PSY 1102 NOTES AND REVIEW SESSION Chapter 4 Nature : this refers to gene, DNA and your genome Nurture : This refers to factors that are nongenetic Most researchers believe that both nature and nurture shape who we are One of the greatest discovery is that there is an interaction between nature and nurture Genes : Based on the latest scientific research, there are about 2025000 genes They are found in the DNA molecules which are also found in the chromosomes Genes are considered to be the basic unit of hereditary They are linked with the production of probases They are the ones that give and organism its characteristics Sometimes a gene is active or expressed and produces an effect. Other times a gene is inactive or unexpressed and can be inactive for a long time. Gene complexes : Multiple genes working together to produce an effect e.g 2000 genes linked to obesity Genes are ,made up of nucleotides ( biochemical bases There are 4 of them (A,C,G,T). In a healthy person, A is linked to T and G is linked to C They are known as the alphabet of life. It is their sequence that will determine what a gene does or does not to. If chromosomes were books. Genes = words Nucleotides = letters To date, every human on earth is 99.99% genetically similar to every other human being on earth. Which leaves 0.01% that is different. This 0.01% that is different is made up of 5% difference between races and 95% difference within a race. The biggest difference is within a race than between them Genome: biochemical units of heredity that make up a chromosome. A study published by Nature, Genetics, 2004. Based on this study, race biologically and genetically does not exist. Race is a social and cultural concept. Conclusion: standard concepts of race ought to be abandoned. EXTRA INFO( NOT IN EXAM ) We are also strongly connected to other beings Chimpazee – 9588% of DNA is the same Banana : 5060% Fruit fly – 4452% Daisy 30% EVOLUTION PSYCHOLOGY – this is the study of the evolution of behaviour and mind using the principles of natural selection . It is the based on the theory of evolution that was developed by Darwin. The main goal for any organism. whether bacterium or human , is to survive and transmit their genes into the future. However, not every organism born is going to survive because of natural selection. Natural selection is such that only the fittest will survive “FITTEST” – any organism id considered to be fit when its characteristic and the demand of the environment are in harmony. The ability to adapt is essential in the case that the environment changes. What are humans afraid of? According to EP, any behaviour or characteristic that helped our ancestors survive and transmit their genes is a behaviour, characteristic that we find among the majority of humans SEXUALITY: APPLICATION OF EP According to some surveys, Men tend to think about sex a lot. They are willing to make more sacrifices for sex. They are more likely to explain a friendly gesture as a come on and masturbate more. This does not mean men are more sexual than women? Women just started owning their sexuality recently because of socialization. According to EP, It seems that women are more into relational sex whereas men are into recreational sex, EP suggests that men and women have the same goal but their strategies are different because of the biological differences between them. If you need to ensure survival of the baby then relational sex is best for the woman to transmit her genes into the future unlike men who can populate the earth in 9 months, the more partners, the more ways to spread their genes and so recreational sex is better CRITIQUE OF EP ∙ Critics show that evolutionary psychologists start with an effect and work backwards. What is the results showed the opposite effect? ∙ Why should we try to explain todays behaviour based on decisions made by our ancestors? They believe social learning theory offers a better explanation for results. Women react to sexual encounters the way modern culture teaches them to. ∙ Social consequences of accepting an evolutionary explanation. Do men have no moral responsibility to remain faithful to their partners? Does it excuse men’s sexual aggression?. Unethical men use such explanations to rationalize their behaviour. BEHAVIOURAL GENETICS: Introduction : BG’s are interested in individual differences. As individuals, we vary from each other. BG wants to find out to what do we attribute these differences between us. Are they due to genes or nurture? BG’s study heritability, which is the degree to which is the individual differences are due to genetics. To find out , they do various studies. TWIN STUDIES: two major types of twins are identical( monozygotic) or fraternal (dizygotic twins) . Identical twins = 1 egg fertilized by 1 sperm which splits into 2. Always the same sex and 100% genetically similar. Fraternal = 2 eggs fertilized by 2 sperms. Either same or opposite sex. They are only 50% genetically similar ( this is within the 0.01% difference between humans). Rationale : if a trait/behaviour/disease has genetic components to it, then identical twins must be more similar on that trait characteristic than fraternal twins Alzheimer’s: Based on research, if an identical twin develops alzheimer’s, there is a 60% chance that the other one will get it. Reason for this Although twins have the same genes,they do not have have the same copies of the gene. One of every 3 sets of twins have a separate placenta. One twins placenta may provide slightly better nourishment. CRITICISM OF TWINS REARED TOGETHER ∙ Identical twins not only have the same genes but the same environment. Given the similarity of both genes and environment. How do we know which one is responsible for the greater similarity. Researchers heard this and started studying twins reared apart. The assumption is that the genes are the same but the environment is different. The name is associated with bouchard. CRITICISM ON TWINS REARED APART? ∙ If 2 strangers spent hours comparing their behaviours ad life histories, they would discover many coincidental similarities. ∙ Even the impressive data is clouded by the reunion of separated twins. ∙ Identical twins share an appearance and the response it evokes. ∙ Adoption agencies tend to place twins in similar homes. Conclusion: critique is far, regardless, identical twins reared together or aprt are more similar than fraternal twins. And identical twins reared together and more similar than identical twins reared apart. ADOPTION STUDIES: The adopted child has two sets of parents. A set of biological parents to whom he shares genes and adoptive parents who he shares the environment. If a trait has a genetic component to it. The adoptive child is similar to the genetic parents. The personality of the adoptive child is similar to his/her parents even though he may have never met them INFLUENCE : ADOPTIVE AND BIOLOGICL PARENTS.
