Darwin's Theory of Evolution for Competitive Exams

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Image of Darwin’s Theory of Evolution

Image of Darwin’S Theory of Evolution

CHARLES DARWIN

Darwin’s Theory Of Evolution: Darwin’s Theory Of Artificial & Sexual Selection (Anthropology)

Darwin’S Theory of Natural Selection

  • The Theory of natural selection was conceived by Darwin during a five-year voyage (1831-36) on board the HMS Beagle, a vessel that had been commissioned to make oceanographic charts for the British admiralty. The Galapagos Island proved to be an important point of research for him, here he intensively studied the bird population of finches.

  • Natural Selection is one of the strongest forces of evolution. Natural Selection as guiding force was principle contribution of Charles Darwin to the evolutionary biology given a early as 1859 in his book “On the Origin of Species”. However, Darwin did not fully comprehend how it operates, as mechanism of genetics were not known at that time.

Darwin studied the finches

Darwin Studied the Finches

Darwin studied the finches

Image of Natural selection of Finches

Image of Natural Selection of Finches

  • In early 20th century, an English mathematician Godfrey Hardy and a German physician Wilhem Weinberg explained the conditions required for gene frequency in the population to be the same. Hardy and Weinberg were of the view that gene pool frequencies are stable and do not change by themselves. The gene or allele frequencies will remain unaltered unless evolutionary mechanisms, such as natural selection and mutation, cause them to change.

Godfrey Hardy and Wilhem Weinberg

Godfrey Hardy and Wilhem Weinberg

Image of Hardy-Weinberg equilibrium

Image of Hardy-Weinberg Equilibrium

  • Hardy and Weinberg developed a simple equation that can be used to find out the probable genotype frequencies in a population and to track generational changes in them. This came to be known as the Hardy-Weinberg equilibrium equation In this equation, ‘p’ is defined as the frequency of dominant allele and ‘q’ as the frequency of the recessive allele for a trait controlled by a pair of alleles.

  • However, it is highly unlikely that any of these conditions, let alone all of them, us actually fulfilled in the actual world. Thus, evolution is inevitable. The natural processes that result in changes in gene pool from one generation to the next are the mechanisms that cause evolution. Natural selection is one such mechanism or force that brings about evolutionary change by favoring differential reproduction of genes, which produces change in gene frequency from one generation to the next.

Darwin’S Theory of Artificial Selection

  • According to Darwin, the commonest method of producing new race of individual is that of selected under human control. The man selects only useful variety of plants and animals and breeds them together; expecting that offspring will have beneficial characters. Thus, various new races of plants and animals are produced which are more useful, viable and of domestic value to common man.

  • Darwin conceived about this selection to act at two levels:

    • At the unconscious- level (Unconscious Selection)

    • At the conscious- level (Conscious Selection)

Darwin’S Theory of Sexual Selection

  • According to this theory, there is always a contest among males for possession of beautiful female. During this contest, inferior males are eliminated (due to their less courageous nature or ill-equipped with weapons of combat) and superior males dominate.

  • Darwin put forth several examples to explain competition among males for possession of females such as: A stag with beautiful horns, A cock with heavy spur and strength in the wings, Fighting among the male alligators for the possession of females, Fighting among the male salmons etc.

Darwin’S Theory of Common Descent

  • The theory supposes that related group of individuals have common ancestors, for example: Man & Apes. Similar to theory of natural selection it has been found correct.

  • Men and apes bear several common characters that can be traced back to their ancestors in the evolutionary sequence.

Darwin’S Theory of Pangenesis

  • As laws of inheritance were not known in the times of Darwin, he proposed theory of Pangenesis to explain the same. The theory is absolute, incorrect and hence abandoned and has only historical significance.

  • According to this theory:

    • All somatic cells of organism produce minute particles, called Pangenes, which are included in the germ cells.

Criticism of Darwinism

  • By Physical Scientist: They were strongly inclined to atomistic reductionism and considered experimentation to be true scientific method. They had great prestige and authority. Darwinism suffered a great deal at their hands because of their demands that evolutionary biology should be a science like physical science, with its set of absolute laws and an ability to supply proofs.

  • Non-Darwinian Biologists: There were two classes of such biologists: a radical minority denied that natural selection played a role in evolution, while the majority did not deny the existence of selection but denied, as had Darwin himself, that selection alone could account for all adaptations and evolutionary changes.

MCQs

Q1. The theory of Natural Selection was conceived by:

  1. E.B. Tylor

  2. Charles Darwin

  3. Jean Baptiste Lamarck

  4. Robert Redfield

Answer: (b)

Q2. The book “On the Origin of Species” was written by

  1. Charles Darwin

  2. Hebert Spencer

  3. Edmund Leach

  4. Alfred Russell

Answer: (a)

Q3. According to Hardy- Weinberg Law, which of the following is not a condition for the gene frequencies to be remain stable.

  1. No mating

  2. No migration

  3. No mutation

  4. No selection

Answer: (a)

Q4. Which of the following is the correct equation for Hardy-Weinberg Equilibrium?

  1. P2 + 2PQ + Q2 =0

  2. P2 + 2PQ + Q2 =1

  3. P2 + 2P2 Q + Q2 =0

  4. P2 + PQ + Q2 =0

Answer: (b)

#Darwin’s theory of evolution

# Darwin’s Theory of Natural Selection

#Hardy and Weinberg Equilibrium

#Darwin’s Theory of Artificial Selection

# Darwin’s Theory of Sexual Selection

# Darwin’s Theory of Common Descent

# Darwin’s theory of Pangenesis

# Criticism of Darwinism

#Physical Anthropology

#NET

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