New Insights into Genetic Basis of Aggression

Honey bees, fruit flies, mice, and wasps all  possess the same genes for aggression, and new research suggest that humans might do too. What’s more, the expression of these genes seems to be highly influenced by social cues in the environment. Corresponding authors Amy Toth and Christina Grozinger believe that this new finding might hint at an ancient biological basis for aggression conserved across all animal species, and weigh in on the nature versus nurture debate.

Insects and mammals are separated by hundreds of millions of years of evolution, which has provided time for the striking genetic changes that explain their differing appearances. Nonetheless, when Toth and Grozinger compared large datasets comprising thousands of genes they observed that genes associated with aggression were highly conserved across both groups. In wasps – organisms with a simple social structure –  these “social aggression” genes seem to relate directly to reproductive dominance.

In other species, the same genes could produce varying aggressive behaviours in line with social cues. In primitively social paper wasps, the gene seems to promote aggression at the expense of reproductive dominance, whereas honey bees exhibit protective aggressive behaviours directed solely towards intruders to the colony.

The researchers also analysed how patterns of gene expression (in cells taken from the wasp brain and ovary) varied with the organism’s position in the social hierarchy. They observed that within the brain, the most important factors influencing gene expression were external, with seasonal cues and social factors such as colony size exerting a significant effect. In contrast, the expression of “aggression genes” in wasp ovarian cells seemed to be less influenced by environmental factors. These results provide a compelling argument supporting the role of the environment in shaping behaviour.

However, the wide range of behaviours in different species associated with these genes raises an important question: do they really underlie aggressive behaviours? The answer may lie in artificially increasing gene expression to create “hyper-aggressive” wasps.

To access the original article, follow this link: http://www.biomedcentral.com/1471-2164/15/75