And just as scientists have traced human lineage back to a mitochondrial Eve, the decline of motherhood can be traced to a single sitcom moment and a single sitcom matriarch.
The F.D.A. said all the infections involved a single lot of Avastin and had been traced to a single pharmacy in Hollywood, Fla., that had repackaged the drug for use in the eye.
The problem was traced to a single person.
And, unlike many cultural inventions, it can be traced to a single person".
At bottom, the problem can be traced to the single currency itself.
The disease was traced to a single animal, which never showed any signs of illness, exported to Canada from South Dakota.
Perhaps unsurprisingly, this great cultural change can be traced to a single source: The Great British Bake Off.
Nearly eighty-five per cent of those can be traced to a single catastrophic breach at the credit-reporting agency Equifax.
The most recent (and serious) outbreak has been traced to a single ranch, the Elk Echo Ranch, near Stoneham.
But amid this diversity, in the Middle East the news can be increasingly traced to a single root – Syria.
