Smoking Prevalence & Music: Biological Rationales (PDF)

DrukQs Smoking Prevalence (2000) Africa – 29% Men – 4% Women United States – 35% Men – 22% Women Europe – 46% Men – 26% Women Western Pacific – 60% Men – 8% Women Smoking (tobacco) Highly addictive Single greatest cause of preventable death globally Leads commonly to diseases affecting the heart, li...

DrukQs Smoking Prevalence (2000) Africa – 29% Men – 4% Women United States – 35% Men – 22% Women Europe – 46% Men – 26% Women Western Pacific – 60% Men – 8% Women Smoking (tobacco) Highly addictive Single greatest cause of preventable death globally Leads commonly to diseases affecting the heart, liver, and lungs Major risk factor for – Heart attacks, strokes, chronic obstructive pulmonary disease (COPD) (including emphysema and chronic bronchitis), and cancer Also causes peripheral vascular disease and hypertension Cannabis Subjective change in perception and mood Short-term physical and neurological effects – Increased heart rate, increased appetite and consumption of food, lowered blood pressure – Impairment of short-term and working memory, psychomotor coordination, and concentration You guys know all about this stuff… Why?! Why do we smoke? – Hint: it’s not ‘cause “it feels good” Proximate causes are well-known – Question is why does it feel good? Why do we have an affinity for drug use in light of all the associated costs? Chemoprophylaxis and Chemotherapy Hypotheses Plants have evolved an enormous variety of toxins to deter herbivores… … in turn, herbivores have co-evolved to use plant toxins to defend against their own parasites – Known as self-medication, zoopharmocagnosy, or pharmacophagy Chemoprophylaxis and Chemotherapy Hypotheses Woolly bear caterpillars (Grammia incorrupta) – Ingest pyrrolizidine alkaloids to protect themselves from tachinid flies Tobacco hornworm (Manduca sexta) – Co-opt ingested nicotine to defend against the wolf spider and the endoparaitoid, Cotesia congregata Chemoprophylaxis and Chemotherapy Hypotheses Tobacco hornworm (Manduca sexta) Chemoprophylaxis and Chemotherapy Hypotheses Urban sparrows and finches – Place cigarette butts containing residual nicotine in nests to defend against nestdwelling ectoparasites such as mites Helminths Helminths – parasitic worms (e.g. hookworm, pinworm, etc. Chemoprophylaxis and Chemotherapy Hypotheses Some species ingest plant toxins to specifically defend against helminths (parasitic worms) – Domesticated Lambs Respond to gastrointestinal parasite infections by increasing their intake of alfalfa tannins – Wild chimpanzees Ingest Aspilia and the bitter pith of Vernonia amygdalina to treat intestinal helminth infections Chemoprophylaxis and Chemotherapy Hypotheses Ethnomedicine – The deliberate use of plants for medicinal purposes in humans Increasing evidence that the plants that are incorporated into many diets provide protection against parasites Billing and Sherman (1998) – Argue that the addition of spices to food functions to defend against meat-borne pathogens Chemoprophylaxis and Chemotherapy Hypotheses So, what are you saying, Ian? – It is possible that “recreational” drug use in humans can be explained by the antiparasitic properties of these plant compounds Chemoprophylaxis and Chemotherapy Hypotheses Three of the worlds most popular recreational drugs are effective treatments against helminthes – Nicotine (the psychoactive component of tobacco) and arecoline (the psychoactive component of betel-nut) Both have been used as commercial anthelmintics in animals – Cannibus Toxic to plant-parasitic nematodes Chemoprophylaxis and Chemotherapy Hypotheses Hypothesis: – Human recreational drug use might involve neuropsychological mechanisms that evolved to regulate the intake of plant neurotoxins Function to prevent or reduce infection of helminthes and other macroparasites – This hypothesis does NOT require conscious awareness of these mechanisms Chemoprophylaxis and Chemotherapy Hypotheses Two pharmacophagy hypotheses for the human use of psychoactive plant toxins – Both are based on plants natural defenses – First Even when they are not under attack, plants maintain a basal level of plant toxins to deter attacks This is a form of chemopraphylaxis known as a constitutive defense – Second When they detect an herbivore attack, plants – Up-regulate energetically expensive toxin production When the attack ceases, plants – Down-regulate expensive toxin production This is a form of chemotherapy (in its non-cancer specific sense) Known as inducible defense Chemoprophylaxis and Chemotherapy Hypotheses Chemoprophylaxis hypothesis – The human propensity to consume neurotoxic