Lecture 1 (04-09)
Psychology: the scientific study of mind and brain to explain behavior. We need science
for that because common sense fails. As seen in the experiment in the lecture, people
tend to accept general and vague personality traits as a trait belonging to their own
individual personality – this is known as the Forer affect.
è Forer affect: individuals give high accuracy ratings to descriptions of their
personality that supposedly are tailored specifically to them. This affect also
shows why so many people believe in astrology, there are general and vague
terms used so everyone sees their own individual in it.
Is it correct to claim that a violent person has violent genes?
è In the seventies: they saw violence as result of the environment someone lives in.
For example, a product of capitalism or having auditory parents. They didn’t saw
violence as something that is originated in your genes.
è In the nineties: they saw violence as something that resulted from your genes. In
this period of time, heritability studies become easier to perform. They were
describing the influence of the genes on behavior. They taught it doesn’t matter
how you raise your children, genes are the part that influence someones
behavior.
è Nowadays: today we perceive behavior as the result of the interaction between
the genes and the environment. So the interaction between the genes and the
environment results in the behavior.
Human skin is made of cells, each cell contains a nucleus. Each human nucleus
contains 23 chromosome pairs and thus 46 chromosomes. Chromosomes carry
instructions for how to build and operate a body. Chromosomes are made up of coiled
strands of DNA. The DNA molecule has a double helix shape. The rungs of the double
helix are made up of complementary chains of adenine (A), thymine (T), guanine (G) and
cytosine (C). The DNA consists of genes, this is the meaningful part of DNA, because
genes govern the cell’s functioning by provides instructions for making proteins. So a
gene provides the blueprint for a protein. There are also non-meaningful parts in DNA.
,Gene expression: whether a gene is turned “on” or “off”. The extent to which a gene is
transcribed into a sequence of amino acids (protein). It can also be that genes aren’t
expressed. In each cell, some genes are expressed at any point in time and others are
not. This is controlled by the biochemical environment inside the cell.
è The biochemical environment inside the cell is influenced by e.g., the
environment outside the cell, the timing in development, the overall
environment, experience, behavior. Cells develop differently by the environment
they are in.
Every cell in your body haves the same genetic information. It doesn’t make any
difference between brain of skin cells.
Genotype: an organism’s specific set of genes.
Phenotype: the overt traits and behaviors of an organism. The phenotype is determined
by the interaction between the genotype and the environment, this is not only the past
environment, but also the current and present environment.
Monozygotic twins, also known as identical twins. This is one single egg which has split
into two, therefore monozygotic twins have the same genotype but have different
environments. Due to the differences in their environment, there are different genes
expressed and therefore they can look and behave differently.
Your genes come from your parents. A female egg (23 chromosomes) and a man’s
sperm cell (23 chromosomes) results in 46 chromosomes (23 chromosome paires).
Each gene is paired with another gene, one from the father and one from the mother.
The pairs are located at corresponding positions on pairs of chromosomes.
Allele is one specific variant of a gene. For example, you may have a gene for eye color,
this may occur in different variants so there can be an allele for brown eyes and an allele
for blue eyes. There is a difference between dominant and recessive alleles.
• Homozygote – alleles on locus are the same.
• Heterozygote – alleles on locus are different.
,Dominant allele: this allele shows their effect even if the individual only has one copy of
the allele. For example, the dominant allele for brown eye color will be shown in the
phenotype, even if the allele from the other parents is blue eye color.
Recessive allele: this allele will only show their effect if an individual has two copies of
this allele. For example, the recessive allele for blue eye color will only be shown in the
phenotype if both parents have the allele for blue eye color, so there need to be two
copies of this allele to be visible.
If a specific gene is expressed, then the way this is expressed depends on the specific
alleles in a gene. A specific trait of behavior is determined by the interaction between
the environment (past and present) and one gene pair and multiple gene pairs. This is
called polygenetic inheritance.
è Polygenetic inheritance: refers to the inheritance of a trait governed by more
than one gene. Generally, three or more genes govern the inheritance of
polygenic traits. Multiple independent genes have an additive or similar effect on
a single quantitative trait.
The genome (= an organisms complete set of DNA) is shaped by evolution over the
years. This represents Darwin’s evolution theory (1859). At that time, he didn’t had the
knowledge we had nowadays. Charles Darwin hypothesized that all modern organisms:
• Are descended from a small set of shared ancestors.
• Have merged over time through the process of evolution.
According to Darwin the key mechanism of evolution is natural selection. There are
three conditions for natural selection to occur:
1. There is variation in the phenotype among individuals of a populations.
2. Individuals with a certain trait survive and reproduce at higher rates than others.
3. The traits associated with this advantage is passed from parents to offspring.
If these conditions are met, those specific traits will be better represented in the next
generation.
Organisms differ in genotype and variations in genotype are passed from generation to
generation. What matters in this context is the survival of genes, NOT the survival of
individuals.
The evidence for modern evolutionary theory comes from many sources:
• The fossil record: fossils show gradual changes along heritage lines, splits in
heritage lines, and transition forms between different species.
• The resemblance between genomes of various organisms.
• Pseudogenes: this is a gene that does not produce any protein, because of some
kind of mutation.
• Distribution of species across the world: there is a distinction between
continental islands (islands that were once connected to the continent) and
oceanic islands (islands that were never connected to a continent). A
continental island such as Japan has originally a very large variety of species.
However, an oceanic island such as Hawaii originally lacked many basic kinds of
animals.
, Despite overwhelming evidence, many people remain skeptical about the theory of
evolution.
With respect to the evolution theory:
• Evolution does not imply that an organism is improved, it only implies that an
organism becomes more and more adapted over generation to its environment.
When this environment changes, the organisms need to change too.
• Evolution does not necessarily lead to rigid behavioral patterns. Organisms keep
changing and therefore will adapt their abilities which have an evolutionary
advantage.
Nowadays, the nature nurture debate became increasingly irrelevant. Instead we know
today, it is a product of both nature (genes) and nurture (environment), there is a
continuous interaction between genes and environment.
Who we are is determined by how our genes are expressed in distinct environments.
Research showed that those who has MAOA for low MAO activity and who were
mistreated in childhood were much more likely than others to be convicted of violent
crimes. It is not the gene, it is not the environment you are raised in, it is the interaction
between your genes and the environment you are raised in.
Each individual has the potential to develop into different persons, this depends on the
environment you grow up in. Your genes set the limits, and depending on your
environment some genes are expressed, and others are not.
Lecture 2 (05-09)
Your phenotype is the product of the interaction between your genes and your
environment. This environment is the current and past environment.
The major diberence in the nervous system is between the central nervous system and
the peripheral nervous system.
What are the building blocks of the brain and the nervous system? The nervous system is
made up of two basic kinds of cells:
1. Glia cells: these cells have supportive functions.
2. Neurons: these cells exchange information by means of electrical impulses.
Because of these neurons, we are able to see and talk for example.
