Evolutionary psychology

UOA test 2 PSYCH109

Why study animal minds?

We’re related to everything that has ever lived on the planet.

Percentages of relation

99% chimpanzees

85% dogs

65% birds

44% insects

Homology

Shared inherited structures (e.g. vertebrate limb, frontal lobe)

Tool manufacturing

• Humans were thought to be the only animal capable of tool manufacturing.

• Primates also use tools such as hammers, spears for fishing, and personal care tools.

• New Caledonian crows manufacture two kinds of tools. One from sticks carved with a hook at the end to extract insects. The second kind is made from pandanus leaves

Convergent evolution

Independent evolution of the same structure where natural selection favors the same outcome from different ancestors

Natural selections requirements

• Variation = Differences amongst creatures

• Heritable = Variation can be passed on to future generations

• Design differences = Some variants are better than others

• Competition = Competition for scarce resources results in better designed traits passed to future generations

Process of natural selection

1. Mutation creates variation

2. Unfavorable mutations selected against

3. Reproduction and mutation

4. Favorable mutations are more likely to survive

5. Those mutations reproduce

Nim Chimpsky

Terrance et al. 1979

“Apes can learn many isolated symbols (as can dogs, horses and other

nonhuman species), but they show no unequivocal mastering of the

conversation, semantic or syntactic organization of language”

Types of intelligence

1. Domain-specific (Specific to a particular domain)

2. Domain general (Applies across a range of contexts

Genotype

• Genotype is inherited

• Set of DNA molecules contained in the nucleus

• Genotypes are responsible for specific traits

Phenotype

• Physcially develops from a genotype

• Organism’s physiology, anatomy and behavior

DNA

• In your body, you have cells. In the middle of a cell is a nucleus, which

contains chromosomes. There are 23 pairs of chromosomes; 22 of those are

autosomal. The 23rd pair of chromosomes are responsible for the sex (XX, XY)

• The DNA sequence is a chain of nucleotide bases linked together. The

  nucleotide bases are adenine, thymine or guanine, cytosine

Chromosome

Threadlike structures are contained in the cell’s nucleus. Each chromosome is a DNA molecule; they occur in pairs. Human somatic cells contain 23 pairs

Gene

Stretch of DNA that produces a specific protein

Allele

Alternative forms of a gene at the same locus

Locus

Position of a gene on a chromosome

Homozygous

Organisms possess two identical alleles for particular trait

Heterozygous

Organisms possess two different alleles for a particular trait

Dominant

An allele that manifests it's effects in both Heterozygotes and homozygotes

Recessive

An allele that manifests its effects only in homozygotes

Polygenic inheritance

Trait whose phenotypic expression is influenced by many genes. e.g. most psychological traits

PKU (Phenylketonuria)

• The test consisted of studying two intellectually disabled children as he wanted to find out what was wrong with them.

• He noticed that their urine smelled odd.

• He then tested it and found that it contained high levels of Phenyl Ketone.

• He suggests there was a metabolic upset that the children inherited in their body that was building up Phenyl Ketones in their body, making them profoundly intellectually disabled.

• PKU is an example of an “inborn” metabolic disorder that causes intellectual disabilities due to a single recessive gene on chromosome 12. You will need to have two copies from each of your parents to have PKU.

Genes and Agression

• The warrior gene is a gene on the X chromosome that affects the production of Monoamine oxidase A.

• That enzyme affects how the body metabolises neurotransmitters such as norepinephrine, serotonin and dopamine in the brain.

• Lower abilities to metabolise the neurotransmitters shown in animal and human studies have led to increased violence and aggression.

• This genetic mutation is paired with environmental factors such as, in this case - severe maltreatment of children

Dictator game

• One player receives a sum of money, and they have to decide how much they’ll give to player two.

• The graph shows that behavior varies across different cultures. People in the United States donate around 47% of their sum. Hunter-gatherers from Africa donate 25% of their sum, such as the Hadza.

Muller-Lyer illusion

• Which line is longer?

• They are actually both the same length.

• Our perception of the length of both lines is not wired into our brain and varies amongst cultures.

• “A 2008 survey of the top psychology journals found that 96% of subjects were from western industrialized countries - which house just 12% of the population.”

• Most of these people are Western, educated, from industrialized societies, rich and democratic (WIERD).

• The issue with this is that psychologists often ignore cultural variation and assume that the entire population sampled represents the world.

Conformity bias

People’s tendency to behave like those around them rather than using their judgement

Prestige Bias

Occurs when individuals predominantly choose to learn from the most prestigious group member

Overimitation

When a child copies everything an adult does, even if the behavior is irrelevant or silly.

Memes as a cultural replicator

Music, ideas, clothes, fashion behaviors propagate themselves in the meme pool by leaping from brain to brain. This process is known as imitation

Cultural evolution and religion

• Religion is a selfish meme

• Copying fidelity.

○ Scared texts.

○ Prohibitions against questioning the tenets of the religion.

○ It’s forbidden to have tolerance toward other worldviews.

• Replication.

○ Missionary/conversion system.

○ You will go to heaven if you believe.

○ You will go to hell if you don’t.

• Believing in a powerful deity who will punish immoral behavior helps individuals trust others in their group, promoting cooperation