These days everyone mentions Wallace alongside Darwin as if the two discovered the theory together. This annoys me! Darwin had discovered the theory long before, and only postponed publishing it for fear of how it would affect people around him, and also probably because he lost himself in the routine of verifying it and perfecting it, itself an excuse for postponing publication. And then suddenly the Wallace letter arrives and Darwin knows he either outs with it or he gets scooped and decades of work go to waste.

Everyone knows Darwin came first, but the rules of today say that if you don't publish, it's your own fault, so strictly-speaking - again by today's rules of bending-over-backwards fairmindedness - the two independently discovered the theory.

But Darwin didn't just discover his theory. The package matters, too. I could give you the gist of Hamlet in this here comment, but Shakespeare I am not. Darwin wasn't just a scientist, he was an artist in how he expounded his theory and was far ahead of his time in many ways, including that he avoided grave mistakes that biologists still make to this day in interpreting his theory. There's still things to be discovered by reading his work.

Wallace, on the other hand, as you say . . . man is an exception . . . spiritualism . . . it's almost like he hit on natural selection by accident. By not applying it to people, he reveals that he didn't really understand the theory. And it's not just him: Michael Shermer has a thing he calls "cognitive creationism, that we accept evolution fully from the neck down, but from the neck up it's all culture." Apparently it's still difficult for people to fully grasp Darwin, and Darwin himself is one of the few people who ever really got it.