Population structure is considered in terms of sex composition, age, literacy, rural-urban composition etc.
Sex Composition is studied with the help of an index which is known as sex ratio. Sex ratio is expressed in different ways in different countries. In India, it is expressed in terms of number of females per thousand males. The current sex ratio in the world is 986 females per thousand males. Latvia in Europe has recorded the highest sex ratio of 1187 females per 1000 males. e lowest sex ratio in the world has been recorded in U.A.E. where there are only 468 females for 1000 males. e sex ratio is favourable for females in 139 countries of the world and unfavourable for them in the remaining 72 countries listed by the United Nations.
In general, Asia has a low sex ratio. Countries like China, India, Saudi Arabia, Pakistan, Afghanistan have a lower sex ratio. On the other extreme is greater part of Europe (including Russia) where males are in minority.
Population of an area may be divided in different age groups but the most widely used categories of age groups are 0-14, 15-59, and 60 years and above. These are known as young, mature and old age groups respectively. People in the age groups of 0-14 and 60 years and above are usually not engaged in any economic activity and are dependent on the economically active age group of 15-59 years. Countries having low life expectancy have less people in the old age group and countries having low birth rate have less people in the young age group.
Age-sex composition is expressed with the help of a specially designed diagram known as age and sex pyramid in shape. It is called so because it resembles in shape a pyramid. It consists of a number of horizontal bars. Bars on the left show males and bars on the right females in percent. Age groups at 5 or 10 years groups are shown vertically in this diagram. Pyramid with broad base and narrow upper shows that large proportion of population is in the lower age group and will lead to rapid population growth in future. Most of the developing and less developed countries have this type of age-sex pyramid because of the high birth rates and high death rates in old age. A bell shaped pyramid which is tapered towards the top shows that the birth rate is almost equal to death rate which leads to a constant population. Australia and some other developed countries have this type of pyramid. A pyramid having a narrow base and tapered top with bulging in the middle shows low birth and death rates. s type of pyramid depicts declining population. Japan in Asia and some European countries like Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Romania and Slovenia have this type of age-sex pyramid. These countries have recorded negative population growth in the recent past.
Literacy rate is the number of literate persons for each hundred people and is expressed in percentages of people age-group 15 and above. Major factors affecting this rate are levels of economic development, urbanization and standard of living, social status of females, availability of educational facilities and the policies of the government. Level of economic development is both a cause and consequence of literacy. The developed and urban economies reflect higher literacy rate and higher standards of education. Lower levels of literacy and education indicate rural-farm economies. There are large variations in the literacy rate in different parts of the world. Most of the developed countries have higher literacy rate while most of the developing countries have lower literacy rates.
The population of any country is divided into urban and rural depending upon the place of residence. The populatio n in towns and cities is called urban population whereas that living in villages is known as rural population. Division of population in rural and urban categories is necessary because both the categories differ from each other with respect to their livelihood and social environment. e occupational structure, density of population and level of social and economic growth vary between the two groups. The ratio of urban population to total population is lower in the developing countries and higher in the developed countries. Percentage of urban population to total population has increased rapidly all over the world. Only 2.5 percent of the world’s total population was living in urban areas in 1800 which increased to 30% in 1960 and 45 % in 1995. At present nearly half of the world’s population is living in urban areas which is likely to reach 61% in 2025. However there are large variations in urban population even at the continent level. For example Asia and Africa have 38% of their total population as urban population while European and North American countries have 75% of their population as urban.
Under Population, Over Population and Optimum Population there is a close relationship between natural resources and population of an area and this relationship is used to determine whether the area is under populated, over populated or it has optimum population. An area is said to be under populated if its population is so small that the resources of the concerned area are not properly utilized. These areas can support a population which could be larger than the existing population without any lowering of the living standards. Such a situation prevails in regions of low technical development like Zaire basin of Africa and Amazon basin of South America and also in Prairie region of North America and in some parts of Steppe region of Eurasia. On the other hand over population is a situation in which the existing populated is too large and the resources of the concerned area are not able to support this population.
This happens due to two major causes viz (i) population growth exceeds the existing resources base and (ii) the resources are depleted. Over population areas suffer from unemployment and under-employment, low income and low standards of living as well as hunger and malnutrition. Some of the Asian and African countries such as India, Bangladesh, Nepal, Myanmar, Nigeria etc. are said to be over populated. In between under-population and over-population, there is a state of optimum population which means that the population of an area is neither too small nor too large and the resources are adequately utilized. In other words, there is optimum utilization of resources and people enjoy the highest standard of living.