Evolution | 6 Evidences of evolution

Evolution:

Evolution is the theory according to which complex forms are considered to have been derived from simpler ones. The word evolution has been derived from a simpler one. The word evolution has been derived from the Latin word evolve, which means to unroll or unfold which means the development of something by slow natural processes.

Evolution, therefore, may be derived as the gradual and slow development and change of something by natural processes. This change may include the change or the development of something like the origin and evolution on the earth, of the living organisms like plants and animals on the earth. The last type means the evolution of living organisms example; plants and animals come under organic evolution.

Evidences of evolution: The doctrine (theory) of organic evolution is supported by many types of evidences. The evidences are provided from any source. Some of these evidences are discussed below-

(1) Morphological and anatomical evidences

(2) Embryological evidences

(3) Paleontological evidences

(4) Biogeographical evidences

(5) Physiological and biochemical evidences

(6) Genetical evidence

(1) Morphological and anatomical evidences: A comparative study of morphology and anatomical structures of different animals and plants provide us with evidences for evolution. This is of following types-

(a) Comparative anatomy: The comparative anatomy of the vertebrates reveals close similarity in structural planning. Example: If we compare the heart of fishes, amphibians, reptiles, and mammals, we will see that the heart is built on the same general plant. The two-chamber heart fish modified into 3 chamber heart of amphibians to check the mixing arterial and venous blood to some extent.

(b) Homologous organs: The homologous organs had the same basic structure and development origin but differ in appearances and function example: The mouth part of cockroach, mosquitoes, butterfly are structural made up of labrum, mandibles, and maxillae but they perform a different function.

(c) Analogous organ: The analogous organ has the same function but different in structure and origin. Example: The wings of a butterfly, wings of a bird, wings of bat are structurally different but they defined the same function. Potato and sweet potato are structurally different but both are cuber and store food.

(2) Embryological evidences: The study of embryonic development of any individual, plant or animal is convincing evidence in the flavour of organic evolution. Example: The early gametophytes of both mosses and ferns early presented by filaments protonema which resembles the green algae, this indicates that mosses and ferns might have originated from green algae.

(3) Paleontological evidences: Paleontology means the study of fossils of ancients plants and animals. Analyzing and arranging fossils in a definite sequence, the paleontologist can show the continuous process of organic evolution. Example: Discovery of fossils of pteridosperm shows the mixing link between ferns and gymnosperm.

(4) Biogeographical evidence: It means the study of the distribution of plants and animals in different parts of the earth. The geographical distribution of plants and animals gives strong evidences in favor of organic evolution.

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Example:

1. Elephants are found in India, Burma and which were once connected together.

2. Plants like Magnolia, Tulip, and Sassafras are found only in eastern U.S.A and China which were once connected together.

(5) Physiological and biological evidence: Both Physiology and biochemistry of living organisms provide sufficient important evidences in support of organic evolution.

Example:

1. The chromosomes of all living organisms consist of nucleic acid and protein.

2. Insulin secreted by Pancreas of different vertebrates is similar.

(6) General evidences: The science of genetics provides enough evidences in support of organic evolution. Example:

(a) The mutation is the basis of evolution.

(b) Gene is the career of hereditary, characters in a living organism.