I could see this being a Twilight Zone episode.
Imagine, if you will, a creationist who is suddenly granted the power to change history…[/Rod Serling voiceover]
Of course the twist is that after he returns to the present and finds that Wallace discovered evolution, he goes back again to kill him too, and as he keeps killing scientists he just finds out that some other scientist discovered the same things, until he accidentally kills one of his own ancestors and vanishes
And thus Mr. Bowler learned, albeit too late, that shooting the messenger will not erase the message… but it may erase other things in… The Twilight Zone[/Rod Serling voiceover]