psych 100- human evolution

what does the theory of nature v nurture include? how does it fit into concepts of nativism and empiricism?

• “is human behavior, intelligence, mental health, and personality shaped by our genetic makeup (nature) or our environment and lived experiences (nurture)?”

• nature: inborn, biological, genetic factors passed down from parents to offspring

  • connected to nativism→ believes that all behavior is inborn

• nurture: external, environmental influences across your lifetime→ parenting styles, peer groups, socioeconomic status, culture, and traumatic events

  • connected to empiricism→ believes that all behavior is learned

what is nativism? what does it believe?

• explanation of human behavior that believes that everything expressed as behavior is inborn/innate

  • “knowledge of the world is mostly innate, and determines certain abilities”

• believes that people cannot truly change their nature, as a person’s genetics determines their behavior

  • “a person is born with all of the skills, ideas, and knowledge they have, their environment and experiences can’t influence who they are or how they act”

  • plato: knowledge is innate, meaning that people are hardwired to be more intelligent than others

• nature (genetics/biology) determines behavior

what is empiricism? what does it believe?

• explanation of human behavior that believes that everything we experience shapes our behavior, with everything being learned over time and shaped by your environment

  • “nothing in terms of behaviour and knowledge is inherited, all is learned”

• believes that people can be shaped/changed, because, at birth, our minds are blank and moldable

  • john locked: tabula rasa→ the mind is a blank slate to be filled by experiences

• nurture (environment) determines behavior

what is interactionism? what does it believe?

• explanation of human behavior that considers the relationship between genes and their expressions

  • genotypes (organisms genes) and phenotypes (overt, observable characteristics)!

  • “certain basic abilities and knowledge are innate, but can be moderated by experience, which in turn can change which innate behaviours are expressed, which influences what will be experienced”

• believes that environmental factors can affect gene expression via epigenetic means

  • “a person may have a genetic predisposition for a trait, but the environment determines whether or not it is expressed”

  • development, physical environment, drugs, or diet can all impact what genes are expressed→ can impact how a person looks, functions, and thinks OR how their brain works→ can impact what kind of life experiences they have, etc…

what does genus mean? what is its human example?

• subdivision of a family —closely related species that evolved from
  recent common ancestor

• HOMO

what does species mean? what is its human example?

• the most basic rank in linnean taxonomy: animals that can interbreed and produce fertile offspring

• SAPIENS

what does family mean? what is its human example?

• animals originating from common ancestor with more detailed
  morphological similarities

• HOMINIDAE

  • includes chimpanzees, gorillas, etc…

what does order mean? what is its human example?

• animals sharing major adaptive traits

• PRIMATE

  • mammals with grasping hands/feet, forward-facing eyes, large
    brains relative to body size

what is the out of africa hypothesis? what is the new, more revised version?

• out of africa: theory that migration replaced all of the hominids→ modern humans originated from one region in africa, dispersed in waves, leading to different ‘waves’ of human evolution to be replaced at different times→ no interbreeding between humans and hominids

• new theory: human beings all originated different regions across africa, with semi-isolated groups intermixing→ people repeatedly left africa, but largely failed→ no replacements of pre-homosapiens (some still exist (ish!)- neanderthals, denisorians)

what is the multi regional hypothesis? how does it fit into the revised out of africa hypothesis?

• multiregional hypothesis: homoerectus evolved simultaneously across the planet at the same time and interbreeding is what spread humanity

  • regional traits disprove the hypothesis→ “if people everywhere were interbreeding, why do people from certain regions all look similar?”

  • pre-homosapien fossils only being on the african continent largely disprove this hypothesis

• new theory: human beings all originated different regions across africa, with semi-isolated groups intermixing→ people repeatedly left africa, but largely failed→ no replacements of pre-homosapiens

  • people did come from multiple places, but all from across the continent

what is the anthropocene? how does it relate to psychology?

