MICHAEL SPECTER

We're lying ourselves into believing things are untrue, like organic food will solve all our problems, or vitamins will make us healthy, or we don't need to vaccinate our children.

Nobody celebrates when they avoid an illness they never expected to get.

'Meat' is a vague term and can be used to refer to many parts of an animal, including internal organs and skin. For the most part, the meat we eat consists of muscle tissue taken from farm animals, whether it's a sirloin steak, which is cut from the rear of a cow, or a pork chop, taken from flesh near the spine of a pig.

Most reputable scientists agree that climate change is real and that the effects are likely to be bad. But nobody can say for sure exactly what 'bad' means. The safest and most equitable way out of this horrific mess is simple: cut fossil-fuel emissions.

Now, as the world's scientists focus with increasing intensity on transforming the genetic codes of every living creature into information that can be used to treat and ultimately prevent disease, Shenzhen is home to a different kind of factory: B.G.I., formerly called Beijing Genomics Institute, the world's largest genetic-research center.

Until the Nineteen-Eighties, when Deng Xiaoping designated the area as China's first special economic zone, Shenzhen had been a tiny fishing village. Suddenly, eleven million people appeared, seemingly out of nowhere; factories sprang up, often housed in hastily constructed tower blocks.

Even a two-degree climb in average global temperatures could cause crop failures in parts of the world that can least afford to lose the nourishment. The size of deserts would increase, along with the frequency and intensity of wildfires.

Just because you read a report in the 'New York Times,' the 'Economist,' or, yes, 'The New Yorker' doesn't make it true. But we do know that a few people have evaluated that story with what strikes me as fairly objective standards of reason.

To suggest that organic vegetables, which cost far more than conventional produce, can feed billions of people in parts of the world without roads or proper irrigation may be a fantasy based on the finest intentions. But it is a cruel fantasy nonetheless.

There are people who could watch a hurricane like Sandy blow out of the Atlantic every other day and blame it on anything but human activity. They are like those who, having been diagnosed with diabetes, eat donuts for breakfast. There's not much to do about them.

By themselves, genetically engineered crops will not end hunger or improve health or bolster the economies of struggling countries. They won't save the sight of millions or fortify their bones. But they will certainly help.

When people say they prefer organic food, what they often seem to mean is they don't want their food tainted with pesticides and their meat shot full of hormones or antibiotics. Many object to the way a few companies - Monsanto is the most famous of them - control so many of the seeds we grow.

'Natural' is a word that has become unmoored by its meanings. If you go into a vitamin shop, things are natural, and people look at that, and they think it's good. It's no different than any other thing you swallow.

The most blatant forms of denialism are rarely malevolent; they combine decency, a fear of change, and the misguided desire to do good - for our health, our families, and the world. That is why so many physicians dismiss the idea that a patient's race can, and often should, be used as a tool for better diagnoses and treatment.

The history of agriculture is the history of humans breeding seeds and animals to produce traits we want in our crops and livestock.

I moved from Moscow to Rome with my family and two bicycles in 1998, and spent a lot of that year- and the next - obsessed, I am sorry to admit, with the bicycles. Italy, after all, was a place where thousands of middle-aged men felt perfectly comfortable spending many hours a week in brightly colored spandex.

With a hundred and seventy-eight machines to sequence the precise order of the billions of chemicals within a molecule of DNA, B.G.I. produces at least a quarter of the world's genomic data - more than Harvard University, the National Institutes of Health, or any other scientific institution.

Although it may seem callous to say so, millions of Americans are lucky that Magic Johnson was infected with H.I.V. There is no way of calculating how many lives he has saved. No advertising agency could have invented a better, or more effective, role model.

The best way to deal with climate change has been obvious for years: cut greenhouse-gas emissions severely. We haven't done that. In 2010, for example, carbon emissions rose by six per cent - the largest such increase on record.

When most members of a community are vaccinated, they protect those who are not by eliminating the viral reservoirs in the population. The effect is known as 'herd immunity.'

Universal vaccination may well be the greatest success story in medical history.

The numbers matter: underreporting of Lyme disease obscures the true burden of the illnesses, on individuals as well as on health-care systems. It also makes it harder to convince Congress to fund research.

Antioxidants are completely useless.

It doesn't seem to matter how often vaccines are proved safe or supplements are shown to offer nothing of value. When people don't like facts, they ignore them.

Most people prepare for travels by reading about their destination; it always seemed an odd approach to me. I find it much easier and more pleasant to focus with the sights and smells of a place rattling around in my mind.