How long can a severed head really live?

Knocking someone's head clean off their body has always seemed to be a surefire way to kill them. It kills vampires. It kills zombies. It kills Highlanders. There's nothing like a beheading to make sure that something stays dead. But how long does it take to die?

Barring a very clumsy axeman, it's thought that beheadings render the victim effectively dead at the moment of the stroke. There are some gruesome legends, however, that the head of the person might retain consciousness from anywhere between five and thirty seconds. One French physician wrote in 1905 of his observations of a recently guillotined head. The previous owner of the head was a prisoner, and after the severing of the head, the doctor picked it up.

I waited for several seconds. The spasmodic movements ceased. It was then that I called in a strong, sharp voice: ‘Languille!' I saw the eyelids slowly lift up, without any spasmodic contractions – I insist advisedly on this peculiarity – but with an even movement, quite distinct and normal, such as happens in everyday life, with people awakened or torn from their thoughts. Next Languille's eyes very definitely fixed themselves on mine and the pupils focused themselves.

When the eyes closed, the doctor called the man's name again. The same thing happened. It was only when he called the name a third time that the head remained unresponsive. The approximate time elapsed was around thirty seconds.

It's not surprising that many are skeptical of the doctor's report. The Journal of the American Medical Association is particularly so. Although it takes time for brain cells to die, a head, they believe, is rendered permanently unconscious by the stroke of the axe, which delivers more force than any knock-out blow to the head. Even if the head should remain conscious due to a very sharp blade or lucky blow, any disruption to the blood flowing to the brain can cause immediate disorientation and loss of consciousness within seconds. By the time someone caught the head, it would be unconscious and it wouldn't regain consciousness just for the sound of its name.

However, since no real experiments can be performed, the legend lives on, even if the head doesn't.

Via JAMA and Mind Hacks.