TOPIC 4: GENETIC & EVOLUTIONARY INFLUENCES ON BEHAVIOUR Flashcards
DNA
- Deoxyribonucleic acid (DNA)
- Double helix joined by nucleotides
- Nucleotides are
(A adenine)<=>(T thymine)
(G guanine)<=>(C cytosine)
Genes
- Made up of DNA segments
- Guide synthesis of proteins which form/alter physiologic systems, via RNA (ribonucleic acid)
Chromosomes
- Structures in cell nucleus
- Comprised of 23,000 genes
- 23 pairs = 46 chromosomes
- 50% of chromosomes inherited from each parent, randomly selected.
Alleles
Pair of genes occupying the same locus on a pair of chromosomes
Gregor Mendel (1865)
Cross bred peas to make hybrids
- Two original purebred strains, differing in one trait, one was round the other was wrinkled
F1 and F2 of Mendel’s pea breeding
F1 : resulted in Rr(round) and Rr(round)
F2 : resulted in RR(round), Rr(round), Rr(round), rr(wrinkled)
Phenylketonuria (PKU)
- Can cause reduced head and brain size, motor coordination problems, intellectual disabilities and physiological disorders.
- effects 10 per 100,000
- caused by an enzyme that produces a enzyme that ineffectively metabolizes amino acid phenylalanine
- Allel is recessive
Where is phenylalanine found
found in some high protein foods, components of aspartame.
Environmental treatment for genetic defect (Phenylketonuria)
avoid phenylalanine
Polygenic
A trait cannot be accounted for by a single gene and is continuous rather than discrete.
(non-Mendelian)
The goal of epigenetics
The goal of epigenetics is to explain how the environment interacts with genetic information In the body.
why and how is protein translated.
Because almost every body cell has a copy of DNA, it has the capability of expressing a gene, by being transcribed into molecules of RNA, which are then translated into protein.
True or False - every gene in any cell is active
FALSE : Only 10-20% of genes are active in any cell.
What does Epigenetics guide?
They guide proper development of stem cells into different specialized cells of the body.
What is Epigenetics the study of?
Epigenetics is the study of changes in the regulation of gene activity and expression that are not dependent on gene DNA sequence.
Epigenomic Mechanisms
Control of gene expression can occur in different ways
- DNA methylation
- Histone modifications
DNA methylation
- Molecules called methyl groups attach to DNA
- This effects what gets translated into RNA and proteins, preventing gene expression.
- Methyl groups are present in foods, household chemicals, and environmental pollutants
Histone modification
- DNA is wrapped around protein structures called histones, like thread around a spool.
- some chemical groups attach directly to histones, loosing or tightening their connection to DNA, turning genes off or on.
How do experiences influence the epigenome ?
Certain antidepressants have been found to reverse both genetic and behavioural effects
How does genetic risk combine with experience and environment to produce identical twins?
- if one of the twins is autistic, there is a 60% the other is too.
- schizophrenia = 50%
- bipolar disorder = 75%
How do psychoactive drugs rewrite the epigenetic code?
- Addictions maybe cured–or even prevented– by interrupting or reversing epigenetic changes. This can alter some genes temporarily, other more permanently.
Can epigenetic information be inherited?
Your experiences may actually cause changes In gene regulation that are passed on to your offspring.
Charles Darwin
- around world Galapagos visit and compared finches and adaptions
- compared present day creatures to fossil record
- wrote On the origin of species, which included evolutionary biology.
what were the 4 premises of On the origin of species.
1) life is dynamic: species change with time
2) evolution is gradual and continuous (sudden environmental changes ==> some species die out)
3) stats quo maintained in a static environment
4) all current organisms descended from an original ancestor
the 2 mechanisms
natural selection and artificial selection
natural selection
selective breeding by nature
Spencer (1864)
“survival of the fittest” : means suitability or match with the environment, not physical strength.
artificial selection
selective breeding by human action.
- individuals with desired traits encouraged by human action.
