The image of Jesus with his hands and feet nailed to the cross is such a ubiquitous symbol in the western world that it’s easy to gloss over the extreme cruelty of the execution method that it depicts, in which a condemned person was forced to suffer a lingering, agonizing death in public. Crucifixion was such a horrible way to die that Rome—who adopted the practice from the ancient Phoenicians in the third century B.C.—generally didn’t use it on its own citizens, instead reserving it for rebellious slaves, foreigners, and soldiers who deserted to join the enemy.
Even so, our knowledge about crucifixion contains gaps and uncertainties. Although crucifixion is mentioned by ancient writers such as Cicero and Josephus, the only archaeological evidence of crucifixion is a heel bone pierced with a large iron nail sometime during the first century CE, which was discovered near Jerusalem in 1968.
There’s been on-going scientific debate over the years about how exactly crucifixion killed its victims. A 2006 article in the Journal of the Royal Society of Medicine, for example, listed 9 different hypotheses about Jesus’ precise cause of death, including asphyxiation, heart failure, a blood clot in the lungs, and hypovolemic shock, in which severe blood and fluid loss prevent the heart from pumping enough blood to the body, causing organ failure. Some researchers conclude that condemned prisoners such as Jesus most likely died from some combination of various life-threatening conditions, which would set in progressively during crucifixion and gradually overwhelm their bodies.
But of all those effects, the most lethal effect of crucifixion was that it was designed to interfere with a condemned prisoner’s ability to breathe. That process likely began before the crucifixion, when guards brutally beat the condemned with a flagrum, a short whip with sharp objects interwoven into its thongs. As medical examiner Frederick T. Zugibe noted in his book “The Crucifixion of Jesus: A Forensic Inquiry,” the repeated blows would cause broken ribs, lacerated and collapsed lungs, and damaged the muscles in the torso, which would make it difficult and painful to breathe. He then would be dragged to his feet and forced to carry part of the cross to his place of the place of execution, which weakened his body even more.
At that point, the Romans attached the prisoner to the cross. In some instances prisoners were tied with rope to it, which might enable them to survive for several days. But according to the New Testament, Jesus and other unfortunates were attached with nails. It is thought that the feet were nailed vertically to the upright beam with the knees bent at around 45 degrees. In the 1950s, French surgeon Dr. Pierre Barbet, based in part upon an experiment that he performed with a cadaver, proposed that the nails were driven between the bones of Jesus’s wrist. That would have severed the median nerve, paralyzing the hands and caused excruciating pain. Zugibe however, argued that the palms, as described in the New Testament, were sufficiently strong enough to support the executed person’s weight, and were “the most plausible location.”
Otherwise, as the cross beam was put into place, the prisoner’s thigh muscles would eventually fail, so that he couldn’t support himself with his legs. That, in turn, transferred his body weight to his arms, pulling his shoulders from their sockets. He was left in a position in which his chest and rib cage were thrust forward. As Jeremy Ward, a physiologist at King’s College London explained to the Guardian newspaper in 2004: "The weight of the body pulling down on the arms makes breathing extremely difficult." In some instances, when the Romans wanted to prolong the suffering, they might attach a sedile, or seat, to the cross, which reportedly allowed some victims to survive for days. But according to Zugibe, they probably did not provide a sedile for Jesus, since Jewish scripture barred executioners from leaving a condemned person on the cross overnight.
The weight of the body pulling down on the arms makes breathing extremely difficult.
As the prisoner struggled to get air, the lack of oxygen in the blood would damage his body’s tissues and blood vessels. That, in turn, would allow fluid to diffuse out of the blood into the tissues, including the lungs and heart sac. The lungs would stiffen, and the pressure around the heart would make it more difficult to pump. The decreased oxygen also would damage the heart muscle, which could cause cardiac arrest. Either way, an agonizing death eventually would result. Sometimes, the executioners would speed the process by breaking the condemned’s legs, which would hasten suffocation.
But regardless of exactly what caused a condemned prisoner to die on the cross, one thing is clear. Crucifixion was a grotesquely cruel form of execution—so much so that over the centuries, religious artists often have toned down the most graphic details. As Dr. Thomas McGovern, a Fort Wayne, Ind. physician who has studied crucifixion, once explained in a newspaper interview: “our crucifixes are much too pretty.”