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The Real Story Behind "21 Grams"

The April 1907 issue of American Medicine featured a paper by Dr. Duncan Macdougall describing his experiment whereby the beds of dying patients were placed on a sensitive balance. Believe it or not, he was trying to weigh the human soul! The paper was titled “Hypothesis Concerning Soul Substance Together with Experimental Evidence of The Existence of Such Substance.” Macdougall of Haverhill, Massachusetts placed six dying patients on the specially constructed balance and concluded that at the moment of death there was a loss in weight of about three quarters of an ounce, or 21 grams. He had previously determined the weight loss attributed to evaporation of moisture form the skin, and by comparison this was sudden and much larger. He even controlled for weight loss due to urine and fecal eliminations and concluded that these could not account for the change in weight. Air loss from the lungs was not the answer either, as he determined by lying on the scale himself and noting that breathing had no effect on weight. After weighing his six patients, Macdougall went to work on dogs. How he got his hands on 15 dying dogs is not clear, but he found no weight loss at the moment they expired. He wasn’t surprised of course because he didn’t think dogs had souls. No one since has confirmed Macdougall’s findings but the movie “21 Grams” was based on this idea.