LS 15 Final

Using an example, describe the interplay between culture and biology

Culture is the transmission of information by extra-cellular means. By passing on ideas within a society, we can build inventions based upon culture that frees us from some biological constraints. Glasses is an invention of culture that alleviates the constraints of poor vision caused by a maladaptive allele. Evolution would remove poor vision in our EEA, but our culture allows the allele to spread with the advent of glasses.

Describe the general process of digestion and absorption

Digestion and absorption happen in four stages: mouth, stomach, small intestine, large intestine. Mouth: The mouth starts the breakdown of food by physically grinding the food into smaller molecules. Salivary amylase starts the chemical breakdown of starches into simpler sugars. Stomach: The stomach continues the physical breakdown of food with churning. It also starts protein digestion by denaturing them with HCl and pepsin. This also kills harmful bacteria in the food. Small intestine: The small intestine neutralizes the chyme with bicarbonate. It finishes the starch and protein digestion and the villi in the small intestine start the absorption of those molecules. The small intestine starts the digestion of fats and lipids by introducing bile from the liver. The emulsified fat is also absorbed by the small intestine. Large intestine: The large intestine absorbs H20 from the chyme, which will be repurposed. It pushes the leftover chyme into the rectum where it can be excreted. It also absorbs any nutrients bacteria produce from the food.

Using an example describe how drugs influence our synapses.

Drugs hijack our synapses by mimicking neurotransmitters or blocking their reuptake. In doing so, it can heighten the effects of NT. Some drugs are designed to block the effect of the NT by binding to receptors. Caffeine is a drug that mimics the NT adenosine. It binds to adenosine receptors and kicks out adenosine, but it doesn't make our body feel tired like adenosine.

What is the EEA ? Why is it important to be aware of it?

EEA is the Environment of Evolutionary Adaptedness. It is the environment in which a species is adapted to be successful in. By removing a species from their EEA causes maladaptive behaviors. It is important for us to be aware of our EEA because it sheds light upon our behaviors. We often act in a way counter-productive in our industrial society because our behaviors that were helpful in our EEA aren't today. We grew up as hunter-gatherers in small groups of 100 where social connections and buffering against future uncertainty were vital to survival.

Why are emotions designed to be less permanent than they feel?

Emotions are brain states that alter our behavior to achieve better outcomes for our genes. As such, we can only be in one state so long until they are no longer beneficial. Our genes only care about improvement in our reproductive success, so emotions change based on whether we are reaching that goal. Happiness tells us when we have reached a beneficial outcome. Since success is relative to other individuals, we cannot stay happy or else we fall behind. Therefore, we wish to keep working to reach happiness again.

Describe the male and female differences in vulnerability in respect to fitness. Why do they exist?

Females tend to exhibit vulnerability after childbirth. Since females can only have so many eggs, they are limited in the amount of offspring they can have, so they maximize their reproductive success by taking care of the offspring. Females need the resources of the male in order to bring up the children, the female is dependent on paternal investment. Males, however, maximize their reproductive success by mating repeatedly. This means that they can leave to find a new mate, leaving the female without the promised resources. Males tend to be more vulnerable before childbirth. They don't know whether they were the ones who fertilized the egg until childbirth. This is paternal uncertainty. Males must minimize cuckoldry in order to maximize their reproductive success.

What is dietary fiber and why is it valuable?

Fiber is indigestible plant matter that consists mostly of the polysaccharide cellulose. It passes through our body undigested because we lack the necessary enzymes to break cellulose down into monosaccharides. Fiber can clean out our digestive tract of lipids, reducing our absorption of fats. Fiber attracts lipids and pulls it through the body. The body cannot absorb lipids fast enough because of the pull from fiber. Therefore, fiber can help us remove fats from our body and lower cholesterol Fiber can also make it easier for chyme to pass through our digestive system. Fiber can bind with chyme to increase its size, which attracts more water to the chyme. When it reaches the large intestine, the extra water keeps the remains of the chyme soft and allow for easier excretion. Too much fiber, however, can cause watery excretion as the large intestine cannot absorb enough water.

Although the science underlying DNA fingerprinting is universally accepted, why is there criticism about its use in criminal cases?

1. The number of loci determine how accurate a test. If the number of loci examined is too small, it will come up with a lot of different people who match the description. There is too much doubt. 2. The test requires careful attention and precision. The results can be easily influenced by human error and thus be inaccurate. 3. The DNA fingerprinting needs to be paired with other lines of evidence. It is not a "silver bullet" because there could be many circumstances where an innocent person's DNA is found at a crime scene.

