Is aggression a learned behavior?
Aggression
Some scholars believe that behaviors like aggression may be partially learned by watching and imitating people's behavior, while other researchers have concluded that the media may have some small effects on aggression.[133] There is also research questioning this view.[134] For instance, a long-term outcome study of youth found no long-term relationship between playing violent video games and youth violence or bullying.[135] One study suggested there is a smaller effect of violent video games on aggression than has been found with television violence on aggression. This effect is positively associated with type of game violence and negatively associated to time spent playing the games.[136] The author concluded that insufficient evidence exists to link video game violence with aggression. However, another study suggested links to aggressive behavior.[137]
Fish aggression
Evolution of aggression can occur in fish due to their genetic makeup. To examine the relationship between aggression and genetic makeup, a team from CNRS/Laboratoire Neurobiologie et Développement conducted an experiment on zebra fish, spiegeldanio. At the beginning, the team of CNRS organized behavioral tests to quantitatively measure the three characters of aggressive behavior. In the experiment, it turned out that this particular fish has a mutation in its fgfr-1 gene summarizing for a membrane receptor sensitive to FGF (Fibroblast Growth Factor), which is a key for growth factor in those fish. As a reaction to the mutation, this group of fish displays low brain levels of histamine. Histamine is a neurotransmitter that controls appetite, sleep and attention in a species. Due to low histamine levels, zebra fish exhibit aggressive behavior. Therefore, the link between the fgfr-1 genes to histamine regulates the behavioral status of aggression in zebra fish. 