Down and dirty: Those nasty, nasty humans

Q. Can you guess the filthiest, most bacteria-laden object in a typical household? The toilet bowl? A wet dishrag? Vacuum cleaner lint? ­Mr. Clean

 A. It's not an object at all but we humans, says Cornell microbiologist Stephen H. Zinder. Forget "filthy," but the body is one whopping breeding ground for bacteria, millions per square cm. in moister skin areas like armpits.

Here, bacteria + sweat = B.O., that old embarrassing equation. Our mouths too harbor billions of bacteria growing on the teeth as plaque, or between our teeth and gums. In fact, our large intestines typically contain 100 trillion bacterial cells, roughly equal to the number of cells that make up our own bodies!

But not to worry, says Zinder, since most "microflora" are our friends, helping keep the bad guys (pathogens) at bay. Actually, it's now believed that insufficient exposure to microbes in our early years may predispose us to allergies and asthma later. "Nevertheless, brushing and flossing one's teeth is a good idea, since too many bacteria can cause cavities and gum disease. As for that vacuum cleaner lint, it's largely sloughed off skin cells, so it comes from us too."

Q. If that special someone hasn't yet appeared in your life, what's this person likely to be like? Can social psychologists help you look into the crystal ball? –E. Taylor

 A. Good chance you'll meet your future partner at your workplace, says Daniel Nettle, lecturer in biological psychology at the Open University, Milton Keynes, England.

If you're a heterosexual woman, he'll almost certainly be taller than you, and probably three to four years older. If you're close in age, the chances are he'll have the same or higher level of education as yourself. Similarity of social background makes for ease of courtship but not necessarily strength of attraction. His personality could be completely different from yours; if you're into dangerous sports, though, he will be too, and if you drive fast, so will he.

For men, most of these predictions hold in reverse. Odds are she'll be shorter and younger than you. The difference in education is likely to be in your favor rather than vice versa, and the greater the age gap, the greater this difference stands to be.

These of course are just statistics, says Nettle. In reality, many relationships start where some of these predictions are not met, and that can make for the stuff of life, edgy or even off the page.

Whatever comes your way, good luck and good loving.

Q. Calculate the shrinking consumers' bull's-eye that advertisers spend hundreds of billions of dollars every year trying to hit. What chance do they have? ­L. Woody

A. Estimate 1 person in 5 will be exposed to any particular ad or series of ads (Probability = .2). Of these, maybe half will pay attention (P = .5). Out of this group, perhaps 9 in 10 will comprehend the ad (P = .9). (Based on Consumer Behavior by William L. Wilkie)

Some 20 percent of this dwindling fraction might then "go along with" the message (P = .2). Of these, maybe 1 in 10 will later bring it back to mind (P = .1). Finally, perhaps 1 in 10 of this select group will buy the product (P = .1).

The likelihood of all these events occurring can be computed as P (overall) = .2 x .5 x .9 x .2 x .1 x .1 = .0002. This suggests that roughly 2 out of every 10,000 consumers in the defined market might be anticipated to make a purchase based on the ad. If 2 out of 10,000 sounds small, consider that for a national campaign where 100 million consumers are exposed to the ads, this might represent some 20,000 additional sales– or, say, half a billion dollars' worth of new cars moved off dealers' lots.

Send strange questions to brothers Bill and Rich at