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Evolutionary neuroscience is an interdisciplinary scientific research field that studies the evolution of nervous systems. Evolutionary neuroscientists attempt to understand the evolution and natural history of nervous system structure and function. The field draws on concepts and findings from both neuroscience and evolutionary biology. Historically, most empirical work has been in the area of comparative neuroanatomy, and modern studies often make use of phylogenetic comparative methods. Selective breeding and experimental evolution approaches are also being used more frequently.[1]

Various lines of research have linked specific neurotransmitter pathways to particular categories of behavior. For example, the brain chemical serotonin plays a role in the development of violent tendencies. Other research strongly implicates dopamine in the control of locomotor behavior through its influences on motivation and reward.[2]

Conceptually and theoretically, the field is related to fields as diverse as comparative psychology, neuroethology, developmental neurobiology, evo-devo, behavioral ecology, biological anthropology, sociobiology, cognitive neuroscience, sociocultural evolution and evolutionary psychology.

History

The field began after the publication of Darwin's On the Origin of Species, but brain evolution was largely viewed at the time in relation to the incorrect scala naturae. The 1936 book The Comparative Anatomy of the Nervous System of Vertebrates Including Man by the Dutch neurologist C.U. Ariëns Kappers (first published in German in 1921) was a landmark publication in the field. Following the Evolutionary Synthesis, the study of comparative neuroanatomy was conducted with an evolutionary view, and modern studies incorporate developmental genetics.[3][4]

Serotonin

Some amount of aggression is often adaptive behavior in the natural world. However, excessive aggression can be maladaptive. Hostility and anger turn into violence usually when they are misinterpreted or when the hostile or angry individual is expressing aggression in a way not typical for that species. Experiments using wild rats and mice have described under what circumstance aggression turns into violence. Aggressive behaviors tend to increase after the individual had prevailed in several aggressive encounters. Also, after multiple social conflicts involving aggressive behavior, individuals can start to display offensive aggression. In examining highly aggressive rats and mice it was shown that they changed their initial defensive aggressive behavior to a more violent method. What could cause such a change in these animal models? The focus has been particularly on the neuro-transmission of serotonin. Serotonin, more than any other neurotransmitter system, has been found to contribute to the development of aggressive behavior. Serotonin concentrations in the brain are strongly positively correlated with animals learning aggressive behavior when engaged in mating, territory, and hierarchical conflicts. Serotonin has an inverse relationship when those individual are displaying violence.[1] Boer et al. (2009) state that as aggression experiences increase there is a decrease in serotonin levels. Serotonin levels are lowered only after an individual has engaged in aggressive behaviors. This can be attributed to the changes in the release of serotonin by specific neurons called auto receptors. When exterminators exposed these auto receptors to agonist, chemicals that bind to the receptor to produce a desired reaction, aggressive behavior declined. This would indicate that increasing receptor function is normal when the brain of an aggressive animal is in a heightened state. When this function is increased too much, violent behavior may occur. [2]

Researchers