Is male more aggressive than female?

It is generally thought that human males tend to behave more violently and aggressively than human females – and it seems true. In United States, most of the homicides during 1980 to 2008 are males, representing 90% of the total number (United States Department of Justice, 2010), and it is also the trend in the whole world. The reason of the difference between man and female in violence is always explained biologically – the testosterone level of adult males is 20 times to females, as testosterone would make people more aggressive (Terburg & Aarts & Honk, 2011). However, it is not a suitable explanation to the question as the testosterone level of boys and girl are same until they are about eight years old and boys actually acting more violently and aggressively since four-year-old. A more reliable explanation would be the different of size of corpus callosum, which is the part that connects the right and the left hemisphere in the brain. As boys are having a smaller corpus callosum than girls, they are more difficult to work under trauma and neglect comparing to girls. Therefore, boys needs to receive more love and caretaking than girls in order to keep their corpus callosum. If their caretaker could not give them enough attention, their prefrontal cortices, which are the part of brain related to self control and empathy would be damaged. The amygdala, which is the part of brain forming the feeling of fear, would also be excited, and fears would be formed. As a result, their serotonin levels would be decreased and product more corticosterone, and these would led to the decrease of calming ability and the increase of stress hormone. Therefore, boys are more easily to have weaker selves, lower empathy, lower control on avoid to behave violently and more fears. However, the society is most likely to give less care and love to males as the society requests males to be brave, strong and independent. Males are hard to gain love and caring as they need to fit in a image