Chapter 3: Biological Bases Flashcards
How is the nervous system organized?
Central nervous system Peripheral
Brain Spinal Cord Somatic Autonomic
- Forebrain - Efferent nerves -sympathetic
- Midbrain -Afferent nerves -parasympathetic
-Hindbrain
Which parts of the peripheral nervous system are voluntary and involuntary?
Autonomic = involuntary Somatic = voluntary
What structures make up the peripheral nervous system?
Bundles of nerves (neuron fibres)
What are nerves?
Bundles of neuron fibres (axons) that are routed together in the peripheral nervous system
What is the somatic nervous system?
System made up of nerves that connect to the voluntary skeletal muscles & sensory receptors
-skin, muscles, joints, CNS
What are the nerve fibres used in the somatic nervous system?
CNS periphery
What structures make up the peripheral nervous system?
Bundles of nerves (neuron fibres)
What are nerves?
Bundles of neuron fibres (axons) that are routed together in the peripheral nervous system
What is the somatic nervous system?
System made up of nerves that connect to the voluntary skeletal muscles & sensory receptors
-skin, muscles, joints, CNS
What are the nerve fibres used in the somatic nervous system?
CNS periphery
What is the Autonomic nervous system?
System made up of nerves that connect to the heart, blood vessels, smooth muscles and glands
&
controls involuntary visceral functions
>heart rate, perspiration, etc.
&
mediates physiological arousal from emotions
Who identified fight-or-flight?
Walter Cannon
What are the 2 branches of the autonomic nervous system?
Sympathetic and parasympathetic
What are the ventricles in the brain and how many are there?
Hollow cavities in the brain that are filled with cerebrospinal fluid.
There are 4
What is the central nervous system?
The brain, spinal column and the protecting enclosed sheaths of meninges that bathe the brain and spine in cerebrospinal fluid
What is cerebrospinal fluid?
A fluid that nourishes and cushions the brain and spine
What is the spinal cord?
The spinal cord connects the brain to the rest of the body via the peripheral nervous system and is an extension of the brain that houses bundles of axons
What can disection of the brain show and not show?
- It can show the structure
- It cannot show the function nor the connection between the brain and behaviour
What are the most common brain research methods?
- Electrical recordings (EEG)
- Lesioning
- Electrical stimulation
- Brain imaging
- Transcranial Magnetic Stimulation
What are electrical recordings of the brain and how are they measured?
They record electrical activity in the brain using and Electroencephalograph (EEG)
> a device that monitors electrical activity in the brain over time via electrodes attached to the scalp> brainwaves
>sums & amplifies electrical potentials in brain cells
>research re sleep, consciousness, processing
What is the EEG most commonly used for?
Clinical diagnosis of brain damage and neurological disorders
&
Identifying brain activity patterns relative to specific behaviours
How is lesioning enacted on animals?
-An electrode is inserted into the brain structure and high-frequency current is passed through to burn and disable the structure
> uses a stereotaxic instrument to place the electrode precisely
What is lesioning and how is it applied?
Lesioning involves destroying a piece of the brain as a case study
- therefore brain damaged patients must be used
- therefore lesioning is applied to animal brains to observe specific structures being disabled and impact on behaviour
- invaluable for research on brain function
What is the most famous lesioning case study?
By Milner on H.M.
‘the brain that changed everything’
-portions of brain were removed to aleviate epilepsy
-resulted in Anterograde amnesia where he had a good pre-surgery memory but after had a good short-term memory but was not able to form new long-term memory
What are the cons of using brain-damages patients?
- subjects not plentiful
- location & severity of the damage is uncontrollable
- variations in patient histories cause too many extraneous variables so cause-and-effect cannot be isolated
What is electrical stimulation of the brain (ESB) and how is it applied?
A weak electrical current is sent into the brain structure to stimulate it by using an electrode (stereotaxic)
> the current approximates normal brain signals to activate
ESB is mostly conducted on animals or on humans during brain surgery
What are the pros and cons of TMS?
