Class 12 Biology Evolution Evolution of life forms- a theory

Evolution of life forms- a theory

  • Conventional religious literature reveals about the theory of special creation based on three connotations-
  • All living organisms were created as such.
  • The diversity in all organisms always the same since creation and will be the same in future.
  • Earth is about 4000 years old.
  • All the ideas were challenged during 19th
  • Charles Darwin concluded that existing living forms share similarities to varying degrees not only among themselves but also life forms that existed millions of years ago.

fig. Charles Darwin  

  • Many life forms do not exist anymore because of extinctions of different life forms and there has been gradual evolution of life forms.
  • Darwin’s theory of natural selection is based on the fact that those who are better fit in an environment, leaves more progeny than others and the progenies will survive more hence are selected by the nature which he implied as mechanism of evolution.
  • Alfred Wallace stated that all the existing life forms share similarities and shares some common ancestors which are present at different periods in the history of earth.
  • The geological history of earth closely correlates with the biological history of earth and a final conclusion is that earth is not thousand years old as was thought, but millions of years old.

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