Crucifixion remains a familiar idea, even though it's a punishment from the distant past. It's so familiar that we no longer consider of the physical realities of it. Those realities are some of the most gruesome ever known. Here's how crucifixion actually kills people.
Crucifixion stopped being a regular practice long before anyone cared how it killed people. This was good news for all of humanity, but it did leave scientists speculating. The method of crucifixion is brutal, but in terms of wounds and exposure people have survived worse. How did crucified people die?
The Method of Crucifixion
To understand how people died, we have to look at the many methods of crucifixion. Today we have a very limited idea of crucifixion. There was no official, regularly-practiced method. Historical records say that people were not just nailed in the pose we see on religious crucifixes, but were "caught to the crosses in different postures by way of jest." People were crucified upside down, or with their hands together. Even when people were crucified in the way we imagine the process today few victims were crucified with nails through their hands. Putting a person's whole weight on a relatively delicate piece of flesh would tear the hand enough that the person could pull the nail through the whole hand and free their upper bodies. People were crucified through the wrists, which were harder to tear loose.
Nailing a person's feet to the upright section of the cross wasn't an afterthought. Precisely how the lower body was treated could affect how long a person lived. Most victims simply had their feet nailed into the wood so that their knees were bent at forty-five degree angles. Some had their legs broken. Whether this was an act of cruelty or mercy depends on one's perspective.
Hanging from the arms for any considerable length of time is painful. Once the muscles give out it is excruciating. Shoulders separate from the sockets and the overall arm can lengthen by inches. Most people would try to support themselves by putting pressure on their injured feet, but with their legs bent and their feet nailed through it was only a matter of time before their leg strength gave way as well. Breaking their legs was horrible, but on the other hand, allowing them to support themselves prolonged their suffering.
The Medical Side of Crucifixion
What part of their suffering lead to death is debatable. Through the centuries doctors have looked into it, and come to different conclusions. Some say that crucifixion alone wasn't enough to kill a person, and so the victims probably died of exposure or thirst after days on a cross. One doctor believed that crucified people, after much torment, died via a "voluntary surrender of life." Some think that the wounds elsewhere in the body sent a blood clot to the heart. One expert in forensic medicine, Frederick Zugibe, actually tied himself and volunteers to a cross to monitor what physically takes place during a crucifixion. He concluded that victims died from "hypovolemic shock." This condition sets in when a body has lost so much blood and fluid that the heart can't continue to function.
If any of these are the case, it's the injuries and exposure that determined the cause of death by crucifixion, not the position of the person on the cross. Most experts agree, though, that what ultimately kills a crucified person is suffocation. Either the body loses so much oxygen that the person smothers, or the carbon dioxide level in the body goes up so much that the body tissues turn acidic and destroy their own cells. How fast it happens depends on a lot of factors.
One common form of crucifixion didn't involve a cross. A person was crucified with their hands over their head. This made it so difficult to breathe (once their strength had given out) that they were dead within an hour. Being crucified with arms outstretched was comparatively much worse. After a person's arms had come out of their sockets the chest would sag downwards, stretching out to its full extent. If you strenuously stretch out your arms, even while seated, you'll recognize the difficulty. It's easy to inhale with arms fully outstretched, but difficult to exhale again. The body needs to work its muscles to breathe in and out, and it is used to doing so with little resistance. Once the chest is fully expanded, it's impossible to breathe in anything more than sips of air. The victim slowly suffocates, unable to get enough oxygen, over the course of a day. There are probably more painful, and horrible ways to die. Let's not look for them.
Top Image: Tretyakov Gallery
Third Image: US National Archives