Prod: circumvents many uncontrolled variables in brain damaged patients
Cons: can’t study deep brain
What is Transcranial Magnetic Stimulation and how is it applied?
-TMS is a new technique that can depress or enhance activity in an area of the brain
- a magnetic coil creates a 2cm magnetic field that stimulates via pulsing which excites neurons in local tissue
> virtual lesions
- investigating therapeutic potential for eating disorders, anxiety and schizophrenia
Meta-analysis is particularly useful with what data?
Imaging data
What is the CT scan?
CT= computerized tomography that is a computer-enhanced x-ray
> multiple images are combined to make a horizontal slice of the brain
> least expensive imaging option
What conditions is the CT linked with revealing?
The association between Schizophrenic disturbance and the enlargement of the brains ventricles
What is the PET scan?
PET = Positron Emission Tomography
- demonstrates brain & behaviour link
- uses radioactively tagged chemicals as markers of blood flow or metabolic activity in the brain & monitors with x-rays to produce a colour coded brain activity map
> FUNCTION
What specifically is a PET scan good for studying?
Neurotransmitter activity
What is an MRI?
MRI = Magnetic Resonance Imaging
- uses magnetic fields, radio waves and computerized enhancement to map brain structures
> better imaging than CT
What are the pros of an MRI?
- 3D image
- better than a CT
- insights into depressive disorders
What is the FMRI?
Functional magnetic resonance imaging
- monitors blood flow and oxygen consumption to identify high activity areas over time
> map activity
What are the benefits of the FMRI?
- It’s exacting
- illustrates function
- illustrates complexity
- good for locked-in patients, same imagery for certain activities
What structures make up the 3 regions of the brain?
Hindbrain- cerebellum, pons, medulla
Midbrain- reticular formation
Forebrain- Thalamus, hypothalamus, limbic system, crerebrum
What structures make up the 3 regions of the brain?
Hindbrain- cerebellum, pons, medulla
Midbrain- reticular formation
Forebrain- Thalamus, hypothalamus, limbic system, crerebrum
What does the medulla do?
Oversees unconscious vital functions > blood circulation > breathing > muscle tone > reflex regulation (sneezing, coughing, salivate)
What does the Pons do?
The pons is a bridge of fibres that is a collection of clusters of cell bodies that are linked to sleep & arousal
> connects brainstem with the cerebellum
What is the Midbrain?
Segment of brainstem between hindbrain and forebrain that is concerned with integrating sensory processes
> vision & hearing
- origin of dopamine-releasing neurons that travel for voluntary movements
What is the Midbrain connection to Parkinson’s?
Degeneration of structure in the midbrain causes a decline in the dopamine synthesis and is causally linked with Parkinson’s
What is the reticular formation?
At the core of the brainstem and contributes to the modulation of muscle reflexes, breathing and pain perception
> sleep and arousal
What is the forebrain?
Largest and most complex region of the brain encompassing multiple structures
- made up of the thalamus, hypothalamus, cerebrum and limbic system*
- core of the forebrain
What is the thalamus and what does it do?
Structure through which ALL SENSORY INFO must pass through (except smell) to get to the cerebral cortex
- ‘way station’ made of soma clusters
- each cluster relays info to part of cortex
What are the 4 Fs of survival drives?
- Fighting
- Fleeing
- Feeding
- Mating
What is the hypothalamus?
Structure near the base of the forebrain involved in regulation of basic biological needs
- controls the autonomic nervous system
- vital link b/w brain & endocrine system
- Regulates survival drives (4Fs)
> hunger, thirst, temperature
What is the Amygdala?
Part of the Limbic System - fear response learning - processing of basic emotional responses - processing of both +/- stimuli > agression
What is the Limbic System?
Loosely connected network of structures located along the border w cerebral cortex and deeper subcortical areas. Includes
- parts of thalamus and hypothalamus
- hippocampus
- amygdala
- other structures
Regulates EMOTION, MEMORY, MOTIVATION & OPTIMISM
> pleasure centres
What is consolidation?
