I have a bit of a soft spot (no pun intended) for Charles Darwin's wen: that fleshy little bump slightly to the right of his nose—or to the left of his nose as you look at it. You must have noticed it. You were just too polite to point it out, that's all.
One reason I have a soft spot for Darwin's wen is that I have a similar wen in almost exactly the same location. In my case, you really might not have noticed it, because it is considerably less pronounced than Darwin's. If it's pronounced wens you're interested in, it's far more likely that your eye will have been drawn to the far more substantial wen on the left side of my forehead—although you'll no doubt have been too polite to ask for a closer look. But I digress.
Wens are benign, little tumours which you should keep an eye on, just in case they decide to stop being benign. They can be removed through a simple operation under local anaesthetic, but I've held on to mine as I'm rather attached to them (and vice versa).
Darwin's wen should be a cause of minor celebration. It is the one noticeable blemish breaking the otherwise perfect bilateral symmetry of his physiognomy. To put it another way, it is the one facial feature which can give us cast-iron proof that an image of the great man has been tampered with. If Darwin's wen appears to the right of his nose (or to the left as we're looking at him), all is well and good with the world. If, however, the wen appears on the wrong side of Darwin's nose (i.e. his left side, our right), we are looking at a mirror image of the great man—an image which has no doubt been turned around by some graphic designer to make it fit more aesthetically into some artty-farty context or other.
I have previously written about how you can use Darwin's buttons to spot when you're dealing with his mirror image. But the wen provides an important indicator when it is not possible to discern Darwin's buttons.
Take, for example, this poster from the recent Darwin exhibition, hanging in pride of place on this Darwin groupie's study wall:
Shame on you, Natural History Museum! We all realise that the hand was Photoshopped in (and we'll let you off the fridge magnet howler), but was it really necessary to turn Darwin's face round the wrong way?