Photography is a kind of virtual reality, and it helps if you can create the illusion of being in an interesting world.

You know that when Irving puts the dog in the car, it is no longer in the yard. When Edna goes to church, her head goes with her. If Doug is in the house, he must have gone through some opening unless he was born there and never left. If Sheila is alive at 9 A.M. and is alive at 5 P.M., she was also alive at noon. Zebras in the wild never wear underwear. Opening a jar of a new brand of peanut butter will not vaporize the house. People never shove meat thermometers in their ears. A gerbil is smaller than Mt. Kilimanjaro.

Solving a problem in a hundred years is, practically speaking, the same as not solving it at all.

Like the early days of the Internet, the dawn of personal genomics promises benefits and pitfalls that no one can foresee.

Of course genes can’t pull the levers of our behavior directly. But they affect the wiring and workings of the brain, and the brain is the seat of our drives, temperaments and patterns of thought. Each of us is dealt a unique hand of tastes and aptitudes, like curiosity, ambition, empathy, a thirst for novelty or for security, a comfort level with the social or the mechanical or the abstract. Some opportunities we come across click with our constitutions and set us along a path in life.

I do look for openings where I can overturn popular misconceptions, but unlike Christopher Hitchens, I am neither a contrarian nor a lone heretic. I like to have a significant number of academics watching my back.

The moral, then, is that familiar categories of behavior - marriage customs, food taboos, folk superstitions, and so on - certainly do vary across cultures and have to be learned, but the deeper mechanisms of mental computation that generate them may be universal and innate.