ABSTRACT
The Cambrian Explosion, sometimes known as evolution’s big bang, was one of the most remarkable episodes in the history of life on Earth. Over a period of about 25 million years (a blink of an eye in geological terms), the number and complexity of species went from a small number of single cell organisms to something approaching the enormous variety of complex fl ora and fauna we know today. In the true sense of the words, it was a wonderful and remarkable event that would never have been predicted by simple extrapolation from the preceding 3.3 billion years of life on our planet. But, to an evolutionary scientist, it makes complete sense. The environment changed, which meant the selection pressures changed. Darwinian evolution did its thing – variation, selection and amplifi cation – and that led to an expansion in life forms. Those life forms helped shape their habitats and accelerated the process of mass speciation. That’s how evolution works. You and I are part of the evidence of that event.
