by Gary Comstock
Imagine yourself fifty years from now standing in the middle of a huge antiseptic warehouse staring at rows of tan colored objects that look something like footballs. Shiny stainless steel pipes descend from the ceiling and disappear into mouth-like orifices on top of each object. Black rubber tubes are attached by suction cups to the bottoms. The only attendant in the building tells you that the pipes bring water and rations to what he calls "the birds," while the rubber tubes carry excrement and urine to a sewer beneath the floor. Every twelve hours each bird drops a no cholesterol egg onto a conveyor belt. "Regular as clockwork," he adds with a wink.
You are staring at thousands of living egg machines, transgenic animals genetically engineered to convert feed and water into eggs more efficiently than any of their evolutionary ancestors, layer hens. The science fiction objects I am asking you to imagine are biologically descended from the germplasm of many species unrelated in nature, including humans, turkeys, and today's chickens, so the worker is not speaking in mere metaphor when he calls the objects "birds." But unlike today's poultry varieties, which are only treated as machines, the brave new birds I have in mind really seem to be more machine than animal. For, in coming up with the new birds, poultry scientists have not only selected for the trait of efficient conversion of feed into eggs; they have also selected for lack of responsiveness to the environment. The result is not a bird that is dumb or stupid, but an organism wholly lacking the ability to move or behave in dumb or stupid ways. Scientific research shows that the egg machine's complete lack of any externally observable behaviors is paralleled by its lack of physiological equipment necessary to support behaviorial activity. The brain of the bird is adept at controlling the digestive and reproductive tracts, but the areas of the brain required to receive and process sensory input and initiate muscular movement have been selected against, bred away. The new bird not only has no eyes, no ears, no nose, and no nerve endings in its skin; it has no ability to perceive or respond to any information it might receive if it had eyes, ears, or a nose.
The unlikely organism I have just described is a philosopher's fantasy, inspired by a remark of Bernie Rollin's. I have never heard a poultry scientist or agbiotech enthusiast describe anything like it as a viable goal at which agricultural genetic engineers should aim.
In 1982, scientists injected a rat growth hormone gene into the chromosome of a mouse. The resultant animal expressed the rat gene and quickly grew to twice its parents's size. The journal Science published a picture of the pair, since become famous. In 1985, researchers at the United States Department of Agriculture hoped to attain similar results by inserting human growth hormone genes into the chromosomes of pigs. At the Agricultural Experiment Station in Beltsville, Maryland, experimenters successfully microinjected the piece of DNA encoding the production of human somatotropin into the nucleus of fertilized pig eggs. The extracted embryos were reimplanted into the uteruses of sows, the pregnant animals came to term, and the first piglets in history with human genes were born.
The Beltsville research program was not aimed at producing hogs twice the size of their parents but at producing more cost effective swine, pigs that would convert grain into lean meat faster than their parents while eating proportionately less grain. Such animals would be a boon to certain sectors of the agricultural economy, including most of the pork industry, some hog farmers, and many meat consumers. The industry might cut costs by slaughtering fewer animals per pound of meat; farmers might reduce expenditures on feedgrains while continuing to sell the same amount of pork; and consumers might benefit from industry and farm savings passed on to them at the meat counter.
Nineteen transgenic swine lived through birth and into maturity. Several expressed elevated levels of the growth gene, but none grew more quickly or to greater size than their counterparts in the control group. Many suffered from "deleterious pleiotropic effects," medical problems not afflicting the controls. They developed abnormally and exhibited deformed bodies and skulls. Some had swollen legs; others had ulcers, crossed eyes, renal disease, or arthritis. Many seemed to suffer from decreased immune function and were susceptible to pneumonia. All were sterile.
Researchers concluded that if transgenic swine were to be produced as successfully as transgenic mice, "better control of transgene expression, a different genetic background, or a modified husbandry regimen" would be required. Further experiments were planned.
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Last Update 06/06/03