plants prevents or limits infection by helminths Chemotherapy hypothesis – Consumption of psychoactive substances should be Up-regulated by infection serving to limit infection levels Down-regulated if and when the infection is cleared Nicotine as a Model Drug Why might we surmise that nicotine might serve as an anthelmintic in humans? – Modern anthelmintic such as levamisole and tetrahydropyrimidines achieve their effects by targeting the same receptors as nicotine Nicotinic acetylcholine receptors (nAChRs) on somatic muscle cells Induces spastic paralysis of the parasite, leading to its expulsion Nicotine as a Model Drug Why might we surmise that nicotine might serve as an anthelmintic in humans? – Nicotine is an extremely potent neurotoxin and the quantities absorbed via smoking and chewing are surprisingly high Nausea and vomiting are induced by doses of 2-5 mg The lethal dose for an adult human is 30-60 mg Smokers typically absorb – 1-2 mg per cigarette – 4.5 mg per “wad” – Thus, tobacco users are absorbing quantities of nicotine just below that which induces acute toxic response Nicotine as a Model Drug Why might we surmise that nicotine might serve as an anthelmintic in humans? – One billion adults are tobacco users These billion smoke about 15 billion cigarettes per day – Approximately one billion people in developing regions of sub-Saharan Africa, Asia, and the Americans are infected with one or more helminths Tobacco use vs. Helminths Roulette et al. (2014) – Experimentally studied nicotine use and prevalence of helminthiasis in the Aka of the Central African Republic (CAR) – Findings Worm burden was inversely correlated with nicotine exposure from tobacco use – Evidence of chemotherapy hypothesis Treating helminth infection with a commercial anthelmintic reduced smoking – Evidence of down-regulation of drug intake Among individuals whose helminth infections were treated with commercial anthelmintics, higher smoking levels limited reinfection with helminthes – Evidence of chemoprophylaxis hypothesis Music Music Music What benefit could there be to diverting time and energy to making music? – What’s the use in feeling sad if no one has died? (Mistaken) Suggestions – Music bonds the social group, coordinates action, enhances ritual, releases tension – This just passes the question along Why do rhythmic sounds bond the group or dissipate tension, etc.? Biologically speaking, music is useless* – Shows no signs of design for attaining goals such as long life, grandchildren, or accurate perception and prediction of the world Music appears to be a pure pleasure technology – “A cocktail of recreational drugs that we ingest through the ear to stimulate a mass of pleasure circuits at once.” Why is Music? If music confers no survival advantage, where does it come from and why does it work? Why is music? What is Music? The Lay of the Land There are billions of ways to divide the increments from one A to the next A (an octave above) – Pretty much every culture uses the same 12 notes This is not a scale, just the available 12 notes – i.e. 12 consecutive white and black keys on a piano – Traditional Chinese and American Folk Typically employ 5 notes selected from these 12 available – Western Classical Music Uses 7 of the 12 available (the eighth note of the Western scale is the octave) The Lay of the Land Arnold Schoenberg created a “democratic” a-tonal system in which all 12 notes were equal – Most people call music using this system dissonant, difficult, and abrasive The Lay of the Land The sonic range that matters and interests us the most is identical to the range of sounds we ourselves produce – Our brains and ears have evolved to catch subtle nuances mainly within that range We hear less, often nothing at all, outside of it. – We can’t hear what bats hear, or the subharmonic sound that whales use Music falls into the range of what we can hear The Lay of the Land Periodic sounds – Sounds that repeat regularly are Indicative of living things – Could be something to be wary of – Could be a friend More interesting to us – Could be a source of food or water – These parameters narrow down toward an area of sounds similar to what we call music The Lay of the Land Bowling et al. (2010) – Surmised that it would seem natural that human speech influenced The evolution of the human auditory system The part of the brain that processes those audio signals – Co-evolution of Our vocalizations Our ability to perceive their nuances and subtleties … and our musical preferences – If this is true, then there should be a biological rational for musical scales Biological Rational for Musical Scales Bowling et