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HBIO2 > Adaptation
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Successful reproduction

  • Primates often give birth to one child (rather than multiple birth)
    • Easier to care for them
    • More food for the child (bigger brain = more energy)
    • Results in fewer birth and longer pregnancy increases survival (allows larger foetus)
  • Food sharing
    • Creates social relationships
    • Provides enough food for big brains
  • Extended childhood (reproductive system does not develop until puberty)
    • Learn complex skills (language, use of tools)
    • Can only reproduce once they are skilled enough to care for their own children
    • Practice adult skills by playing with other young primates (fighting, finding food, social skills)
    • Allows high culture
    • Greater intelligence

Adaptations of form


  • Pelvic bone (shorter and broader than it is in apes)
    • Allows hip muscles to stabilize body when walking
    • Supports internal organs when upright
    • Positioning of knees supports body when walking upright
  • Spine has an S-shaped curve
    • Rigidity and balance when standing
  • Foramen magnum (whole through which spinal cord attaches to brain) position more forward than apes
    • Balance
  • Advantages
    • Hands can be used to carry food, communicate, throw
    • See over tall grass to watch predators
    • Use weapons to hunt
    • Travel over long distances

Opposable thumb

  • Thumb can touch each of the other fingers (pincer grip)
  • Precise fine motor skills allow manipulation of small objects
  • Allows to bring food to mouth, development of tools, ...

Skin colour

  • Darker skin in tropical environment, where ultraviolet radiation from sun is intense
    • Melanin protective shield against UV radiation
    • Prevent sunburn which may result in DNA changes and, subsequently, melanoma (skin cancer)
  • Northern environment
    • Solar radiation is weak
    • People with brighter skin have advantage (less melanin)
    • Dark skin: ultraviolet cannot penetrate skin
      • Prevent production of vitamin D
      • Osteoporosis or rickets/osteomalacia

Surface area to volume ratio in humans from different countries

  • Large organisms have a small surface area : volume ratio
  • Decreases the rate of diffusion
  • Large animals loose less heat than small animals (advantage in cold climate)
  • Small mammals lose heat very readily (advantage in hot climate)
  • This topic is also in Unit1

Adaptations of behaviour

  • Communication using facial expressions
    • Innate features (people who are born blind have facial expressions)
    • Important signals to other members of a social group
  • Development of language
    • Inform about good hunting areas, water supplies
    • Pass on experience, culture, education
    • Form social groups
    • Older people
      • More valued because of their knowledge
      • In return, they received care in case of illness
    • Allows to think in complex ways (new ideas)
  • Extended childhood
    • Learn more complex skills
    • Develop problem solving skills
    • Increases intelligence
    • (-) Not born with innate behaviour
      • More time to develop skills
      • Need to be protected from danger by mother