if other conditions remain the same.

Another, still more startling, is that when the population of a country is increasing rapidly, liberal ideas prevail and democracy is popular, but when the increase slows up, as it must do if other circumstances remain unchanged, a reactionary political outlook sets in and fascism appears.

In general, Prof. Bodenheimer found amazing similarities between the reactions of fly-populations in the laboratory milk bottles and those of human populations in the nations of the world.

Professor Bodenheimer, son-in-law of Menachem M. Ussishkin, world president of the Jewish National Fund, is head of the Hebrew University’s department of entomology and animal ecology, and one of the foremost experts in his field. He attained world-wide renown ten years ago when, on an expedition into the Sinai Peninsula, the desert where the Jews wandered for forty years on their way from Egypt to the Promised land, he re-discovered the “manna” mentioned in the Bible.

His present researches are being conducted not only with the flies in his university laboratory, but in field laboratories at Kiriat Anavim, Jewish colony in the Judean hills, and at Petah Tiqva and Hedera. At Kiriat Anavim Prof. Bodenheimer is directing studies of pests which attack fruit trees of the hills, and at the other two laboratories, of pests attacking citrus trees.

From these and other studies, coordinated with the work of scientists throughout the world, there have come discoveries of great value about various insect, rodent and other pests and the means of combatting them.

In the course of this research, Prof. Bodenheimer explained, statistics on animal population had to be gathered in great abundance and exhaustively studied. These studies were made with the bottled flies, with field mice, with bees, and with locusts. Besides, data compiled by Aldo Leopold, of the University of Wisconsin, a study of game bird populations financed by American gun manufacturers, and of the Hudson Bay Company’s 150-year records of population of fur-bearing animals in Canada, were also consulted by Prof. Boden-heimer.

Basing his work on that of his friend Dr. Raymond Pearl, of Johns Hopkins University, Prof. Bodenheimer said, he went on to draw some conclusions of his own. The bottles of flies were studied, he said, in order to obtain an exact daily census of the fly population within a closed area under controlled conditions, from the egg until the death of the insect, and also to learn the rate of increase of adult fly populations. The flies used were the fruit fly, Drosophila.

The experiment was started by placing a measured quantity of food gelatine in each bottle, and two pairs of adult flies. Within a few days all the bottles were swarming with flies. Given a certain quantity of food, the number of flies in a bottle, it was found, would always reach the same amount. If the amount of food were larger, the number of flies would be greater, if less, there would be fewer flies.

Then Prof. Bodenheimer began the same process again, but this time, as the experiment progressed, he introduced “immigrant” flies into the bottles. No matter how many additional flies were introduced, and how long the “immigration” kept up, the end result was always the same — with a certain amount of food, the population of the bottle reached a certain number.

If a very big “immigration” sent the fly population above the normal number, then the birth rate declined and the life-span of the individual furies was shortened, so that the total soon fell to normal. Whatever variation was tried, the end result was always the same — with a certain amount of food the bottle’s population reached a certain number, no more, no less. The decline in birth-rate of the Drosophila flies in an overcrowded bottle was enormous, Prof. Bodenheimer said. It fell to 1/1,000 or less of its original level.

“Here,” he said, “we have a living parallel to the reproduction conditions in over-populated cities where these are primarily dependent on purely biological factors.”

The explanation, Prof. Bodenheimer speculated, may be that ultra-density of population, acting indirectly on the general nervous system, reduces the fertility of the female. “The growth of human population,” he said, “proceeds according to the same laws as that of the protozoa in the test tube or the Drosophila in the bottle.”

Pointing out how the experiment might be applied in human affairs, Prof. Bodenheimer cited the case of Palestine. Before the World War, he said, the Holy Land was supporting all the people it could, in the state of industry and agriculture at that time. Its population had remained stable for many years. After the war, Jewish activities and investments enormously increased the number of persons whom the country could sustain, he added.

“You might say that the food-space was increased,” Prof. Bodenheimer continued. “It is just as if you put more food jelly into the bottle. Nature abhors empty space. The additional space the Jews created in Palestine — not additional area, but accommodation for more people — will be filled up. If the Jews are not allowed to fill it the Arabs will.”