The conversion of information into a durable code
What is the hippocampus?
Part of the limbic system that surrounds the thalamus and is involved in
LEARNING & MEMORY
- memory processes
- consolidation of memories for factual information
- prediction & imagination
Who created the pleasure centre experiment and what was it?
James Olds
- rat would press the lever to stimulate pleasure centre which was supposed to be in reticular formation but was in hypothalamus
> pleasured until collapsed
Where are the self-stimulation centres?
In the Limbic System in the mdeial forebrain bundle that passes through the hypothalamus where it is rich in dopamine-releasing neurons
What is the corpus callosum?
The structure of thick band of fibres that connects the 2 cerebral hemispheres
How is each hemisphere divided?
Into 4 lobes:
- Occipital
- Parietal
- Temporal
- Frontal
What is the occipital lobe?
Lobe @ back of head
- visual signals & processing begins
- houses the Primary Visual Cortex
What is the Parietal Lobe?
In the middle b/w the occipital and frontal lobes on top
- houses the Primary Somatosensory Cortex
> sense of touch
> integrates visual input + body’s position in space
> visual control of reaching
What is the temporal lobe?
Lobe near the temples and below the parietal lobe
- Primary Auditory Cortex
> auditory processing
What is the Frontal Lobe?
The largest lobe at the front of the brain
- Primary Motor Cortex
- Cortex allocation depends on body part diversity & precision of movement
- Prefrontal cortex
What is the Prefrontal Cortex and what does it do?
‘Executive control system’
> monitor, organize, integrate & direct thought processes
- In the front portion of the frontal lobe and accounts for 1/3 of cerebral cortex
- high-order functions
WORKING MEMORY + REASONING BW OBJECTS & EVENTS + DECISION MAKING
What is the Cerebrum and what does it do?
It’s the largest and most complex part of the brain, responsible for
LEARNING, REMEMBERING, THINKING + CONSCIOUSNESS
- outer layer is the cerebral cortex
What is brain plasticity?
Brain’s ability to change structure and function
How does experience link to plasticity?
Experience stimulates plasticity and affects dendritic length, synapse formation and altered metabolic activity
What are neurotransmitters?
How are they stored?
- Chemicals that transmit information from one neuron to another
- They’re stored in synaptic vesicles in the terminal buttons
How are neurotransmitters released?
A vesicle fuses with the membrane of the pre-synaptic cell and its contents spill into the cleft
What happens to the neurotransmitters once they are released?
They diffuse across the cleft to the membrane of the receiving cell and bind at receptor sites with special molecules
Can neurotransmitters be received at all sites?
No, they can only bind to receptor sites that their particular molecular structure fits into
What are post-synaptic potentials?
PSPs- occur when a receptor combines with a neurotransmitter on the receiving cell, causing a voltage change at the receptor site
Do post-synaptic potentials follow the all-or-none law?
No, they are graded
- they vary in size and increase/decrease the probability of a neural impulse in the post-synaptic neuron
> relative to the amount of voltage change
What are the types of post-synaptic potential messages?
- Excitatory: + voltage shift that increases the likelihood that a post-synaptic neuron will fire an action potential
- Inhibitory: - voltage shift that decreases the likelihood that a post-synaptic neuron will fire an action potential
What happens to neurotransmitters after the PSP?
- They are inactivated by enzymes and metabolized
- They are recycled through Reuptake
What is reuptake?
When neurotransmitters are sponged up from the synaptic cleft by the presynaptic membrane
What does Temporal Summation mean?
When PSPs add up at the same receptor site of one neuron
What does spatial summation mean?
When PSPs add up via signals from many neurons arriving at the same time to different sites of one neuron
What must neurons do before deciding to fire an impulse?
They must integrate signals which is a balance between excitatory & inhibitory influences
> millions must fire at once
Which neurons are likely to fire at the same time in the neural network?
