BIOL1100 Notes - Lectures 1-6 PDF

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BIOL1100 – Evolutionary Perspectives on Modern Society Lecture 1: Early Hominin Evolution & Modern Human Psychology

Step 1: Leaving the trees   

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Rainforests in Africa begin to dry out due to continental plates ripping Africa apart (7-8 million years ago) cause the chimpanzees to move to the ground, where they have evolved to survive The chimpanzees encounter new evolutionary pressure in the savannah such as lions, leopards and Sabertooth tigers o A successful evolutionary outcome is very rare in this case This can be studied by other primates in the savannah and fossil records o Senegal Chimpanzees in the Savannah have been observed with unique behaviours such as using tools. They also sleep in caves o Savannah Baboons, are monkeys not apes but have been observed with evolutionary behaviours that help them to survive The change in environment produced many changes o It aligned individual goals and group goals for the first time in our line

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There is an advantage to cooperation & Kindness  Cooperation and Kindness evolved to make us more effective killers

Australopithecus (1) Lucy was a fossil record who demonstrated many psychological and physiological evolutionary steps towards modern humans Physiological Changes  She was Bipedal (she walked upright) and could lock her knees (discovered by bone structure and footprints) o Bipedalism is the important factor that set in the evolutionary changes to come in the future.  Could have possibly developed due to fear, and their need to have a tool such as a stick to protect themselves in the savannah (psychological)  It is calorically efficient to walk on two legs, so it is energy conservative and could have allowed them to tire out their prey (biological)  She had similar pectoral muscles similar to humans, which shows how muscles have changed to not be as inclined for climbing  She had a waist that could rotate, less stiff shoulders, arms and legs o This is an important evolutionary step as it allowed the animal to efficiently throw, which allows them to kill a physically stronger animal at a distance while in complete safety. Psychological changes  Lucy’s evolutionary ancestors, chimpanzees don’t have obvious sharing behaviours and are non-cooperative o This is visible by their eyes which do not show where they are gazing, but humans have the white in our eyes that show where they are looking. Our gaze allows non-verbal communication that allow for cooperation  At a fundamental level chimpanzee are competitive and are hierarchal in nature o Humans have evolved in a way that involves sharing and cooperation o Lucy needs to be in a group where they cooperate as they will die alone in the savannah  This is why humans have a sensitivity to rejection, as they need to survive in a group

Step 2: Expansion

The Homo Erectus would move out of Africa, into western Europe, the Middle east and Asia. They were able to utilise the Division of Labour and could plan for the future Division of Labour  Evidence of Cooperative hunting, where elephants and horses was butchered from many different tools o Elephants and horses are extremely large and resilient and must have been killed using teamwork indicative of division of labour o Cut marks near the top of limbs and the torso indicate that the homo erectus killed the animal not scavenged it as the primary predator would have ate all the high up meat.  The evidence we had included cooperative hunting, where elephants were butchered, from different tools o These elephants must of have been killed using team work, which illustrate division of labour and planning for the future  Different areas being used for different processes of tool making may illustrate specialisation and therefore division of labour  We have found an upside-down elephant skull, where the homo-erectus must of have worked together to turn over the head, and possibly by a lever mechanism like structure which was found near the skull Planning for the Future  Tools being used by the Homo Erectus also shows their planning for the future o Studies where people are taught how to make primitive tools and when shown a half-finished tool and   

scanned through fMRI parts of the older brain light up, so it shows evidence for planning for future Chimpanzees can only plan for needs they already have o We have no evidence that chimpanzees can plan for the future The Homo erctus would create tools and carry them great distances, illustrating their ability to plan for the future through the reuse of tools Cooperative hunting requires planning for the future.

After this step we began shaping our own evolutionary pathway via social organisation, tools, & fire  Fire is important as it allows us to extract more nutrients from food, which allowed humans to grow a larger brain and form a better metabolism, and fat storing capabilities (protects brain). Notch 2NL and Brain Expansion  This gene is responsible for brain expansion, where the brain remains stem cells for a longer time so that there can be more neurons so a larger brain  Without enough food, ancestors before Lucy would not get enough food for brain expansion  This was possibly apparent in Lucy but became more apparent in the Homo Erectus as they would be allowed more food through social capacity (social Brain hypothesis)

How has this affected Modern Humans There is a common interest in sharing our own interest in something  Humans are the only animal who point to gain other attention to something o There is advantage to the group and to the individual when we do this 

It is important for humans to share not only the content of our mind but our feelings too o A group is efficient when everyone agrees on what they’re doing and how they feel about it

Humans often share emotions more than knowledge  We often might exaggerate so that we can make someone agree with our own emotions o We have a desire to be on the same page as something and to feel similarly towards something  It helps if the group knows how we feel and you know how the groups feels Animals often communicate but only Humans communicate information that is of no current value  It allows you to be on a similar emotional page. When people do not see each other for a long time they often drift as they are no longer on a similar emotional page

Seeing Minds  Humans have the capability to understand that humans have beliefs and thoughts that are different from our own o We lack egocentricity except during our early developmental stages   

You can attribute emotions and intentions to everything Autistic individuals are unable to do this to some degree o They lack the ability to understand the capacity of other people’s minds My knowledge and our innate desire to understand someone’s mind allows for cooperation

Lecture 2: Early Hominin Evolution & Modern Human Psychology (cont.)

