AEC 360  Ecology

Lecture 15:  Human Population Growth

I.  Introduction
    A.  How does population size change with density?

    B.  UN currently predicts the 2050 population size to be ~10 billion

II.  Human demography
    A.  The demographic transition:  the shift from high birth and death rates to low birth and death rates
        Stage 1:  Birth and death rates high but in balance
        Stage 2:  Changes in technology and medicine cause death rates to fall, but not birth rates
        Stage 3:  Birth rates fall
        Stage 4:  Birth and death rates low and in balance

    B.  Some countries have undergone the demographic transition, while other have not


    C.  Human demography can be unpredictable

    D.  Can get some idea for future population growth by looking at age structure
        1.  Constant age structure is indicative of stable population

        2.  Pyramid age structure is indicative of growing population

    E.  What factors could lead to stabilization or decline in human population size?

III.  The carrying capacity concept
    A.  Definition:  the upper bound of population size beyond which no major increase can occur

    B.  Impact = Population * Affluence * Technology  (The IPAT equation)

    B.  What factors limit human population size?