Man is constantly searching for answers to questions of both the scientific and the spiritual. In 1907, a Massachusetts doctor decided to conduct an experiment that would combine both, when he set out to determine the weight of the human soul.
To conduct his tests, Doctor Duncan MacDougall found 6 patients at a retirement home that were dying of tuberculosis. Dr. MacDougall’s plan was to determine when death was hours away, and to place the entire bed on a huge scale that was sensitive to “two-tenths of an ounce”. He would then stay by their bedside and await death, keeping his eyes on the scale.
When the first patient died, Dr. MacDougall proceeded as he planned. He was immediately excited to see the scale swing at death. He believed that he was onto something big. He said:
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.
The instant life ceased the opposite scale pan fell with a suddenness that was astonishing – as if something had been suddenly lifted from the body. Immediately all the usual deductions were made for physical loss of weight, and it was discovered that there was still a full ounce of weight unaccounted for.
The second patient passed in the same way. The third patient did not immediately lose weight upon dying. However, after a minute, his weight dropped. Dr. MacDougall explained:
I believe that in this case, that of a phlegmatic man slow of thought and action, that the soul remained suspended in the body after death, during the minute that elapsed before its freedom. There is no other way of accounting for it, and it is what might be expected to happen in a man of the subject’s temperament.
After all 6 patients had passed, Dr. MacDougall determined that uniform weight loss of 3/4 of an ounce had occurred in each one. From this he concluded that a human soul weighed 21 grams.
The doctor then performed similar tests on dogs. He found that their weight did not reduce upon death, which he deduced meant that dogs did not have souls. Based on his complaints regarding the ability to find dogs dying of natural causes, it can be assumed that MacDougall was sacrificing dogs for the experiment.
On March 10, 1907, before MacDougall’s results were published in the New York Times. Later in the year they were published in the Journal of the American Society for Psychical Research and the medical journal American Medicine.
At the time, several physicians countered the test results with possible explanations, such as the final exhalation, body sweat, and changes in body density. MacDougall argued back, stating that he had conducted separate tests for each those items and had seen loss, but none were significant enough nor happened quickly enough to cause a change of 21 grams at the time of death.
Today’s scientists and doctors primarily dismiss the results of the test. The sample size was too small, the equipment was not sensitive enough, and MacDougall generally ignored the results that did not fit his theory. The physicist Robert L. Park has written MacDougall’s experiments “are not regarded today as having any scientific merit” and the psychologist Bruce Hood wrote that “because the weight loss was not reliable or replicable, his findings were unscientific.”
After this experiment, MagDougall began a project with the goal of photographing the soul as it left the body. Dr. MacDougall failed to establish any scientific breakthroughs, and passed away in 1920.