Demography (population)

Demography Definition

The study of human populations. Demographers look at birth, death and migration rates to explain population change.

Population Pyramids

They are graphic examples of the age and sex composition of a population. From them you can make certain inferences about problems the society might be facing or is likely to face in the future. Large young population = possible problem providing schools, not having right kind of health care facilities in place, poorer society because of the high proportion of dependent population; high birth rate, probably hispanic/Latino. More women then men = poorer society Bulge toward top of the age bars = baby boomers; imply future concerns about the infrastructure as it applies to the elderly, along with health care considerations; bulge places large demands on social security system.

Demographic Transition

This theory postulates that a country's birth and death rates are linked to its level of industrial or economic development and that the so-called developing countries will eventually achieve birth and death rates like those of Western Europe and North America by following the same pattern as the industrialized countries there. Technology decreased death rates.In Stage 2, there was actually a population explosion, people were living longer but not reducing the number of babies born. Eventually birth rates declined as large families became a burden in a nonagricultural economy, as infants and childhood mortality declined, as technology introduced birth control. In Stage 3 we see low birth rates and low death rates and a pretty stable population growth rate. In Stage 4 both birth rates and death rates are low but also birth rates have fallen below replacement level - 2 babies born (and survive) to 2 adults. While death rates are low,there is an increase of lifestyle diseases caused by lack of exercise, poor nutrition and obesity.

Characteristics of a Population

1. Age Composition: The percentage of the population falling in to particular age categories. if a population is very young, or very old, then it is more likely to be poorer since most members of those age categories do not work. Working age adults support the "dependent" population, those in non-working ages. 2. Sex Ratio: The number of males for every 100 females. A completely balanced society would have a sex ratio of 100/100. If a population has a sex ratio of 85/100 this means many fewer males. Since men make more money than women, if the sex ratio of a population is low like this, the population is likely to be poorer. 3. Ethnic Composition: Birth, death and growth rates are affected by culture. In the US, Hispanics/Latinos tend to have high birth rates, mostly because of their religious affiliation. They value a larger family size than do most other ethnic groups. So, if a population has a high proportion of Hispanics/Latinos, it is likely to have a higher birth rate. A higher birth rate leads to a younger population.

Three Demographic Variables

1. Fertility: births. The fertility rate is the number of children the average woman bears. Replacement fertility would be about 2. A fertility rate that stays below 2 for several years could indicate and impending decline in population size. A higher fertility rate indicates rapid population growth. 2. Mortality: deaths. The mortality rate is the number of deaths per 1,000 in the population. As technology allows people to live longer, population size increases unless there is a corresponding drop in birth rates. 3. Migration: moving from one place to another. In the US, as birthrates are stable and death rates drop (but not dramatically), migration is the major force in changing the make-up of a population. The average migrant is male, in their early 20s, moving for economic reasons. When a migration occurs, there is an area of origin and an area of destination. The area or origin is said to have "push factors" while the area of destination is said to have "pull factors".

Theories of Limiting Population Growth

The first demographer was Thomas Malthus, who examined the differences between the rate of food production and population growth. His studies showed that population growth grows exponentially. According to Malthus, population growth would overwhelm food production if not checked by something. He pointed to natural checks on population growth (famine, disease, war). These forces have not provided enough of a check on population growth. In the past that was not even necessary because there was enough food produced in the world to feed the entire world population adequately. People still starve because of unequal distribution of valued resources. But climate change is affecting food production as well. The substitution of growing crops to provide bio-fuels as opposed to food humans eat is decreasing the available food and may not, according to some scientists, even reduce warming and pollution. Malthus was incorrect.

Demography

The size of a population, the absolute number of people in a society, is sociologically the most important feature of a society because size affects the kinds of social structures which must be created to support and organize the population. The rate of growth in a population, the speed with which new people are added (or the population is declining), is important because this rate determines how much burden is being places on existing social structures and how much change in these structures will be necessary to accommodate new people (or how much extra infrastructure) is sitting around unused because of a declining population. The relationship between birth and death rates influence the size of population. The population rose when horticulture and then agriculture emerged on a wide scale. It should be clear that population growth. as a whole, is an increasing concern, particularly in certain countries and areas.