Open up the Human Population Clock and explain. http://www. census

5.2 & 3: Limits to Growth & Human Growth Patterns

Population size won’t grow forever! It is limited by different factors: Those factors fall into two broad categories: ~ density-dependent factors ~ density-independent factors

density-dependent factors the greater the population, the greater effect these factors have disease predators parasites food water 4

density-independent factors doesn’t matter how large or small the population, all are affected in the same manner temperature extremes natural disasters some human activities 5

Human populations can be studied using the same techniques. demography: study of human populations focuses mainly on birth rates, death rates, & age structure Human growth was slow for much of history then grew exponentially after the 1800s. 6

WHY THEN? 7

Human population is still growing rapidly BUT the rate of growth is slowing. HOW? Developed countries – US, Japan, Europe – have declining birth rates. Some European countries are actually seeing a DROP in their populations as young people are having fewer or no children. 8

show demographics of a population using age-structure diagrams males females 9

http://lcmrschooldistrict.com/roth/PowerPoint_Lectures/chapter44/videos_animations/age_structure_v2.swf 10

starts with high birth and death rates (Stage I) Demographers believe human populations will undergo a demographic transition – a three-stage process for all countries. starts with high birth and death rates (Stage I) moves to high birth with low death (Stage II) finishes with low birth and death (Stage III) 11

Stage I: high birth & high death Stage II: high birth & low death Stage III: low birth & low death

Open back up the Human Population Clock to see the change during class!