Those neurons that are wired together fire together
> patterns
What has more influence in sculpting the neural networks than the creation of new synapses?
Pruning or elimination of old synapses
Whose work determined that neurons are linked in complex networks called assemblies to influence behaviour?
Donald Hebb
What are the common neurotransmitters?
- Acetylcholine (Ach)
- Norepinephrine (NE) > monoamine
- Dopamine (DA) > monoamine
- Seratonin > monoamine
- GABA > amino acid
- Glycine > amino acid
- Glutamate > amino acid
- Endorphines
Why is it good that only specific transmitters work at specific synapses?
Specificity reduces cross-talk between densely packed neurons
What is an antagonist?
A chemical that blocks the action of a neurotransmitter by binding to receptors and blocking the receptor sites, ultimately failing to produce a PSP
Abnormal levels of what are linked to the development of psychological disorders?
Monoamines
What are the Monoamine neurotransmitters?
What do monoamines regulate?
- Norepinephrine
Dopamine
Seratonin - They regulate aspects of everyday behaviour
What is seratonin known for?
- regulation of sleep, wakefulness, eating & agression
- Abnormal levels may lead to depression & OCD
- synapses targeted by antidepressants
What are the amino acid neurotransmitters?
What are they affected by?
- Gamma-aminobutyric acid (GABA)
Glycine
Glutamate - Convey the affects of alcohol
What is the Hebbian learning rule?
One neuron stimulating another neuron repeatedly produces changes in the synapse > learning
What is an agonist?
A chemical that mimics the action of a neurotransmitter
> fools the receptor site
What is norepinephrine known for?
- modulation of mood & arousal
- cocaine & amphetamines increase activity at NE synapses
- NE synapses are targeted by anti-depressants
What are endorphines?
- Internally produced chemicals that resemble opiates in structure and effect
- Pain relief & pleasurable emotions
- modulation of eating behaviour & response to stress
- triggered by pain > runners high
What is glutamate known for?
- Always excitatory
- learning & memory
- glutamate disorders are linked to schizophrenic disorders
What are GABA & glycine known for?
- producing only inhibitory potential at all synaptic receptors they bind to
> can be present @ 40% of all synapses
> responsible for much of the inhibition in the CNS - regulation of anxiety
- valium & other anti-anxiety drugs
What is the Dopamine Hypothesis?
Abnormalities in activity at dopamine synapses play crucial role in development of schizophrenia
What is Acetylcholine?
The only transmitter between motor neurons & voluntary muscles
- contributes to attention, arousal & memory
- inadequate supply > memory loss in Alzheimers
- may be influenced by other brain chemicals
- some Ach receptors stimulated by nicotine
What is known re dopamine?
- contributes to control of voluntary movements
- pleasurable emotions
- decreased levels linked to Parkinson’s
- overactivity at DA synapse linked to schizophrenia
- cocaine & amphetamines increase activity at DA synapses
What is the nervous system and what is it composed of?
It is living tissue composed of cells
> specifically NEURONS & GLIA
Describe the anatomy of the neuron.
- Soma: cell body that contains the nucleus
- Dendrites: branches that receive info from other cells
- Axon: the thin fibre that transmits messages/signal away from soma to the other neurons via terminal buttons
- Myelin sheath: the axon insulator made up of glia cells that promotes speed
- Terminal buttons: small knobs that secrete neurotransmitters across the synapse
What is the resting potential
The stable negative charge when the cell is inactive
> -70 mV
What is the relative refractory period?
The time immediately following the absolute refractory period where a neuron can fire but the threshold is elevated so more intense stimulation is required to initiate the AP
What law do action potentials follow?
How do they convey strength of stimulus?
- APs follow the all-or-none law meaning they either fire or not
- Strength of stimuli is conveyed by rapid firing
> thicker axons > rapid transmissions
What is the synapse?
Junction where information is transmitted from one neuron to another via chemical messages
What is the synaptic cleft?
