+ Exam focused question: Outline (about 200 words) evolutionary explanations of two forms of human aggressive behaviour.

+ Genetic factors in aggression To know and understand how genetics can play a part in aggressive behaviour

+ What Causes Aggression? Psychological factorsBiological Factors

+ Design an Experiment... In pairs, design an study/experiment that could test the theory that aggression is an inherited behaviour. Be prepared to present to the rest of the class. All experiments have to be ethical!

+ Evidence Lagerspetz (1979) Mice were raised in isolation. He separated the mice into two groups depending on the level of aggression displayed when they were mixed with other mice. The mice that were most aggressive were classified as aggressive(TA) and the others as non-aggressive (TNA) These mice were interbreed. – By the 19 th generation aggressive biting behaviour in TA mice 52% – In TNA it was only 5% – There were also structural differences. TA mice had heavier testes, and increased serotonin. However, the environmental still had an influence as both types of mouse could be tamed

+ Mice! You are going to replicate Lagerspetz’s experiment in class. But you are going to be breeding paper mice! Each person gets one mouse with a number on it. The higher the number, the more aggressive the mouse is. Decide if you want to breed aggressive mice or calm mice. You then need to find someone to breed your mouse with

+ Mice! To get the aggression score for the offspring, Add together the numbers from the parents and divide by 2 to get an average. Flip a coin. If it is heads, add 2 to the number. If it is tails, take 2 two away. You have two babies each time a pair breeds, so you have to do the above twice. Once you have bred a pair, decide which of the offspring you are going to breed and repeat the above with your new mouse.

+ Twin Studies Miles and Carey (1997) did a meta-analysis of 24 twin and adoption studies They concluded that genetic influence could account for up to 50% in the variance in aggressive anti social behaviour. Use this evidence to support the role of genetics in aggression. Use this evidence to contradict the role of genetics MZ (Identical) TwinsDZ (Non-Identical) Twins reared togetherreared apartreared together reared apart

+ Adoption Studies Hutchings (1975) – Studied 14,000 adoptions in Denmark, and found that a significant number of adopted boys with criminal convictions had biological parents (particularly fathers) with criminal convictions. – However, the highest rates of criminal violence occur when both biological and adoptive parents have a history of violent crime. Use this evidence to support the role of genetics in aggression. Use this evidence to contradict the role of genetics