Since January, ALP been producing and delivering combinations of live bacteria to some 170 officially recognized Emmentaler producers to use in their cheese. The bacteria has specific DNA sequences that can prove whether the cheese is authentic Swiss Emmentaler.

The new, traceable cheese will start arriving in stores in May, said Mr. Kriech, as production rules dictate Emmentaler must mature for at least four months before it can be sold. Employees of Switzerland Cheese Marketing will then be on the lookout for counterfeit cheese, including shredded versions used in warm dishes that are easier to fake because there is no rind with the dairy’s number.

Once a suspicious cheese is sent back to the lab, scientists will extract the entire DNA from about one gram of cheese and then search it for the specific DNA sequences to see if the bacteria added by the dairies are present, according to Mr. Wechsler.

The settlers, wielding their sickles, kept moving farther and farther north, right into the territory of backward peoples. The newcomers were industrious and used to working hard in the fields. Clay statues show that the men were already wearing trousers and shaving. The women dyed their hair red and decorated it with snail shells. Both sexes wore caps, and the men also wore triangular hats.

By comparison, the more primitive existing inhabitants of the continent wore animal hides and lived in spartan huts. They looked on in bewilderment as the newcomers deforested their hunting grounds, tilled the soil and planted seeds. This apparently upset them and motivated them to resist the intruders.