“There is a very special place in fly hell reserved for me,” said Christi Gendron, a neurobiologist at the University of Michigan.
Gendron earned it by investigating how live fruit flies respond to seeing dead flies. To study this so-called death perception, you need corpses, and she uses hunger to get them.
This morbid research, recently published in the journal PLOS Biology, revealed clusters of neurons in the brains of insects that make them age faster after seeing dead flies. The results will help scientists understand how an animal’s brain converts what it perceives into physical reactions in the body.
Animals are very aware of death. Elephants mourn their dead; ravens celebrate “funerals”; and for bees, ants, and termites, burial is a specialized task performed only by certain members of the colony.
Gendron and Scott Pletcher, a biologist at the University of Michigan, were originally trying to see if the flies would show a response, such as a boosted immune system, after being around other flies that had gotten sick.
“The only types of responses we saw occurred after the flies we infected died,” Pletcher said. They found that flies that had seen corpses were avoided by other flies, as if they were marked for death. Cadaveric bystanders also quickly lost stored fat and died before their non-traumatized counterparts.
Dissection of these flies revealed activity in the ellipsoid body, which integrates sensory information into the brain. Gendron and Pletcher then identified the key neurons in the ellipsoid body. When these were turned off, seeing dead flies did not affect the life of the living ones. When the researchers activated those groups of neurons, the flies died sooner, even if they had never been exposed to dead flies.
“Our lab has long been interested in how the brain controls aging,” Pletcher said.
“They show that living flies use a specific set of neurons that have serotonin receptors” to sense dead flies, said Marc Tatar, a biologist at Brown University in Rhode Island who was not involved in the study. “That’s the beauty of this research.”
Tatar suspects that dead flies are a sign of danger to living ones, so he surmises that seeing them causes flies to put more energy into reproduction at the expense of longevity.
However, Pletcher and Gendron did not see increased reproductive output from their flies exposed to death.
Another hypothesis is that the shorter lifespan results from the stress caused by perceiving death. Chronic stress in animals leads to health problems. “If we suddenly found ourselves in a sea of dead humans, it would be very stressful,” Pletcher said.
By: DARREN INCORVAIA
BBC-NEWS-SRC: http://www.nytsyn.com/subscribed/stories/6790214, IMPORTING DATE: 2023-07-04 20:50:06
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