- pass on their genetics or characteristics.
how does genetic change occur
through two ways:
sexual reproduction and mutation
sexual reproduction
“shuffles the deck” of genes from parents
mutation
change in DNA sequence
- offspring has gene neither parent has
can an individual evolve
no, evolution occurs across individuals as a whole. as a species.
the three types of adaptions
1) evolutionary adaption
2) individual adaption
3) cultural adaption
evolutionary adaption
genetic makeup of species modified by natural selection
- change across generations
individual adaptions
physical, mental changes, occurring on momentary, daily, or yearly basis.
- change within lifespan.
cultural adaption
changes in ideas, institutions, tools shared by a community
- change within lifespan and across generations.
Darwins Black Box: The biochemical challenge to evolution (Behe 1996)
- argues that the fossil record has gaps
- many biological systems are ‘irreducible complexity”
- argues for “intelligent design”
- Parallels Wm. Paley’s (1802) watchmaker analogy
irreducible complexity
comprised of multiple interacting parts that contribute to the basic function, such that the system fails hen any part is removed
Wm. Paley’s (1802) watchmaker analogy
if a pocket watch is found on a field, it is most reasonable to assume that someone dropped it, and that it was made by a watchmaker and not by natural forces
which book rebottled against Darwins black box.
The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe Without Design(Dawkins, 1996)
Rebuttal:The Blind Watchmaker: Why the Evidence of Evolution Reveals a Universe Without Design(Dawkins, 1996)
- transition forms do exist
- systems which are complex today did not have to be so in the past in order to provide a survival advantage; no outside agnate needed to explain the origin of complexity
- the ‘blind watchmaker’ is natural selection.
Intelligent design
- proponents claim that evolutionary theory is flawed; favour conclusions that life is not the product of random mutations.
- critics claim that intelligent design is a pseudoscience.
- debate includes court challenges in the U.S allowing intelligent design to be taught/ preventing from being taught.
Kitzmiller v. Dovertrial verdict (2005)
intelligent design is veiled creationism
what did the APA conclude?
American Psychological Association concluded that ID is not a science
why is intelligent design not a science ?
- it cannot be tested by experiment
- it does not generate any predictions
- it proposes no new hypotheses
Ethology
the scientific study of animal behaviour under natural conditions
the three Nobel prize winners involved in ethology
- Konrad Lorenz (b.1903-d.1989)
- Karl von Frisch (b.1886-d.1982)
- Nikolas Tinbergen (b.1907-d.1988)
Konrad Lorenz (b.1903-d.1989)
discovered imprinting in birds
Karl von Frisch (b.1886-d.1982)
deciphered the meaning of the waggle dance of honey bees
Nikolas Tinbergen (b.1907-d.1988)
studied mating behaviours of the three-spined stickleback fish
who studied species-typical behaviours
Nikolas Timbergen
species-typical behaviours
(orspecies-specific behaviours) exhibited by all members of a certain species
- are characteristic of that species (may even be used to identify the species)
- includefixed action patterns: consistent behaviours elicited by environmental stimuli
» not modifiable
» more complex than a reflex
Tinbergen’s (1963) Four Questions of Behaviour
Ultimate (evolutionary)explanations(“why” questions about the species):
1. Adaptation (function of the behaviour): • What survival advantages does the behaviour provide? 2. Phylogeny (evolutionary history of an organism): • What were the past environments that shaped the behaviour? 3. Causation (mechanisms of the behaviour): • How is the behaviour triggered by internal processes or environmental conditions? 4. Ontogeny (development of an organism and its behaviours from embryo to maturity): • How did genetics and the environment interact to establish the behaviour?
Proximate explanations
“how” questions about the individual
Ultimate explanation
“why” questions about the species
biological preparedness
the physical, physiological, and structural adaptations that allow an organism to do certain acts and things.
Marler (1970)
studied sparrows
a) some hear species-typica song first summer after hatching
b) some hear no songs (deprivation experiment)
only sparrows that hear other sparrow one sang
conclusion of Marler’s experiment
hearing song X genetic predisposition required to produce behaviour
what are the two ways for species-typical behaviour to evolve ?