• no specific start date- could be the late 18th century (post industrial revolution, could be around the 1950s/60s (post WWII expansion)

• epoch defined by the period in earth's history when human activity became the dominant force shaping the planet's climate, environment, and ecosystems

  • outcomes of prior revolutions (cognitive, agricultural, scientific, industrial) led to a new era in human history, characterized by humanity’s new ability to modify the entire biosphere (climate change, geology, ecosystems)

• connection: how have planetary crises reshaped human minds, behavior, and emotional well-being (consciously and unconsciously)

what is a phenotype?

• the overt characteristics of an organism (the properties we can observe, resulting from what genes are expressed)

  • product of genotype, environmental factors, and experience

• prevalent in interactionism: believes that human behavior can be explained via the relationship between genes (genotypes) and the ways that they are expressed (phenotypes)

what is a genotype?

• your unique, inherited genetic makeup— the specific set of genes and alleles fixed in their DNA at conception

  • a complete set of an organism’s genes

• interactionism: your underlying biological makeup determines your potential for certain things, and when you interact with your environment, it produces certain behaviors, which impact how you interact with that environment again (etc, etc)

what are epigenetics? what role do chromosomes and DNA play?

• “environmental factors can impact gene expression”

  • development, environmental chemicals, drugs, aging, and diet can impact what genes are expressed→ impacts how someone looks, functions (how your brain works, how you sleep), and thinks (how you process things)→ altered brain chemistry

• chemical tags (methyl groups) attach directly to DNA, usually turning a gene "off" by blocking protein production→ histones (proteins that package DNA) can tighten or loosen, making genes either hidden or accessible for reading

what does the term innate behaviors of humans mean? what are some examples of this?

• many abilities, characteristics, and tendencies in human beings are either present at birth or develop rapidly as a child matures

• EXAMPLES

  • inborn reflexes

  • attraction to novelty

  • wanting to explore, change things, and play

  • capacity for basic cognitive skills

  • grasping reflex, rooting reflex

what is the kindchenschema?

• also known as baby schema!

• certain facial characteristics associated with babies have high appeal to humans, and are often perceived as cuter or more attractive

  • this phenomena is found in humans and animals

  • often can elicit certain caretaking behaviors from humans

what is piloerection? how does it relate to psychology?

• a phylogenetically conserved behavior where an animal or human will have its hair stand up (or get goosebumps)

• social signalling: in some circumstances, it makes the animal look bigger and even more threatening, giving it (potentially) more protection

• emotional triggers: can be activated by the sympathetic nervous system by fear, strong emotions, awe, surprise, or danger

  • “involves sympathetic nerve activation and contraction of arrector pili muscles at hair follicles”

describe the human ‘preference for cover.’ how does it relate to psychology?

• spatial inborn behavior

• humans unconsciously use environmental factors to provide cover

  • kids build forts, dig holes/caves

  • most people prefer to sit with their backs against the wall

  • people usually prefer higher lookout points when ‘dwelling’

  • humans first occupy seats at corners and at the borders/edges

what is the grasping reflex?

• inborn behavior!

• “human newborns are remarkably strong, being able to support their own weight with the grasping reflex”

  • potentially reflects the fact that primates used to have fur, and grasping allowed the newborn to attach itself to the mother

what are dizygotic twins? what are monozygotic twins? how do they relate to psychology?

• dizygotic twins: fraternal twins, share only half of their genetic makeup

• monozygotic twins: identical twins, share all of their genetic makeup

• used in examples of IQ test: “how do genetically identical people differ from one another?”→ trying to test the impact that genes have on someone’s intelligence, and how much the environment can influence this (nature v nurture)

  • identical twins score similarly on IQ tests than fraternal twins, but fraternal twins score higher than siblings raised together

  • this proves that heritability estimates for IQ test performances based on genes

    • BUT this isn’t a measure of intelligence- it’s just a way to measure the relationships between nature and nurture

    • genes don’t code for intelligence! but how they are expressed based on someone’s environment can impact someone’s ability to process information, which can, in turn, make them appear more intelligent. but intelligence is also conceptual!

what is natural selection? what are some key factors and features? how does is relate to psychology?

