Biographical and Other Information on Darwin - a nice site from Denmark
The theory of evolution originated in England in the first half of the 19th century. The original version was codified by Charles Darwin in one of the most famous books ever written, On the Origin of Species by Means of Natural Selection (1859).
Darwin envisaged all living creatures in a struggle for survival. Only those that were the fittest in some way survived and were able to successfully reproduce. In the complex natural world on earth, there are many measures of fitness, and many different species of lining creatures have succeeded in finding niches where, locally at least, they have the required fitness to reproduce.
For those with a morbid sense of humour -- The Charles Darwin Awards
What is being preserved in this endless cycle of death and reproduction? Darwin did not know, but today we realize that it is a species' genetic code which is preserved through the generations. Individuals are bearers of this genetic code. Individuals are born, and die, but the genetic code is immortal, unless the species becomes extinct.
At the basis of genetics are naturally occurring genetic operations on chromosomes. In nature, chromosomes are a 'character strings' in nature's base-4 alphabet. These are the 4 bases which appear along the length of the DNA molecule: adenine (A), cytosine (C), guanine (G) and thymine (T). This sequence of nucleotide bases constitutes the chromosome string or genome of a biological individual. The human genome contains about 2,870,000,000 nucleotide bases.
Molecules of DNA are capable of accurate self-replication. Substrings containing ~1000 nucleotide bases from the DNA molecule are translated using the so-called genetic code into the proteins and enzymes that create structure and control the behaviour of biological cells. The structures and behaviors thus created enable the individual to perform tasks in its environment, to survive, and to reproduce at different rates. The chromosomes of offspring contain strings of nucleotide bases from their parents. The strings of nucleotide bases that lead to higher performance are passed along to future generations of the population at higher rates than those leading to lower performance. Occasionally, mutations, random changes occur in the chromosomes.
A whole field of research, Evolutionary Biology, attempts to relate different aspects of individual human behaviour (and that of other species) to the value of these behaviours in preserving the gene pool of that individual, or of his group. One of most famous books on this topic is The Selfish Gene, by Richard Dawkins. which makes a case that much of what we think is our freely chosen behaviour is actually controlled by our genome's desire to preserve itself forever. So, for example, heroic military behaviour, where thousands of young men are killed,is seen, from a genetic point of view, not as death, but as a sacrifice of individuals to preserve the gene pool of the people for whom they are fighting.
An Interview with Richard Dawkins.
Whatever the value of such arguments, it is certainly clear that evolution is controlled by the interaction of the genetic codes of species with the earthly environment in which they live. There seems also to be trend to more and more complex and successful creatures, such as us. There is a kind of evolutionary progress from the less fit to the more fit.
Evolution seems to be searching for the best adapted creature in an environment. Given an environment, species gradually, over many generations, become more adapted to it. The better adapted individuals reproduce more often than less adapted individuals, who are more likely to get eaten, or are not fast enough to catch dinner). The quality of the population as a whole gradually improves. In some sense, evolution is an optimization process. Some fitness measure is being maximized.
AI researchers, ever on the alert to steal good ideas from other fields, were inspired by the natural search mechanism of natural evolution, to try to simulate it in a computer. The goal was (and is) to solve otherwise intractable optimization problems. (Such as those where, for example, the A* search algorithm is ineffective.)
The computer science concerned with these ideas goes under various names: Evolutionary Programming, Genetic Programming, Genetic algorithms. There have been many sophisticated developments since the original Genetic Algorithms became well known in the 1980s. For the most part, cps721 will only look at the basic Genetic Algorithm (GA) which started the whole field off.
At first you might think that the idea of using Evolution as a method of programming is too far out to be of any use in the real world. However ...
Some thoughts from the real world.