Biological origin of life:

• There are many opinions regarding the appearance of creatures.
• All living things on earth have many similarities in structure and
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• These, such diverse organisms in the past themselves to the evidence.
• Organism’s origin, universe’s origin, glory origin and the origin of solar system were looked upon as a set.

Theories:

There are many theories about the origin of life. Some of them are

1. The theory of special creation:

• This theory was published by Hebrew et al.
• Suarez was a large supporter of this theory.
• The sudden nature of advanced energy vectors was said to be the origin of organisms.

2. Destruction theory:

• The leading scholar of this theory was George Cowier.
• According to this, the formation of organisms is said to have been caused by some geological disturbances.

3. Biological theory:

• It was asserted by the Greek scientists Thales Plato and Aristotle.
• Thus organisms are said to have evolved from inanimate objects.

4. Theory of life:

• This was emphasized by Louis Pasteur.
• Thus life is said to have originated from living things.

5. Modern theory of the origin of life:

• Heckle emphasized this theory.
• This concept is described in detail in the theory of chemical evolution by Opparin and Halden Ponro.
• Opperin published the book, “The Origin of Creatures” in 1938.
• In this book he describes the origin of life.

Evidence of Evolution:

• Father of Evolution – Charles Darwin
• The father of ideas about evolution – Empedocles.
• Herbert Spencer was the first to use the term evolution.
• The word evolution means flowering (or) expansion.

Human evolution:

Chimpanzees – had human bodies.

Hominids – People who lived in East Africa. They ate fruits and had a steady walk.

Homo habilis – Human nature.

Homo erectus – carnivores.

Neanderthal – lived in Asia (1 million years ago).

Archie Homo sapiens – Frozen humans.

Homo sapiens – modern humans.

Evidence of evolution:

1. Archaeological evidence:

• The field of science that helps to learn about fossils is called archaeology (paleontology).
• Father of archaeology was Leonardo da Vinci.
• Huxley points out that the dead bodies of prehistoric plants and animals turninto bacilli.

2. Types of tombstones:

The whole body of the creature is buried intact e.g. Bones of humans

Carbolites:

The waste products excreted from the animal’s body are hardened and found in small pieces.

3. Evidence of organ analogy:

• The elements are similar in basic structure but used for different functions.
• In mammals, the forelegs of human, horses and birds have the same skeletal structure, but their function is different.

4. Active similar elements:

Elements that have different elements in a system that perform the samefunctions e.g. Butterfly wing, bat wing.

5. Residual elements:

• Humans have 180 residual organs. These are inactive.
• g. Auricular muscles – those that help to move the ear.

6. The rest of the antecedent attribute:

• The sudden appearance of certain traits that were seen many times before.
• Appearance of dense hairs all over the body.

7. Instrumental evidence:

Sensing the development of the mature organism from the eggs.

Lamarckism

• Jean Baptiste de Lamarck (1744 – 1829) is well known for his theory of evolution.
• In 1809 he published his book titled ‘Philosophie Zoologique’.
• This book contains his views on evolutionary mechanisms.
• The theory of evolution as proposed by Lamarck is popularly known as the ‘Theory of inheritance of Acquired Characters’.
• According to this theory modifications or changes acquired during the lifetime of an organism can automatically be transmitted to succeeding generations.
• While elaborating this theory, Lamarck advanced four laws or propositions.

1. Law (or) Proposition

• ‘In evolution, during course of time, organisms or their component parts gradually tend to increase in size.
• Lamarck cited the evolution of horses as an example to explain this law.

2. Law or Proposition

• ‘If an organism is ‘in need’ of an organ, sooner or later it will arise.
• This view of Lamarck emphasized the significance of mind and its thinking being related to needs in an environment.
• Thus, according to Lamarck a continuous thinking for several generations can lead to the origin of an adaptive character.
• Lamarck elaborated his view citing the lengthening of neck in giraffe over the years.

3. Law (or) Proposition – Law of use and disuse

• According to this law, constant use of an organ changes its efficiency and makes that organ to increase in size with better development.
• Similarly, if an organ is not used for a long time, it might lead to reduction in efficiency and size of that organ.

4. Law (or) Proposition. Inheritance of Acquired Characters

• ‘Bodily changes or new characteristics obtained by an organism during its life time will automatically get transferred to the next generation’.
• While proposing this law, Lamarck did not provide any specific example.
• The IV Law of Lamarck had been subjected to severe criticisms. Several experiments had been carried out, either to prove or disprove this concept.
• In 1890, the German Scientist, August Weismann performed some experiments with the rats.
• This lead to the formulation of the ‘Germplasm theory’ which states that ‘any change to the somatoplasm will not have Neo-Lamarckism
• Lamarck’s ‘theory of inheritance was further studied by a group of scientists.
• Their ideas supporting Lamarck’s opinion collectively constitute Neo-Lamarckism.
• McDougall (1938) tried to prove that learning is an acquired character that can be inherited. He did his experiments on rats.
• However, the controversy over ‘inheritance’ of acquired characters still continues.
• This theory of Lamarck while has not been disproved totally, it remains to be proved correct.

Darwinism

• Darwinism comprises the natural selection concept as advanced by Charles Robert Darwin in 1859.
• His theory provided the correct idea to explain all processes and intricate mechanisms of evolution.
• The theory of natural selection is considered on par with Newton’s law of gravitation and Einstein’s theory of relativity.
• The monumental work of Darwin was titled as “The Origin of species”
• The book of Darwin convincingly demonstrates the fact of evolution.
• Further, it elaborates on the theory of natural selection as a convincing mechanism for providing evolutionary transformations.
• While Darwin prepared his work for publication, a similar idea to explain evolution was proposed by another naturalist, Alfred Russel Wallace (1823-1913) from Malay Archipelago.
• Charles Darwin gracefully accepted for the publication of his theory as a joint paper with Wallace.
• Thus, the theory of natural selection is actually titled as ‘Darwin-Wallace theory of evolution’.

The Theory of Natural Selection

1. Overproduction or Prodigality of nature

• All living beings have an innate desire to reproduce and form their own progeny.
• In this attempt they have the capacity to multiply in a geometrical manner.
• Such an enormous reproductive potentiality can be observed in all species of organisms.
• For example, a single female salmon fish can produce 28,000,000 eggs in a season.
• Struggle for existence
• According to Darwin while the population increases in geometric ratio there is no corresponding increase in food production.
• This causes an intensive struggle for living.

3. The universal occurrence of variations

• The occurrence of variations is a characteristic feature of all groups of animals and plants.
• The variations may be morphological, anatomical, physiological or behavioral.

4. Survival of the fittest

• While all living organisms face the struggle for existence, certain organisms possessing adequate modifications are able to escape and survive.
• Such modifications are due to inherent variations.
• Hence favorable variations make an animal or a plant to be successful in life.

5. Natural Selection

• According to Darwin ‘the fittest’ forms that are allowed to survive are chosen by ‘Natural Selection’.
• The forces of natural selection will encourage only those that have suitable variations as adaptive features, to survive.
• Darwin designated them as ‘fittest’ forms.
• Darwin strongly believed that using the natural selection concept, all evolutionary processes in the living world can be explained