• believes that organisms best adapted to their environment have a better chance of surviving and reproducing

• proposed by charles darwin from his theory of evolution

• key principles

  • rapid multiplication

  • limited environmental resources

  • struggle for existence

  • variation/mutation

  • survival of the fittest

what are darwin’s principles of natural selection?

• limited resources: population increase demands more resources→ individuals compete for limited resources

• competition/struggle for existence: competition for said limited resources

  • plays out within species (intraspecific), between species (interspecific), and because of the environment

• rapid multiplication: most organisms will produce more offspring than will survive

• variation and adaptation: genetic variations within a species can help it adapt to changes in its environment

  • some individuals can adapt better than others, and they survive

• natural selection: most adaptive traits=higher likelihood of survival and reproduction

  • acts on phenotype

what is heritability? how does it relate to psychology?

• heritability measures how the variation in a trait expression in a certain population is due to genetic differences, not environmental factos

what was the scientific revolution? how does it relate to psychology?

• took place about 500 years ago (1543-1687)

• galileo, bacon, descartes and others developed scientific method to
  understand nature with the aim to control it→ groundwork for eventual empirical approach is laid

what was the cognitive revolution? how does it connect to cognitive evolution? how does it relate to psychology?

• about 300,000 years ago! characterized primarily by the GROWTH OF THE BRAIN and all that followed!

• dramatic increase in hominid brain size following ooa migration= new tools and art produced→ cognitive evolution!

• consequences of increased brain development

  • people spent more time looking for food

  • muscle atrophy

  • human premature birth→ people needed to spend more time caring for babies

  • cooking→ food had increased nutrient density, changes in digestion

  • people further developed their ‘capacity for friendliness’

  • language→ people have many unique advantages in evolution because of language

    • ability to communicate knowledge about the world (planning, organizing, gossiping)

    • ability to communicate social structure

    • ability to communicate about things that don’t exist (myths, laws, concepts)

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what are some of the abilities of evolution because of human language? how does this relate to cognitive evolution?

• brain growth after ooa migration→ cognitive evolution→ innovations in tools, art, communication→ development of language

• human language lets people evolve and create on levels untouched by most other groups!

• advantages

  • ability to communicate knowledge about the world (planning, organizing, gossiping)

  • ability to communicate social structure

  • ability to communicate about things that don’t exist (myths, laws, concepts)

    • concepts of friendliness and cooperation

    • forming sets of shared beliefs to build communities and maintain them

    • rapid innovation of social behavior

what was the agricultural revolution? how does it relate to psychology?

• also the neolithic revolution! about 12,000 years ago! characterized primarily by DOMESTICATION OF HUMANS AND ANIMALS!

  • hominids used to depend on hunting and gathering, but after the revolution, they adopted agriculture and domesticated animals

• this new agricultural lifestyle had lots of consequences for hominids

  • introduced the concept of ownership

  • places started having default social structures instead of kinship

  • diet changes→ people can eat more, populations grow, nutrition related diseases emerge

  • settled humans=less knowledge of surroundings (animals, plants, geography)

  • sedentary lifestyle=work related disease

• people’s minds stayed in the ‘hunter-gather mindset,’ which led to conflicts with their more settled lifestyle

what is the rooting reflex?

• inborn human behavior!

• touching/stroking corner of the baby's mouth leads to a head turn, opening of mouth, pursuit of and root into direction of stroking.

  • usually goes away after the first 4 months

• searching for a place to breastfeed

how do laughing and crying relate to inborn behaviors of humans?

• inborn behaviors used to express emotion or receive attention from caregivers!

  • “research has shown that human brains respond in a specific way to crying sound of human babies. the sound readily activates the amygdala and promotes a fear response”

what is a social inborn behavior? what are some examples?

• an instinctive, genetically hardwired action performed without prior training or learning to signal social behaviors

  • stretching out hand in primates and humans signals initiation of contact, body contact signals affection and caring