The microscopic gap bw terminal button of one neuron & the cell membrane of the other (dendrite)
When are neurotransmitters released?
When the AP reaches the axon’s terminal buttons
What are glia cells?
Cells in the nervous system that provide support for neurons by:
- providing nourishment
- removing waste
- providing insulation
- embryonic nervous system development
> smaller and more populous (x10) than neurons
can send & receive message
involved in memory formation, pain & Alzheimers
What is the absolute refractory period?
The minimum time after an AP during which another AP cannot begin
> neuron must rest for 1-2 milliseconds and closes its channels
What is the action potential?
A brief shift in a neuron’s electrical charge that travels along an axon to release neurotransmitters at the terminal buttons
What are the names for neurons that send and receive info?
- Pre-synaptic neurons > send signals across the synaptic cleft
- Post-synaptic neurons > receive the signals
What are neurons?
Individual cells in the nervous system that receive, integrate & transmit information
> typically communicate with other neurons
What is a neural impulse and how does it work?
- a brief change in electrical charge that occurs when ions move in and out of the cell
- different flow rates result in the cell having a negatively charged resting potential
- chloride carries the negative charge
- sodium & potassium carry the + charge
- when stimulated the neuron opens channels that allow + ions in
> sodium comes in and K goes out as the impulse moves - impulse travels at 100 m/s
What are the 3 conclusions that brain plasticity findings are based on?
1) experience can sculpt features of brain structure
2) damage to sensory pathways or destruction of brain tissue can lead to neural reorganization
3) adult brain can generate new neurons, either through natural repair process or contribute to learning
What is it called when the brain generates new neurons?
neurogenesis
What are the unspecialized cells that renew themselves through cell division & can be induced to become suitable for other purposes?
Stem cells
What is correlated with decline in plasticity?
Age
What is the area of the brain that is responsible for speech production and where is it?
- Broca’s area
- Left frontal lobe
What is the area of the brain responsible for language comprehension and where is it?
- Wernicke’s area
- Left temporal lobe
Why was the left hemisphere assumed dominant and why did that change?
- Dominance was associated with language, thoughts, reasoning, planning and problem solving which were all thought first to be on the left (Broca & Wernicke)
- This changed in the 60s with split-brain research for which Sperry won the Nobel Prize
What is split brain surgery?
When the corpus callosum is severed to reduce the symptoms of epileptic seizures
What is remarkable about how the body and brain hemispheres are wired together?
Each hemisphere is mainly connected to the opposite side of the body
Why is split-brain research problematic?
- it’s an abnormal situation
- subjects are people with rolonged epilepsy
- number of patients is small > small sample
What is the congenital malformation or absence of the corpus callosum called?
Agenesis
What does research comparing lack of callosum with having callosum?
That there is a limit to plasticity indicated by children with their callosums but hampered by immaturity
What are the left-right imbalances bw the hemispheres called and what metric is applied?
- perceptual asymmetries
- speed of visual/auditory processing > time required to recognize stimuli bw the two hemispheres
What are the specialties of the right hemisphere?
Right hemisphere: non-verbal processing
- spatial
- musical
- visual recognition
- perception of emotions
What are the specialties of the left hemisphere?
Left hemisphere: verbal processing
- language
- speech
- reading
- writing
What is the system of glands that release hormones into the bloodstream?
The endocrine system
How are hormones like neurotransmitters?
- They help control body functioning
- are stored for release as chemical messengers
- diffuse through the bloodstream and bind to special receptors > some chemicals function as both
How are hormones different from neurotransmitters?
- hormones can travel slowly over long distances to far away cells
- hormones tend to be less specific > act on many target cells in the system
What cognitive differences might hormones be responsible for?
Cognitive differences between men and women
What are examples of some of the conditions throughout the body that hormones regulate day to day?
- stomach and intestinal hormones help control digestion
- kidney hormones help regulate blood pressure
- pancreatic hormone (insulin) enables cells to use sugar from blood
In what pattern are hormones typically released?