Using two examples, explain what constrained learning is and how it illuminates culture-biology interplay?

Constrained learning is how we are more inclined to learn things based upon natural connections or timing. We are less able to learn when connections don't normally happen in nature or if we miss a critical period. It is a "genetically-coded hypothesis". In lab rats, rats that exposed to nausea after drinking funny, but not bad, water learn adversity towards the funny taste. However, if they were shocked, they don't learn the connection because it wouldn't be likely for them to be shocked after drinking water in their EEA. For humans, we are exposed to language as soon as we are born in our EEA. We are in a critical period to learn language and are able to do it easily. We are unlikely to encounter another language, and therefore our critical period of enhanced learning becomes closed as we grow up. That makes it difficult for adults to learn new languages because of biological constraints.

Describe 3 lines of evidence that support the idea that emotions are tools that genes use to manipulate our behavior.

Happiness: We strive to be happy. Happiness is the reward our genes give us after we accomplish something beneficial to our reproductive success. Therefore, we are controlled by our genes to keep doing things beneficial to them. Sadness: When we fall below our expectations and achieve outcomes not beneficial for our genes, we are punished with sadness. We try to avoid this feeling, and so we are pushed by our genes to achieve beneficial outcomes. Success is relative: We are never satisfied even when we think once we get something we will be. Since success is relative, we are always striving to get as much as possible.

Hormones: What are they and how do they work?

Hormones are chemical messengers made of fats or proteins that are released by glands when signaled by motor neurons. They are able to induce changes, like the production of a protein, activating an enzyme, or increase the rate of transcription, to a cell's behavior by binding to receptors on or inside the cell membrane. While they make contact with a lot of cells, only target cells with the specific receptor bind to the hormone and induce change. If the hormone is made of proteins, it binds to the outside. If it is made of fats, the hormone travels into the nucleus of the cell where it gives instructions.

Why is it hard to be a teenager?

It is hard to be a teenager because society tells them to have children later in life, while their biology tells them to have kids now. In our EEA, they are at the age where they should be having children. However, in today's society, it would be inappropriate. Trying to maximize reproductive success would in fact do the opposite; they would be stigmatized and unlikely to further reproduce. This struggle to reconcile biology and culture is what makes being a teenager hard.

Describe three examples about species having a different EEA than their current environment

Livestock: Livestock are raised purely for meat and other bodily products. They are fed excessively to produce the desired product. Animals respond by performing actions beneficial to their EEA: consuming all the food they can. Therefore, they are maladapted because easy access to food fattens them up and brings them closer to the slaughter. Zoo animals: Zoo animals are obese because they live a life of luxury. They don't need to work for their food as much as wild animals because they are fed. As such, they laze around for most of the day while accumulating weight. Their genes compel them to be lazy and eat easy food when it is not beneficial because their genes think there will be an unexpected famine. Their actions would be justified in their EEA, but they are maladaptive now that they are removed from the EEA. Marine Life: Fish evolved in an environment without plastic. Since small pieces of plastic resemble food, fish may eat them without realizing that they are poisonous. While eating everything that resembles food would help them in their EEA, it is maladaptive in an ocean filled with plastic.

Mating systems: what are they and why is variance in reproductive systems important?

Mating systems describe how a population of a species of males and females get together and mate. There are three main mating systems: polygamy, polyandry, and monogamous. Polygamy is when one male mates with several females. Polyandry is when one female mates with several males. Monogamous is when one male mates with one female. This classification is important in predicting the sexual dimorphism and variance in reproductive rates of a population. If there is a polygamous mating system, the sex that has a smaller initial investment will be one that competes for the other sex's attention. This will cause a high variance in RS in the sex that competes. A monogamous system creates males and females of similar size and features because there is no competition and initial investment is equal. This causes low variance in the reproductive success for both sexes.

What does mismatch mean? What are its implications for our instincts?

Mismatch refers to behaviors that would've been beneficial in our EEA, but are not in our current environment. It means that our instincts should not be trusted because they may lead us to behaviors that are detrimental in our current environment.

What are the features of biological macromolecules?

Monosaccharides consist of a ring of carbon with hydrogen and oxygen bonds. Polysaccharides are made up of multiple monosaccharides linked together. Fatty acids are chains of carbon linked together and bonded with hydrogen. The fatty acids are then linked to a backbone of carbon and oxygen. Proteins are made up of amino acids. They are distinguished by their nitrogen and amino group which defines the protein.

Describe three other examples of conflict that humans experience due to the alien nature of our world.

