Walk into a Jusco supermarket in Yamato, a small city near Tokyo, Japan, and you can glimpse the future of meat. In addition to a conventional bar code, each steak package sports its own ID number. Type the number into the computer sitting on a nearby table, and up pops information about the cow the steak came from: a scanned copy of its negative test result for mad-cow disease and, in case you are interested, its breed and sex, its date of slaughter, and the name of the producer. At some Japanese meat-counter displays, you'll even see a picture of the family that raised the animal.

All this information is available because the steaks come from Japanese cattle that have been individually tracked from birth, generally with radio frequency identification (RFID) tags; each of the cows has an ID number correlated with a database entry that documents its birth date, medical history, and movements from feedlot to slaughter, and the results of mandatory mad-cow tests. At slaughter, the ID numbers, and all data linked to those numbers, are passed on to individual boxes of meat.