 Throughout history, mankind has sought to answer what happens after death. After all, the end of life is part of the human condition. In an effort to alleviate our fears of demise, many theologians, religious scholars and scientists have sought to discover proof of the soul, and to a greater extent, where it goes post-death. One such scientist would set out to find if the very centre of our being has a physical weight. Although an impossible task you might think, a theory was conceived that concluded that a soul weighs around 21 grams. Derided as a case of selective reporting, the theory would see widespread rejection within the scientific community. Despite this, many see the results as a hopeful glimmer of life after death. In order to prove this, the study would go down a dark path. Welcome to the dark side of science. It is 1907, and a new theory of proof of the soul is leaked in the New York Times. The headline exclaims, the soul has a weight. Decision from Haverhill, Massachusetts, Duncan McDougall thinks. But our story starts all the way back in Glasgow in 1866, with the birth of Duncan McDougall. He emigrated to Haverhill, Massachusetts in the United States at around the age of 20. Shortly after emigrating, he attends the Boston University School of Medicine, receiving his medical degree. He would return to Haverhill where he would meet Mary and have a son in the mid 1890s. Like many people of this era, McDougall was fascinated with death and the human condition. As such, he devised a way to prove the existence of the soul. He surmised that if we have a soul, that it must hold a physical space and therefore can be weighed. Once death is complete, then in theory, as consciousness is extinguished, when the soul leaves the body, then the weight of the deceased will change. In his 1907 hypothesis, published in the Journal of the American Society for Psychical Research, he said, Since therefore, it is necessary to the continuance of conscious life and personal identity after death, that they must have a basis that which is space occupying or substance. The question arises, has this substance weight? To prove the theory, McDougall needed access to people near the point of death. But not only that, but also incapable of being able to move, as this would make conducting the weighing easier and more accurate, as said by McDougall himself. It seemed to me the best to select a patient dying with a disease that produces great exhaustion, the death occurring with little or no muscular movement. Because in such a case, the beam could be kept more perfectly at balance, and any loss occurring, riddily noted. Needless to say, this task is easier said than done. As very few people in their last moments of life would be willing to take part in a study, but a disease that killed roughly 25% of the adult population would create a ready supply of bedridden subjects, and this was named consumption, or better known today as TB. The disease takes a relatively easily predictable progression, allowing sufferers time to make arrangements for their affairs post death. This prediction of the time of death was assisted with the discovery of the X-ray in 1895 by Wilhelm Röntgen. As the disease was spreadable by kissing, coughing, breathing or sneezing, many sufferers were sent to homes for treatment and to stop the spread. One of these was Dr. Cullis's Consumptives Home. Between the 1860s and 1890s, the institution based in Roxbury, Massachusetts, had taken care of over 2,000 critically ill patients. Dr. Cullis believed in cure by faith, in which prayer would help heal the sick. Although not the most scientific method, the home offered comfort and care for its patients. MacDougall had been refused by many homes for his morbid study into the point of death, but Cullis's home offered an opportunity for MacDougall. The faith-based institution who agreed to allow the scientific experiment thought that proving that the cell was real could have both spiritual and medical importance. In total, six dying people would volunteer for the experiments. The process set out for the experiment involved taking the patient as their last moments approached, and placing them into a cot suspended from a Fairbank scale, sensitive to two-tenths of an ounce. Due to the progression of the disease, the patients were so ill they did not move, allowing the measurements to be accurate. MacDougall and two physicians carefully observed the patient, noting the weight on the scale. As the moment arrived, they recorded the exact time of death and looked for any change or weight at that moment. The experiments would start on the 10th of April 1901, when the first volunteer was wheeled into a room which housed the cotton scales. The man continued to breathe for three hours and 40 minutes before death. Suddenly, coincident with death, the beam end dropped with an audible stroke hitting against the lower limiting bar, and remaining there with no rebound. The loss was ascertained to be three-fourths of an ounce, or roughly 21 grams. The second subject, a man also suffering from TB, was observed for four hours and 15 minutes before his death, at which time the weight dropped half an ounce. Four more patients would be observed by MacDougall. Patients three and five were observed losing a small amount of weight, but four was discounted due to scale failure and six was disallowed due to the patient dying while entering the cot. In MacDougall's thinking, animals didn't have souls, so as a control of sorts, he conducted the study on 15 dogs. He would later state, surrounded by every precaution to obtain accuracy, and the results were uniformly negative, no loss of weight at death. Although not explicitly stated, it is likely that the dogs were poisoned in order to measure the moment of death. The tests on the dogs were vitiated by the use of two drugs, administered to secure the necessary quiet and freedom from struggle, so necessary to keep the beam at balance. Six years later in 1907, before his results were published in the Journal of American Society for Psychical Research, The New York Times released the story. The study, upon publication, received strong criticisms. One of the loudest was from physician August P. Clark. Clark explained that the difference in weight loss between humans and dogs was primarily due to one thing, sweat. You see, as the body dies, the cooling effect of breathing no longer takes place, leading to a momentary increase in body temperature, causing a quick burst of sweat, which would evaporate, and this could easily account for the missing 21g. The big difference with dogs is that they don't have sweat glands, so wouldn't lose the weight in this manner. The criticism from the wider scientific community wouldn't stop there, as it was pointed out that only one case after the four recordings of weight resulted in 21g, which would suggest a case of selective reporting. From a modern perspective, the methods used in 1901 to ascertain the exact moment of death are not as accurate as you would have liked. Wiringly for the results, this is even semi-admitted by McDougal himself for the second patient. For the last 15 minutes, he had ceased to breathe, but his facial muscles still moved, convulsively, and then coinciding with the last movement of facial muscles, the beam dropped. Another criticism is the sample size, which, by most scientific standards, is way too small to yield any discernable result of a total of 6, with only 4 results being allowed. Many other variables were not controlled, for example, temperature of the room, cause of death, and even it's being limited to just one institution. The imprecise nature of the study meant the results were far from reliable. But the reason that the experiment is known today, and not just a bizarre footnote of strange history of science, is its cultural impact. Needless to say, fundamentalist religious groups of the day embrace the findings, and even though Dr. Duncan McDougal would pass away in 1920, the weight of 21g permeated itself into modern day culture. More modern attempts of a recreation of the study by Lewis E. Hollander Jr. on various animals actually yielded an unaccounted-for weight gain. So I'm going to rate the 21g experiment to 5 on my ethics scale, and that's mainly for the needless slaughter of the dogs. How would you rate this experiment? Let me know in the comments below. This is the Plain Difficult Production. All videos on the channel are creative commons attribution share alike licensed. The Plain Difficult videos are produced by me, John, in a currently sunny southeastern corner of London, UK.