Why were Charles Darwin’s and Alfred Russel Wallace’s papers presented together in 1858?

In 1858, Charles Darwin received a paper from Alfred Russel Wallace that outlined a theory of evolution by natural selection strikingly similar to his own. Fearing the loss of priority for his long-developed work, Darwin consulted his colleagues, the geologist Charles Lyell and the botanist Joseph Dalton Hooker.12

To resolve the situation, these men arranged for joint extracts of Darwin’s previous writings and Wallace’s paper to be presented together at the Linnean Society on July 1, 1858. This compromise, reached without Wallace’s prior knowledge, was intended to avoid a conflict regarding priority interests. The resulting set of papers was subsequently published as a single article in the Proceedings of the Linnean Society under the title "On the Tendency of Species to Form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection".12