Pulsatile:
> several times a day in brief bursts that last a few minutes
> levels increase & decrease throughout the day
What parts of the brain control the endocrine system?
The hypothalamus enables the nervous system to control the endocrine system via the pituitary gland
What gland releases hormones throughout the body to stimulate actions in other endocrine glands?
The pituitary gland
‘Master Gland’
What pathways are activated during fight-or-flight?
The hypothalamus triggers signals when stressed along 2 pathways:
- autonomic ns> adrenal glands> secrete stress hormones to prep for emergency
- pituitary gland
What is the hormone released by the pituitary gland to regulate reproductive behaviours?
Oxytocin
What effects does oxytocin have?
- triggers contractions, breast milk, complex social behaviours
- can increase empathy and foster trust
- adult-adult pair bonding
What is the primary process that hormones are known for?
Regulating human physical development
What hormones are responsible for the formation of external sex organs before birth?
Gonadotropins
What is a key determinant of hormonal actions?
Genetic make-up
What is the field of study of the influence of genetic factors on behavioural traits?
Behavioural genetics
What is the basic principle of genetics?
Inherited messages are found in chromosomes which are in the cell nucleus
What are the strands of DNA molecules called that carry genetic information?
Chromosomes
What are the only cells that do not contain 46 chromosomes and what do they have?
Egg and sperm cells only have 23 chromosomes each instead of twenty-three pairs
Each cell contains how many chromosomes and in how are they organized?
- 46 chromosomes in 23 pairs
- 1 chromosome in each pair is from each parent
What is the single cell formed by the union of an egg & sperm?
Zygote
What are the DNA segments that serve as key function units of hereditary transmission?
Genes
What dictates which member of each chromosome pair ends up in sperm & eggs?
Chance
What are genetic mutations? !
Changes in the genetic code
What is genetic crossing over? !
The interchange of material bw chromosomes
Who are the only people who do not have their own unique genetic blueprint?
Identical twins
What is the condition when 2 genes in a specific pair are the same?
Homozygous
What is the condition when 2 genes in a specific pair are the different?
Heterozygous
What determines the trait?
The pair of genes
What is the gene that is expressed when a pair of genes is different?
The Dominant gene
What is the gene that is masked when a pair of genes is different?
The Recessive gene
What occurs in heterozygous conditions?
The dominant gene will overide the recessive gene
What is the genetic relatedness for parents and siblings?
50% which is the probability of inheriting a specific gene from a given pairing
What is a person’s genetic make-up called that is determined at birth and fixed for life?
Genotype
What are the ways a person’s genotype manifests in observable characteristics called, that may change over time?
Phenotype, can be influenced by envrionmental factors
Are all gene pairs expressed by a dominant gene?
No, some average out or compromise
What are characteristics influenced by more than one pair of genes (most human traits)?
Polygenetic traits
What kind of traits are most psychological characteristics that appear to be hereditary considered to be?
Complex polygenetic inheritance
What are 3 methods for researching hereditary influence?
- Family studies
- Twin studies
- Adoption studies
What is the strongest linkage hereditary influence studies in humans can determine and why?
- Correlation
- Genetic manipulation not possible in humans therefore only animals can be used for selective breeding
What are assessments of hereditary influence by examining blood relatives to see how much they resemble one another on a specific trait?
Family studies
What should exist if a family study reveals a resemblance re a specific trait? !
Phenotypic similarity
What other findings have come out of family studies? !
- Should be a phenotypic similarity if there is resemblance
- link with schizophrenic disorders
- because families share environments genetic and environmental similarities are greater for closer relatives
> confounding variables
> CANNOT PRODUCE DEFINITIVE EVIDENCE
What are assessments of hereditary influence by comparing the resemblance of identical twins & fraternal twins re a trait?
Twin studies
What are monozygotic twins and why are they called that?
- Identical twins
- Because they emerge from one zygote that splits in two > 100% relatedness
What are dizygotic twins and why are they called that?
