The short answer
Yes. When he was a child. He greatly regretted it. Yet creationists draw all sorts of crazy inferences from the act.
The longer answer
I. When he was a child
On occasion, a creationist will quote Darwin as saying, “I beat a puppy I believe, simply from enjoying the sense of power.” Sometimes, the quote is even accompanied by a picture of a cute puppy, staring up at us with sad and innocent eyes. Bad Darwin! Bad!
One might imagine that we are not quite being given the full story, and, indeed, we are not. Here’s the context in Darwin’s Autobiography:
Once as a very little boy, whilst at day-school, or before that time, I acted cruelly, for I beat a puppy I believe, simply from enjoying the sense of power; but the beating could not have been severe, for the puppy did not howl, of which I feel sure as the spot was near the house. This act lay heavily on my conscience, as is shown by my remembering the exact spot where the crime was committed. It probably lay all the heavier from my love of dogs being then, and for a long time afterwards, a passion. Dogs seemed to know this, for I was an adept in robbing their love from their masters. (Darwin 1876:27)
Not admirable, but hardly uncharacteristic for a young boy: if there is anything unusual in the event, it is how much Darwin regretted it.
II. Hyperbolic inferences
Even creationists who acknowledge the full context still manage to draw some amazing lessons from it. One creationist sees it as proof that Darwin had a “sadistic impulse” which (of course) was kept partly in check only by the young Darwin’s belief in God:
A clearer example of his sadistic impulse was when, as a young boy, Darwin “beat a puppy…simply from enjoying the sense of power.” He even admitted that he later felt much guilt over his behavior, indicating that he knew his actions were wrong (p. 27). At this time, he still had a strong faith in God, and this fact may partly explain his guilt (p. 25). (Bergman 2005:1, page numbers refer to Darwin 1876.)
I suppose the authorities had better excavate the garden at Down House: only God knows how many dismembered corpses they will find buried there from after Darwin became an agnostic.
Bergman J. 2005. Darwin’s passion for hunting and killing. Impact 383.
Darwin C. 1876. The Autobiography of Charles Darwin. Edited by Nora Barlow, 1958. New York: W. W. Norton & Co.