Why Do Even Microbes Commit Suicide? Page 2

A 250-fold magnification of two E. coli colonies. The phage could eat holes into the colony of a susceptible strain (left bottom), whereas colonies of the suicidal strain remain unharmed (upper right).
Rolf Kummerli

Even among lowly microbes, such behavior would seem to go against survival and procreation mechanisms. Behaviors that benefit others, at the expense of the individual, however, can emerge when multiple relatives are saved. They can also emerge to benefit unrelated others when the cost of suicide is low.

In the case of E. coli cells, they would likely die from the viral attack anyway, and their death prevents parasite transmission to nearby other E. coli cells.

Suicide is also well documented in social insects that tend to live in large populations, such as ants and bees. Some ants will even explode themselves to prevent intruders from attacking their relatives.

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Suicides among non-human mammals and other larger animals are mostly anecdotal, but they do tend to once again apply to social species, such as dogs and dolphins. Dolphin trainer Ric O'Barry, for example, claimed that he watched the famous TV star dolphin, Flipper, take her own life out of sheer depression due to confinement in captivity. O'Barry later became an animal activist.

Gaining a better understanding of the drivers behind suicide could lead to life-saving benefits. Researchers in future might be able to coax harmful bacteria, viruses and other microbial organisms to kill themselves, potentially saving human and other animal lives.

Stuart West, a professor of evolutionary biology at the University of Oxford, commended the new research, saying the researchers "show here that if the costs of suicide are low (the individual is unlikely to reproduce anyway), then relatedness doesn't have to be very high, although it does have to be above zero."

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