Evolutionary factors in the development of human intelligence

  • Created by: Rebekah
  • Created on: 03-06-15 18:02


  • The evolutionary explanation of intelligence suggests that intelligence has evolved through natural selection as it provided our ancestors with the greatest change of survival
  • Clearly, those who were intelligence survived and passed on their genes
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Ecological Theory AO1

  • Intelligence has evolved due to our ancestors food patterns as a result of climate change
  • Initially, humans were leaf eaters which required little cognitive or physical skill
  • Due to climate change, humans had to shift to fruit based diets and this led to our ancestors needing to understand the seasons by which fruit will grow, and create cognitive maps for these
  • Finally, we became meat eaters which seemed to require a theory of mind in order to deceive and understand the thoughts of other animals
  • In addition, the ability to get meat required the construction and usage of tools which again is seen as an intelligent skill
  • Thus, it seems that natural selection favoured those who were the most intelligent; intelligent early humans were more likely to successfully adapt and cope with increased cognitive demands associated with changing food.
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Ecological Theory AO2

  • Fruit eating monkeys
    • These monkeys seem to have a larger brain size than non-fruit eating monkeys
    • Therefore it seems that the demands of cognition to understand when and where to get fruit from means that animals have higher intelligence levels
    • However, this research has used animals, and thus it may not be representative to generalise the findings from animals to humans
    • We have large changes in our anatomy and therefore the findings in animals may not be applicable to humans, reducing the usefulness of this study in supporting the ecological theory
  • Tool creation and brain size
    • Over the last 50,000 years, there has been a huge increase in tool creation and usage
    • However, there has been little change to brain size over the last 50,000 years
    • These two factors are meant to be correlated
    • It would seem that another factor influences brain size and tool usage as these two variable do not primarily influence each other
    • Therefore, the ecological theory seems to be flawed as it cannot explain the reasons as to why these factors don't correlate
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Social Theory AO1

  • The main concept is that living in large groups require intelligence
  • This is because we need a theory of mind to anticipate the thoughts and emotions of others, and to understand who is a friend and who is a threat
  • In addition, the ability to work together as a group also requires intelligence as it is not as easy as working alone as the thoughts and understanding of the group need to be known
  • Ancestors who had the intelligence to cope with these additional demands of group living were more likely to survive
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Social Theory AO2

  • Pack of hyenas
    • This knowledge and understanding of group dynamics require intelligence and thus supports the social theory of intelligence
    • This is because these animals understand status in groupings and thus who is best to make alliances with
  • Dunbar - brain size hypothesis
    • He found that group size correlated with brain size, suggesting the larger the group an individual is involved in, the more intelligent
    • When applying this to the social theory, this could be because larger groups are more demanding of intelligence regarding a theory of mind and coalition formation
    • Thus supporting the social theory of intelligence in relation to social demands requiring intelligence
    • This study is purely correlational, and thus cannot establish a cause and effect, this is because there could be many other extraneous variables which could impact on brain size which Dunbar hasn't considered. This reduces the validity of the research in supporting the social theory of intelligence
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  • The evolutionary approach can be deemed unscientific as the hypothesis cannot be tested. You can't test if early humans really did evolve intelligence as a result of social or ecological causes
  • The evolutionary approach is deterministic - suggests modern humans level of intelligence is predetermined by genes inherited by early ancestors
  • The focus on the relationship between brain size and intelligence in the area is socially sensitive - e.g. there are gender differences and racial differences in brain size
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Brain size and EQ

  • When looking at brain size and IQ we can see that having a larger brain size has advantages
  • Psychologists measure brain size using the EQ measurement which is: actual brain size divided by expected brain size for an animal your size
  • The standard size for cats is 1, dolphins is 5 and humans is 7.6
  • We have the largest brain size, and seeing as we are the most intelligent animal, it would appear IQ does correlate with brain size
  • However men have larger brains than women, yet are not seen as more intelligent
  • Therefore, there appears to be some flaws with this concept and thus not perfect in explaining why brain size and IQ correlate in animals
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