Evolution

• Theory of evolution


  • all lives on the planet earth inherit their genetic information from their ancestors
  • the common ancestor of all species is a very basic simple organism
  • natural selection - only organisms that are fit enough to survive in their environment have a chance to pass on their genes to the next generation
• principles of evolution 


  • principle of inheritance - physical and behavioural traits are heritable:
  • appearance
  • personality
  • physical and behavioural traits are inherited from parents and are passed down generations as we give them our genetic codes
  • principle of variation - individuals within a species show variation in their traits
  • genetic differences is part of the reason as to why are different
  • some genes lead to successful adaption
• Genetic codes that affect our working memory capacity 


  • working memory - ability to hold information temporarily active in our mind
  • associated with the COMT gene
  • COMT gene regulated dopamine in the prefrontal cortex
  • different variants of the COMT gene affect PFC dopamine release
• principle of evolution

  • principle of adaption - some variants of genes are more adaptive than other genes, and organisms with those adaptive genes can survive better
  • principle of time - over time, natural selection results in changes in species; changes need to take decades to occur; successful variation accumulates over time in a gradual process
• Directional selection 


  • for one extreme trait
  • against the other extreme
• stabilising selection 


  • for moderate traits
  • against both extremes
• diversifying selection


  • for both extremes
  • against moderate traits
• Natural selection strategies 


  reciprocal altruism:

  • natural selection is biased towards favouring those species who are willing to reciprocally support others as it increases the chance of the species surviving as a whole

  Kin selection:

  • people are willing to make sacrifice or share resources as our relatives share genes with us
  • we want to help our family to support the transmission of family genes
• Supporting evidence: biogeography


  • studies the distribution of animal species
  • the distribution of marsupials as evidence
  • localised change in characteristic due to localised events
• Supporting evidence: fossils


  • systemic changes through geographical layers
• Supporting evidence: comparative embryology 


  • compare the processes of development across species to determine evolutionary similarities
  • if two animal species look very similar to each other until very late stages of their embryonic development, they are more likely to be close relatives on the evolutionary tree
• Supporting evidence: molecular biology 


  • we can analyse the degree of similarity between genetic codes of two species
  • if two species are close to each other in evolution = high degree of similarity
• The solution of evolution 


  • divergent evolution - organs with similarity due to being derived from a common ancestor
  • convergent evolution - organs with similarity due to performing similar function
• Process of human evolution 


  • began 7 million years ago
  • human lineage broke away from chimpanzees
  • there were about 20 early human-related species, but nearly all became extinct