al. (2010) – Recorded ten- to twenty-second sentences by 600 speakers Included English and other languages – Then broke these sentences into 100,000-sound segments Digitally eliminated all elements of speech that are unique to various cultures – Leaving only the sounds that are common to us all Stripped away all S sounds, percussive sounds from P’s, and clicks from K’s – This left only vowel sounds made with vocal cords – Goal was to be left only with universal notes and tones Biological Rational for Musical Scales Bowling et al. (2010) – All utterances were of “proto-singing” The vocal melodies embedded in talking The notes we sing when we talk – Found that the loudest and most prominent notes fell along the 12 notes of the chromatic scale – In speech (and in normal singing) notes are further modified by our tongues and palates to produce particular harmonics and overtones – These additional pitches fell in line with what we think of as pleasing “musical” harmonies Biological Rational for Musical Scales Bowling et al. (2010) – “Seventy percent… were bang on musical intervals” – All the major harmonic intervals were represented Octaves, fifths, fourths, major thirds, and a major sixth – “There’s a biological basis for music, and that biological basis is the similarity between music and speech.” – “That’s the reason we like music. Music is far more complex than [the ratios of] Pythagoras. The reason doesn’t have to do with mathematics, it has to do with biology.” Listen to How Musical This All Is… Biological Rational for Musical Scales What other information might be represented in speech vowels? Biological Rational for Musical Scales Gill and Purves (2009) – Found that Happy (excited) speech vowels fall within major scales Sad (subdued) speech vowels fall within minor scales – Speech vowels as a signal of emotional content We have evolved the ability to – Encode emotional information within our speech – What about the ability to decode emotional information within others’ speech??????????????????? Biological Rational for Musical Scales Pinker Music – “I suspect that music is auditory cheesecake, an exquisite confection crafted to tickle the sensitive spots of at least six of our mental faculties…” – “… a standard piece tickles them all at once, but we can see the ingredients in various kinds of not-quite-music that leave one or more of them out.” Music 1. Language – We can put words to music We wince when a lyricist gets lazy – This suggests that music borrows some of its mental machinery from language Music and language work in similar ways – The metrical structure of strong and weak beats – The intonation contour of rising and falling pitch – The hierarchical grouping of phrases within phrases – These parallels may account for The gut feelings that a musical piece conveys a complex message The emphasis of some portions while others are whispered to the side The making of assertion by introducing topics and commenting on them Music 2. Auditory Scene Analysis – The ear receives many jumbled frequencies at once The brain must segregate the streams of sound that come from different sources – E.g. voice in a noisy room, animal in a chirpy forest – One of the brain’s tricks to identify soundmakers is to pay attention to harmonic relations Components that stand in harmonic relations are grouped together and perceived as a single tone rather than separate tones – Harmonic relations (a component at one frequency, another at twice that frequency, and another at 3 times that frequency) Simultaneous sounds in harmonic relation are probably the overtones of a single sound coming from one soundmaker in the world This is a good guess for the brain to make because many resonators emit sounds of many harmonic overtones – i.e. plucked strings, struck hollow bodies, calling animals, etc. Music 3. Emotional calls – Melodies might evoke strong emotions because their skeletons resemble templates of our species’ emotional calls Whimpering, whining, crying, weeping, moaning, growling, cooing, laughing, yelping, baying, cheering. – These all have acoustic signatures When people try to describe passages of music, they use these calls as metaphors – Ersatz emotion is a common goal of art an recreation Music 4. Habitat Selection – Visual scenery can signal safe, unsafe, or changing habitats. E.g. distant views, greenery, gathering clouds, sunsets – Features of the auditory world may also signal safe, unsafe, or changing habitats E.g. thunder, wind, rushing water, birdsong, growls, footsteps, heartbeats, snapping twigs – These all have emotional effects presumably because they are thrown off by attention-worthy events