PSY 1102 Chapter Notes - Chapter 4: Twin, Prenatal Nutrition, Prenatal Development

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Nature, Nurture, and Human Diversity
Human families share biological heritage and behavioral tendencies
Nature and nurture together shape our developmentevery step of the way
With chimpanzees, humans share 96% of DNA sequence
Some terms
Behavior geneticsthe study of the relative power and limits of genetic and environmental
influences on behavior
Environmentevery nongenetic influence, from prenatal nutrition to the people and things
around us.
Chromosomethread like structure made up of DNA molecule that contains genes.
Genesthe biochemical unit of heredity that make up the chromosomes; a segment of DNA
capable of synthesizing a protein.
Genomethe complete instructions for making an organism, consisting of all the genetic material
i that orgaiss hroosoes.
Identical vs Fraternal Twins
Identical twins developed from single fertilized egg (monozygotic).
o They are genetically identical. They have same genes, conception and uterus and usually
have same birth date and cultural history. Although they have same genes, but not same
number of copies.
o These twins share placenta during prenatal development, but one of three sets has
separate plaetas. Oe tis plaeta a proide etter ourishet, hih
contribute to identical twin difference.
Fraternal twins develop from separate fertilized eggs (dizygotic).
o They share a fetal environment, but they look like ordinary brother and sisters.
Identical twins have 60% chances of getting same disease.
Separated twins
Separated identical twins are shown to have remarkable similarities
Temperamenta persos harateristi eotioal reatiit ad itesit.
Molecular geneticsthe subfield of biology that studies the molecular structure and function of genes.
Heritability (exam)the proportion of variation among individuals that we can attribute to genes. The
heritability of a trait may vary depending on the range of population and environments studied.
It is the extent to which variations among individuals can be attributed to their different genes.
For example, height and weight are highly heritable
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Gene-environment interaction
Both are important but they interact. Environment triggers gene activity.
As we grow older, we choose environment well suited to our nature.
Genes can be active and inactive. They can also be epigenetic that means in addition to ar above
or beyond genetics. Epigenetics influence gene expression. Environments factors such as diet,
drugs, and stress can affect epigenetic molecules that regulate gene expressions.
Evolutionary Psychology: understanding human nature
Evolutionary psychologist focuses on what makes humans much alike. Evolutionary psychology is the
study of the evolution of behavior and mind, using principles of natural selection.
They use Charles Daris priiple of atural seletio to uderstad the roots of ehaior ad etal
Natural selection, the principle that among the range of inherited trait variation, those that lead to
increased reproduction and survival will most likely be passed on to the succeeding generations.
Natural selection is the process whereby organisms better adapted to their environment
tend to survive and produce more offspring
Interaction is the interplay that occurs when the effect of one factor (such as environment) depends on
another factor (such as heredity).
Behavioral geneticists are most interested in exploring differences in our behavior and evolutionary
psychologists are most interested in exploring commonalities.
Evolutionary success helps explain similarities
Our behavioral and biological similarities arise from shared human genome. There is no more than 5% of
genetic difference among the humans. 95% of variation exist within the population.
It Effect of gender sexuality difference and works backward to propose an explanation
Unethical and immortal men could use such explanation to rationalize their behavior towards women
This explanation may overlook the effects of cultural expectations and socialization
An evolutionary explanation of human sexuality
Sex drive is the largest gender difference between men and women
Experience and brain development
Genes dictate overall brain architecture, but experience fills all details, developing neural connections,
and preparing brain for thoughts and language and other later experiences.
How do early experiences leave their marks? living in enriched environment simulate a natural
environment, usually developed a heavier and thicker brain cortex.
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