Conspiracy theories can be stubborn, particularly in the echo chamber of the internet.
One persistent belief in some quarters is that the government — or business, perhaps — is deploying a fleet of jet aircraft to spray chemicals into the sky to control the population, food supply or other things.
As evidence, they point to what they call “chemtrails,” which are more commonly known as contrails, or condensation trails, produced at high altitudes as water vapor in jet engine exhaust condenses and freezes.
Adding fuel to the chemtrails theory is the fact that there are a few legitimate reasons for atmospheric spraying — “seeding” clouds to make rain, for example — and in recent years there has been some research on the idea of spraying chemicals as a potential way to fight global warming.
But now, scientists have become more organized in their efforts to shoot down the idea, conducting a peer-reviewed study in Environmental Research Letters that debunks chemtrails supporters’ claims.
The goal, the researchers say, is not so much to change the minds of hard-core believers, but to provide a rebuttal — the kind that would show up in a Google search — to persuade other people to steer clear of this idea.
Steven J. Davis, a climate scientist at the University of California, Irvine, said he had the idea for the study after a conversation with a salesman at a mattress store.
When the man found out what he did for a living, Dr. Davis said, “he had very serious questions about what we were going to do about the chemtrails problem.”
Dr. Davis said that when he got home, he searched the internet for peer-reviewed studies on the conspiracy theory, but found none.
The theory has been popularized on websites that display photographs of contrails but are described instead as chemtrails that persist in the atmosphere and contain harmful chemicals like strontium, barium and aluminum.
By MOISES VELASQUEZ-MANOFF via The New York Times
Wheat was first domesticated in southeastern Anatolia perhaps 11,000 years ago. (An archaeological site in Israel, called Ohalo II, indicates that people have eaten wild grains, like barley and wheat, for much longer — about 23,000 years.)
Is this enough time to adapt? To answer that question, consider how some populations have adapted to milk consumption. We can digest lactose, a sugar in milk, as infants, but many stop producing the enzyme that breaks it down — called lactase — in adulthood. For these “lactose intolerant” people, drinking milk can cause bloating and diarrhea. To cope, milk-drinking populations have evolved a trait called “lactase persistence”: the lactase gene stays active into adulthood, allowing them to digest milk.
Milk-producing animals were first domesticated about the same time as wheat in the Middle East. As the custom of dairying spread, so did lactase persistence. What surprises scientists today, though, is just how recently, and how completely, that trait has spread in some populations. Few Scandinavian hunter-gatherers living 5,400 years ago had lactase persistence genes, for example. Today, most Scandinavians do.
Here’s the lesson: Adaptation to a new food stuff can occur quickly — in a few millenniums in this case. So if it happened with milk, why not with wheat?