Evolution

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Organic evolution is the slow and gradual change in living organisms over a long period of time. Darwin described it as living organisms developing by descent with modifications from a common ancestor…

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Unicellular organisms appeared first, and multicellular organisms appeared later. Evolution also showed a trend from simpler forms to more complex forms.

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Jean-Baptiste Lamarck was the first French biologist who tried to explain evolution. He published his views in Philosophie Zoologique in 1809. His theory is called the Theory of Inheritance of Acquire…

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Lamarckism includes four main ideas: tendency to grow, formation of new organs due to need, use and disuse of organs, and inheritance of acquired characters. In this view, changes gained during life c…

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Lamarck said that the ancestors of giraffes were goat-sized. When grass was not available on the ground, they stretched their necks and forelimbs to eat leaves from trees. This acquired long neck was …

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A vestigial organ is an organ that is non-functional in present-day organisms but was functional in ancestors. Examples in humans are vermiform appendix, wisdom tooth, muscles of ear pinna, and coccyx…

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The vermiform appendix is a blind tube-like structure connected to the caecum. It is considered vestigial because it is the remnant of a once more useful caecum. Human ancestors were herbivorous, and …

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The coccyx is the fused remnant of tail vertebrae. Mammals have a tail at some stage in embryonic development. Human ancestors were tree-dwellers and used the tail for balance. When they began living …