Charles Darwin

Today, it is generally accepted that present-day species have arisen by change from ancestral forms of life. By ‘evolution’ we mean the gradual development of life over very long periods of time (i.e. geological time), from its earliest beginnings to the diversity of organisms we know about today, both living and extinct. Evolution is the development of new types of living organism from ones that already exist through the gradual build-up of genetic differences. Charles Darwin developed the theory of evolution by natural selection, which explains how changes in species can occur through variation and selection. It has been said that ‘Nothing makes sense in biology without evolution’: this is because the theory links all aspects of Biology and forms a framework for study, in the same way that the periodic table in Chemistry does.