Obesity: The best way to save food and survive the next famine in our EEA is to eat it all. Food expires, but fat stays. Therefore, we should eat as much as we can. However, because of easy access to food, this leads to obesity. As such, our tendency to eat as much food as possible is a maladaptive behavior and demonstrates conflict between our genes and our alien world. Altruism to strangers: In our EEA, we should look for every opportunity to improve our relationships within our groups. Since we lived in relatively small groups, word about reputation spreads quickly. However, nowadays, we see thousands of different people a day and will most likely never meet them again. Being altruistic comes at a cost to us which may never be paid back because we lack multiple interactions. However, we still do it expecting compensation because of our EEA. Drugs: Our endocrine system works around the interaction between neurotransmitters and receptors. However, our receptors activate whenever a molecule that resembles the target NT is able to fit in the "key"; it never knows if it is the actual NT or not. Drugs are made to take advantage of this recognition issue. They may resemble our NT but act differently at the synapse. Therefore, it has become maladaptive because drugs, which weren't in our EEA, can hijack our endocrine system due to this flaw.

Why is the EEA sometimes different from our current environment?

Our EEA can differ from our current environment because of slow adaption or removal from the EEA. Adaption is a catch-up game with our environment, and so our genes may not change fast enough to keep pace. Therefore, some behaviors can become mismatched. Our environment could also change from the EEA. If we were to experience sudden changes, like industrialization, or removal from our EEA, we will still carry the same behaviors into the different environment. Since our behaviors were adapted for a specific behavior, they could now be mismatched.

Happiness: Why is the rate and direction of change more important than levels? How does this relate to material acquisition?

Our happiness (or unhappiness) is derived from the change in our current state. The higher the rate of change, the more often we are happy or unhappy. Levels affect our degree of emotion, but our minds adjust quickly so that we don't stay sulking or content. Rather, we are designed to be happy when we feel like we are making progress, so our levels become less relevant. Therefore, the rate and direction of change is more important than levels because the more change that occurs, the longer we feel the emotion. Our happiness is an equation of our performance - our expectations. If our expectations are set, going above them is what registers as progress and makes us happy. Similarly, below our expectations we feel disappointment and wish to avoid sad feelings. Material acquisition can make us happy for the short term, but we quickly adjust to our newfound wealth. This is why additional income doesn't bring us happiness past poverty. We become used to our current income to become hungry again and strive for more for our genes.

What do our senses all have in common with respect to how they help our bodies respond to external stimuli?

Our senses carry information about the outside world to our brain and spinal cord, which interpret it and send commands to our muscles via motor neurons. They are all versions of the same neuron, just specialized to respond to certain stimuli.

Describe when oxytocin and cortisol release is stimulated and the consequences

Oxytocin: The "cuddle" hormone. This hormone is stimulated through proximity to others and skin-to-skin contact. It promotes trust and positive interactions. It reduces cortisol levels, stimulates uterine contractions, and promotes milk production. Cortisol: The "stress" hormone. It is released when we are exposed to situations where we need heightened performance and awareness, like fight-or-flight scenarios. It is what causes stress with increased muscle and brain activity, decreased immune response, and decreased appetite and digestion. Short term, it increases our performance. However, long term it can impair our body's maintenance.

Nutrition and digestion: Are all proteins, fats, and carbs made equal?

Proteins: Made up of amino acids. The shape of the protein is what determines its function. There are 20 amino acids that build our proteins, but our body only naturally produces 12 of them. The other 8 we must consume and are called essential amino acids. Fats: We have saturated and nonsaturated fats. Saturated fats are chains of fatty acids that contain the maximum number of hydrogen possible connected to a backbone of carbon, oxygen, and hydrogen. The carbons are all linked by single bonds, which cause the fatty acids to take on a straight shape. This shape makes saturated fats easy to pack together and store, which make them more likely to be stored as body fat. Unsaturated fat have double bonded carbon and a smaller number of hydrogen than the maximum. This causes bends in the fatty acid chains, which create bent shapes. This makes it harder to pack fatty acids and more likely that they will be used for energy. Carbs: We have monosaccharides and polysaccharides. Monosaccharides are simple sugars like glucose that are converted by our cells into ATP for cellular processes. Polysaccharides are macromolecules like starch and cellulose that are made of monosaccharides. They must be broken up into monosaccharides first before they can be converted into energy.

What is revealed preference and why is it important?

Revealed preference is the actions of someone that reveal what the person prefers. It tends to tell the truth, rather than stated preference which relies on people's statements. It is important to revealing the true preferences of a person. A person cannot hide their preferences through repeated actions. People can sometimes unknowingly prefer other than their stated preference or intentionally lie. This makes stated preferences unreliable. Revealed preferences get to the truth hidden by stated preferences.