in the world – Some of the stripped-down figures and rhythms at the heart of a melody are simplified templates of evocative environmental sounds “Tone painting” – when composers intentionally try to evoke environmental sounds like thunder or birdsong in melody Music 5. Motor Control – Music may be a concentrated dose of motor rhythms to pleasure Rhythm is the universal component of music – In some idioms it is the primary or only component There are strong hints that music taps into the system of motor control – People dance, nod, shake, swing, stride, clap, and snap to music Many other repetitive actions also have an optimal rhythm – E.g. walking, running, chopping, scraping, and digging Muscle control also embraces – Sequences of tension and release – Actions carried out with urgency, enthusiasm, or lassitude – Erect or slumping body postures that reflect confidence, submission or depression Music 6. Something else – Something that explains how the whole is more than the sum of the parts – Something that explains why other activities don’t have the same effect Perhaps a resonance in the brain between neurons firing in synchrony with a soundwave and a natural oscillation in the emotion circuits? An unused counterpart in the right hemisphere of the speech areas in the left? Some kind of coupling that came along as an accident of the way that auditory, emotional, language, and motor circuits are packed together in the brain? Health Why We Get Sick The Mystery of Disease Why in a body of such exquisite design, are there a thousand flaws and frailties that make us vulnerable to disease? If evolution by natural selection can shape sophisticated mechanisms such as the eye, heart, and brain, why hasn’t it shaped ways to prevent nearsightedness, heart attacks, and Alzheimer’s disease? If our immune system can recognize and attack a million foreign proteins, why do we still get pneumonia? If a coil of DNA can reliably encode plans for an adult organism with ten trillion specialized cells, each in its proper place, why can’t we grow a replacement for a damaged finger? If we can live 100 years, why not 200? The Mystery of Disease The common answer “that natural selection just isn’t powerful enough” is usually wrong – It’s a bundle of crap The body is a bundle of careful compromises The Causes of Disease Nesse and Williams (1995) – Why We Get Sick – Propose six categories of evolutionary explanations of disease – Excellent book!!! The Causes of Disease … and an excellent follow-up released recently!!! 1. Defenses Not actually explanations of disease, but often confused with disease A fair-skinned person with severe pneumonia may take on a dusky hue and have a deep cough These are 2 signs. One a defect, one a defense – Skin is blue because hemoglobin is darker in color when it lacks oxygen. A defect. Like a clank in a car A happenstance result with no particular utility 1. Defenses Cough is a defense – Like the light on the dashboard that turns on when the gas tank is low – Results from a complex mechanisms designed specifically to expel foreign material in the respiratory tract When we cough, a coordinated pattern of movements involving the diaphragm, chest muscles, and voice box propels mucus and foreign matter up the trachea and into the back of the throat, where it can be expelled or swallowed to the stomach where acid destroys most bacteria – Cough is not the problem Cough is a protective response to a problem – A coordinated defense shaped by natural selection 1. Defenses Defenses vs. Defects – Distinction is crucial for someone who is sick – Correcting a defect is almost always a good thing Stopping the clank in the car or doing something to turn the pneumonia patient’s skin warm pink is almost always beneficial – Eliminating a defense by blocking it can be catastrophic Cut the wire to the light that indicates a low fuel supply and you are more likely to run out of gas Block your cough excessively, and you may die of pneumonia 2. Infection A never-ending arms race – Bacteria and viruses treat us mainly as meals We have evolved defenses to counter these threats They have evolved ways to overcome our defenses and even use them to their own benefit – This endless arms race explains Why we cannot eradicate all infections Some autoimmune diseases 3. Novel Environments Similar to the Mismatch hypothesis – Our bodies were designed for lives spent in small groups hunting and gathering on the plains of Africa – Natural selection has not had time to revise our bodies to cope with novel environments Fatty diets, automobiles, drugs, artificial lights, central heating, etc. – From this mismatch arises most