Oh, I see, I should have posted the entire Descent of Man. Tell you what, you read that drivel and report back to us. However, if you want more juicy quotes from Darwin, I'll be glad to provide them.
As I pointed out the quote is central to his theory, it is not out of place. Besides, he took ten years to write the Descent, he had plenty of time to consider whether he wanted people to read those words.