Human Population Growth trends and implications

Ecology vs. Environmentalism The Human Population Population Growth Milestones Agriculture increases world population Human Population Stable from 8000 BC To 1600 AD Industrial Revolution Begins Scientific Agriculture Why so much growth since 1600? Concerns Will the human population stop growing? Population Dynamics Example of population Dynamics of humans Two types of Growth Example w/ cars and water-fleas Example w/ cars and water-fleas Population growth Is this real Population Growth? The Australian Rabbit Plague Brown area: geographic Range of rabbits now Why a problem? Top: with rabbits Bottom: without rabbits Exponential Growth and Rabbits Example: For every 7 rabbits born, only one dies Each circle = 1 rabbit; Start with 2 rabbits. Next: Each rabbit has 7 babies Example: For every 7 rabbits born, only one dies Each circle = 1 rabbit; Start with 2 rabbits. Next: One rabbit dies Example: For every 7 rabbits born, only one dies Each circle = 1 rabbit; Start with 2 rabbits. Next: Each rabbit has 7 babies Example: For every 7 rabbits born, only one dies Each circle = 1 rabbit; Start with 2 rabbits. Next: Every rabbit has 7 babies What stops exponential growth? Example: Same two rabbits. For every 7 rabbits born, 7 starve Each circle = 1 rabbit; Start with 2 rabbits. Next: Each rabbit has 7 babies Example: Same two rabbits. For every 7 rabbits born, 7 starve Each circle = 1 rabbit; Start with 2 rabbits. Next: 14 rabbits starve Example: Same two rabbits. For every 7 rabbits born, 7 starve Each circle = 1 rabbit; End with 2 rabbits. Balance of Births and Deaths: Births Balance of Births and Deaths: Deaths Balance of Births and Deaths Populations with different r grow at different rates Limiting Growth Example of Deer Only so much food in environment Logistic Growth Logistic Growth and Carrying Capacity Carrying Capacity Two Reproductive Strategies Population implications: Elephants vs. Some insect Survivorship Importance of Age in Populations Age Pyramids Back to Humans Will unlimited growth continue? • Already starting to slow • In fifty years, Kenya expected to show similar age pyramid to U.S. Kenya example of worldwide trend Female Fertility Across Countries Also change in less developed nations • Female fertility declining in many developing nations Birth/Death Balance Example with Oil Prices