When Charles Darwin published his theory of evolution nearly 150 years ago, he shattered the dominant belief of his day – that humans were the product of divine creation. Through his observations of nature, Darwin proposed the theory of evolution by natural selection. This caused uproar. After all, if the story of creation could be doubted, so too could the existence of the creator. Ever since its proposal, this cornerstone of biology has sustained wave after wave of attack. Now some scientists fear it is facing the most formidable challenge yet: a controversial new theory called intelligent design.