— PsyPost.org (@PsyPost) March 17, 2016
The authors, among them Eider Pascual-Sagastizabal, a researcher at The University of the Basque Country, measured the levels of three steroid hormones: testosterone, estradiol and cortisol. The results demonstrated that there was indeed a change in the levels of aggressive behaviour.
“This only occurred in boys: at ten years of age they were more aggressive than at eight years of age. The girls, nevertheless, did not experience any changes to their levels of aggression during these two years” explains Pascual-Sagastizabal to Sinc.
The experts analysed whether changes in any of the hormones that were measured were associated with the change in aggressive behaviour that occurred between these two ages. They discovered that the subjects whose levels of aggression had increased most by the age of ten were those whose levels of cortisol had also increased over the two years.
On the contrary, the boys whose levels of aggression had decreased most between eight and ten years of age were the ones whose levels of estradiol had increased most between the two ages.