Darwin and Evolutionary Theory

Darwin and Evolutionary Theory

• Darwin was diligent and curious, revolutionizing science despite his self-doubt.
• He theorized that life evolves over time via adaptation through biological changes passed down.
• Evolution explains animal traits (e.g., wings) for survival in their environment.
• Darwin's work informs evolutionary psychology, linking evolution to human thought and behavior, especially for survival and reproduction.
• Understanding human behavior requires understanding evolution.

Darwin's Journey

• Darwin travelled as a naturalist on the HMS Beagle for five years, exploring South America, Australia, and various islands.
• He collected many animals, plants, and fossils on his travels.
• Initially believing in creatonism, his theory of evolution developed later.

Natural Selection

• Darwin studied selective animal breeding, inspiring the idea that nature might also select traits.
• Malthus's work on population growth led Darwin to realize that only the fittest survive and reproduce.
• This process leads to the spread of beneficial traits and the formation of new species.
• The Origin of Species was published when Alfred Russel Wallace discovered the same idea.

Darwin's Ideas

• Adaptation evolves over generations to fit their environment better
• Natural selection passes on and keeps helpful traits, and loses the ones that aren't

Darwin's Key Points

• Species evolve over time through survival or extinction
• Evolution consists of slowly and steadily adapting, unless there's a sudden and extreme environmental shift
• All living things are related to a shared early ancestor
• Under stable conditions, natural selection fosters species adaptation while maintaining stability

Natural Selection

• Malthus inspired Darwin with the idea that limited resources lead to competition where the best adapted organisms survive and reproduce, resulting in reproductive success.
• Natural selection isn't pre-planned; it favors traits that enhance survival and reproduction.

Variation

• Variation between individuals (genotype) and environmental factors create differences (phenotype).
• Environmental factors includes diet, tallness, beak shape and strength.
• A finch study showed changes in beak thickness depending on drought, and then food types, showing environmental selection.
• Competition drives the best-suited to outcompete others.
• Winners reproduces and spread their genes.

Acceptance of Evolution

• Evolution acceptance varies globally.
• Acceptance is low in the US compared to Europe and Japan.
• Many in the US are unsure or reject evolution.
• Basic biology knowledge is lacking for some, leading to rejection.

Human Evolution

• Reconstructing human evolution is challenging due to incomplete data that include missing and broken parts
• Methods like carbon dating and DNA analysis provide estimates.
• Humans share a portion of DNA with chimps with the main difference being gene regulation.

Key Ancestors

• Homo habilis: early human with larger brain
• Homo erectus: used fire, more advanced tools, continents.
• Homo sapiens: evolved in Africa and spread
• Neanderthals: Extinct after existing in Europe for a period

Natural Selection and Evolution

• Natural selection heavily shaped human evolution.
• Bipedalism, developed over 4 million years ago, helped humans reach food and use hands for tools.
• Encephalization contributed to complex thinking, problem-solving, and planning beginning around 2 million years ago

Brain Growth Advantages

• Improved survival through better hunting, tool use, and defense.
• Planning skills allowed future event anticipation.
• Language developed that allowed vital information sharing and strengthened social bonds.
• Bipedalism, brain growth and language combined help set cultural foundation.

Heredity & Genetics

• Darwin's natural selection theory led to genetics study, but he didn't describe trait inheritance
• Gregor Mendel discovered heredity via pea experiments, explaining trait inheritance from parents.
• Genes, made of DNA, dictate development.
• 3 billion nucleotide pairs guide our development.

Protein Synthesis and Heredity

• Protein synthesis influences development and behavior through DNA sequences
• Proteins create structures and regulate bodily processes.
• No single gene controls behavior, but genes enable behavior.
• Mapping human DNA, the Human Genome Project determined 25,000 genes per cell.

Chromosomes and Meiosis

• Genes are on chromosomes in the cell, and humans get 46 chromosomes which is 23 pairs total
• Chromosome pairs contain sex chromosomes
• Meiosis shuffles chromosome pairs, increasing genetic diversity and variation in siblings.
• Sex is determined by the 23rd pair

Dominant and Recessive Alleles

• Alleles are inherited from parents, being homozygous or heterozygous
• Dominant allele expression will appear
• Recessive alleles require two allele copies for expression
• Gene variation creates eye colors

Genetic Complexity

• Behavior is polygenic and is affected by genetics, environmental factors, muscle and coordination and exercise.

