Evolution

Subject: Science

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Overview

Organic evolution is the process of gradual and orderly changes in organisms from one form to another. According to Modern concept of origin of life theory, the first living cell arose from simple elements. This note gives us the information about evolution.
Evolution

About the origin of life, several hypotheses have been put forth. Some of them, with their short explanation, are given below.

  1. Theory of special creation
  2. Theory of spontaneous generation
  3. Modern concept of origin of life

Theory of special creation

According to this theory, on the earth, life was created by supernatural power, the god. This theory has no scientific evidence; therefore, it is not widely accepted.

Theory of spontaneous generation

According to this theory, life originated on the earth from the non-living things spontaneously. It was believed that the mud of Nile River could give rise to living creatures like frog, toad, snake and crocodile; when warmed in sun.

Modern concept of origin of life

Modern concept was suggested by opera in 1930 AD. According to this theory, the first living cell arose from simple elements. Micro-molecules like carbon, hydrogen, oxygen, nitrogen etc. united to produce macro-molecules like proteins, carbohydrates, enzymes, nucleic acids etc. Then they interact to produce the first living cell by a process called abiogenesis. Abiogenesis means development of living things from non-living matter.

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Things to remember
  • Organic evolution is the process of gradual and orderly changes in organisms from one form to another.
  • According to Modern concept of origin of life theory, the first living cell arose from simple elements.
  • According to Theory of spontaneous generation, life originated on the earth from the non-living things spontaneously.
  • According to Theory of special creation on the earth, life was created by supernatural power, the god.
  • It includes every relationship which established among the people.
  • There can be more than one community in a society. Community smaller than society.
  • It is a network of social relationships which cannot see or touched.
  • common interests and common objectives are not necessary for society.
Videos for Evolution
Evidence of Evolution:
Evidence of Evolution: Paleontology
How Evolution works
Neil deGrasse Tyson on Creationism
What is Evolution?
What is the Evidence for Evolution?
Questions and Answers
The series of related and gradual changes in plants and animals which occur due to the continuous variation is called organic evolution.
The major evidences that support the theory of organic evolution are listed below:
a) Evidences from the study of fossils or paleontological evidence.
b) Evidences from comparative morphology and anatomy.
c) Embryological Evidences.
d) Evidences from the study of vestigial organs.
e) Evidences from the geographical distribution of organisms.
f) Evidences from the connecting links.

Evolution is defined as the series of changes which occur, each step depending on what has gone before.
Or, Evolution can be defined as the descent with the modification.

Homologous organs are those organs which have a similar embryonic origin and basic plan but different function. The forelimbs of whale, horse, man, bat and bird are homologous organs.When the wings of a bird or bat are compared with the wings of an insect, it is found that they have similar functions but different in basic plans, such organs are analogous organs.
Fossils give the information about the past organisms that came into existence on the earth as fossils are the remnants of them. Now technologies like carbon dating and uranium dating help to know their age also. Thus, we can find out time period at which they existed, the climatic condition of that period etc. By studying fossils scientists have traced the evolutionary history of animals like horses, dog, cats, camels and human beings too. So, fossils are the strongest evidences of evolution.
All animals and plants cannot be fossilized. They need to have the following properties for fossilization:
a) The organisms should have hard parts in their body.
b) The remains of organism should be buried quickly under a thick layer sediments over millions of years.
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