21 grams: the experiment that measured the weight of the Soul

It was 1901, and Duncan MacDougall, a physician from Haverhill, Massachusetts, thought of measuring the weight of the soul, intrinsically proving its existence. According to him, at the moment of passing away the human body would lose the weight of its soul, free to migrate to other places than our mortal remains.

MacDougall, who wished to scientifically determine if a soul had weight, identified six patients in nursing homes whose deaths were imminent.
MacDougall recorded their weight during the hospitalization, and when the patients looked like they were close to death, their entire bed was placed on an industrial sized scale that was sensitive within two tenths of an ounce (5.6 grams). Four were suffering from tuberculosis, a disease that in the United States often meant ending up in hospital awaiting the death, one from diabetes, and one from unspecified causes. He specifically chose people who were suffering from conditions that caused physical exhaustion, as he needed the patients to remain still when they died to measure them accurately.

In a 2015 article in Discover Magazine, the body weighing process is described in detail. “MacDougall recorded not only the exact time of each patient’s death, but also the total time spent on the bed, as well as any changes in weight occurring near the time of death. He even calculated the losses of body fluids such as sweat and urine or gases such as oxygen and nitrogen“.
In support of his theory that humans have souls and that animals do not, MacDougall later measured the changes in weight from fifteen dogs after death. MacDougall said he wished to use dogs that were sick or dying for his experiment, though was unable to find any. It is therefore presumed he poisoned healthy dogs, reporting no weight loss.

MacDougall published his own study in American Medicine and before he was able to publish the results of his experiments, The New York Times broke the story in an article titled “Soul has Weight, Physician Thinks”. However his report, which was not published until 1907, stated the experiment would have to be repeated many times before any conclusion could be obtained.

MacDougall’s conclusion was surprising: the soul weighs 21 grams, or three quarters of an ounce.
One of the patients lost weight but then put the weight back on, and two of the other patients registered a loss of weight at death but a few minutes later lost even more weight. One of the patients lost “three-fourths of an ounce” (21.3 grams) in weight, coinciding with the time of death. MacDougall disregarded the results of another patient on the grounds the scales were “not finely adjusted”, and discounted the results of another as the patient died while the equipment was still being calibrated.

In reference to a case, MacDougall told the New York Times: “When life ceased the scale of the balance suddenly fell, as if something had immediately risen from the body“.
However, the news was treated with a certain skepticism by his contemporaries. In particular, physician Augustus P. Clarke noted that at the time of death there is a sudden rise in body temperature as the lungs are no longer cooling blood, causing a subsequent rise in sweating which could easily account for MacDougall’s missing 21 grams.
Clarke also pointed out that, as dogs do not have sweat glands, they would not lose weight in this manner after death.

MacDougall disputed the criticisms, and supported his own theory by citing a particular case. He spoke of a patient of large physical build and lazy temperament, who showed no weight changes for a full minute after his death.
After a minute or so he lost exactly 21 grams
MacDougall concluded that the soul “of a phlegmatic man, slow in thought and action … remains suspended in the body after death, during the minute that passes before consciousness of his freedom arrives“.

The scientific community did not accept the MacDougall studies, but he had a considerable following of supporters. The scientific value of the study cannot be ascertained because the exact measurement systems used during the experiment could not be understood. The doctor even photographed the faces of other patients at the time of death, claiming that an ethereal light was spread at the time of death, a test that was difficult to consider in a scientific way.
Although the value of MacDougall’s research is essentially everything to prove, in the last 110 years no other similar research has been conducted, but the “weight of the soul” is famous for being 21 grams, a legend also taken up by the director Alejandro González Iñárritu in his famous “21 Grams” of 2003.