Step 2: Agriculture Why did it take so long to develop Agriculture?

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Requires Division of labour and Planning for the future which developed through the homo-erectus, but agriculture would require an extreme psychological shift o With Agriculture came semi-permanent homes, as a hunter gatherer would have to move home often, and the tools required for agriculture would not be carried Hunter gatherer culture is an opposite to agriculture o After a Hunt people would expect immediate return with food, for food needs to be ate

o Refusing someone to eat food would be a conflicting social interaction which would be bad o For example, though a chicken could be used for more and more food through eggs, people would   

expect the chicken to be killed and ate, so the beginnings of agriculture would be halted Modesty is revered in a hunter-gatherer society as a testament to the sharing culture Though Agricultural implements were present, agriculture itself required new tools & a new lifestyle to develop In this society people are extremely modest and had no understanding of inequality. They were essentially communists

Step 1: Agriculture required a change from universal sharing to acceptance of inequality  Our best look at inequality, is through burials o The presence of flowers, or jewellery

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Because people now stay in their dwellings and their farms conflict begins with another, as hunter-gatherers would have just split ways

Step 2: Slavery, Serfdom, & greater gender inequality  As inequality begins to show in society and in our psychology, it begins to manifest in slavery  Wealth is now apparent and now people can base the importance of a person on the wealth they can see  Gender equality began by men gathering many partners so that they can have many children, and this is done by gathering wealth.  When trying to enslave hunter-gatherers they were unable to do so as they were un-subjugateable as they fundamentally could not understand slavery. New Opportunities – New costs  Hunter-gatherers used to have good teeth but after agriculture developed, oral bacteria would begin to feed on the sugars, causing bacteria to break down teeth.  Hunter-Gatherers were taller and lived longer, as farmers would have a limited diet, but HG would get a variety of foods across the seasons. Population Growth Impact of Cities  Allow for greater trading  A development from interaction with only familiar people to interactions with strangers  The world used to be a zero-sum game but now people can pursue their passions

The return of Reputation  The internet and reputation  In a small community, everyone knows everyone, so reputation is known  In a larger city it is less effective, as there are so many people  But now as the internet has become extremely popular, anyone can find out information about anyone, sharing one’s reputation with the world.

Deception and Self-Deception Dishonest Signals  If deception helps someone succeed in some manner, they will do it o If you buy a fake Rolex, you are trying to deceive someone for your own gain – you seem rich o Animals do so through camouflage to help them hunt or help them hide, each advantage o o

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Killdeers pretend to be wounded away from home to draw away the predator from their homes Females of a species are naturally attracted to stronger and larger males. One form of bird do not go through the final stage of development and look like females, so that they can surprisingly mount a female in hopes of spreading their genetics Monkeys will deceive their own kind so that they can hoard food.

Honest Signals  This is a single that is impossible to fake o Peacocks are easy prey for tigers, so that means their colourful and obvious tail is a handicap. Surviving with the handicap is a message to females that the bird is impressive and strong. o Very colourful birds require the movement of keratanoids from their immune system to their feathers to produce the colours. By doing this it shows females he must be strong enough to compromise his immune system and still survive. Self-Deception  If deceit is fundamental in animal communication, there is high change of self-deception, that can occur unconsciously without us knowing o There is evolutionary advantage to self-deception o If you can lie to yourselves and in turn, make someone else more likely to believe that lie there is an advantage to self-deception o You believe that you are 30% more attractive than you really are. But if you believe you are more attractive then you are you will be more confident and therefore more likely to reproduce. o You lie to the extent where it is believable

Lecture 3: Natural Selection and Evolution

Parallels between humans and Animals Infanticide  When a new alpha-male enters a group, he kills all the offspring that isn’t genetically related to him o This is so he can reproduce and continue his genetic line  Humans are also statically more inclined to this behaviour, with children homicide being extremely higher with step-fathers and decreasing over age. Nuptial Gifts  Is prostitution an act that can be seen in nature other than in humans  Yes, as flies illustrate behaviour where they present food to a female, and while the female is eating it they mate with it o This is an exchange of resources which prostitution can be viewed as  Chimpanzees exchange meat for sex on a long-term basis  The Ache people in Paraguay, where better hunters who are better at the provision of protein receive greater sexual reciprocity

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There are biological parallels to prostitution in nature, but the most obvious difference is the humans disconnect between sex and bearing children. o Historically this was not so.

