Can chickens really survive after their heads are cut off?
In September 1945, Lloyd Olsen and his wife Clara, farmers in Colorado, USA, encountered a chicken that they had beheaded and slaughtered, but which was still alive, albeit without its head. This chicken, known as '
Can chickens really run around with their heads cut off? | Live Science
https://www.livescience.com/animals/birds/can-chickens-really-run-around-with-their-heads-cut-off
According to Marcy Logsdon , an associate professor at the Washington State University School of Veterinary Medicine, chickens generally flap their wings and move their legs after their heads are severed. However, she says, 'I don't think a chicken that has been decapitated will actually run around. Usually, the muscles in its wings and legs just contract tightly, which is normal,' and these movements only last for less than a minute.
However, there is disagreement among experts on whether a chicken is still alive in the few seconds immediately after its head is severed, depending on the definition of death. In the case of a decapitated chicken, brain death occurs first, followed a few seconds later by cardiac death. Therefore, Live Science states that in the few seconds between brain death and cardiac death, the chicken could be said to be both alive and dead.
In many countries, brain death is defined as a state in which all functions of the cerebrum , cerebellum , and brainstem are permanently lost, and in this state, the organism is unable to breathe on its own. According to a paper published in the academic journal Animals in 2019, electrical activity in the brain of chickens stops within 30 seconds of a neck fracture (cervical dislocation), but electrical activity remains for a few seconds. Since cutting the neck includes neck fractures, there is a time lag of a few seconds between when a chicken is decapitated and when it becomes brain dead.
Dr. Andrew Ivaniuk, who studies the brains of birds at the University of Lethbridge in Canada, said, 'This doesn't mean that the animals are consciously aware of what is happening in those few seconds, but residual electrical activity is occurring.'
According to Iwaniuk, chickens continue to move after their heads are severed because some nerve activity remains in their spinal cord. Meanwhile, the heart muscle, which powers the heart, continues to contract and relax even without nerve stimulation until it runs out of energy and oxygen.
Cardiac death, when the heart completely stops, can occur a few seconds after brain death. Ivaniuk says the time difference between brain death and cardiac death is 'less than 10 seconds.'
Because of these differing definitions of death, Logsdon considers the movements of chickens after their heads are severed to be merely 'postmortem reflexes,' while Ivaniuk considers the chickens to be 'alive' even while their muscles are twitching after their heads are severed.
Experts believe that chickens die immediately after their heads are cut off, or at best, can only survive for a few seconds. However, in the case of the famous headless chicken Mike, he continued to move for 18 months after his head was severed.
Logsdon points out that Olsen, who cut off Mike's head, did not completely separate the body from the brain, but rather 'part of the brain and most of the face.' According to reports, while Mike's head was indeed severed, the back of his brain and one ear remained attached to his body.
In Mike's case, it's possible that the brainstem, which controls basic physiological functions such as breathing and heart rate regulation, remained in the torso, and that the cerebellum, which controls movement, also remained. Logsdon said, 'This is probably why Mike was able to not only run around and flap his wings, but actually stand up and walk.'
Mike, the headless chicken who survived for 18 months after his head was cut off, has his great-grandchild recount the events - GIGAZINE
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in Free Member, Science, Creature, Posted by log1h_ik