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Trains, now on Uber. T's and C's apply. Check the Uber app. This is a scientific American 62nd Science. I'm Aline Augenbrand.

It came to our attention a few years ago that there were fraudulent whiskies on the market.

Gordon Cook of the Scottish University's Environmental Research Center.

Scotch Whiskey is Scotland's product and we felt that being a radiocarbon laboratory in Scotland we should take a lead on this.

Scotch whiskey is made from barley which absorbs carbon dioxide from the air as it grows.

Most of the carbon is carbon 12, but a small percentage is the radioactive isotope carbon 14,

which decays at a constant known rate, and has therefore long been used to carbon

date biological samples.

Then in the early 1950s, we had the start of the atmospheric weapons test and these produced carbon 14.

By 1963 there were twice the natural level. In 63 there was a test ban treaty, so 63 was the maximum and since then the level in the atmosphere has decreased

as the radi carbon goes into the biota and the oceans.

So unusually high levels of carbon 14 are associated with barley grown during the years

when nuclear testing was widespread. There's obviously a lot of money in whiskey and some

classics get bought not as imbibments but as investments.

Last October a 60 year old 1926 bottle was auctioned off for 1.9 million dollars.

To make sure that the stuff inside bottle for 1.9 million dollars.

To make sure that the stuff inside bottles of Scotch whiskey matches what's on the labels, Cook

and his colleagues looked at levels of carbon 14 in the drink.

They calibrated levels of the radioactive variant of carbon in more

than 200 different single malt scotch whiskey samples of known ages. The researchers

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