The following historical incident illustrates well the dangers of haphazard sampling. In the case of status thymicolymphaticus, failing to identify a representative sample actively led to the death of hundreds of people who were otherwise totally heathy.
A second lesson from this history is how women researchers tend to be ignored. Following the advice of a single woman scientist (way back in 1927) would have saved hundreds of lives. The prejudices we develop in our ordinary lifes carry over into our research.
Passages excerpted from the essay "Poverty's Remains" by Robert Saplosky. Reprinted in Saplosky's The Trouble with Testosterone New York: Touchstone, 1997.
The overreliance on anatomical material from the poor has led to other medical mishaps that are not so humorous. On at least one occasion, the distorted data base has had tragic consequences.
When a person is in a state of stress, the hormones secreted by the adrenal glands suppress the immune response. The chronic stress experienced by poverty-stricken people eventually can cause glands essential to the immune system, such as the thymus, located in the throat, to shrivel away to virtually nothing. As a result a disproportionately large amount of autopsy material -- derived as it is from people with diseases caused by chronic stress and deprivation -- included atrophied thymus glands. Thus what was regarded in the 1930s as a normal-sized thymus was actually a greatly shrunken one. The stage was set for a horrendous medical blunder.
For some time pediatricians had identified a relatively new disorder known colloquially as crib death and now called sudden infant death syndrome. Seemingly at random, parents who tucked their healthy infant into bed for a peaceful night's sleep would return in the morning to discover the infant had died. Modern medical scientists have made some progress in understanding SIDS: the disorder seems to occur in infants who in their third trimester as a fetus suffer an oxygen deficiency that damages the brain cells responsible for controlling respiration. At the time, however, physicians had no insight at all into the cause of the mysterious deaths.
Faced with this enigma, a pathologist named Paltauf, working at the end of the nineteenth century, adopted a logical course of research: He carefully autopsied SIDS infants and compared the results with autopsies of non-SIDS infants. Not surprisingly, Paltauf quickly spotted a whopper of a difference: The thymus glands of SIDS infants were far lager than those of the non-SIDS infants. It is perfectly obvious today what was occurring. The latter group, of course, had died of chronic, stressful illnesses that caused thymic atrophy, whereas the former had died suddenly. In examing the SIDS infants, Paltauf was the first pathologist to be systematically observing normal-sized thymuses.
But he had no way of knowing this, and Paltauf framed a hypothesis for the cause of SIDS that got normal and abnormal confused. In some infants, it seemed to him, the thymus was so abnormally enlarged that during sleep it pressed down on the trachea, suffocating the infant. By the turn of the century this disorder had a name, status thymicolymphaticus, and by the 1920s all the leading pediatric textbooks were offering the same advice: To prevent SIDS, infants' throats should be irradiated to shrink the menacing thymus. The treatment became a pediatric fad, persisting well into the 1950s. Irradiation of the thymus, of course, had no effect on the rate of SIDS. But next to the thymus, and equally exposed to radiation, was the thyroid gland, which helps control growth and metabolism. The spurious cure for this spurious disease eventually led to tens of thousands of cases of thyroid cancer.
The original observation of "englarged" thymuses in SIDS infants was reported by A. Paltauf, "Plotzlicher Thymus Tod, Wiener klin," Woeschesucher (Berlin), nos. 46 and 9. The supposed disease was named a few years later in T. Escherich, "Status thymico-lymphaticus, Berlin klin," Woeschesucher, no. 29. An example of the typical 1920s textbook giving advice on preventing the disease with throat irradiation would be W. Lucas, Modern Practise of Pediatrics (New York: Macmillan, 1927); this is the text that contained the information on the personality profiles of infants with status thymicolymphaticus.
Lost amid this consensus of the savants was a 1927 study by E. Boyd ("Growth of the Thymus, Its Relation to Status Thymicolymphaticus and Thymic Symptoms," American Journal of Diseases of Children 33: 867), which should have put the whole thing to rest. Boyd showed for the first time that a stressor (malnutrition, in this case) caused thymic shrinking. She demonstrated, moreover, that children who died in accidents turned out, upon autopsy, to be "suffering" from status thymicolymphaticus, and suggested for the first time that the whole thing might be an artifact. By the mid-1930s, the first studies had been conducted showing that an array of physical or psychological stressors would shrink the thymus, but it was not until 1945 that a leading textbook in the field emphatically stated that the disease was an artifact and that its treatment was a disaster: W. Nelson, Nelson's Texbook of Pediatrics, 4th ed. (Philadelphia: Saunders, 1945). And despite this information, the practice continued widely well into the 1950s.