Scientists have found new discoveries about how death actually works by studying earthworms.
The new research shed lights on the mechanisms at work when animals including humans die, particularly as a result of old age.
Legally and medically, death is usually defined as one specific point: when the brain stops working or the heart stops beating. But in practice, death is actually a long and slow process, which starts long before and continues after a person has been officially declared dead.
"Cell death has been widely studied but much less is known about death of whole organisms, how it happens, what triggers it, and when it begins and ends. But it's extremely important for understanding fatal diseases in humans, especially those caused by ageing," said Professor David Gems (UCL Institute of Healthy Ageing), who led the team of researchers.
Using the earthworms, scientists traced that process as it spread through the body. They found that dying cells triggered the death of their neighbours by sending out calcium, which shoots quickly between cells – first causing rigor mortis, as in humans, and then shooting into the intestine.
"The way death spreads from cell to cell by calcium is like a house burning down," said lead author Dr Evgeniy Galimov, from the UCL Institute of Healthy Ageing.
It could eventually be used as a way to slow or reverse that process in humans.
"Discovering rigor mortis in worms is exciting as it highlights a key step in the chain of events leading from healthy adulthood to death from old age. It helps us to understand death in humans, and perhaps in the future to prevent death in mortally ill patients," concluded Professor Gems.
The work is part of a broad study looking at the phenomenon of senescence, or how bodies deteriorate with age. That is now the main cause of death in the world, and is likely to affect most of the people in it.
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