The Darwin–Wallace Medal is a medal awarded by the Linnean Society of London for "major advances in evolutionary biology". Historically, the medals have been awarded every 50 years, beginning in 1908. That year marked 50 years after the joint presentation by Charles Darwin and Alfred Russel Wallace of two scientific papers—On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection—to the Linnean Society of London on 1 July 1858. Fittingly, Wallace was one of the first recipients of the medal, in his case it was, exceptionally, in gold, rather than the silver version presented in the six other initial awards. However, in 2008 the Linnean Society announced that due to the continuing importance of evolutionary research, the medal will be awarded on an annual basis beginning in 2010.