By studying male flies from a large panel of lines, which each carry a mutation in a single gene but are otherwise genetically identical, researchers identified particularly angry and particularly placid insects, uncovering 59 mutations in 57 genes that affect aggressive behaviour.
"Many of the genes we identified affect the development and function of the nervous system, and are thus plausibly relevant to the execution of complex behaviors. We studied nine mutations in extra detail and found that each had multiple effects on the size and shape of an insect's brain," study's lead author Trudy Mackay, from North Carolina State University, said.
To measure aggression in the flies, Mackay and her colleagues starved them for a short period, and then allowed them to compete for and defend a limited food resource.
They found that 32 of the mutations studied resulted in increased aggression while 27 caused flies to become more placid.
None of the candidate genes identified in this study have been previously implicated in determining aggressive behaviour.
According to the researchers, these results may also be relevant to behaviour in other animal species.
"Given the conservation of aggressive behaviour among different animal species, these are novel candidate genes for future study in other animals, including humans," they said.
The study has been published in the open access journal BMC Biology.