In psychology, the term aggression refers to a range of behaviors that can cause both physical and psychological harm to oneself, others, or objects in the environment. Aggression can take various forms, including: physical, verbal, mental and emotional. Aggression can also serve a number of different purposes such as asserting dominance, intimidating or threatening, or expressing anger or hostility. We've all experienced anger at some point in our lives, and some of us have channeled that anger into violence, perhaps throwing a punch during a heated argument or after too many beers at the bar. Then there is aggression on a larger scale, in the form of murders, wars and genocides. Trying to understand what fuels different levels of human aggression, from fistfights to battles between nations, has long concerned human biologists. Through research it has become clear that human aggression is not simply “bad behavior” and that problematic impulsive aggression can be viewed as an identifiable behavioral disorder with genetic, biological, and therapeutic correlates. This research occurred through animal studies involving lower- and higher-order nonhuman subjects and clinical research with people. Animal research has often stimulated work on human populations. Research into the biology and treatment of human aggression has found that when biological substances, such as neurotransmitters and hormones, are able to inhibit or facilitate aggression in lower animals. Aggression in humans and animals has been linked to serotonin function (Bethea, Reddy, Robertson & Coleman, 2013). Serotonin is known as the natural feel-good chemical. It is the most widely distributed and most studied neurotransmitter at the center of the article… an aggressive social encounter can cause changes in the brain that lead to depression, anxiety and immune susceptibility. related diseases. Surprisingly, animal research shows that attackers can suffer from many of these same effects. Aggressive encounters increased circulating levels of stress hormones in both dominant and submissive mice, suggesting that aggression affected both groups similarly. Chronic exposure to social stress increased susceptibility to bacterial infections in both groups, but more so in dominant mice than in submissive ones. Unlike most behaviors, individual acts of escalating aggression and violence have the potential to impact society as a whole. Research, from fruit flies to humans, is helping to decipher the biological causes of these abnormal behaviors. This research promises to reveal new avenues of treatment and prevention in the years to come.