Darwin's Theory Of Human Evolution

Human Evolution

Darwin's Origin consisted of two parts. The first described observations in support of common descent, the second a mechanism to explain how it was the case. Provide examples of the observations Darwin used (1 page). Be specific. Provide a description of Darwin's mechanism (1 page). Provide as much detail and give examples as needed.

Q1. To support his idea of common descent, Darwin used observations from the natural world around him, which he saw on his voyage. His idea of common descent was based on observations of homologous structures, convergence of form, embryology, vestigial structures and imperfect structures. A homologous structure is an example of an organ or bone that appears in different animals, showing similarities

An example of this is that flying insects, birds, and bats have all evolved the ability to fly independently. Darwin also proved common descent by observing similarity in the embryology of all vertebrates. He observed that developing embryos are identical at certain stages, and then different features develop, such as gill pouches in tetrapod embryos. Two creatures are more closely related the longer their developing embryos stay similar. Vestigial structures are structures which have lost most of their ancestral function but have been retained through evolution. Examples of these are the Os Coccyx (tailbone) in humans, the appendix in humans and leg bones in whales. These structures, which Darwin observed, also prove his idea of common descent. Imperfect structures are structures which are designed in a very unintelligent way. An example of this is the human oesophagus. At the bottom of the throat, the trachea (the passage that leads to the lungs) enter the oesophagus. When you swallow food or water, a structure called the epiglottis closes to cover your trachea so that these materials do not go into your lungs but the system does not work perfectly every time, as food can go down the wrong way. These structures prove Darwin’s theory of common descent as they are evidence that a system evolved from a starting point, optimizing what it had to begin with. Darwin also used fossils in support of common descent. There was fossil record at the time and he collected fossils while on the Beagle voyage. He observed that many of the fossilised species did not exist anymore and had evolved (Darwin., 1859). All of these observations that Darwin made support his idea that species share a common