Since the birth of civilisation, human beings have manipulated other life-forms. We have selectively bred plants and animals for thousands of years to maximise agricultural production and cater to our tastes in pets. The observation of the creation of artificial animal and plant variants was a key stimulant for Charles Darwin's theory of evolution. The ability to directly engineer the genomes of organisms first became possible in the 1970s, when the gene for human insulin was introduced into bacteria to produce this protein for diabetics. At the same time, mice were modified to produce human...