Duncan MacDougall and weighing the dead

Science does not exist in a vacuum. Throughout time, it has been utilized and sometimes highjacked in order to have some sort of tangible, "verifiable" confirmation of cherished beliefs. One might argue that part of the success of Christianity and Judaism is because they are historically based. The idea that material, flesh and blood people existed and real events occurred—ones that can be unearthed and studied. It is also part of the reason some fight tooth and nail when the suggestion that some of things in the Bible may be metaphorical—more message than occurrence. This isn't just a religious thing (Darwin did not formulate "social Darwinism") but matters of faith and of the metaphysical variety are common candidates for these attempts to use science in order to "prove" the veracity of key beliefs.

One important belief—not confined to just the two aforementioned religions by any means—is a belief in something called a "soul."1 A part of the person that exists, a spark of life that makes the person special, "human," different from mere animals. It is also a human's connection with the eternal. Not only is the soul a part of "who you are" and the lifespark, it is a part of the person that continues well after the death of the body. Of course, a soul is apparently intangible and invisible; it is a matter of faith. But if someone could show, somehow, that such a thing existed. If someone could verify that belief in eternal life. That would fulfill the all-too-human desire to, Thomas-like, probe the wounds for proof that can be seen and felt.

In the early twentieth century, a certain Massachusetts (Haverhill) doctor named Duncan MacDougall thought he could do just that. MacDougall felt that the soul did indeed have a materiality—at least as far as weight goes (this belief would expand later on). It was probably very little but he was convinced that careful experiments would reveal that shortly after death—when the soul vacated the body—there would be a measurable decrease in the weight of the body. He wasn't the first one to posit this "theory" that souls might have measurable characteristics, but in 1907 he became the first to test the idea.

Setting to work, he constructed a special bed in his office. It was "arranged on a light framework built upon very delicately balanced platform beam scales." Since he would need to be precise and because the soul would likely have very little weight, he made his creation sensitive to 0.2 ounces. Then, of course, came the next step. He would need subjects who would agree to be monitored before, during the death process, and following the actual death. Of these six subjects, four suffered tuberculosis, one diabetes, and the sixth an indeterminate illness (or one that was not recorded).

While making sure of each patient's comfort, he carefully studied any changes in weight throughout the period. A person's weight fluctuates quite a bit over time (though often by amounts that most typical scales cannot measure). MacDougall needed to determine those fluctuations and the conditions under which they would take place. This way he hoped to control for variations that might lead to false conclusions. One patient was closely observed over a period of three hours and 40 minutes (until death). MacDougall determined that from evaporation of sweat and moisture from respiration, the patient lost about one ounce per hour.

When the patient finally "expired," he noted a drop of approximately three-fourths of an ounce (just about 21 grams) beyond what was expected from previous measurements. He could not otherwise account for the loss. There was no bowel movement and though a small amount of urine flowed at death, it remained on the bed, meaning that it could not account for the loss of weight. He and his partner then checked to see what difference full or empty lungs would make. They determined that it didn't affect the weight.

MacDougall was fairly sure he could explain the experimental evidence with his theory. Another test was done to see if the loss was human-specific. The experiment was reproduced using fifteen dogs (presumably killed for the purpose of his proving the existence of the human soul).2 Generally, animals are thought not to have souls so if there was no weight difference before and after death, then it would bolster his contention that the weight change was (or at least might be) the soul. It confirmed his expectations, "the results were uniformly negative, no loss of weight at death."

Confident that he had made a breakthrough in science and religion, he published his results in both the New York Times and a medical journal (American Medicine). His conclusions and methodology were attacked immediately. To be fair, even MacDougall recognized that many more trials had to be made and the results replicated. But he felt that he had proved that "there is in the human being a loss of substance at death not accounted for by known channels of loss" and that the dog trials showed that the loss was unique to humans.

So aside from the dogs, what about those human subjects? The results were inconsistent across the board (his small sample of only six people was one of the many objections to his conclusions). Sure there was the already noted "three-fourths ounce" change. But moving on to the others, his results were inconclusive. Another was found to only lose a half ounce. Apparently not realizing if the patient was dead, MacDougall's partner listened to the heart (called by the fancy term "auscultation") and found it had stopped beating. They checked the weight again and found the loss to one and a half ounces (and 50 grains). That would be about 45.6 grams. In the third case, the person lost a half ounce at death. Then lost another half ounce a few minutes later. 28.3 grams.

The fifth one was indeed curious. It "showed a distinct drop in the beam requiring about three-eighths of an ounce which could not be accounted for. This occurred exactly simultaneously with death but peculiarly on bringing the beam back up again with weights and later removing them, the beam did not sink back to stay for fully fifteen minutes." In other words, the weight slightly increased at first but reversed before later returning to a higher weight.

So far, there were three clear drops, though only one was a single event rather than an initial drop followed by a later additional loss. Then there's the puzzling fifth trial. Worse are the other two. The fourth case was thrown out by MacDougall ("I regard this test as of no value") because the scales "were not finely adjusted" and "a good deal of interference by people opposed to our work." The sixth was useless because the subject died on the bed before the scales were all adjusted.

MacDougall's conclusions were solely on the back of 15 dead dogs (no record that he bothered to test any other animals—perhaps one that had approximately the same weight as a given human subject), and only one patient that showed the expected results. The other two that dropped are at the least very problematic unless the nature of the weight drop can be explained or controlled for. There is also the distinct differences in the weight of the hypothesized "soul" without much attempt to explain why "souls" would not have a uniform (or narrower range) weight. And if they do not have a uniform weight, then there must be some way to determine when a weight change is due to the evacuation of the soul or something else.

Other problems were apparent, one being the determination of the exact moment of death (accompanied by the assumption that it is at that precise moment the soul leaves the body). MacDougall said the moment in question was when the person exhaled the final breath and would try to explain away the inconsistencies between the drop rate by claiming that "the soul's weight is removed from the body virtually at the instant of last breath, though in persons of sluggish temperament it may remain in the body a full minute. Of course, one wonders how he was able to determine that as the reason (or what qualifies as a "sluggish temperament"). Assumptions are at every step of his experiment and are later used to make the evidence conform to the "theory."

But MacDougall was convinced. A true believer. Even considered an "expert" of some sort on the subject of science and souls. Four years later he made the front page of the New York Times discussing the use of x-ray technology to photograph the soul (a serious program being undertaken at the University of Pennsylvania, apparently). He dismissed the idea that a simple x-ray could capture the soul because an x-ray was "in reality a shadowy picture." On the other hand, he felt that at that precise moment of death "the soul substance might become so agitated as to reduce the obstruction that the bone offers" to x-rays and would be revealed as a "lighter spot on the dark shadow of the bone" in the developed plate.

The article went on to say that he believed that this "soul substance gives off a light resembling that of interstellar ether."

McDougall died in 1920 and his legacy that we have inherited is the idea that upon death the soul exits the body, leaving it 21 grams lighter. Even though only one of the six exhibited that weight change. And after all those additional assumptions that allowed him to believe that he had discovered scientific proof of the human soul.

Hope springs eternal....

1For the sake of discussion, I'm using a general mainstream Christian view (since specifics can vary from denomination to denomination, not even counting personal variations within denominational views). It is likely the view which the doctor was working with.

2In his own words, "the ideal tests on dogs would be obtained in those dying from some disease that rendered them exhausted and incapable of struggle." He would also add that "it was not my fortune to get dogs dying from such sickness." The reader may draw his or her own conclusions.

Source and all quotes: "Soul Man" http://www.snopes.com/religion/soulweight.asp