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The third big idea: Evolution

Evolution is the process of change in an organism that occurs over a long period of time.

The origin of species

Charles Darwin published his book The Origin of Species to much furore in 1859. Darwin’s ideas were not new, but he provided an example of how evolution may occur by a process called natural selection.

Darwin’s idea was that a population must have some variability and the individuals best suited for survival continue to breed and increase in numbers.

Bringing together cells, genes and evolution

The genes expressed by a cell determine its function. Genes are packaged up neatly into the nucleus of cells in structures called chromosomes.

The three big ideas – cells, genes and evolution – are intricately linked.

When genes are passed from parents to offspring, some variability may occur. This variability can cause changes in the structure and function of an organism. For example, if an organism inherits an advantageous genetic variation, it is more likely to be successful, to breed and to produce offspring carrying these same genes on to the next generation. This forms the basis for the theory of natural selection.

An inherited idea

Darwin’s grandfather, Erasmus Darwin, was also an advocate of evolution. He was an English doctor with a passionate nature and one of the real characters of science.

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