Maybe it's the carryover from that mindset that makes us mutt owners want to categorize our dogs, too. Maybe it's our need to label; maybe it's our desire to better understand them. Maybe it's just something to talk about.

When it comes to pet ownership in the U.S., the American Pet Products Manufacturers Association says mutts account for nearly half the dogs. The fastest-growing segment of the dog population, though - more than purebreds or mystery mixes - are hybrids, or so-called designer dogs: two breeds crossbred to produce, say, a puggle, a labradoodle or a chug, also known as a pugwawa.

Ace, I'm pretty sure, wasn't designed. He just happened when an unspayed somebody got together with an unneutered somebody. Maybe a fence was jumped. Maybe there was a back-alley meeting. Maybe (my favorite theory) a police dog responding to a call fell under the charms of an attractive golden retriever.

All these things fell into the category of things I didn't know and didn't really need to know, but very much wanted to.

So I set off to seek Ace's roots - to find out where he came from, how he ended up in the city dog pound and maybe, with a little help from technology, just exactly what breeds are in him.

I knew when the quest started that I probably wouldn't find all the answers. But I was pretty confident about the scientific piece of the puzzle. A new test, made available to the public this year, can tell you which of the 38 most popular dog breeds are in your mutt based on a DNA sample you provide by swabbing inside your dog's mouth.

That information, though its usefulness to the average mutt is debatable, would at least put me in a position to finally answer the question that - from strangers on the sidewalk, kids on the playground, even through rolled-down windows of passing cars - I'm constantly being asked:

"Hey, Mister, what kind of dog is that?"

Free screenings of the "dogumentary" Hey, Mister, What Kind of Dog is That? will be held at 7 tonight at the Idle Hour, 201 E. Fort Ave.; at 9 tomorrow night at Captain Larry's, 601 E. Fort Ave.; and at 7:30 Wednesday night at the Sly Fox Pub, 554 E. Fort Ave.

Donations will be accepted on behalf of the Baltimore Animal Rescue and Care Shelter, a nonprofit organization created in 2005 to operate the city animal shelter. Working with the city Bureau of Animal Control, its mission is to protect animals from neglect, abuse and exploitation.