Transcript: Half a billion years ago, Earth’s oceans present a perfect environment for the diversification of life. It was a ready source of nutrients and a long term stable environment for diversification and natural selection to operate. In the Cambrian period, the fauna included the first hard bodied sea creature, the trilobite, which lived for two hundred million years but did not survive to the present day. Many other body plans were laid down in that era that did not survive to the present day. Natural selection acts to cull according to the success rate of an organism, it’s ability to adapt and reproduce. It’s sobering to realize that 99.999 percent of all species in the history of Earth have become extinct. Even successful creatures that have survived for hundreds of millions of years eventually become extinct. Our place in the history of life is not yet secure.