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Social organization and behaviour: key points
- Human behaviour is built on selected and therefore genetically determined components of brain function.
- This evolved brain is the substrate on which individual experience and the current environment shape abilities and behaviour, giving humans the flexibility to exist in a wide range of societal environments.
- Humans are social animals characterised by living in groups larger than their immediate family. Selection has favoured traits which promoted fitness within this environment, such as cooperation, reciprocal altruism, and the abilities to interpret the actions of other members of our species and to detect freeloaders.
- Emotions have adaptive value for a social species, but they can become maladaptive with psychiatric consequences.
- Such maladaptations may have arisen because of changes in the human social environment, or because of genetic/developmental factors creating functional variation in pathways determining behaviour.
Decision making activity may not mature until about 20 years of age
This contrasts with the secular trend of earlier puberty discussed in previous chapters, and the outcome of this duality may be maladaptive. There is growing empirical evidence to show that this mismatch plays a role in teenage depression, acting out behaviour, drug abuse and suicide. Boys who underwent earlier puberty, spending a longer period of their lives in a biologically mature but psychologically immature phase, were much more likely to be suicidal than those who had biological puberty at later age. As biological and cultural evolution proceed in very different ways and paces, we can anticipate that the consequences of the inevitable mismatch between brain and environment will be reflected in disorders of behaviour and mental health.