Answer to Question 1
Answer: Geographers who analyze human movements divide the causes for those movements into push factors and pull factors. Push factors drive people away from wherever they are. Push factors include unemployment, disasters, and political and religious persecution. Pull factors attract people to new destinations. Pull factors include economic opportunity and the promise of religious and political liberty.
Throughout history, the major push and pull factors behind contemporary migration have been economic and political. This remains true today. People are trying to move from poor countries to rich countries and from politically repressive countries to more democratic countries. In addition, millions of people are fleeing civil and international warfare.
Answer to Question 2
Answer: In Stage 1 there are high birth rates and high death rates, as a result, the population is fairly stable. In Stage 2, typically due to advancement in medical technology, the death rate falls, but birth rates remain high. This creates a rapid population increase. In Stage 3, people realize that children are expenses rather than assets, and the birth rates drop. This decrease in birth rates causes the population increase to slow. In Stage 4, the populations become stable again with low birth rates and low death rates. Stage 5 is where the death rates exceed the birth rates and populations decline.
A comparison between anagenesis and cladogenesis: two patterns of speciation.
Environmental factors restricting the distribution of Chthamalus to the upper intertidal zone.
Black and White Out-Migration from Virginia and North and South Carolina, 1870–1940 (in thousands)
Risk Factors of Osteoporosis
Globalization and Migration
Common restriction enzymes, with their recognition sequence, DNA cutting patterns, and sources