I’ll admit, as a student of science, I have a tendency to assume some degree of validity and accuracy in my reading and work. But recently I came across a podcast from NPR’s Radiolab which dramatically shook the foundations of my assurance. It’s changed the way I approach my experimental work, it’s changed my perception of science, and for at least a few days, it developed into my way of greeting friends – “So, you’ll NEVER believe what I heard the other day…”

This story begins in the early 1920s, when researchers first started considering possible causes for SIDS (Sudden Infant Death Syndrome), the unexplained and unexpected death of infants during sleep, which is responsible for 2500 infant deaths per year in the U.S. alone. The obvious approach was to autopsy afflicted infants and compare the autopsy results to non-SIDS related infant deaths. Researchers found that many of the SIDS infants seemed to have enlarged thymus glands, especially in comparison to non-SIDS infants.

Soon a plausible hypothesis emerged: maybe the swollen thymus glands were putting pressure on the trachea of the infants during sleep, resulting in suffocation. Almost immediately, potential treatment options starting catching on in an almost fad-like fashion; all experts in major pediatric circles advised that parents irradiate their childrens’ thymus glands to limit thymus swelling and growth. You were considered an irresponsible parent if your children did not undergo the procedure, so thousands of concerned parents urgently scheduled doctors’ appointments. It seemed as though science had provided another miraculous breakthrough- SIDS would be eliminated, and thousands of infants and their parents could sleep easy at night. But everyone was completely wrong.

Flash back to the Revolutionary War, just as our predecessors were beginning to establish medical schools. Of course, no medical school could provide comprehensive medical education if did not include cadaver dissections in its curriculum, so medical schools needed bodies. Lots and lots of bodies. It turns out that the easiest bodies to attain were those buried just below the surface. These were the bodies of the impoverished and poor, the unfortunate many who could not afford lavish funerals. Therefore, medical schools started performing research on these bodies and built vast stores of knowledge based on the data they collected.

What does all this have to do with SIDS? Quite a bit, actually. The thymus gland is a part of the human body’s natural immune defense system, so it is especially sensitive to prolonged stress. In fact, it will shrink in individuals who are chronically stressed. We know today that individuals living in poverty are subject to significantly more prolonged stress than average individuals, since they have to deal with issues like putting food on the table and paying the rent every day. In other words, the cadavers that medical schools had been studying since the Revolutionary War, which were often obtained from these poorer families, tended to have shrunken thymus glands. The apparently swollen thymus glands first observed in SIDS infants in the 1920s were, in fact, our first glimpse at normally-sized thymus glands. In other words, the irradiation treatments had been useless; all the doctors had been wrong.

However, this mistake also had a real human cost. The thyroid gland, which is located next to the thymus gland, had been equally exposed to the irradiation during the treatments. By the time scientists realized their error, thousands of children had already received treatment, and many passed away in early adulthood due to thyroid cancer.

One innocent, unnoticed bias in data collection, that’s all it took. We had been wrong for centuries. And who knows how many times we’ve repeated similar mistakes or how many lives have been lost as a result? It’s another reminder that, although we take comfort in the beautiful precision of scientific experimentation, these are just clumsy attempts to navigate a world which is vastly unknown.