Flashcards in 8. Evolution and Psychopathologies reading Deck (68)
but what are criticisms of anorexia as an extreme female strategy missing out on?
• Those who view anorexia as a product of sexual competition do Not assume that anorexia itself is an adaptation. Most note Only this extreme competitive strategies to get mail is often overshoot. It seems possible-the rate of anorexia Is 10 times higher for women than for men.
what three diseases show cliff-edged fitness
According to Nesse, 2018 (Good reasons for bad feelings)
Autism and Bipolar
what is schizophrenia
Schizophrenia is a cognitive collapse in which every event is imbued with excess personal meaning and the inability to separate inner life from outer Life gives rise to hallucinations and delusions.
what is autism?
Autism is manifested in early childhood by lack of social connectedness and solitary Preoccupation with repeated emotions and nonsocial thinking.
what is bipolar?
Bipolar disease is the product of a broken motor stop that causes alternating periods of depression and mania.
why is an evolutionary perspective especially useful for studying autism, bipolar and schizophrenia?
These are dire diseases. Despite their differences these diseases have overlapping features which makes an evolutionary perspective especially useful. Each reflects approximately 1% of populations worldwide. Each has multiples that affect 2 to 5% of people. Vulnerability depends overwhelmingly on what genes person has, but people with schizophrenia autism have fewer children than other people.
what is the evolutionary question for bipolar, autism and schizophrenia?
The Evolutionary question is obvious-why hasn’t natural selection illuminated by genetic variation is causing these diseases? The evidence for genetic causes a struggle
genetic variations and risk for schizophrenia stat
Genetic variations explain about 80% of schizophrenia (Sullivan and Allen ,2004)
genetic variations and risk for bipolar stat
Genetic variations explain about 70% of the risk of bipolar disorder ( Smoller and Finn,2003).
genetic variations and risk for autism stat
Genetic variations explain about 50% of autism.(Sandin et al., 2014).
twin stat for autism, bipolar and schizophrenia
Having an identical twin with one of these disease increases the risk of over 50% Kendler et al., 2000
but what is the issue with genetics and bipolar/ schizophrenia/ autism?
But it seems that no specific gene is the cause of these.
study for not being able to find genes to explain bipolar/ autism / schizophrenia
The entire genome has been scoured for specific genes. Research that looked at markers spread over all 23 chromosomes to see if variations at certain locations were more common in people with these diseases that we were on other people. The conclusion was firm, there are no common genetic variations that substantially increase the risk of schizophrenia, autism, or bipolar disease (Anttila et al., 2016; Kendler, 2013). Some increase the risk, but almost all by less than 1%.
give e.g. of disease with clear genetic effects
Some genetic disorders are caused by specific genetic mutations with big Effects. Poor disease such as cystic fibrosis caused by recessive genes, you get the disease if you have two copies of a defective allele.
what is the difference between cystic fibrosis and most other diseases? give some e.g.'s
However, most common genetic diseases are very different. Instead of a few identifiable genetic variations with big effects, they Are caused by Thousands of variations spread across the genome, each with only a tiny effect. This is not the case only for schizophrenia autism and bipolar disease but also for Type II diabetes blood pressure and obesity to name a few. this is called the problem of missing heritability.
quote abut individual gene variants for explaining disorders.
Kendler (2013) has said “ despite our wishing so, Individual gene variants of large effect appear to have a small to non-existent role in the aetiology of major psychiatric disorders. In hindsight, this should not of been surprising Natural selection tends to eliminate alleles that cause dire illness.
what does it seem genetics is doing in terms of risk to schizophrenia/ autism/ bipolar?
It seems that disease risk is influenced by variations in thousands of genes with tiny affects interacting with one another and the environment.
what does the mechanics model of the brain suggest?
. The mechanics model assumes that the brain is constructed of discrete circuits with specific functions with specific functions. It assumes specific disorders that can be defined By specific identifiable brain pathology With specific genetic causes. It assumes that normal grains are made by normal genomes And abnormal brains are products Of abnormal genes.
what is the suggestion that's not the mechanics model that seems more likely
A deeper evolutionary perspective Suggests the need to embrace the reality of organic complexity and look for causes Not just in mechanisms but in trade-offs that cause intrinsic vulnerabilities. Instead of just looking for broken parts And the causes of disease in some individuals, we can also ask why all members of our species are vulnerable.
why must disorders such as autism/ bipolar/ schizophrenia not have been cut out of the gene pool?
The huge fitness costs of these diseases has inspired suggestions that their symptoms, or the alleles that cause them must offer selective advantages.
who developed the Shaman hypothesis of schizophrenia?
One idea is that schizophrenics become Sharmans or charismatic leaders and the resulting status Get them extra matings (Stevens, 2000)
what is the Shaman hypothesis at odds with?
This is inconsistent with data showing that people with these diseases have reduced number of children with her recent report suggests that people would create a trade related to schizophrenia may have increased mating opportunities (Nettle and Clegg, 2006)
what thus seems more likely as an explaination for schizophrenia
More plausible possibility is that the same genetic tendency is to make a disorder likely also give up advantages. T
possible pros to bipolar?
he Association of creativity and intelligence with bipolar disorder has spurred enormous interest and many studies (Greenwood 2016)
Several new studies support the idea that associated benefits preserve alleles that increase vulnerability. A study of twins found that the likelihood of Developing Bipolar disorder is associated with higher than average levels of sociality and Verbal skills (Higier , 2014)
possible pros to autism?
Polinanti and Gelernter, 2017 found that alleles that increase the risk of autism spectrum disorder have been subject to positive selection, presumably because they give cognitive benefits.
verbal ability and schizophrenia study?
Another study found that the amount of protein made by genes related to schizophrenia was related to verbal learning ability (Borg et al., 2016)
how does Nesse explain the three examples of bi-polar, schizophrenia and autism?
evidence supporting bipolar as cliff edged
Akiskal et al., 2003, 2007- Have showed that full-fledged bipolar illness is just the tip of a spectrum of moods instability disorders. Modern versions of mood instability maybe common because they increase reproductive success on average over the long run despite their malign effects on health for some people. This could be because productivity during burst of manic energy or because such individuals get more sex partners.
what was cliffed edged fitness based on?
Based on findings of Lack (1854;1957) Who wondered why birds Didn’t lay more eggs in order to have more offspring and suspected that additional eggs With sometimes pay off But sometimes result in fewer total surviving Offspring. To test this idea he moved eggs from one nest to others. As he suspected, adding one egg to a nest Increased the number of fledgelings hatched somewhat on average, but to beyond a certain number Added eggs Decreased the total number of chicks fledged