Florian Hollfelder is based in the Department of Biochemistry at the University of Cambridge. He is interested in mechanism in chemistry and biology. Here he describes using principles of natural selection to make functional proteins. The Royal Society hosted a worldwide scientific discussion meeting on 'Bioinspiration of new technologies' on Wednesday 27 May 2015, 8:30 am-6:00 pm, live video streamed from the Royal Society, London. Read more on the website: royalsociety.org/events/2015/05/bioinspiration-of-new-technologies/