Comedy and Tragedy

Do you feel a story must be dark to be serious, or does humor have a home in your deeper stories? William Skidelsky's article in the Guardian.co.uk/TheObserver ("Women authors can lighten up and still be taken seriously: When Daisy Goodwin complained of too much 'grimness' in this year's list, she was lambasted. She should have been applauded") makes some points about the lighter points in life--and thus, in writing. Here's an excerpt:

...As a form, the novel has always worked best when, like life itself, it contains both joy and sorrow. Most great novelists have been brilliant at comedy as well as tragedy. And this is no less true of Jane Austen and George Eliot than it is of Tolstoy and Dickens.

Recently, however, there does seem to have been a movement away from comedy in fiction, a growing feeling that, in order to be serious", novels have to be dark in tone....

I admit that I'm biased on this point; I was raised by parents who believed that if you'd lost your sense of humor, you'd lost it all. I've had to suppress laughter at a funeral, and in the midst of every crisis I've had a moment during which I laughed to avoid crying. What do you think? Does comedy, however dark, find its way into your writing? Must a piece be devoid of humor to be "serious"?
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Photo courtesy of Julie Elliott-Abshire at http://www.sxc.hu/photo/306215