Chapter 11: Personality (Genome)

•The tension between universal characteristics of the human race and particular features of individuals is what the genome is all about.

• Somehow the genome is responsible for both the things we share with other people and the things we experience uniquely in ourselves.

• To seek out the genes that influence personality, it is time to move from the hormones of the body to the chemicals of mind – though distinction is by no means a hard-and-fast one.

• On short arm chromosome 11, there lies gene called D4DR which encodes for dopamine receptor protein switched on in certain brain cells.

• Dopamine pathways control many things, including flow blood through brain; shortage causes indecisive personality; excess may cause schizophrenia.

•The D4DR gene on chromosome 11 has a variable repeat sequence in the middle, a minisatellite phrase forty-eight letters in length repeated between two and eleven times.

• Most people have four or seven copies of the sequence, but some people have two, three, five, six, eight, nine, ten or eleven.

• The larger the number of repeats in the gene sequence (i.e., the “longer” the gene),the less responsive dopamine receptors are to dopamine.

• Hamer and colleagues wanted to know if people with the long gene had different personalities from people with shorter genes – they found that those with longer genes were more novelty-seeking than those with shorter genes.

•Personality has a strong genetic component

• The discovery of this can be used in non-genetic therapy

• Understanding that personality is innate often helps to cure it

• Telling people that their personality is innate often helps them overcome that shyness

• Marriage counsellors report good results from encouraging their clients to accept that they cannot change their partners’ irritating habits – because they are probably innate.

•Dopamine, norepinephrine, and serotonin are all monoamines that play a role in personality.

• Serotonin is more complicated than the other two chemicals and its characteristics are hard to pin down.

• High levels of serotonin in the brain have been linked with compulsive behavior, while low levels have been linked with impulsive behavior.

• Prozac works by affecting the serotonin system in some way (the exact mechanism is still unknown).

• There is a gene on chromosome 17 that influences how much serotonin is produced in the brain. People with one version of this gene tend to be neurotic while people with another version tend to be agreeable.

• Low cholesterol has been linked with violence, suicide, and bad temperamental monkeys) and high cholesterol has been linked with heart disease

•The serotonin system is about biological determinism.

• Your chances of becoming a criminal are affected by your brain chemistry.

• But that does not mean, as it is usually assumed to mean, that your behaviour is socially immutable.

• Quite the reverse: your brain chemistry is determined by the social signals to which you are exposed.

• Biology determines behaviour yet is determined by society.

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Related posts:

1. Law 17: Seize the Historical Moment (The Laws of Human Nature)
2. Part 2: Isolate the Victim (The Art of Seduction)
3. Chapter 16: The Capitalist Creed (Sapiens)
4. On Nietzsche’s Thus Spoke Zarathustra Summary (8.4/10)