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The Importance Of Demography

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Demography is the branch of science that studies the changing human population. Demographers track population changes in different countries and regions. The changes are represented in graphs and tables called survivorship curves and life tables. Survivorship describes the pattern of survival in a population, in this case, humans. Life tables track groups of organisms born at the same time throughout their life span, recording how many continue to survive in each succeeding year. Survivorship is displayed through three types of curves on a graph, types I, II, and III. The type I curve, shows us a high age-specific survival probability in the early and middle stages of life, followed by a decline in survival later in life. A type I curve can typically be seen within species that produce fewer offspring, but care for them well, this is mostly viewed in humans and mammals.…show more content…
This includes birds, reptiles and many other animals. A type III curve, is characterized by a decreasing concave line. This curve shows a higher death rate early in life, if the organism survives, it has higher chances for a longer life. This is seen in small mammals and marine invertebrates. “The general shape of the survivorship curve is fixed for each species, however, the convexity of the curve is highly sensitive to environmental conditions and the genetic constitution of the population. This fact suggests that the general shape of the life table may provide information about the genetic variability in the population, the range of environmental factors that impinge on the population or the incidence of random events in the lifetimes of different individuals” (http://www.nature.com/nature/journal/v275/n5677/abs/275213a0.html) . Here, we will view the survivorship between urban and rural population’s pre and post
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