Gaulin & McBurney - Chapter 9: Individuality: Intelligence and Personality
Evolutionary psychology is interested in mechanisms that all people have in common (i.e all people have hearts with four chambers). Alternatively, behavior genetics focuses on the genetic and environmental bases of the differences between people. Although evolutionary psychology is not primarily focused on individual differences, there is overlap between behavior genetics and evolutionary psychology when you take into consideration an evolutionary basis for such individual differences.
Variability in intelligence and personality (height and eye color) is a byproduct of sexual reproduction. There is normal variation around an Optimum. Optimum values of a trait may vary over time due to a changing environment. With each generation these optimal values shuffle genetically with sexual reproduction. Environmental factors vary from generation to generation and under “this kind of more rapid fluctuation, natural selection would favor the evolution of facultative mechanisms to monitor the current environment and adjust behavior appropriately” (p. 199). Also, Frequency-Dependent Selection aids to variation of the population depending on which mating strategies are more successful. Lastly, personality traits are facultative (meaning that they are reactive to the environment) and personality traits may vary due to the demands of particular social settings.
Individuals gather resources such as food from their environment. Intelligence and personality are potential resources for people as well.
Charles Spearman believed there was a “general or overarching intelligence” (p. 201). Spearman referred to this general intelligence that underlies special abilities as: (g). Louis Thurstone on the other hand believed that intelligence consisted of seven separate factors: verbal comprehension, verbal fluency, inductive reasoning, spatial visualization, number, memory and perceptual speed.
Geoffrey Miller holds that high intelligence is the result of sexual selection. During evolution mates were valued for their intellect opposed to other traits. Sexual selection traits are signs of both: good fitness and high variability between individuals.
Robert Sternberg ascertains that current intelligence tests ignore creative intellect and practical intelligence and focus too much on analytical skills. He is working to develop a test that can predict accomplishments beyond classroom achievement.
Howard Gardener lists seven different intelligences: linguistic, musical, logical/mathematical, spatial, bodily-kinesthetic, interpersonal and intrapersonal. In order to be considered an intelligence, a skill must meet three criteria points: (i) it can be affected selectively by brain damage, (ii) there are prodigies and idiot savants who have uneven distribution of skills, and (iii) there is an evolutionary basis.
Our ancestors used skills such as face recognition and tracking animals, etc. which are not included on IQ tests. Therefore there are many separate abilities that make up intellect, however, they are not included on tests of intelligence.
The human brain is a product of evolution and “certain features are highly conserved; that is, during the course of evolution features that worked were kept and passed on” (p. 207). According to Skoyles, human’s brain size has increased to allow attainment of proficiency, not necessarily intelligence.
“Variation in intelligence follows a normal (bell-shaped) curve, indicating that it is influenced by a large number of independent factors” (p. 210). Intelligence is a polygenic trait that shows variation due to the mixing up of genes in sexual reproduction. Developmental conditions can reduce intelligence if a mother is exposed to rubella, chicken pox, drinking alcohol or inhaling nicotine during pregnancy. Such teratogens have negative documented effects on intelligence. Moreover, social deprivation (how a mother responds to her child’s needs and the quality of home environment) has effects on intelligence and can result in considerable variation in intellect. Lastly, intelligence may vary because it is a sexually selected trait and variability in such case is automatically expected.
Due to the fact that reading, writing, and arithmetic are new tasks in which we don’t yet have modules in our brain to handle, we have to go to school and learn how to use modules designed for the challenges of the EEA in order to accomplish such skills. “We do not have modules designed for these evolutionary novel tasks, we need formal schooling to master them” (p. 211).
Coding and decoding of speech does not require conscious attention; however, reading requires effortful learning to make connections between sounds and markings on a paper. The “process has placed new demands on a brain whose structure was designed for other purposes” (p. 212).
Math is a novel task that uses modules that have evolved for other specific reasons. There are basic mathematical operations that occur below the level of consciousness; however, “counting in base 10, addition and subtraction with carrying, fractions, exponents, and the like . . .must be learned with effort and with instruction in the rules” (p. 213). Children are not intrinsically motivated to practice these skills in which we do not have automatic adaptations, so they must be practiced as well as having the concepts mastered.
Hyperactivity Disorder (ADHD) affects 10% of school-aged boys and 3% of school-aged girls. “Because school is an evolutionary novel situation, it is possible that the traits that make up ADHD were either neutral or even beneficial in the EEA” (p. 214).
There are 5 traits that account for the variation among people. These 5 traits make up the “Big Five” model of personality. Such traits include: Openness, conscientiousness, extraversion, agreeableness and neuroticism. Buss (1991) states that each one of these traits represents “an adaptation to a problem presented by the social landscape 215”(p. 215).
