As experiments have shown, flies begin to act withdrawn, lose their fat deposits, and age so quickly that they die earlier than individuals who have not seen a corpse.

the effect of death

But why is this happening? What causes flies to react this way to observing death? Scientists now understand this process better.

When fruit flies see dead mates, two types of neurons sensitive to the neurotransmitter serotonin are activated, and this increased activity accelerates the aging process.

Understanding the neural circuits in which death perception influences these phenotypes can inform future studies aimed at understanding the consequences associated with this and possibly other sensory experiences in humans, and may provide insight into how specific neural states affect behavior and physiology.
– Writes a research team led by physiologists Christy Gendron and Tuhin Chakraborty of the University of Michigan.

Sensory processes can affect aging, but we don’t know very well how. Similar effects were observed in other animals and insects.

In fruit flies, the changes appeared to involve serotonin, an important neurotransmitter that transmits signals between nerve cells, and 5-HT2A, one of the serotonin receptors. The researchers began by examining how neurons expressing 5-HT2A might be involved in the physical effects of “death perception.” They injected live flies with a fluorescent protein and showed them dead flies. The researchers then observed and noted which parts of their brains became active when they spent time on the carcasses of live flies. Finally, they began artificially stimulating neurons in these regions in flies, which had not seen dead individuals until they found two, designated R2 and R4, that had the same effect as sensing death.

There’s not much we can do with this information yet. A fly’s brain is very different from a human’s, but the team hopes this will one day help us better understand how our brains work, and particularly the aging process in people who regularly encounter the dead.

“By contributing to the understanding of the physiological consequences of death exposure and the biological mechanisms that govern them, our findings may be helpful in the treatment of people who are regularly exposed to stressful situations related to death, including soldiers engaged in combat and fast-paced response services.”– write researchers.