PSYC 110 Lecture 3: Evolutionary Foundation of Behavior
27 Jun 2018
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Chimpanzee (98.8% DNA match) and bonobo - two closest animal relatives
Adaptation is modification as a result of changed life circumstances. Evolution is a long-term adaptive
process, spanning generations, that equips each species for life in its ever-changing natural habitat.
Four Principles:
Overproduction of offspring in each generation
Variation in features and traits within members of a generation
Individual differences are inherited from one generation to another
Individuals with collections of traits that fit well with current conditions will survive to pass on
their traits
Physiological adaptation: Loss of tail, desert plants absorbing water, fur, scales
Behavioral adaptation: Disgust (example of sterilized cockroach in water), altruism, migration,
hibernation
Genes do not produce or control behavior directly. They directly contribute to the development of
various brain systems via their ability to create various proteins. They are "associated" with behavior.
Genes don't cause singing ability but create circumstances for singing ability by modifying the physical
structure of the vocal chords or developing the brain area that helps with singing. There's always an
interaction between genes and environment.
Songbirds sing during the mating season and their hippocampus helps them remember the
songs because their brain enlarges during the mating season --> influenced by environment.
Galapagos tortoise - when the temperature is hot, the egg hatches into female and when its
cold, the egg hatches into male. Females need more resources to thrive than men do, and thus,
hatching the egg to be a female is useful in the summer so they can make use of the abundant
resources found in the summer to lay more eggs and the males hatch in the cold when there is a
lesser need for resources in a scarce environment due to the cold.
Adult mice and rat that haven't given birth to anyone will avoid a newborn of their species when
placed in their cage. However, after a few days of not being able to avoid it, they will start caring
for them because of the sight, sound, and smell of the newborn activates gene activity that
provokes them to care for the newborn.
Genes affect the body's development because of their influence on the production of protein molecules.
Genes are components of DNA, which help in replicating themselves during cell division for the body's
growth and development. It was believed that the genes only function was coding to produce protein
molecules but it has been found that there are coding as well as regulatory genes that work through
biological means to suppress and activate specific coding genes and influence the body's development.
Genotype: What genes are specific to you or inherited by you
Phenotype: Which of those genes get expressed (behavioral traits)
Genes can influence intelligence, religiosity, social attitudes, psychological disposition and more.
Genes not only provide codes for building proteins but are also replicated and passed down from
parents to off springs as a biological unit of hereditary. When chromosomes divide to form other cells,
its called mitosis. But when sex chromosomes divide to form sperm or egg, it is called meiosis. When
they divide, the create two replicas that are next to each other and then exchange genetic material. The
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result of this is that each egg or sperm cell is genetically different from others and contains only half of
the full number of chromosomes (one member of each of the 23 pairs).
Two genes that are identical and occupy the same locus on chromosomes are called homozygous.
Two genes that are unidentical and occupy the same locus on the chromosomes are called
heterozygous.
Different genes that can occupy the same locus, and thus can potentially pair with each other are called
alleles.
To the degree that individuals within a species differ in any measurable characteristic because of
differences in their genes, that characteristic can be modified over successive generations through
selective breeding.
Epigenetics: Traits that are heritable but not necessarily caused by changes in the DNA sequence.
Depression, anxiety passed onto offsprings. Traits of genes passed on from grandmother to
grandchildren.
PreDarwinian and very highly discounted for except recently.
Lamarckian Inheritance - organisms can pass on acquired characteristics. Giraffes lengthening
their necks to reach the leaves. A blacksmith through his upperbody and muscular daily work will
lead to his offsprings having similar muscular development when they mature.
Nuclear vs Mitochondrial DNA - Passed down via the mothers eggs. Greater susceptibility to mutation
--> the egg destroys the sperm and mitochondria so only the maternal ancestry can be identified and
traced back - mutations are more likely to take place
Human controlled selective breeding - artificial selection
Mutations are errors that occur occasionally and unpredictably during DNA replication causing the
replica to be not quite identical to the original.
Natural Selection as a foundation for functionalism
An explanation of behavior in terms of what it accomplishes for an individual.
Genetic variability on which natural selection acts:
Reshuffling of genes that occurs in sexual reproduction
Mutation: errors that occasionally and unpredictably occur during DNA replication, causing the
"replica" to be not quite identical to the original.
Distal vs Proximate explanations of behavior:
Distal - explanations at the evolutionary level, ultimate causation - how the behavior helped the
individual's ancestor's genes make it into the next generation.
Proximate - explanations that deal with a specific mechanism
Humans wearing make-up --> Distal: Attract mates
Proximate: Blush on cheeks makes one look youth and vitalized, red
lipstick (red skin) sign of ovulation towards mates in olden times,
symmetrical faces through foundation
Buying rich cars --> Distal: Attract mates
Proximate: Buying fancy cars to portray you are a provider and good at taking care of
yourself and others, fight predators
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Document Summary
Chimpanzee (98. 8% dna match) and bonobo - two closest animal relatives. Adaptation is modification as a result of changed life circumstances. Evolution is a long-term adaptive process, spanning generations, that equips each species for life in its ever-changing natural habitat. Variation in features and traits within members of a generation. Individual differences are inherited from one generation to another. Individuals with collections of traits that fit well with current conditions will survive to pass on their traits. Physiological adaptation: loss of tail, desert plants absorbing water, fur, scales. Behavioral adaptation: disgust (example of sterilized cockroach in water), altruism, migration, hibernation. Genes do not produce or control behavior directly. They directly contribute to the development of various brain systems via their ability to create various proteins. Genes don"t cause singing ability but create circumstances for singing ability by modifying the physical structure of the vocal chords or developing the brain area that helps with singing.
