Final answer:
Alfred Wallace independently came up with the theory of evolution similar to that of Charles Darwin during the 19th century, and they both discovered the concept of natural selection.
Step-by-step explanation:
During the middle of the 19th century, it was Alfred Wallace who independently derived and proposed a theory of evolution that was similar to Charles Darwin's. The scientific concept that both Charles Darwin and Alfred Wallace independently discovered was natural selection. Wallace's paper on natural selection was presented together with Darwin's at the Linnean Society in 1858.