- Fraternal twins
- Because they emerge from two eggs that are simultaneously fertilized by two different sperm cells forming 2 separate zygotes > 50% relatedness
Why are twin studies useful?
The siblings are raised in similar environmental conditions therefore it is reasonable to infer similarity due to heredity
What are assessments of hereditary influence by examining the resemblance bw adopted children & their biological & adoptive parents?
Adoption studies
What are the adoption conditions required for effective adoption studies?
That the child was adopted in infancy and had no further contact
When is it likely that genetic factors influence a trait in adoption studies?
If adopted children resemble their biological parents in a trait
> reversed for environmental factors
What can only adoption studies show compared to the other types of studies?
Findings re links with environment and heredity
When is it likely that genetic factors influence a trait in adoption studies?
If adopted children resemble their biological parents in a trait
> reversed for environmental factors
What can only adoption studies show compared to the other types of studies?
Findings re links with environment and heredity
What is the process if determining the location & chemical sequence of specific genes on specific chromosomes?
Genetic mapping
How are genetic maps helpful? !
- Allow behavioural geneticists to fin dout how heredity influences behaviour
> NOT how much - They help pinpoint links bw specific genes & traits and disorders
> NOT which genes govern which traits
What has been identified for almost all human genes?
The chromosomal locations
How are genetic maps helpful?
They help pinpoint links bw specific genes & traits and disorders
> not which genes govern which traits
What has mapping revealed with certainty about traits?
Dichotomous traits which you either have or you don’t
> such as muscular distrophy
What are most behavioural traits?
Polygenic and shaped by many genes > gene constellations have modest influence
How to genetics and the environment interact?
They play off of each other
What is schizophrenia’s link to heredity?
The condition is not inherited directly but the vulnerability to it is
> dispositions are inherited, not destinies
What is the study of heritable changes in gene expression that do not involve modifications to the DNA sequence?
Epigenetics
What was the primary message from Darwin’s principles of natural selection?
Variations in hereditary traits might affect organisms ability to obtain the resources necessary for survival & reproduction, if effect is positive then more offspring will be produced > trait prevalence
Can epigenetic marks be passed on to subsequent generations?
Yes
What is the referred to as the reproductive success (# descendants) of an individual organism relative to the average reproductive success in the population?
Fitness
What fuels evolutionary change?
Variations in reproductive success
What must traits provide in order to prevail?
Survival or reproductive advantage
What is it called when heritable characteristics that provide a survival or reproductive advantage are more likely to be passed on to subsequent generations?
Natural selection
What are 2 implications of natural selection?
1) life is the result of unplanned natural processes rather than divine creation
2) humans are not unique and they share common ancestry with other species
Why were refinements made to evolutionary theory and what are they? !
- inheritance process explanation was inadequate
- Natural selection works on a gene pool
- Adaptation
- Inclusive fitness
What is gene pool makeup shaped by?
- Genetic drift: random fluctuation in gene frequencies over generations
- Mutations: spontaneous heritable change in an organism’s DNA
> unpredictable errors
> new genetic material for natural selection & increase variability - Gene flow: shifts in gene frequencies in a population due to individuals leaving or entering
> neighbouring populations genetically similar
> can counterbalance mutation
> can enable a population to diverge into new species
What is an inherited characteristic that increased in a population due to helping solve a problem of survival or reproduction at the time it emerged?
Adaptation
What is inclusive fitness and why did it emerge?
- Sum of an individual’s own reproductive success + effect it has on reproductive success on related others
- emerged due to paradox of self-sacrifice
What happens to the probability of self-sacrifice in inclusive fitness? !
It increases when relatedness bw the help & recipients decreases
What is the limited span during the development of an organism known as when it’s optimal for certain capacities to emerge due to receptivity?
Critical period
What occurs when an effect is estimated by extending beyond some known values or conditions?
Extrapolation
What are wild leaps of speculation based on loosely related data?
Overextrapolations