preventable modern disease e.g., heart disease and breast cancer 3. Novel Environments Examples: – Population migration and skin cancer – Caloric availability and obesity as a cancer risk factor – Higher availability of fats that promote tumor growth – Tobacco availability and smoking as a cancer risk – Differences in number of reproductive cycles and breast cancer – Exposure to light at night may increase cancer risk 4. Genes Some of our genes are perpetuated despite the fact that they cause disease – Some are genetic “quirks” that were harmless in our more natural environment Genes that predispose to heart disease were harmless until we began overindulging in fatty diets Genes that cause nearsightedness cause problems only in cultures where children do close work early in life Some of the genes that cause aging were subject to little selection when life spans were shorter 4. Genes Many genes that cause disease have been selected for because they provide benefits – Either to the bearer or to other individuals with the gene in other combination For example, the gene that causes sickle-cell prevents malaria There are also sexually antagonistic genes that benefit fathers at the expense of mothers (or vice versa) 5. Design Compromises Costs and benefits – There are costs associated with every major structural change preserved by natural selection Walking upright – Gives us the ability to carry food and babies – Predisposes us to back problems – Many of the body’s apparent design flaws aren’t mistakes, but compromises – To better understand disease, we must understand the hidden benefits of apparent mistakes in design 6. Evolutionary Legacies Evolution can only make small changes which must be immediately beneficial – Fires occurred when a popular line of pickup truck was struck from the side because the gasoline tanks were located outside the frame To relocate the tanks within the frame would require a major redesign of everything now there – This would cause new problems and require new compromises – Our food passes through a tube in front of the windpipe, exposing the danger of choking It would be more sensible to relocate the nostrils to somewhere on the neck That will never happen… Signs and Symptoms of Infectious Disease Say you are on the side of the mouse in a cat and mouse conflict… – The mice say they hate the smell of a cat Makes them jittery and unable to concentrate on important matters such as food, courtship, and babies – You know of a drug that will dull this sense so the mice won’t be bothered by the smell as much – Do you prescribe the drug? Signs and Symptoms of Infectious Disease The ability to detect cat odor, however unpleasant is a valuable asset for mice The presence of the cats smell may signal the imminent arrival of its claws and teeth Avoiding the cat is far more important than the stress of an unpleasant odor Signs and Symptoms of Infectious Disease Suppose you are a pediatrician treating children with colds Colds bring symptoms that children may dislike – Runny nose, headache, fever, malaise, etc. Tylenol can reduce or eliminate some of these symptoms Do you prescribe Tylenol? Fever As Defense Against Infection Matt Kluger – “There is overwhelming evidence in favor of fever being an adaptive host response to infection that has persisted throughout the animal kingdom for hundreds of millions of years.” – Kluger believes that using drugs to suppress fever can make people sicker – and even die Fever As Defense Against Infection Kluger showed that cold-blooded lizards benefit from fever – When infected, they seek out a place warm enough to raise their body temperature about two degrees Celsius – If they cannot move to a warm place, they are more likely to die Body temperature is carefully regulated – When the lizard is infected, it just has a higher set point Fever is an adaptation to combat infection Abnormal Psychology Abnormal Psychology “We are all the same and we are all different…” – Evolutionary Psychology – Behavioral Genetics Post-Traumatic Stress Disorder PTSD – syndrome of emotional reactions to extremely stressful events – “Events so powerful that they threaten life or well being, severely tax or overwhelm coping capabilities, and challenge the assumptions that people make about the world and the way it works.” Post-Traumatic Stress Disorder PTSD – “Shell Shock” During WWI, doctors believed that it was a response to the physical concussion caused by exploding artillery – “Railway Spine” During the Industrial Revolution, doctors believed that it was caused by twisting or concussion of the spine What are some causes of PTSD? Post-Traumatic Stress Disorder An