6.3: Population Dynamics: Natural ChangeWorld Geo 3200/3202May 2011

Outcomes• 6.3.1 define the terms natural change, natural

increase, and natural decrease; (k) • 6.3.2 express population change in mathematical

terms; (a) • 6.3.4 examine the relationship between birth

rate and death rates to determine natural change in a population; (a)

• 6.3.5 analyze factors that affect birth rates; (a) • 6.3.6 analyze factors that affect death rates; (a) • 6.3.9 describe the factors that contribute to a

graying of the population; (k) • 6.3.10 project future population trends from data

provided. (i)

Overview

•There are only two factors that can increase a population: births and immigration.  Natural change in a population considers only births as a means of increasing the population.

•Likewise there are only two factors that can decrease a population: deaths and emigration.  Natural change in a population considers only the deaths as a means of decreasing the population.

Natural Change•Natural change in a population is defined

as the difference in births and deaths.

•Natural Change = difference in births & deaths

▫Natural Increase occurs when there are more births than deaths

▫Natural Decrease occurs when there are more deaths than births

Rate of Natural Change• Population growth rate considers all aspects of

population change.  However Rate of natural increase (RNI) takes into account only birth rate and death rate.

• Birth Rate (BR) is measured as the number of births (in one year) per 1000 people.

•       The formula is     BR =        births      X 1000                                            population

• Death Rate (DR) is measured as the number of deaths (in one year) per 1000 people.

•       The formula is      DR =      deaths     X   1000                                            population

Rate of Natural Increase

•Rate of Natural Increase  (RNI) is a measure of how fats the population is increasing due only to the births and deaths.

•The formula is     RNI =  BR – DR

PGR & Standard of Living

•Generally speaking stable populations are characteristic of a high standard of living due to:▫low birth rate caused by good family

planning, access to birth control, financial planning, education, etc.

▫Low death rate caused by good medical care, nutrition, education etc. 

PGR & Standard of Living

•Generally speaking an expanding population is characteristic of a lower standard of living:▫high birth rate due to poor access to birth

control, lack of education etc.; ▫high death rate due to poor medical care &

nutrition

Assigned Readings

•"Natural Changes in Populations" on pages 310-311 of your text book.