After writing about cadavers yesterday, I was reminded of this story that I heard from ... somewhere. I can't remember where I heard this. I'll try to relate this story as far as I can remember.
Up until about 1930, experts believed that SIDS, or sudden infant death syndrome, was caused by an enlarged thymus.The thymus is near the base of the neck. The doctors who did an autopsy on the infant noticed that each babies' thymus was larger than that which was considered normal. They thought that by having a large thymus the infant's thymus may have pinched off the trachea while sleeping and the baby would have suffocated to death.
In fact, the common treatment for preventing SIDS at that time was to have your baby's throats irradiated. The stress caused by the radiation made the thymus shrink, reducing the risk of thymus-induced suffocation. Every concerned parent would have done this for their child because you couldn't tell if your child had a large thymus until it's too late.
There was a problem, though. The thymus doesn't play any role in SIDS. How did doctors get this so wrong? It goes back to the days when medical students would take bodies from the graveyards to dissect and inspect. The families of the dead didn't like this, of course, so medical schools made arraignments with poor houses so that the schools will get all the dead bodies that died in the poor houses. The bodies dissected from the poor houses became the text book standards used for years to come. The problem with this is that people who lived in poor houses lived very stressful lives, and the stress they experienced made their thymuses smaller! The doctors assumed (incorrectly) that the small, stressed-out thymus size was the normal size, so when the autopsies were performed on the SIDS infants, the doctors thought that their healthy thymuses were too big!
This is a really unfortunate accident that caused over 30,000 cases of thyroid cancer from children having their throats exposed to high doses of radiation. It makes you wonder if there is something that we're doing now that we'll regret later.