Have you ever wondered how there came to be so many different species on Earth? One explanation is that evolution, a process of gradual change over millions of years, has produced this enormous diversity.
Charles Darwin was one of the first people to propose a convincing theory which could account for changes within species that might eventually give rise to new species. In 1859 he published a book entitled On the Origin of Species by Means of Natural Selection. It is the process of natural selection that is explained in this exhibition.
Darwin had observed domestic or artificial selection at work in the breeding of plants and animals. By deliberately selecting certain characteristics in the individuals that are to be bred, people are able to produce changes in a wide variety of plant and animal species. In the exhibition, you can see how new kinds of dogs have been bred in this way.
Darwin developed his theory from several other observations of species. He noticed that all living things can produce far more offspring than are needed to replace them, but not all the offspring survive to reproduce.
Living things must compete for limited resources, such as food and space. Sometimes it is a matter of luck which survive and which die. But because no two members of a species are exactly alike, some may have an advantage over others. This advantage may be controlled by the environment or by genes, which are passed from one generation to the next.
If an individual inherits a characteristic that makes it better adapted to its environment than other members of its species, it will have a better chance of survival. One example shown in the exhibition is that of a mouse with dark fur. Dark fur may provide better camouflage from predatory owls than light fur. The dark mouse will therefore be more likely to survive to reproduce than its paler-coloured relatives, and over several generations the proportion of dark mice in the whole population will increase. Since environments differ from place to place and may vary with time over thousand of generations, populations may adapt and change again and again. In some cases a population may become geographically divided and the separated groups change so much that they eventually become separate species.
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