Psychology as a Science: Biological Foundations

Focuses on the biological aspects of psychology.
Based on Darwin's natural selection.
Traits are naturally selected to ensure the survival and improvement of the population.
Genes and environment interact to ensure survival.
Mental capacities and abilities are naturally selected through evolution.
Psychological disorders might be leftover or the next step in evolutionary traits.
- Examples: ADHD and ASD

Humans differ in personality traits and experiences.
Genetic code varies by only 4-5% between individuals.
Variability is minor, especially in similar geographic areas.
Adaptation has occurred throughout time.
Humans have adapted significantly in a relatively short period.
Adaptation and behavior are key aspects of evolutionary psych.
Predisposed behavior patterns aided survival in the past but may be less helpful now.
Example: Stress response (fight or flight) was helpful against physical threats but is less helpful against modern stressors.

Socioeconomic status and cultural practices can lead to hereditary traits.
Example: Socioeconomic status affects food availability, impacting individuals with genetic predispositions to specific foods.
Genes are like the "neurons of your body" - the smallest piece with a significant influence.
Genetic evolution takes time.
Example: Mexicans and diabetes: genetic predisposition not well-suited for high-sugar American diets.

Human and chimpanzee genetic difference is less than 2%.
Humans are 98% genetically similar to chimpanzees.
Small genetic differences matter.
The 2% difference between humans and chimps is in critical areas.
Example: Humans closer genetically to banana.
Small variations within a species adapt to local environments.
- Examples: Height, hair color, susceptibility to illnesses, and ability to tan.

Monozygotic twins (identical): One egg splits.
Dizygotic twins (fraternal): Two separate fertilized eggs.
Twin studies are valuable for behavior genetics.
Unethical to seek out twins raised separately, but case studies are done when it happens naturally.
Identical twins raised separately help study nature vs. nurture.

Adoption provides insights into biological vs. adoptive influences.
Adopted people's personalities are often more like their biological parents.
Adoption time doesn't significantly change personality traits.
Biology plays a large role in personality, but environment influences expression.
Example: Jesus vs. Hitler: similar personality traits, different environmental influences.

Interaction: How environment and heredity work together.
Epigenetics: Study of how the environment impacts DNA expression through molecular mechanisms.

The body's communication system consists of nerve cells (neurons).
Two main branches: central and peripheral.
Neurons use neurotransmitters for communication.
Neurons process information, make decisions, and send neurotransmitters where needed.
Thoughts, movements, and feelings result from neuron communication.
Central Nervous System (CNS): Brain and spine.
Peripheral Nervous System (PNS): Everything else (glands, muscles, sensory information).

CNS includes brain and spinal cord.
PNS is everything else.
PNS includes autonomic and somatic systems.
*Your peripheral nervous system breaks up into autonomic.

Sympathetic: "On switch" (fight or flight).
- Mobilizes resources for fighting or fleeing danger.
- Increases heart rate, dilates pupils, stops digestion.
Parasympathetic: "Off switch."
- Returns body to normal after danger passes.
- Slows heart rate, constricts pupils, restarts digestion.
- Sympathetic Examples: Pupils dilate, heart rate accelerates, digestive system stops, liver releases glucose, adrenal glands release epinephrine and norepinephrine, bladder relaxes.
- Parasympathetic Examples: Pupils constrict, heart rate decreases, digestion restarts.

Cell body (with nucleus): Receives messages.
Dendrites: Receive messages from other cells.
Axon: Transmits messages.
Myelin sheath: Protects axon and speeds up neurotransmitter travel.
Axon terminals: Release neurotransmitters.
Glial cells: Support nervous system with nourishment and protection; important for learning, memory, and problem-solving.