Drumming in Culture  In so many cultures, there is a love for rhythm and music, seen by the presence of drumming in a number of cultures  Cockatoos drum to attract females by pulling stick off and whacking it on a branch on the top of a canopy o Cockatoos who do this with no rhythm do not mate

Natural Selection and Evolution Natural Selection 1. Variation in traits 2. Trait variation has a genetic basis 3. Trait variation affects the probability of reproduction 4. Change in frequency of trait in next generation Evolution occurs all the time  Poison resistance in rats o Individuals vary in their tolerance which has a genetic basis o Higher tolerance rats survive and therefore have children o If the trait passed on more poison tolerant rats in the next generation Natural Selection and Skin Colour  Mammals who are darker express high level of eumelanin  Ones who express high levels of phaeomelanin have lighter skin  Near the equator there is more sun-exposure, so people with darker skin are less likely to die from suncancers  People with darker skin get less vitamin D, so people who live in areas with lower sunlight lighter skin are less likely to die from compromised immune systems  Europeans have the greatest risk of developing melanomas and risk also increases over age  Every Biological Trait has Genetic & Environmental Components o One example of this is how people tan, where environmental exposure of the sun is able to cause melanin to be produced in the body, so the trait of darkness can be affected by both genetic and environmental factors.

Lecture 4: Sexual Conflict

Where does Sexual Conflict arise from? Energetic Costs to Reproduction  All animals want to reproduce but if possible attempt to do so with the least energy loss  If the animal is hermaphroditic both animals want to impregnate the other, as fertilizing the young consumes more energy, while the other gets all the gain (genetic offspring) with much less energy use. o This can be seen in slugs and through penis fencing in flat worms, where the winner fertilises the eggs, and the loser becomes pregnant  This is one reason why sexual conflict emerges Sexes can differ in how much they invest in reproduction  Becoming pregnant is an extreme energetic investment  The investments can be split into o Producing Sperm o o

Producing Eggs Supporting growth of eggs or young

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o Parental care Because human females invest much greater energy into their offspring sexual conflict arises

Males can have more reproductive output  Males can reproduce more than females, as sperm is continually produced but females have a cap due to their finite number of eggs  Elephant seals through fear and oppression create an area where only they can reproduce, so that 5% of males only reproduce but every female on the beach reproduce  Humans have a genetic signature that is related to Genghis Khan’s Mongols, so that 1 In 200 men are related to Genghis Khan.  The best strategy to maximise reproductive output will differ between the sexes – the basis of sexual conflict  Superb Fairy Wrens are birds where the parents reproduce and raise the young together o But the female’s children are often from many males who are different to the male who is raising the young as the birds are extremely sexually promiscuous o The female bird needs a male to help her raise the young, but you also want good genes, so by having multiple children from different fathers

Sexual Conflict What can Sexual conflict lead too  Differences in Mate Choosiness o A female would be choosier as they want a high-quality male as pregnancy is a high energy investment This is how complicated elaborate dances and attractive qualities males have throughout the animal kingdom o But why are male seahorses more choosey- Males carry the children so they would be choosier due to the same principle Resource trading for sex o Because there are differences in resource use in pregnancy, one way to rectify this is by trading a resource to reach some sort of equilibrium Differences in preference for mate variety o Males prefer variety o This has been tested where it was found that a sheep takes exponentially o

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longer to ejaculate after each trial as they mate with the same female. But when presented with a new female each time their time to ejaculate only increases incrementally o This has also been seen in humans where by testing penile circumference and subjective arousal, a man’s arousal seeing the same pornographic material drops over trial number but increases extremely when presented with new material. Change in timing of ovulation o Animals can advertise ovulation – which limits male attention to a specific period, increases male-male competition, and allow males to be more certain of paternity o Some animals have hidden ovulations These mostly have social benefits, where more social attention is brought to females throughout cycle, and decreases male-male competition  One problem is that it creates uncertainty about paternity, which can cause men to be less likely to father their children Is hidden ovulation actually hidden?  Studies have found that at a strip club that that strippers during the fertile period get the most tips. This could be due to a possible pheromone or a change in behaviour, or just a random statistical phenomenon. Does female behaviour change through ovulation? 

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During ovulation, female in a study were more likely to spend time with their boyfriends if they were rated as being attractive, and less likely to spend that time if they rated their boyfriends as being unattractive. Differences in fidelity 

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What happens when females use the pill  Studies show that being on the pill affects mate choice, and behaviour  When off the pill women have preference of males who look feminine for a long-term relationship o This could be due to, masculinity being associated with high testosterone behaviours, such as aggression and being indicative of a lesser quality parent o In the short term, attraction matters more Both sexes cheat- but what should each care about  Males care about extra copulations, where they have offspring’s that aren’t there’s.  Females may be worried that the male is giving resources to another offspring.  In a study, human males care more about sexual behaviour when it comes to their SO cheating whereas women care more about the emotional attachment

Lecture 5: Introduction in Sexual Selection Theory

Sexual Selection Sexual reproduction  Asexual: Do not need a combination of gametes, and have sexual organs built in to reproduce by themselves  Hermaphrodite: Have both male and female sexual organs  Sexual reproduction: Females investing in one gamete and multiple male gametes Sexual Selection  Often involves conspicuous traits which have no direct evidence to survival  Sexual Selection is based on sexually dimorphic traits which gain an individual advantage in reproductive competition  Intra-sexual selection: Selection between members of the same sex for the opposite sex  Inter-sexual selection: Selection through features that enhance apparent attractiveness to me...