Explain how your genotype for a single gene can influence your novelty seeking risk taking behavior.

Risk-taking is a complex behavior, however a gene that influences neurotransmitters can affect the rate at which risk-taking occurs. If a gene codes for a higher number of dopamine neurotransmitters than average, the brain receives greater pleasure from risk-taking. This encourages the individual to keep seeking out risk-taking behavior in order to achieve the same high.

What STR loci and how do they differ? Use them in a description of how DNA fingerprinting works.

STR loci are the location of short tandem repeats on an allele. They are repeating sequences of DNA which have no effect on its expression. Some of STRs are longer than others and can have a wide range of number of repeats; within a population, there could be many different alleles. Every person has two alleles, so it could be unlikely that a person has the same alleles as someone else at a highly variable loci. People can be identified if a DNA sample contains the same STRs at a number of locis as the person in question. DNA fingerprinting works by running a sample of DNA through gel electrophoresis. This causes segments of DNA to separate at their loci. Longer STRs flow slower and get stuck closer to the top. This eventually creates a pattern within the gel. If a person's DNA creates the same pattern, they are identified as the DNA donor.

What is the fundamental reproductive equation and what does it reveal about culture and biology?

Sex=Pregnancy=Babies=maternal child care=loss of female economic opportunity=loss of female political power. Culture disrupts the fundamental reproductive equation by breaking the connections. Condoms allow us to have sex without pregnancy. Abortions allows us to have pregnancy without babies. Day care allows us to have babies without maternal child care. It signifies that culture allows us to break the constraints of biology. We no longer have to be follow what our biology has set for us.

How do male-female differences lead to mate guarding? Why?

Since females lay the eggs or perform gestation, they know the offspring is their's. However, males have paternal uncertainty because another male's sperm could've fertilized the female without them knowing. This paternal uncertainty leads to mate guarding in order to ensure the male is the one siring the offspring. Several forms of mate guarding can happen. An organism can stay attached to the female longer than is needed to fertilize the eggs in order to ensure another male doesn't insert his sperm as well. Organisms can develop anti-sperm which kills competitive sperm within the female. They can also develop physical means of mate guarding, like scooping out other male sperm or breaking their sex organ within the female to ensure they cannot mate again. All these are meant to ensure that the babies are the males in the face of paternal uncertainty.

Male-female physical differences: What are its implications for mammals and birds?

Since males are often the ones to compete for female attention and mating, they have developed physical characteristics that attribute to better genes. Some of these genes are linked to physical ability, like size in elephant seals, or outrageous displays of beauty, like a peacock's feathers. This creates a situation where females mate with the best candidate, which can cause high variance in a mating system if one male is chosen by a lot of females. These physical differences also mean different traits are selected for for the two sexes. Males are selected for competitive traits that may make them stand out more, but lower their survival rate. Peacocks with the best feathers tend to be attracting and are at a higher risk of predation. Elephant seal victors often die the next year due to the fatigue and damage they sustain from extended fighting and mating. Females, on the other hand, have no selective pressure to evolve competitive traits. Therefore, they are often more drab and smaller in order to better survive in their environment until mating.

Why do we expect humans to be symmetrical? Is it related to fitness?

Symmetry is to be expected of individuals because we don't have different genes coding for different sides of our body. In theory, this should create a symmetrical body. However, due to the norm of reaction, our body doesn't express our genes equally. Different parts of our body can be exposed to different environments and create differing expression. Symmetry becomes a sign of good genes and a desirable environment. This is related to fitness as we find individuals who are more symmetrical more attractive. Since it is an honest sign of good genes, it increases fitness. Biracial people have set of two alleles that most likely have different expression and resistances; they have more genetic diversity. Therefore, an individual can use the allele that is better suited to the environment and produce a more symmetrical look.

What are taste preferences and why do they exist?

Taste preferences are our tendency to prefer foods with a certain macromolecule content. We like foods high in sugar to a certain point because they give us quick access to energy. We also like fatty foods because fats contain the most amount of calories per gram. They exist for our genes to nudge us to consume calorie-efficient food. Since we can only eat so much, the more the calories a food has per gram, the more our body can synthesize energy from our food. This saves us time and energy into finding more food which could be spent on reproducing. If we were to prefer foods with high caloric value, it would also prepare us better for famines. If someone were to eat the same mass of fatty food as someone who eats carbohydrates, the person who eats fatty foods will be more likely to survive the famine.

