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Ch35: Population Change Higher Human Biology

Ch35: Population Change Higher Human Biology. Population. A population is a group of individuals of the same species which makes up part of the community in an ecosystem.

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Ch35: Population Change Higher Human Biology

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  1. Ch35: Population Change Higher Human Biology

  2. Population A population is a group of individuals of the same species which makes up part of the community in an ecosystem. When a population colonises a new environment the population increases rapidly until it reaches the carrying capacity - the maximum population size that can be maintained by the environmental conditions.

  3. Birth rate – the number of new individuals produced by a population during a certain time interval. Death rate – the number of individuals within a population that have died during the same time interval. Populations terminology Population density – the number of individuals of the same type present per unit area (or volume) of a habitat.

  4. Exponential growth Rapid increase in population size Carrying capacity Population colonising a new environment Population Growth Curve Number of Individuals Birth = Death rate rate Time

  5. Population Stability When the population reaches the level that the available environmental recourses can just maintain the population becomes stable. At this stage it is in a state of dynamic equilibrium (there are very slight changes but overall it is relatively balanced) and the population has reached its carrying capacity and birth rate equals death rate. Human interference has caused many populations to become unstable or threatened.

  6. Population Regulation The carrying capacity is determined by: • Food • Oxygen • Water • Space If one is limited it prevents the population increasing Regulatory Effect Death by…. • Predation • Disease • Pollution by organism’s waste Population decrease

  7. factor limited e.g. food, water Population increase Population decrease Death rate increases Population at Carrying capacity (maximum supported by the environment) Population increase Birth rate increases Population decrease Factor plentiful e.g. food, water Regulation of population size

  8. Agricultural Rapid population increase Industrial Human Population Explosion Humans have overcome causes of mortality (e.g. predation) so have increased our carrying capacity & have increased exponential growth. Revolutionary changes

  9. Kalahari Bushmen (Africa) Undeveloped Societies • Totally dependent on immediate environment for food, water, shelter. • Live ‘hand to mouth’ • No agriculture • No modern technology

  10. Aborigines (Australia) • e.g. Hunter-gatherers • remote locations • low carrying capacity • low population density • shared society Arctic Inuit (Eskimos) Population limited by water availability Population limited by low temperature

  11. Influence of modern society on undeveloped societies • Modern societies have introduced: • tools • technology • disease – led to a population decline • Caused problems: • Less land to live off • Traditional cultures are disappearing • Economic & social problems

  12. Subsistence farming • Grow crops on own land to meet the families own needs. • Store excess crop for use during times of shortage • Rarely sell any crops or animals • Use basic tools • Use family labour Common in Latin America, Africa & Asia

  13. Subsistence farming (cont’d) • Low standard of living • Often no electricity or sanitation • Lifestyle similar to 10,000 y.a. at start of agricultural revolution • Population denser than hunter-gatherers

  14. Effect of Science on Human Population Growth Modern sanitation Immunisation against diseases e.g. smallpox & polio Better housing Piped water Improvements in child care Efficient food production Antibiotics

  15. Effect of Science on Human Population Growth Scientific discoveries & Inventions 1650 AD Advances in science Advances in medicine Industrial revolution These advances have contributed to a human population boom by removing limiting factors that in the past regulated the population.

  16. Less child mortality Overcoming predation (due to guns) Increased female fertility Increase in life expectancy Exponential Growth of Human Population The human population is now growing exponentially due to:

  17. Increased food availability Machinery Pesticides Fertilisers Exponential Growth Also due to…

  18. Change in Cultural Habits Women tend to suckle their young for less time, as ovulation is inhibited during breast-feeding, women are more likely to conceive their next child sooner. Births no longer spaced out Birth rate increases

  19. Doubling time … the length of time for the worlds population to double. Actually the population growth rate is slowing down due to… In 1980s doubling time was decreasing steadily thus the world population was rapidly increasing • use of contraception • social pressures (e.g. China) • deaths from AIDS

  20. World’s wealth is not distributed evenly The highest population growth is in the poorest nations so 50% of the world population live in poverty!

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