Genetic Diversity

• Genetic diversity is important for adaptation to environmental changes.
• Variation increases chances for survival traits.

Heredity Influence Via Sex

• Haemophilia affects males more due to having one X chromosome
• Females can carry the trait and not show it
• Sex-influenced genes, like baldness, affect one sex, but baldness can show with just one allele

Mutations and Aberrations

• Mutations may or may not be beneficial, and result from radiation
• Haemophilia is is a notable mutation example that began in the Queen Victoria family.
• Chromosomal aberrations or total chromosome number change that can cause Cri-du-chat syndrome.

Epigenetics

• Environmental factors altering gene expression without DNA change.
• Factors like trauma, drug abuse, affection can affect protein creation which is vital for body and brain activity.
• Gene silencing stops gene access
• Licked rat pups had less anxiety

Brain Derived Neurotrophic Factor

• BDNF is important for cell function
• Low BDNF is linked to depression and distressing events may affect DNA.
• Antidepressants can increase BDNF levels.
• Spatial learning is aided by genetics and can be hindered by genetics that have been knocked out

Heredity

• Genetic instructions and environmental factors combine to shape a person.
• Inherited traits are heredity, but differences influenced by genetics are heritable traits.

Behavior Genetics

• Heritability is the measure of a traits variability within a population
• Genetic are analyzed for how they contribute to psychology like memory
• Gene variance affects memory
• Allele E4 is linked to Alzheimer's and decline.

Genetic Influences

• Genetics were studied in a historical context that went back to Mendels heritability experiments of traits
• Intelligence was studied through family relations

Artificial Selection

• Artificial Selection selectively breeds animals with desired traits
• The study of rats learning mazes done by Tryons showed that selecting rats by traits could be successful
• Environment plays a role in expression of genetics via rats showing differences in the mazes after being placed in different environments that were either enriched or impoverished.
• A traits frequency can be influenced, but motivation could have affected results.

Manipulation of Genes

• Genetics behavior shown via genetics
• Genes mapped to assist research on behavior, memory and disorders
• Advances are being led to develop therapy.

Genetics

• Genetics and environment create an interplay and role in shaping behaviors.
• Genes and environment complex interaction seeks to understand how different behaviors influence each other.

Twin Studies

• Twin studies essential study tool to understand genetics.
• MZ vs DZ twins: allow a great ability for psychologists to look at manipulating environments
• Looking at twins of MZ variety that share 100% genes, researchers are able to find how genetics contributes to personality and look at attitudes that are a result
• Degree of trait sharing and genetics can be analyzed by researchers

Traits

• High concordance rates show that MZ twins genetics are connected to traits, vs DZ twins.
• Heredity and genetic traits are high for MZ twins

Examples

• Shared personality and attitudes, and brain structures are a result of genetic traits
• Olson research discovered identical twins and shared traits/attitudes, where it could be due to heritable traits like sociability
• Jahanshad found brain structure similarity between twins.

Challenges

• Even when twins exhibit similarities, traits may not link to gene
• Shared behaviors may point to a genetic disposition for certain aspects of environments

Implications

• Nature versus nurture are resolved
• Traits result through psychological conditions

Sociobiology

• How act behaviors based on how biology works, and looks at relationships
• Study done in animals and applied to humans.
• However some don't agree and think things are overly simplified for behavior
• Sociobiology includes how animals care for babies
• Studies include monogamous one on one relationships, vs several male polygyny examples, and polyandry with several males as well.

Male and female investments

• Several different mating evolutions and how they vary, like parental investment.
• Mothers invest greatly in parental care
• Trivers theory is shown as the theory as the theory as women choose a mate based on investment ability and caretaking
• Resources and time important in this theory.

Mate Competition

• Competing more often happens in competitive species.
• Aggressive males typically will win the offspring which yields more offspring
• Human attraction comes down to humor for long term as well as shorter attraction relationships.
• Societal mating comes down to Polygny, commonly used where powerful men will more often take a number of wives.

Common Mating

• Common strategy is monogamy at 15%
• Rare stratgies come down to polyndry for multiple men
• Sociobiologists suggest species carefully select mating options because investment is a highly valued resource to them.