evolutionary perspective would expect that PTSD would primarily be a disease of modern life – Based on the frequency of its causes Post-Traumatic Stress Disorder Less than 10% of individuals exposed to natural disasters get PTSD – Tornadoes, cyclones, volcanoes, etc. 20% to 50% of individuals exposed to humanengineered disasters get PTSD – Airplane crashes, flooding caused by broken dam, automobile accidents, etc. PTSD can be seen as a susceptibility to stress that overwhelms our normal defense against threats The frequency of its occurrence reflects that mismatch between our evolved defenses and modern environment Major Depressive Disorder Criteria for Major Depressive Episode – Five (or more) of the following symptoms have been present during the same 2-week period and represent a change from previous functioning At least one of the symptoms is either – Depressed mood – Loss of interest or pleasure Not including any symptoms clearly due to a general medical condition Major Depressive Disorder 1. 2. 3. 4. 5. 6. 7. 8. 9. Depressed mood most of the day, nearly every day, as indicated by either subjective report or observations made by others Markedly diminished interest or pleasure in all, or almost all activities most of the day, nearly every day Significant weight loss when not dieting or weight gain, or decrease or increase in appetite nearly every day Insomnia or hypersomnia nearly every day Psychomotor agitation or retardation nearly every day Fatigue or loss of energy nearly every day Feelings of worthlessness or excessive or inappropriate guilt nearly every day Diminished ability to think or concentrate, or indecisiveness, nearly every day Recurrent thoughts of death (not just fear of dying), recurrent suicidal ideation without a specific plan or a suicide attempt, or a specific plan for committing suicide Major Depressive Disorder Nesse (1991, 2000) – Suggests that depression is nature’s way of telling us that we are barking up the wrong tree Keeps us from spending energy on activities that are unlikely to contribute to our fitness or from taking senseless risk Keeps us from spending more energy on futile goals which would risk even greater loss – Often seen in depressed individuals coming into therapy Major Depressive Disorder Evolutionary Psychology suggests that those who were prone to depression out-reproduced those who did not experience depression For this to be effective, proper calibration is necessary – “Depression Threshold” Experience depression only at functional times Death of a loved one vs. parking ticket Those with clinical depression may have too sensitive a depression threshold Major Depressive Disorder Depressive Realism – People who are depressed have a lower opinion of themselves and of their prospects for success This assessment is more accurate – Normally, it is adaptive to have an inflated self-image – Depression takes off these “rose-colored glasses” Depression tells us when to cut our losses Helps us to realize when our goals are unrealistic – Competing for attractive mates – Competing for higher positioning Major Depressive Disorder Pomerleau (1997) – Depression is much more common in the winter – Seasonal Affective Disorder (SAD) Winter – Food is more scarce – Moving is more metabolically expensive SAD may have kept our ancestors from wasting energy on activities that were less fruitful in the winter Major Depressive Disorder Hagen (1999) – Suggests that depression serves as a negotiating tool to extract more investment from others – Primarily concerning post-partum depression Rearing a child is extremely expensive Mothers suffering from post-partum depression may need to negotiate higher levels of cooperation to succeed Major Depressive Disorder Hagen (1999) – “I argue that PPD may be a strategy to negotiate greater investment from father and kin, or to reduce the mother’s costs by functioning somewhat like a labor strike. In a labor strike, workers withhold their own labor in order to force management to increase their wages or benefits, or reduce their workload. “ – “Similarly, mothers with PPD may be withholding their investments in the new and existing offspring, or , in cases of very severe depression, putting at risk their ability to invest in future offspring by not taking care of themselves. This may force the father and kin to increase their investment.” Suicide Why??? Suicide Suicide – 8th leading cause of death in the U.S. Accounts for 1.4% of all deaths – Suicide rates increase with age 50% higher rate in the elderly (65 and older) than the young (15-24) Seems to contradict the principles of evolutionary psychology Why? Suicide Kin Selection – Can