Chapter 3
About genetics and their role on our behaviour / evolution
Basic genetic mechanisms
Genes never produce or control behaviour, but they are associated with our behaviour.
The physical structure of the body made by genes AND the environment, produce behaviour.
Genes influence the production of protein molecules, and in this way affect the body.
Genes = components of extremely long molecules of a substance called DNA.
or even more valid: = a segment of a DNA molecule that contains the code that dictates the
particular sequence of amino acids for a single type of a protein.
2 separate genes:
1. Coding genes genes which code for unique protein molecules
2. Regulatory genes genes which helps activate or suppress coding genes
Regulatory genes can be very important for developing new characteristics.
(experience genes activated proteins produced new function behaviour)
Environment = every aspect of an individual except from the genes
Genes + environment control behaviour
Genotype = the set of genes that an individual inherit
Phenotype = the observable properties of the body and the behavioural traits.
- these two could be different due to different environments
Mitosis = duplicating system leads to body cells, are all the same
Meiosis = duplicating system leads to egg/sperm cells, are different (divides into 4 cells)
Zygote = the result of when a sperm cell and egg cell meet each other. (46 chromosomes again)
by creating different offspring, the offspring won’t die all at the same time
Identical twins = twins from the same zygote
Fraternal twins = twins coming from 2 different zygotes differ from each other
Homozygous = when genes at the same locus of the chromosome are exactly the same
Heterozygous = when genes at the same locus of the chromosome are different
Alleles = different genes that can occupy the same locus (recessive vs dominant)
Mendelian pattern of heredity ( if both parents are heterozygous 3 times RR; 1 time rr)
Inheritance of behavioural traits
Single-gene inheritance
A timid dog was being crossbred with a fearless dog offspring = timid.
Because of this, scientists concluded that the difference in fearfulness is controlled by a
single locus. (environment was the same for both, so in this case not affective)
, PKU, a disease, caused by a single error in one gene. PKU only has effects when eating
Phenylalaline. People go on a phenylalaline-free diet. In this way, environment and genes
interact with each other.
Some behaviour can be put into categories.
Some behaviour is measurable in degrees (skin colour) continuous behavioural measures
- most of the time the continuous behaviour measures have a normal distribution.
Normal distribution = when most scores fall near the middle. (normal curve)
Polygenic characteristics = characteristics that vary in a continuous way
affected by multiple loci on many genes
Selective breeding
o Immediate effect with single-gene characteristics
o Gradual and cumulative effects on polygenic characteristics
Epigenetics
o The field of epigenetics examines ‘gene-regulating activity that doesn’t involve
changes to the DNA code and that can persist through one or more generations’’.
o Epigenetic mechanisms are responsible for putting genes on/off.
o Are responsible for change of behaviour because of experience
o Genotype stays the same, but the phenotype might change
Evolution by Natural Selection
2 different types of selection:
1.) Artificial selection = plants and animals are modified by selective breeding
2.) Natural selection = selective breeding in nature
4 core concepts of natural selection:
1.) There is overproduction of offspring in each generation
2.) There is variation in features or traits within a generation
3.) Individual differences are inherited from generation to the next
4.) Individuals who are more adapted to the environment have higher chance to survive and
higher chances of creating offspring.
Mutation = the source of all genetic variation (DNA replica isn’t exactly the same)
The mutated gene will increase in frequency when it’s useful (because those will survive)
Evolution is spurred by changes in the environment.
species have to adapt to the environment to survive
3 corrections on mistaken beliefs about evolution:
1.) Evolution has NO foresight
2.) We aren’t more evolved than other animals
3.) Natural selection isn’t good/bad or moral/immoral
About genetics and their role on our behaviour / evolution
Basic genetic mechanisms
Genes never produce or control behaviour, but they are associated with our behaviour.
The physical structure of the body made by genes AND the environment, produce behaviour.
Genes influence the production of protein molecules, and in this way affect the body.
Genes = components of extremely long molecules of a substance called DNA.
or even more valid: = a segment of a DNA molecule that contains the code that dictates the
particular sequence of amino acids for a single type of a protein.
2 separate genes:
1. Coding genes genes which code for unique protein molecules
2. Regulatory genes genes which helps activate or suppress coding genes
Regulatory genes can be very important for developing new characteristics.
(experience genes activated proteins produced new function behaviour)
Environment = every aspect of an individual except from the genes
Genes + environment control behaviour
Genotype = the set of genes that an individual inherit
Phenotype = the observable properties of the body and the behavioural traits.
- these two could be different due to different environments
Mitosis = duplicating system leads to body cells, are all the same
Meiosis = duplicating system leads to egg/sperm cells, are different (divides into 4 cells)
Zygote = the result of when a sperm cell and egg cell meet each other. (46 chromosomes again)
by creating different offspring, the offspring won’t die all at the same time
Identical twins = twins from the same zygote
Fraternal twins = twins coming from 2 different zygotes differ from each other
Homozygous = when genes at the same locus of the chromosome are exactly the same
Heterozygous = when genes at the same locus of the chromosome are different
Alleles = different genes that can occupy the same locus (recessive vs dominant)
Mendelian pattern of heredity ( if both parents are heterozygous 3 times RR; 1 time rr)
Inheritance of behavioural traits
Single-gene inheritance
A timid dog was being crossbred with a fearless dog offspring = timid.
Because of this, scientists concluded that the difference in fearfulness is controlled by a
single locus. (environment was the same for both, so in this case not affective)
, PKU, a disease, caused by a single error in one gene. PKU only has effects when eating
Phenylalaline. People go on a phenylalaline-free diet. In this way, environment and genes
interact with each other.
Some behaviour can be put into categories.
Some behaviour is measurable in degrees (skin colour) continuous behavioural measures
- most of the time the continuous behaviour measures have a normal distribution.
Normal distribution = when most scores fall near the middle. (normal curve)
Polygenic characteristics = characteristics that vary in a continuous way
affected by multiple loci on many genes
Selective breeding
o Immediate effect with single-gene characteristics
o Gradual and cumulative effects on polygenic characteristics
Epigenetics
o The field of epigenetics examines ‘gene-regulating activity that doesn’t involve
changes to the DNA code and that can persist through one or more generations’’.
o Epigenetic mechanisms are responsible for putting genes on/off.
o Are responsible for change of behaviour because of experience
o Genotype stays the same, but the phenotype might change
Evolution by Natural Selection
2 different types of selection:
1.) Artificial selection = plants and animals are modified by selective breeding
2.) Natural selection = selective breeding in nature
4 core concepts of natural selection:
1.) There is overproduction of offspring in each generation
2.) There is variation in features or traits within a generation
3.) Individual differences are inherited from generation to the next
4.) Individuals who are more adapted to the environment have higher chance to survive and
higher chances of creating offspring.
Mutation = the source of all genetic variation (DNA replica isn’t exactly the same)
The mutated gene will increase in frequency when it’s useful (because those will survive)
Evolution is spurred by changes in the environment.
species have to adapt to the environment to survive
3 corrections on mistaken beliefs about evolution:
1.) Evolution has NO foresight
2.) We aren’t more evolved than other animals
3.) Natural selection isn’t good/bad or moral/immoral
