I really like this project, and I might also ask: which writers have beards, and which don't? At the risk of stealing Coolie's thunder, let me also nominate the following gentlemen for consideration:
[Incidentally, if you click on the images, you will find the original context.]
Charles Dickens
Hemingway
D.H. Lawrence
Lytton Strachey
Thomas Carlyle
William Morris
Dostoevsky
Wole Soyinka
J.M. Coetzee
Chaim Potok
Alain Robbe-Grillet
Tahar Ben Jalloun
Rohinton Mistry
Pankaj Mishra
Is there a pattern? One can compare the bearded to the non-bearded male writers.
And as of this moment, I haven't been able to identify a pattern -- the result of the experiment (conducted with the help of images.google.com) is negative. But it's not entirely hopeless; I solicit your help.
Here's some data from my lunch-hour experiment:
Charles Dickens had a beard, but William Makepeace Thackeray and Henry James did not. D.H. Lawrence had a beard, but Joyce, Proust, and T.S. Eliot did not. I have trouble finding French writers with beards -- even Honore de Balzac, who seems like he almost requires a beard -- didn't have one (though he did have a bushy mustache). But then, Robbe-Grillet has a beard, so throw that out.
Very few Arab writers have beards (one can certainly speculate as to why; clean-shaven suggests "secular"). But the very secular Tahar Ben Jalloun has a beard, though it is closely cropped -- you wouldn't confuse it with the beards worn by devout Muslim men.
I can't find any Latin American writers with beards. And most of the Jewish and Israeli writers I can think of offhand (the two Roths, Amos Oz, A.B. Yehoshua) don't have beards, though Chaim Potok does. (But then Potok is a former Hasid, so it kind of makes sense.)
I thought maybe gay men would tend to be less likely to have beards. And indeed, Marcel Proust, Henry James, Roland Barthes, and Jean Genet don't have beards. But Strachey has quite a beard! So that rule doesn't quite work.
Maybe experimental, avant-gardist writers don't have beards? No beard on Borges, Kafka, or Joyce. But Coetzee has one, so scratch that too.
With the African writers, I think it's somehow fitting that Soyinka has a beard, but Achebe doesn't. I also think Dickens (yes) vs. Thackeray (no) makes sense, in terms of the way they write.
But with the others... ? There does seem to be a correlation between writers who pose themselves as self-consciously "serious" or "philosophical" and beardedness. But it's only a rough correlation, hardly a rule.
Finally, some of you may have noticed that this completely useless exercise obviously only includes writers who are men! I'm curious to know whether women writers could also be categorized with some superficial aspect of their appearance? I don't think so -- beards have a kind of historical constancy to them since the 19th century: they are sort of always a little out of fashion, but suitable for writers and philosophers. Whereas women's dress and hair have changed quite radically during the same era. Perhaps: women writers who keep their hair pulled back vs. those who have their hair down? Short vs. long hair?