As you know, the unfortunate, penurious, hard-working Wallace discovered the theory of natural selection and made the mistake of sending his paper to the lucky, well-off, hypochondriac Charles Darwin, who proceeded to take most of the credit. Here's a short biography. Later in life, to Darwin's distress, Wallace decided that evolution could not explain the human mind, and took to spiritualism. Other interesting papers include descrriptions of his problems with Crumpet (and Flunkie).