Describe 3 lines of evidence for each suggesting that estrogen and testosterone are responsible for male female sex differences.

Testosterone 1: Increased testosterone has been linked to enhanced physical performance. This evidence suggests that males are built with higher muscle mass because testosterone stimulates muscle growth. Testosterone 2: Higher testosterone increases mental rotations and spatial awareness. Males tend to do better on these tests than females. Testosterone 3: Testosterone has been linked to increased aggression, which can explain the population within prisons that is disproportionately male. Estrogen 1: Estrogen has been linked to higher memory, which can explain why females do better on object memory tests than males. Estrogen 2: Estrogen levels have been linked to mood. When a female enters menopause, her estrogen levels decrease dramatically. This has been the linked to depression amongst middle age women, and elevating their estrogen levels to pre-menopause levels helped to alleviate their depression. This could explain the colloquial belief that women tend to have more mood swings then men which varies upon her menstrual cycle. Estrogen 3: Estrogen is what causes the development of secondary sex organs in females, like breasts and ovaries. Females have larger breasts than males because of their exposure to this hormone. Males exposed to greater levels of estrogen tend to develop bigger breasts, so it is the hormone influencing this gender-related difference.

What is the myelin sheath and how is it related to development and disease?

The myelin sheath is a layer of fat that insulates the axon. It helps to keep the ions from crossing the axon and speeds up the electrical signal carried by the axon. It serves a vital function to keep the resting state of the neuron so it can fire its action potential. Babies are unable to walk because the myelin sheaths that direct movement of feet aren't developed yet. If the myelin isnt developed yet, then the neurons can't fire and send signals to the muscles to move. Diseases like multiple sclerosis are caused by the degradation of the myelin sheath. Just like with babies, because the myelin sheath disappears, the neurons are unable to fire; thus, people with multiple sclerosis are unable to use their muscles.

What is the naturalistic fallacy and give an example in which people commit it.

The naturalistic fallacy is when people believe something that is natural is good, and just because something is unnatural it is bad. This relates to advertisements of food. If companies label a product as natural, people are more inclined to believe that it is good for them and buy. However, it doesn't mean that it is good for the consumer. For example, Quaker cereal is labeled as all natural, yet it has a high sugar content above the recommended daily intake of sugar. Vitamins are also natural, but not necessarily good for people in excessive quantities. Companies can label foods with vitamins in order to increase sales. People believe that vitamins are natural and good for the body; however, they can be toxic in large quantities. Companies take advantage of the naturalistic fallacy to promote vitamin rich foods that are supposedly "more healthy".

Describe the organization and function of the nervous system. Compare and contrast it with hormones.

The nervous system is made out of neurons which are divided into motor, sensory, and interneurons. Motor neurons are the neurons in our brain and spinal cord that communicate actions to muscles, gland, etc. Sensory neurons are the neurons within our peripheral nervous system that transmit information about our environment to our central nervous system. Interneurons connect our sensory neurons together. Our nervous system works upon electrical signals, which are fast-acting. They produce reflexive actions and other actions that are fast, but fleeting. Our endocrine system work by using hormones, which are chemical messengers that flow through the bloodstream. They are slower, but produce longer lasting changes. They are mostly in charge of growth and bodily changes.

What are vitamins and minerals? Should you take supplements?

Vitamins are organic molecules that help catalyze reactions in our body by binding to enzymes. By doing so, they help our body grow and maintain its health. Minerals serve a similar role, but they are inorganic molecules. We don't need supplements because a normal diet will provide our daily dose of vitamins and minerals. Too many fat soluble vitamins will build up in our fat and eventually become toxic.

What is an action potential? How, when, and why does it occur?

What: An action potential is a neuron firing its electrical signal down its axon which releasing neurotransmitters into the synapse. How: Na+ ions flow into the axon while K+ ions flow out at the nodes of Ranvier. It is initially at a resting phase, then crosses a threshold into depolarization as Na+ ions flow in. The neuron then repolarizes by letting out K+ ions. It goes into a refractory period as the neuron overshoots and releases too many K+ ions. The neuron then goes back to resting phase as it pumps K+ ions in and Na+ ions out. When: When the neuron receives a strong enough electrical impulse, the neuron fires the action potential. Why: An external stimuli sends an electrical signal to the neuron via its dendrites.

What is the relationship between sexual dimorphism and mating systems?

When there is a polygamous mating system, the sex that has the lower parental investment must make up for it with a more demanding physical appearance. This causes sexual dimorphism as the sexes have different appearances, and you can tell if an individual is male or female based on appearance.