our own death further the success of our genes? – As we age, our reproductive value declines At some point, an elderly person becomes a net drain on resources, rather than a producer of resources – Another mouth to feed – Evolutionary psychology would predict that the rate of suicide should go up as one’s capacity to promote his or her genetic interests declines This matches the demographic fact that suicide rates increase with age Grief Game theory (again) – Schelling: Self-control is unmistakably a tactical battle between parts of the mind Grief “But precisely Mr. President, it is not only possible, it is essential. That is the whole idea of this machine. Deterrence is the art of producing in the enemy the fear to attack. And so, because of the automated and irrevocable decision-making process which rules out human meddling, the Doomsday Machine is terrifying, simple to understand, and completely credible and convincing.” Schelling Grief – The tactics that people use to control themselves are interchangeable with the tactics they use to control others – How do you prevent your child from scratching his hives in his sleep? Put mittens on his hand – How do you prevent yourself from scratching your hives in your sleep? Put mittens on yourself – Common behaviors Set your watches 5 minutes fast Place our alarm clocks away from the bed Grief If you didn’t grieve when someone died, could you really have loved him when he was alive? – It is logically possible, but seems psychologically impossible Grief is the other side of love Grief could be an internal doomsday machine – Pointless once it goes off, useful only as a deterrent – What parent has not worried himself sick with awful images when a child is late or sick? These thoughts are powerful reminders to protect and cherish a loved one – Like all deterrents, grief would be effective only if it is certain and terrible Anxiety Anxiety Anxiety can be useful – It can be adaptive for us to have a healthy fear Heights, venomous creatures, unfamiliar surroundings, whether our children are safe, etc. – Too little concern can be disastrous Fall off cliffs, end up with snakes in our beds, get lost, lose our children, etc. Anxiety What happens – To the berry picker who does not flee a grizzly bear? – To the fisherman who sails off alone into a winter storm? – To the student who does not shift into high gear as a term paper deadline approaches? Anxiety In the face of threat, anxiety alters our thinking, behavior, and physiology in advantageous ways – If the threat is immediate, a person who flees will be more likely to escape injury – While fleeing, the person experiences Rapid heartbeat, deep breathing, sweating, increase in blood glucose and epinephrine levels – Walter Cannon’s “fight or flight” response Anxiety Anxiety usually seems excessively unnecessary – Lose our concentration during exams – Refuse to fly on airplanes – Stumble over words when speaking in public 15% of the population has had a clinical anxiety disorder Anxiety How can we explain the apparent excess of anxiety? – In order to determine when it is useful and when it is not, we need to ask how the mechanisms that regulate anxiety were shaped by natural selection Anxiety Why not be anxious all of the time? – Because anxiety is useful, it might seem optimal to adjust the mechanism so that we are always anxious – This would be distressing, but natural selection cares only about our reproductive fitness, not our happiness The costs of anxiety Anxiety – The reason that we are sometimes calm is not because discomfort is maladaptive – Anxiety Uses extra calories Makes us less fit for many everyday activities Damages tissue Anxiety Why does anxiety damage tissue? – Imagine a host of bodily responses that offer protection against danger Those that are “inexpensive” and safe can be expressed continually Those that are “expensive” or dangerous cannot The “expensive” responses are bundled up into an emergency kit opened only when the benefits exceed the costs – Some components are kept sealed in the emergency kit precisely because they cause bodily damage Anxiety If anxiety can be costly and dangerous, why isn’t the regulatory mechanism adjusted so that it is expressed only when danger is actually present? Anxiety Unfortunately, in many situations it is not clear whether or not anxiety is needed The Smoke Detector Principle – The cost of getting killed even once is enormously higher than the cost of responding to a hundred false alarms Anxiety Imagine that you are alone in the jungle, and you hear a branch break behind a bush… Anxiety It could be a tiger or it could be a monkey – You could flee, or