- Primates give birth to one child - easier to care for them, more food for the child (bigger brain = more energy), results in fewer births and longer pregnancy = larger foetus = increased survival.
- Food sharing - provides enough food for big brains, creates social relationships.
- Extended childhood (reproductive system does not develop until puberty) - learn complex skills e.g. language and use of tools. Can only reproduce once they are skilled enough to care for their own, practice adult skills by playing with other young primates e.g. fighting, finding food and social skills. Allows high culture (cultural patterns that distinguish a society). Greater intelligence.
Adaptations of anatomy - bipeadlism
- Pelvic bone (shorter and broader than it is in apes) - allows hip muscles to stablise body when walking. Supports internal organs upright, positioning of knees supports body when walking upright.
- Spine has S-shaped curve - ridgidity and balance when standing.
- Foramen magnum (whole through which spinal cord attaches to brain) - positioned more forward than apes = balance.
- Hands can be used to carry food, communicate, throw.
- See over tall grass to watch over predators.
- Use weapons to hunt.
- Travel over long distances.
Adaptations of anatomy - opposable thumb
- Thumb can touch each of the other fingers (pincer grip).
- Precise fine motor skills allowing manipulation of small objects.
- Allows to bring food to mouth, development of tools etc.
Adaptations of anatomy - skin colour
- Darker skin in tropical environment, where UV 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: UV cannot penetrate skin = prevent production of vitamin D = Osteoporosis or rickets.
Adaptations of anatomy - surface area to volume ra
- Large organisims have a small surface area to volume ratio.
- Decreases the rate of diffusion.
- Large animals e.g. Inuk, loose less heat than small animals (advantage in hot climate).
- Small mammals e.g. Masai man, loose heat very readily (advantage in hot climate)
Adaptations of behaviour - facial expressions
Communications using facial expressions;
- Innate features (people who are born blind have facial expressions).
- Important signals to other members of the social group.
Adaptations of behaviour - language
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 receive care in case of illness.
- Allows to think in complex ways (new ideas).
Adaptations to behaviour - 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.
Adaptations of parasites
Parasite - organism that live in or on another living organism, called their host. Feed on the organism and cause it harm.
- Modification of mouthparts and digestive enzyme - allow attachment to host and allow use of host's food supply, blood or tissues.
- Reduction of unnecessary sensory organs and locomotory organs in adult stage - not required as they live in protected, optimum conditions.
- Specialised reproductive strategies - may have male and female reproductive systems, may reproduce asexually and may produce large amounts of eggs/larvae.
- Resist attack by immune system - inaccessible to immune system in the gut, adapt antigens from host (host recognises parasite as own tissue) and change its own antigens.
- Infect two hosts - asexual reproduction in secondary host, use secondary host to infect primary host. Can survive if one host is unavailable, can spread through different environments e.g. water and land.
Toxocara canis - a roundworm that lives in the gut of dogs, but can infect humans.
How Toxocara can infect animals:
1) Toxocara canis infects dog, larvae become active when a female dog is pregnant.
2) Larvae from mother infect puppies via the placenta or milk.
3) Larvae become adults in puppy's intestines.
4) Adults produce eggs that are released in the puppy's faeces.
5) Eggs in the soil are accidentally swallowed by humans and animals.
6) Eggs swallowed by humans hatch into larvae that cause illness but cannot reproduce.
Toxocara infection in humans:
1) Fertile egger eaten, usually when a child eats soil or something contaminated with Toxocara eggs.
2) Larvae hatch in the small intestine and burrow into the lining of the intestine.
3) The larvae enter the blood vessels and travel to the liver. Some larvae are trapped in the liver.
4) Larvae enter the systemic circulation and may travel to any organ. These larvae usually do not develop any further.
5) Occasionally the larvae might migrate to organs such as the eye, where they can cause pain and problems wih vision. Other organis that may be infected include the lungs, heart, brain, liver and kidney.
Adaptations of Toxocara:
- Sticky eggs increase infection.
- Attaches to intestine by hooks.
- Lacks unnecessary organs e.g. locomotory and nervous system.
- Produces large amounts of larvae to increase infection.
- Anaerobic respiration allows survival in the small intestine.
- Produces enzymes that prevent degradation by host's digestive enzymes.
- Larvae form cysts around them which allows them to hide from immune system.