1. Name Gurjit Kaur Class 9th E Roll No. 5 House no. T-841

2. INTRODUCTION A population is a summation of all the organisms of the same group or species, who live in the same geographical area, and have the capability of interbreeding.In ecology the population of a certain species in a certain area is estimated using the Lincoln Index. The area that is used to define a sexual population is defined as the area where inter- breeding is potentially possible between any pair within the area. The probability of interbreeding is greater than the probability of cross-breeding with individuals from other areas. Under normal conditions, breeding is substantially more common within the area than across the border. In sociology, population refers to a collection of human beings. Demography is a social science which entails the statistical study of human 3. Population genetics In population genetics a sexual population is a set of organisms in which any pair of members can breed together. This means that they can regularly exchange gametes to produce normally-fertile offspring, and such a breeding group is also known therefore as a gamodeme. This also implies that all members belong to the same of species, such as humans. If the gamodeme is very large (theoretically, approaching infinity), and all gene alleles are uniformly distributed by the gametes within it, the gamodeme is said to be panmictic. Under this state, allele (gamete) frequencies can be converted to genotype (zygote) frequencies by expanding an appropriate quadratic equation, as shown by Sir Ronald Fisher in his establishment of quantitative genetics. Unfortunately, this seldom occurs in nature : localisation of gamete exchange through dispersal limitations, or preferential mating, or cataclysm, or other cause may lead to small actual gamodemes which exchange gametes reasonably uniformly within themselves, but are virtually separated from their neighbouring gamodemes. However, there may be low frequencies of exchange with these neighbours. This may be viewed as the breaking up of a large sexual population(panmictic)into smaller overlapping sexual populations. This failure of panmixia leads to two important changes in overall population structure: .the component gamodemes vary (through gamete sampling) in their allele frequencies when compared with each other and with the theoretical panmictic original nd the level of homozygosity rises in the entire collection of gamodemes. 4. As of today's date, the world population is estimated by the United States Census Bureau to be Expression error: Unrecognized punctuation character . billion.The US Census Bureau estimates the 7 billion number was surpassed on 12 March 2012. According to a separate estimate by the United Nations, Earths population exceeded seven billion in October 2011, a milestone that offers unprecedented challenges and opportunities to all of humanity, according to UNFPA, the United Nations Population Fund. According to papers published by the United States Census Bureau, the world population hit 6.5 billion on 24 February 2006. The United Nations Population Fund designated 12 October 1999 as the approximate day on which world population reached 6 billion. This was about 12 years after world population reached 5 billion in 1987, and 6 years after world population reached 5.5 billion in 1993. The population of some countries, such as Nigeria, is not even known to the nearest million, so there is a considerable margin of error in such estimates. Researcher Carl Haub calculated that a total of over 100 billion people have probably been born in the last 2000 years. 5. In the year 2005, the world population isestimated to have reached 6.5 billion, more than two and a half times the level in 1950; according to the medium-variant projection of the 2004 Revision, it is expected to reach 9.1 billion in 2050 The less developed regions, with 5.3 billion people in 2005, account for the vast majority of the world population (81.3 per cent). The more developed regions have an estimated population of 1.2 billion, or 18.7 per cent of the world population. More and more of the worlds inhabitants are coming to reside in the less developed regions, increasing from 67.7 per centin 1950 to a projected 86.4 per cent in 2050.Within the less developed regions in 2005, the least developed countries account for about 0.8 billion and otherless developed countries for 4.5 billion. The share of the least developed countries is projected to grow from 8.0 per cent in 1950 to 19.1 per cent in 2050. 6. Population growth is the change in a population over time, and can be quantified as the change in the number of individuals of any species in a population using "per unit time" for measurement. In biology, the term population growth is likely to refer to any known organism, but this article deals mostly with the application of the term to human populations indemography. Population growth rates might have declined, but in 2013 every 60 minutes there are another 8,000 people in the world: about 75 million every year. In demography, population growth is used informally for the more specific term population growth rate (see below), and is often used to refer specifically to the growth of the humanpopulation of the world. Simple models of population growth include the Malthusian Growth Model and the logistic model. The world population grew from 1 billion to 7 billion from 1800 to 2011. During the year 2011, according to estimates, 135 million people were born and 57 million died, for an increase in population of 78 million. 7. WORLD HUMAN POPULATION 10,000BC - 2000AD. 8. Three Processes of Population Change Natural increase of population is the difference between birth rates and death rates. Birth rate is the number of live births per thousand persons in ayear.It is a major component of growth in India because birth rates have always been higher than death rates here. Death rate is the number of deaths per thousand persons in a year.Main cause of rapid rate of growth of the Indian population is the fast decline in the death rates Migration is the third component of population growth: It is the movement of people across regions and territories. ii. It is both internal and international. Internal migration is the movement of people from one region to another within the country. International migration is the movement of people from one to another country. 9. A further demographic feature that has implications for current economic status and future economic need is the contrast between the age distribution of the Indigenous and non- Indigenous populations (as shown in for the East Kimberley region as a whole. For the Indigenous population, several features are noteworthy. First, the broad base of the age pyramid describes a population with continued high fertility (a Total Fertility Rate (Second, the rapid taper with advancing age highlights continued high adult mortality. Using the ABS experimental Indigenous life table for the Northern Territory (which arguably reflects age-specific mortality rates closest to those of the East Kimberley population), life expectancies for males and females are seemingly stuck at around 56 and 63 years respectively, with much of the excess mortality occurring in adult Third, uniformity in the decline of population with age suggests net inter-regional migration balance. Finally, the relatively large numbers of women in the childbearing ages, and the even larger cohorts beneath them, indicate substantial population momentum with associated high potential for future growth in numbers. Actual numbers in each age group are shown for Indigenous males and females in