Evolution is the study of how life changes over time. Life began in the ocean around 3.5 billion years ago and has evolved continuously since. Single celled organisms (microbes) evolved new ways to fix carbon into organic molecules and ultimately to make oxygen by splitting water with energy from the sun. About 600 million years ago microbes evolved to form animal life, and later, plants. Life in the ocean continues to evolve – changing in response to new biological and environmental conditions. Will life be able to evolve quickly enough to keep up with climate change and other human-induced pressures?