∙ Why should we try to explain todays behaviour based on decisions made by our ancestors?
What is the results showed the opposite effect?
What are humans afraid of?
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TEMPERMENT STUDIES: My temperament is part of my behavior. It is the typical emotional way to which you react to life and its problems and it is the intensity of the reaction. It seems temperament has a genetic component to it. Based on this, researchers identify 4 different temperaments in babies ∙ Easy babies (40%) – their patterns of eating, sleeping are very predictable ∙ Slowtowarm babies (15%) Shy, it takes them a while to warm up to a new situation. ∙ Difficult babies (10%) – Irritates, fussy, their patterns are unpredictable. ∙ Combo babies (35%) – Sometimes easy and sometimes difficult or shy, they are a bit of everything. Identical twins are more similar in terms of temperament meaning it has a genetic component to it. PHYSIOLOGICAL STUDIES: Difficult babies in nervous situation, their NS is aroused in these situations releasing more stress hormones. Temperament tends to endure and be long lasting. Those who were happy and relaxed at age 3 grew up to be happy. Those who were fussy at age 3, grew up to be more aggressive and conflict prone. However, nurture and environment can still make a difference. American babies express more positive emotions than Russian or Asian babies. Statistically, some of us are going to have difficult babies. Heritability – degree to which our differences between us as individual are due to genetics The % variation within a given population that is due to heritability is quantified by a statistic known as h2 H2= heritability coefficient h2 = variance genes/ variance genes+ variance environment h2 varies between 0 and 1 h2= 0 – no genetic influence h2 =1 – all variance is due to genetics h2= 0.4 40% genes and 60% environment h2= 0.6 – 60%genes and 40% enevironment. Points to remember about heritability∙ It does not apply to 1 single individual. It applies to differences between individuals and differences within a group. ∙ Genetic influnces explains variation among people ∙ h2, its value for the same variable can differe from one study to the next. One major reason is the environment of the subject. If the subject comes from the same environemtn, then the value of h2 will be higher than if they come from different environments. Nature and nurture interaction. Genes are selfregulating which means genes are not rigid or fixed. The same gene will behave differently in different environments. Sometimes, genes need environment to nurture or activate them. HOW DOES THE ENVIRONMENT ACTIVATE GENES? Genome – all genetic instructions of an organisms but those instructions need something to activate or deactivate and that is known as an epigenome. Epigenome – a set of markers that switch on of genes without changing the sequence of DNA Methyl groups – chemical molecules when present in the epigenome, they deactivate a gene and stop it from expressing itself. Acetyl group molecules when present in the epigenome, they activate the gene and cause it to express itself. The environment influences and affects the formation of molecules. Epigenetics – scientific study of all factors that influence gene expression without changing the sequence of DNA MOLECULAR GENETICS – research done in order to identify the gene/genes responsible for a trait, disease etc. . they are gene detectives and the study the DNA itself. They do it by comparing the DNA of family members. Relevance to PSY ∙ In psychology, we want to identify all the factors that affect psychological factors PROMISES AND DANGER ∙ Discrimination ∙ Abortions