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Essays

Essays On Evolution


Evolution is a scientific theory used by biologists. It explains how living things change over a long time, and how they have come to be the way they are.

Essays On Evolution

The combination of continental drift and evolution can explain what is found in the fossil record. Glossopteris is an extinct species of seed fern plants from the Permian period on the ancient supercontinent of Gondwana.

Glossopteris fossils are found in Permian strata in southeast South America, southeast Africa, all of Madagascar, northern India, all of Australia, all of New Zealand, and scattered on the southern and northern edges of Antarctica.

During the Permian, these continents were connected as Gondwana. This is known from magnetic striping in the rocks, other fossil distributions, and glacial scratches pointing away from the temperate climate of the South Pole during the Permian.

When biologists look at living things, they see that animals and plants belong to groups which have something in common. Charles Darwin explained that this followed naturally if "we admit the common parentage of allied forms, together with their modification through variation and natural selection".

Strong evidence for common descent comes from vestigial structures.[21]p397 The useless wings of flightless beetles are sealed under fused wing covers. This can be simply explained by their descent from ancestral beetles which had wings that worked.

Charles Darwin lived in a world where animal husbandry and domesticated crops were vitally important. In both cases farmers selected for breeding individuals with special properties, and prevented the breeding of individuals with less desirable characteristics. The eighteenth and early nineteenth century saw a growth in scientific agriculture, and artificial breeding was part of this.

There is no real difference in the genetic processes underlying artificial and natural selection, and the concept of artificial selection was used by Charles Darwin as an illustration of the wider process of natural selection. There are practical differences. Experimental studies of artificial selection show that "the rate of evolution in selection experiments is at least two orders of magnitude (that is 100 times) greater than any rate seen in nature or the fossil record".

After thirty-five generations, the two groups and their offspring were isolated reproductively because of their strong habitat preferences: they mated only within the areas they preferred, and so did not mate with flies that preferred the other areas.

  Maliha Akhtar       Tuesday, 19 Nov 2019       168 Views