Gaulin & McBurney - Chapter 11: Abnormal Psychology
The DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4th edition) classifies disorders (abnormal behavior) in a non-theoretical way. Psychologists have not been able to agree on the causes or treatment of many of the disorders.
There are possible evolutionary causes for psychological disorders:
(i) they are actually defenses, not disorders, providing psychological defense (non clinical depression)
(ii) they are side effects of genes with fitness benefits (bi-polar and schizophrenia)
(iii) they are the result of frequency-dependent selection (sociopathy)
(iv) they may be the absence or malfunctioning of a particular module (infantile autism)
(v) they is a mismatch between the current environment and the one that existed during much of evolution (Post Traumatic Stress Syndrome and Anxiety Disorders)
(vi) Some disorders are the extremes of polygenic traits (Clinical depression)
Some disorders may have more than one contributing factor or cause.
Post traumatic stress disorder (PTSD) is “primarily a disease of modern life” (p. 241). Only 10% of people affected are due to natural disasters, opposed to 20 – 50% of people experiencing trauma from a man-made disaster (i.e. plane crash or auto accident). From an evolutionary standpoint, this shows a clear mismatch between evolved mechanisms and our contemporary environment.
Depression, according to Nesse, may be nature’s way of telling us that we are “barking up the wrong tree” (p. 242). We are spared wasting valuable resources on events that will not further our fitness and from taking silly risks. People, when action was not going to succeed, who were sad or depressed may have out reproduced those who did not have these feelings. Depression aids in cutting our losses in the “never-ending competition for resources” (p. 243). Additionally, seasonal affective disorder (SAD) may have saved our ancestors energy from looking for food when it was scarce and expending too much effort when it would have been too costly compared to the rewards. The sex differences of depression may have an evolutionary basis as well due to the fact that women are physically weaker than men and “depression is an adaptation that removes us from a situation in which we have more to lose than gain” (p. 243). Lastly, postpartum depression, according to Hagen, could possibly be a negotiation tool for women to get others to invest more effort and negotiate for more help.
Suicide reinforces the theory of kin selection such that resources that would have been spent on the elderly (65 and older) are reserved for furthering the reproductive efforts of our relatives. The high suicide rate of those individuals over the age of 65 years corresponds with this theory as well as their reports of feeling like a burden.
Anxiety disorders and “things we develop phobias about tend to be things that were genuine dangers in the EEA” (p. 246). We do not really develop phobias about electrical outlets or seat belts, generally phobias such as fear of snakes (that was relevant in the EEA) are common. There are two reasons proposed for evolutionary perspective developments of anxiety disorders: (i) there is mismatch between our contemporary environment and the EEA, and (ii) genetic reshuffling (some people end up with higher and lower than optimal levels of traits).
Sociopathy may possibly be the result of frequency-dependent selection since sociopaths’ lack of shame guilt and remorse, places them “at a competitive advantage to those with normal emotions” (p. 248).
Autism affects one out of 1,000 people and it is between 2-4 times more common in males than females and it affects one’s ability to understand another person’s motives, feelings and intentions (p. 250). There is thought to be a lack of a reading module that causes “mind blindness” according to Baron-Cohen.
There are 2 disorders that may be side effects of genes with fitness benefits, Bi-polar Disorder and Schizophrenia. The “very genes that promote creativity may also, perhaps when they occur in certain genetic combinations, have disruptive effects” (p. 251). There is a documented connection between creativity and psychopathy.
Bipolar disorder is marked by depression in combination with bouts of high energy levels, limitless enthusiasm and need for little sleep. Artists who experience these manic episodes have found much success in utilizing their time to produce successful bodies of work. “If, in the EEA, creativity provided sufficient benefits, it may have been favored despite hat is also inflicted some costs in terms of impaired performance during the depressive phases” (p. 253).
Schizophrenia is a problem in brain functioning. It is a debilitating disorder that approximately 1% of our population suffers from. First-degree relatives have a high probability of being involved in creative professions. The idea behind this, according to Karlsson, is that “individuals with the schizophrenia gene but not the disorder gain an advantage in creativity” (p. 254).
Frith and \Frith propose that individuals with schizophrenia may have a disturbance with their mind-reading module, as with autism. The difference is that schizophrenic patients had a relatively normal mind-reading module in youth and autistic patients never had one. This causes schizophrenics to “know that people have their own thoughts and feelings, but they are unable to interpret them correctly” (p. 255). Also, they misinterpret their own thoughts and feelings as those of others and have hallucinations. Schizophrenia is broken down into positive symptoms that normal people do not do (i.e. hallucinations and paranoid delusions) and negative symptoms where they lack normal functioning (i.e. social withdrawal and poverty of speech). Autistic and schizophrenic patients only share the negative symptoms.