-we can understand how population is distributed by identifying two basic properties.
-two thirds of the world’s population is clustered in 4 regions: East Asia, South Asia, Southeast Asia, and Western Europe. - The clustering of the world’s population can be displayed on a cartogram, which despites a countries size according to its population not its land area. Major population clusters
-1/5 of the world’s population lives in east Asia.
-1/5 of population lives in south Asia
- Southeast Asia is world’s 4th largest cluster and Western Europe is the third largest. Other population clusters
-The largest population cluster in the western hemisphere is the northeastern U.S and southern Canada. Sparsely populated regions
-Human beings avoid clustering in certain physical enviorments, because either too hot, too cold, too dry, etc. - The portion of the earth’s surface preoccupied by humans is known as ecumene.
1. Ecumene has increased over the last centuries.
* Geographers frequently use arithmetic density which is the total number of people divided by the total land area. * Geographers rely on this to compare conditions in different countries because the info needed to calculate the measure is easy to obtain. * Arithmetic answers the where question but doesn’t answer the why Physiological density
-A more meaningful population measure is afforded by looking at the number of people per area of a certain type of land in a region. -In a region, the number of people supported by a unit area of arable land is called physiological density. -The higher this is the greater pressure that people may place on the land to produce enough food. - Physiological density provides insights into the relationship between the size of a population and the availability for natural resources in a region. Agricultural density
-This is the ratio of farmers to the amount of arable land. -This measure helps account for economic differences.
Where has the world’s population increased? Key issue 2
-Population increases rapidly in places where more people are born than die. -Population also increases when more people move in than moved out. Geographers most frequently measure population change in a country or the world as a whole through three measures:
1. Crude birth rate is the total number of live births in a year every 1,000 people alive.
2. Crude death rate- is the total number of deaths in a year for every 1000 people alive in a society.
3. Natural increase rate- Is the percentage by which a population grows a year. It is computed by cbr-cdr and converting that number to a percentage. 15 per 1000 would be 1.5%. Natural increase
-The rate of natural increase affect the doubling time, which is the number of years it takes needed to double a population, assuming a constant rate of natural increase rate. Fertility
-Geographers use the TFR to measure the number of births in a society. The TFR is the avg number of children a woman will have during her child bearing years. Mortality
Two useful measures of mortaility are:
1. infant mortality rate- the annual number of deaths of infants under one year of age, compared with total live births.
The Demographic Transition
The demographic transition model seeks to explain the transformation of countries from having high birth and death rates to low birth and death rates. In developed countries this transition began in the eighteenth century and continues today. Less developed countries began the transition later and are still in the midst of earlier stages of the model. Stage I
Prior to the Industrial Revolution, countries in Western Europe had a high CBR and CDR. Births were high because more children meant more workers on the farm and with the high death rate, families needed more children to ensure survival of the family. Death rates were high due to disease and a lack of hygiene. The high CBR and CDR were somewhat stable and meant slow growth of a population. Occasional epidemics would dramatically increase the CDR for a few years (represented by the "waves" in Stage I of the model. Stage II
In the mid-18th century, the death rate in Western European countries dropped due to improvement in sanitation and medicine. Out of tradition and practice, the birth rate remained high. This dropping death rate but stable birth rate in the beginning of Stage II contributed to skyrocketing population growth rates. Over time, children became an added expense and were less able to contribute to the wealth of a family. For this reason, along with advances in birth control, the CBR was reduced through the 20th century in developed countries. Populations still grew rapidly but this growth began to slow down. Many less developed countries are currently in Stage II of the model. For example, Kenya's high CBR of 32 per 1000 but low CDR of 14 per 1000 contributes to a high rate of growth (as in mid-Stage II). Stage 3- Moderate growth birth rate begins to fall, Cdr continues to fall but at a much slower rate. Less babies are born due to a cultural change. Stage 4- Low growth Crude birth rate declines to point where it equal CDR. Zero pop growth.