This explanation of aggression states that it is hormones such as heightened levels of testosterone that lead to aggressive tendencies. Hormones are chemical substances that regulate the mood of your body; unregulated hormones therefore can cause mood changes. Testosterone works by modulating neurotransmitter pathways. It does this by lowering the amount of serotonin in the brain/nervous system.
There are two models that give an insight into how testosterone can affect aggression. The Basal model suggests testosterone causes heightened dominance; thus explaining that the testosterone levels are the cause of aggression alone leading to other factors, feeling a sense of dominance over other gives a heightened sense of security, therefore leading to irrational behaviour. Research by wagner supports this model; he castrated mice and proved that the overall levels of aggression decreased if the male mouse was castrated. Moreover, upon giving the castrated mouse testosterone again he found aggression increased. Although this study is done on mice therefore becoming less appropriate in generalizing the findings to human behavior it does show scientific evidence that testosterone has an effect on aggression levels. Most research done which supports the Basal model is conducted on animals due to the difficulty in carrying on any scientific research on humans which is down to ethical reasons. This lessens the validity of the Basal model as a whole. .
Despite this, more animal research, for example, reducing serotonin levels in monkeys resulting in an increase in aggressive behaviors replicates patterns in the experiment conducted by Wagner. With a distinct pattern showing, and monkeys being are closest relatives, some conclusions can be draw on how testosterone may act in an human body. Serotonin is the hormone which makes us calm and is affected by the heightened levels of testosterone, therefore it is another hormone responsible for aggression; both studies hence show that heightened testosterone and reduced serotonin are distinctive in aggression.
