Why Flies Die Faster after Witnessing Death
By: Zaiyi Yang ‘26 and Jessica Lin ‘27 STEM In The News: Issue 4. Intriguingly, “flies that had seen corpses were avoided by other flies, as if they’d been marked by death (how this works is still a mystery). The carcass-viewers also quickly lost stored fat and died sooner than their non-traumatized counterparts” (2).
Flies, persistent and relatively harmless insects on a larger scale, exhibit a bizarre behavior that has puzzled scientists for years. Why do flies die faster after witnessing death? Many studies have shown that different animals react to the death of one of their own differently. Elephants grieve for their dead; crows hold ‘funerals’; and for bees, ants, and termites, some colony members undertake specialized tasks when one of their own passes away (2). Although many believe animals don’t have the same concepts of death as humans do, they experience the grief and sadness of the loss of a loved one just like we do (3). In the case of flies, this experience can shorten their lifespans, speeding up aging while ultimately leading to an early death. Like many other animals, flies are sensitive to environmental stressors and alterations in their surroundings. When a fly witnesses the death of another fly, this can elicit a physiological stress response. This heightened stress can lead to the release of stress hormones such as cortisol, which can lead to negative impacts on a fly’s health if prolonged or severe. High levels of stress can alter a fly’s metabolic system, immune system, and, in rare cases, behavior (4). Flies that come in contact with diseased flies may also contract and spread disease and pathogens, which can be deadly.
According to the ‘Michigan Medicine of the University of Michigan,’ fruit flies experience accelerated aging after witnessing the death of another fruit fly due to a type of serotonin receptor in their bodies. This serotonin receptor, which controls aging, can be strongly affected by the witnessing of death. There are R2 and R4 neurons in the brain cells of flies that are instantly activated after the fly sees the death of or comes into contact with a postmortem fly. Flies that witness death experience a shortened lifespan. While the regular life span of a fly is over 60 days the lifespan of a fly who has witnessed the dead body of another fly is around 45 days (1). This is related to sensory perception in the fly, which controls energy homeostasis, tissue physiology, and organism aging (1). While more research is needed to fully understand all the aspects of a fly’s lifespan after witnessing death, the stress response, potential disease transmission, and the serotonin receptors play central roles in this observed phenomenon. The study of these topics not only provides insights into the world of insects, but also teaches valuable lessons about the links between stress, social structures, and health in various species, including our own. Understanding these connections will contribute to a better understanding of the importance of knowing how to maintain a rich and complex world humans and insects share. Works Cited 1. How seeing corpses reduces the lifespan of flies. (2023, June 15). Michiganmedicine.org. https://www.michiganmedicine.org/health-lab/how-seeing-corpses-reduces-lifespanflies#:~:text=The%20study%2C%20published%20in%20the,leads%20to%20more%20rapid%20 aging. 2. These Flies Age Faster After Witnessing Death. (2023). The New York Times. https://www.nytimes.com/2023/06/13/science/fruit-flies-deathaging.html#:~:text=Gendron%20found%20that%20flies%20that,sooner%20than%20their%20n ontraumatized%20counterparts.
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