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
Bipedalism
- 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
- 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