you could stay where you are To determine the best course of action, you need to know – The relative likelihood that a sound of this magnitude would come from a tiger – The relative frequency of tigers and monkeys in this location – The cost of fleeing (false alarm) – The cost of not fleeing (cost of false negative) The individual whose anxiety level is adjusted by an intuitive, quick, and accurate signal detection analysis will have the survival advantage Anxiety This suggests that there might be a category of people with unrecognized anxiety disorders – Those who have too little anxiety Isaac Marks – “Hypophobics” Don’t complain and don’t seek psychiatric treatment Instead end up in emergency rooms or fired from their jobs As psychiatrists prescribe new anti-anxiety drugs with few side effects, we may create such conditions Disorders That May Be Side Effects of Genes With Fitness Benefits Genes spread if, on average, they enhance fitness Creativity – A gene that enhanced creativity could spread even if it sometimes caused a mental disorder if the benefits exceeded the costs – Creativity would have been of great use to our ancestors Creating better weapons and tools, traveling more efficiently, eliciting cooperation better, outsmarting competitors, etc. Folk/Intuitive psychology often links creativity with madness Disorders That May Be Side Effects of Genes With Fitness Benefits “Name one genius that ain’t crazy.” – Kanye West Disorders That May Be Side Effects of Genes With Fitness Benefits Research shows a link between creativity and mental disorder – Adreasen (1987) Found that 80% of faculty at a workshop had suffered either depression or manic depression Found that only 30% in a control group suffered from depression or manic depression – Ludwig (1995) Found that individuals in the creative arts had more psychopathology than those in other professions Those in creative positions had between two and three times more alcohol problems, drug use, depression, mania, and suicide Bipolar Disorder Bipolar Disorder – characterized by severe mood swings – Depression – similar to unipolar or major depressive episode – Mania – characterized by euphoria, high energy levels, boundless enthusiasm, little need for sleep Often spend money impulsively, engage in sexual activity more often Often at risk for suicide, especially when going from depressive to manic phase Bipolar Disorder Individuals in a manic phase show signs of increased creativity – Speech contains three times more rhyming, alliteration, and idiosyncratic words than normal individuals – Complete word associations much faster Robert Schumann wrote 40% of all his compositions during a 2-year manic phase out of a 24-year career If, in the EEA, creativity provided fitness benefits, it may have been favored despite impaired performance during depressive phases Bipolar Disorder Thom Yorke – Example of a highly creative person who suffers from psychological problems Schizophrenia Schizophrenia – disorder characterized by incoherent thoughts, inappropriate emotions, and hearing voices – Affects about 1% of the population (throughout all cultures) Schizophrenia is so debilitating that sufferers have lower reproductive success than the rest of the population – A gene for schizophrenia cannot be conveying a reproductive advantage in those who have the disorder A prevalence of 1% in the population – This is too high for the disorder to be maintained in the population by mutation of one or many genes. Schizophrenia Heterozygote superiority – It is possible that the gene for schizophrenia conveys some advantage on individuals who carry it, but do not have the disorder As in sickle-cell anemia Incomplete penetrance – the situation in which a gene is expressed only in a minority of cases because of environmental reasons, or interaction with other genes – The gene for schizophrenia could be dominant, but only expressed in a minority of cases – This would require some advantage to those who carried the gene but weren’t affected with the disorder Schizophrenia Karlsson (1984, 1985, 1988, 2001) – Found that first degree relatives of schizophrenics were 2 times as likely to be members of creative professions – He proposes that those with a gene for schizophrenia, but not the disorder, gain an advantage in creativity It is likely the case that schizophrenia is caused by more than one gene – Karlsson’s hypothesis of a single gene with incomplete penetrance is most likely wrong – It is still likely that the one or more genes for schizophrenia convey and advantage in non-affected carriers This helps to explain why the disorder is still present in the population