About a year ago, an Editorial in these pages urged scientists and their institutions to 'spread the word' and highlight reasons why scientists can treat evolution by natural selection as, in effect, an established fact (see Nature 451, 108; 2008).

This week we are following our own prescription. Readers will find at http://www.nature.com/evolutiongems a freely accessible resource for biologists and others who wish to explain to students, friends or loved ones just what is the evidence for evolution by natural selection. Entitled '15 evolutionary gems', the document summarizes 15 lines of evidence from papers published in Nature over the past 10 years. The evidence is drawn from the fossil record, from studies of natural and artificial habitats, and from research on molecular biological processes.

In a year in which Darwin is being celebrated amid uncertainty and hostility about his ideas among citizens, being aware of the cumulatively incontrovertible evidence for those ideas is all the more important. We trust that this document will help.