Charles+Darwin

Darwin is the first of the evolutionary biologists, the originator of the concept of natural selection. His principal works, T//he Origin of Species by Means of Natural Selection (1859) and The Descent of Man (1871)// marked the creation of a new central dogma. His works were violently attacked and energetically defended throughout his lifetime.

Charles Robert Darwin was born at Shrewsbury, England. His father was a doctor and his mother was the daughter of Josiah Wedgwood. Darwin first studied medicine at Edinburgh. Will as they might, it soon became clear to the family, and particularly to young Charles, that he was not cut out for a medical career (In fact he was considered a failure in the subject!); he was transferred to Cambridge (Christ's Church, 1828), there to train for the ministry. While at Cambridge, Darwin befriended a biology professor, John Stevens Henslow, and his interest in zoology and geography grew. Eventually, Darwin came under the eye of a geology professor, Adam Sedgwick. Just after a field trip to Wales with Sedgwick -- during which Darwin was to learn much from "Sedgewick's on-the-spot tutorials" and was to develop "intellectual muscle as he burnt off the flab"-- he was to learn, that, through the efforts of Professor Henslow, that he had secured an invitation to go aboard the //Beagle//, which, apparently, was being outfitted by the admiralty for an extended voyage to the south seas. In a letter, Henslow was to advise that "you are the very man they are in search of."

The vovage planned to take in the southern islands (Galapagos Islands), the South American coast and Australia. While aboard the vessel, Darwin served as a geologist, botanist, zoologist, and general man of science. On this voyage to these islands, he observed different species of finches and was able to develop his theory of natural selection. (See below)

__//**B. Theory of Natural Selection**//__

Natural Selection is the mechanism by which better-adapted organisms and they are most likely to be the parents of the next generation. This is usually known commonly as "survival of the fittest" where the unfit diminish and eventually die out. "The fittest organisms are not necessarily the strongest or the most intelligent, but those who are most responsive to change"- Charles Darwin. Darwin proposed four premises for evolution by means of natural selection:

1. __//**Variation**//__: The individuals in a population exhibit variation. Each individual has a unique combination of traits and abilities, such as resistance to certain parasites or infections and the ability to hide from predators successfully and efficiently. Some traits improve an individuals's chances of success, whereas others do not. The variation must be inherited, even though Darwin did not know anything about DNA.

2. __//**Overproduction**//__: The reproductive ability of each species has the potential to cause its population to geometrically or exponentially increase over time. For example, various species of fish produce thousands of eggs in one sitting! However, only a handful of those offspring survive to reproduce more offspring. Thus, in every generation, each species has the capacity to produce more offspring than can survive.

3. **//__Limits on population growth__//**: There is only so much food, water, light, space, and other integral resources available to a population, so organisms compete with one another for these limited resources. This creates a struggle for existence among organisms. Because there are more individuals than the environment can support, not all survive to reproduce. This was also seen in Thomas Malthus' proposal, which states that the reproductive potential of organisms outweighs their ability to obtain resources.

4. __//**Differental reproductive success**//__: Those individuals that have the most favorable combination of characteristics (those that make individuals better adapted to their environment) are more likely to survive and reproduce. Offspring tend to resemble their parents, because the next generation inherits the parent's genetically based traits. Successful reproduction is the key to natural selection: The best adapted individuals produce the most offspring, whereas individuals that are less well adapted die prematurely or produce fewer or inferior offspring.

Sources: http://www.blupete.com/Literature/Biographies/Science/Darwin.htm Solomon Biology Textbook, 8th Edition See also: There's Evidence for Evolution? and Hardy-Weinberg Principle