- analogy
- homology
Analogy
species have similar characteristic, but evolved separately. convergent evolution
characteristics:
- shows similarity in function and gross form, but differences in underlying structure.
- used to compare common environments to determine adaptive significance
convergent evolution
evolved independently
Homology
species evolved in similar ways because they share a common ancestor
characteristics:
- Shows similarity in underlying physiology and mechanisms, but differences in grade function or form.
- Used to trace evolutionary path of a behaviour.
Darwin (1859): homologous structures made by bees
- shaped by evolution
- more efficient configuration gradually developed over
generations:
bumblebee=>Melipona=>honeybee
- advantageous to have more efficient shape–more likely to survive and proliferate
Guillaume-Benjamin-Amand Duchenne de Boulogne (1862)
Mapped facial muscles by applying electrical stimulation; discovered two kinds of smiles:
- Duchenne smile
- Non Duchenne smile
Duchenne smile
Slight crinkling of crows-feet, droop in the eyelid toward the temples, plus a lift of the cheeks and corners of the mouth
Non Duchenne smile
Involves only muscles of the mouth
Darwin (1872): two contexts for smiles:
1) Genuine happiness
2) Wish to show your favourable disposed towards another person
van Hooff, 1972
1)relaxed open-mouthed display
2)silent bared-teeth display
Silent bared-teeth display
- thought to indicate submissiveness, non-aggression
- homologous to non-genuine greeting smile
Relaxed open-mouthed display
- believed to signal that aggressive like behaviour is only playful
- homologous to laughter and genuine smile
Ekman (1992)
- considers the false smile a derivative of the felt (Duchenne) smile.
- used in deception–shaped to appear when expected or appropriate in social situations.
E.O. Wilson (b.1929)
- sociobiologist who determined ants communicate chemically, a genetically based ability
- tried to apply findings across species to all animals: To what extent are behaviours genetically determined?
- wroteSociobiology: The New Synthesis(1975)
what does sociobiology focus on?
sociobiology focuses on the reproductive aspect of genes
(in contrast, evolutionary psychology studies the adaptive significance of all human behaviours that have evolved through natural selection)
Mate selection/parental investment(Trivers, 1972)
- parental investment includes gametes (egg vs. sperm), gestation, feeding, and protection
- sexual differences in reproductive strategies in humans are based on genetics; should be analogous to other species
- for proliferation: reproduction
- males should have sex with many different females (goal: spread genetic material)
- females should seek best mates (goals: strong offspring; protection?)
evidence to male selection / parental investment
Todd, Penske, Fasolo, & Lenton (2007)
• participants first filled out dating questionnaires:
- both men and women reported a desire to match with someone similar to themselves (in terms of wealth, status, appearance, healthiness, etc.)
- this finding replicated previous self-report studies
• then men and women participated in speed-dating: - 20 mini-dates, each lasting 3-7 minutes
- after the date, each person fills out a card indicating interest in dating that person again
• results differed from self-
reports:
- men were generally less discriminating, and chose women based on the women’s physical attractiveness.
- women were more choosy, and selected men whose mate desirability matched the women’s’ self-perceived attractiveness
Monogamous mating system
Equal parental investment between the parents. unlikely a single parent can raise the offspring by themselves.
Polyandry
one female mates with many males
Polygynandry
all members of the group mate with all other members of the group.
Altruism
- helping others increase their chances of survival, but decreases your
two parts of Altruism:
- kin selection theory
- inclusive fitness
kin selection theory
you are Moree likely to help someone, the more(genetically similar they are to you.
inclusive fitness
you may not survive, but genes close to yours will.
reciprocal altruism
mutual cooperation assures propagation of both sets of genes.
(u scratch my back ill scratch yours)
what is a reputed or criticism to sociobiology
biological determinism
biological determinism
- biological factors (genes), NOT the environment , govern behaviour.
- -BUT “what should be” don’t not mean “what is”
- cultural evolution now shapes our behaviour
- -BUT cultures was made possible by natural selection.
- analogies between humans and animals are simplistic
- -BUT much an be learned about basic principles of behaviour
- Explanations limited to genetics
- -BUT genes and environment interact.