Physical Attractiveness

• Size study done for body based on mass index
• BMI is a better predictor of attractiveness then WRP in one study
• Both genders attracted to a curvy shape with good BMI
• BMI shows more regarding fertility and health because it’s connected to child rearing

Thinner Men

• Thinner shows better trustworthiness, intelligence and good mate choice
• Faces commonly seen because they're visible
• People viewed healthier more sexier when considering attractive faces, more fertile and attractive.
• Symmetry a key sign of attractiveness

Non-Physical

• Extravert individuals show more attractiveness vs shy
• Traits like religion, politic and stability is what women want.
• Males want physical appearance

Attraction

• Showing too much attractiveness shown disadvantage
• Middle class attracts women because risk to be wanting a family vs high status men
• Men compete through gambles to increase probability.
• Speed dating shows value in earning potential.

Matching Phenomenon

• People select a similar mate
• Phenomenon comes down to feeling more secure when with similar mate or looks
• Self perception may suggest bias for higher attractiveness.

Monogamy

• It exists in relationships when two parents contribute, is shown.
• Species contribute to raising
• Moms contribute in monogamous relationships as well.

Monogamy

• Monogamy and hormones play a role and have been studied, for example by prairie vole
• Hormones such as OT affect mating in prairie voles
• OT and AVP are important for both individuals
• Some findings show reliability debates regardless of relationships.
• Men and women react differently to infidelity based on evolutionary factors or emotional.

Behavior

• Mate poaching suggest levels of resources cause people to be more aggressive to partners
• Mate poaching happens when regions of the brain are activated, causing psychological and sexual actions.

Jealousy

• Jealousy is the perception of a threat from an emotional rival to one's relationship

Gender Jealousy

• Men shown greater sensitivity, while women feel upset at emotional infidelity instead of sexual feelings
• Universally this standard remains throughout the population, and research also has shown there's basis for brain activity in how both react.
• Men often show more amygdala (the aggressive centre) activation.
• STS activation helps in detection of norms in violaton.

Priming Jealousy

• Jealousy can be unconsciously prompted
• Prompts suggest and elicit feeling related to priming that can be subconscious.
• The research focuses on neural mechanism for jealousy.

Sex

• Personality is closely linked to sensations and relationships, and includes conscientiousness, extravert qualities etc
• Dominant can show higher traits
• There is a perception of attraction in restriction level that have to do with WMH levels and are highly attributed to the BMI levels.

Polyandry

• Female and make invest occurs where woman contain husbands in remote villages for better wealth conditions

Polygynandry

• Promiscuous behavior in chimpanzees provides co-operation of children
• Consort has monogamy for temporary periods to help stabilize child raising in relationships to provide more certainty.

Altrusim

• Altrusim is self sacrificial for higher good of kin
• Selection can benefit survival in shared behavior
• Kin selection says higher will do more altruistic actions.

Fitness

• Selection helps the shared relation and success
• Related success provides material for parenting.

Relationships

• Closeness through study and support is an indication of altruism
• Stepfamily often lack true altruism because there is more harm done in stepfamilies due to less commonality
• Cohabitiation is the greatest risk and one cause can be due to possible feelings of insecure and possesivness.

Altruism

• Reciprocal altrusim supports cooperation and chances of survival of a chance for future aid
• Sociobiology, tries explanation based on inheritance of social behavior
• Selective maximizes successful rates and fitness
• Psychology indicates that there are to many simplifications as maximizing is incorrect.

Selective Adaptive

• Evolutionary psychologists disagree with Sociobiology's view and suggests adaptive helps evolved mechanisms by assisting humans in adaptive ways.
• This has helped support more complex processes for assisting children instead of simplistic maximizing
• Criticism comes from unethical standpoints, thinking Sociobiology is a political one due to justification.
• Sociobiologists say that it is misinterpretation to think of Nazi ideals and naturalistic superiority in thought,

Evolutionary

• Evolutionary psychology has its limitations in behaviors like homosexuality or suicide that do not assist the process of reproduction.
• There is missing information from the past, which makes it only able to theorize adaptations.
• Cultural is more difficult because of tasks that help women or men better, and the differences between the same sex.

Conclusion

• In conclusion, Sociobiology differs vastly from their opinion of behavior and genes
• They emphasize strength and continue in adaptation.