What's in a Face?

I recently bought iLife '09 for my home computer and was thoroughly pleased with how iPhoto '09 reorganized my collection of about 10,000 photos.  It was cumbersome to have to scroll through that many thumbnail images, and I had gotten spoiled by having the latest version on my work computer.  I had noticed that iPhoto was running face detection in the background when it installed, and that took at least a couple of hours.

I didn't realize when I identified faces, that it would take so long to come up with matches.  The first one I tried was my new son-in-law, because I figured there were fewer pictures of him than of anyone else in the family.  That was a good first step!  iPhoto brings up images that you can confirm or deny.  Apparently the software is "trainable" in that the more confirmed images it has to match, the more accurate the matching process becomes.

When I picked out my daughter's face to match, it took hours and produced some unexpected results!  (Click to zoom.)  Notice the first one is the face of Jesus on a stained glass church window, LOL!  One of the possible matches is a picture of a photo of a much younger daughter, but the software also picked out a picture of a photo of her husband as a kid!  I expected to see myself in the possible matches, since we have a strong resemblance.  I didn't expect to see almost everyone else or the random images such as those above!  Or are they random?

Now I wonder what's in a face that makes it recognizable to a human but not necessarily recognizable to mathematical analysis?  (It's said that babies recognize faces immediately and that humans in general never forget a face.)  This question brings to mind the television ads showing inanimate objects or collections of objects that resemble faces.  :-)

What do you see in a face?  What do you want to see?

EDIT due to high demand for more gingerbread.  :-)  Somehow this face materialized from the last scrap of dough that was rolled.

And these faces could tell a tale or two!!