Bio1110 Chapter 5 Human Populations
  1. Human population has been growing at an almost exponential rate in recent decades.
    • • The human population started to experience a rapid growth around the time of the industrial revolution in the 18th century.

      Factors that contributed to this rise included increased food production, better health care and sanitation, leading to decreased death rates while birth rates remained high.

    • • China and India are by far the most populous countries, though China and the U.S. have about the same land area.

      Bangladesh has 12% of China's population, but only 1% of China's area.

    • • Bangladesh has the highest population density at almost 1,000 people per square kilometer.

      About 90% of the people live on 10% of the land area, usually near water.

  2. Demographics strongly influence a population's current and future growth.
    • Demographic factors strongly affect a population's growth rate.

      These factors include birth and death rates as well as income and education levels

      Developed countries tend to have lower birth rates and population growth rates than developing countries.

      The lower wealth in the developing countries also lead to quality of life issues such as higher infant mortality rate and shorter life expectancy.

      As developing countries improve their economies, a demographic transition may take place.

    • • Most of the projected growth in coming decades are expected to come from developing nations due to their higher growth rates.

      Most developed nations have relatively low growth rates, reflecting balanced birth and death rates.

    • • A demographic transition often occurs as developing (industrializing) countries improve their technologies.

      Usually the death rates fall first, due to improvements in health care and sanitation.

      After some time, birth rates also begin to fall, as education levels rise.

      The period between the initial death rate decrease and the eventual birth rate decrease is the demographic transition, where the population experiences rapid growth.

  3. Achieving zero population growth must address other demographic factors that affect fertility.
    • • The world population growth rate has been declining in recent decades, to about 1%.

      However, the world population size is still growing.

      A population's size will not stabilize until its growth rate is zero.

    • Infant mortality rate is strongly correlated with Total Fertility Rate (TFR): the total number of children a woman bears over her lifetime.

      Both tend to increase as poverty increases.

      On the other hand, TFR tends to decrease as education levels rise.

    • • In most populations, TFR is also correlated with desired fertility.

      Thus lowering the infant mortality rate may also lower how many children a family desires.

    • • A major factor in Total Fertility Rate (TFR) of a population is educational level among women.

      As women receive more education, the TFR tends to decrease, resulting in slower population growth.

  4. An age structure may also predict population growth trends.
    • Age structure diagram
      Niger's young population has high population momentum (capacity for population growth). China's transitional population exhibits moderate, stable growth. Japan's mature age structure with low proportion of young individuals shows low population momentum.

    • Age structure of a population is a predictor of growth trends.

      The fastest growing regions (high population momentum) are those with a youthful or very young population.

  5. Rising incomes may also be associated with rising ecological footprints.
    • • As nations develop and incomes rise, their populations also tend to increase resource use.

      In some areas, their ecological footprint may have already exceeded the biocapacity of the region to support sustained use.