In the mine, a canary’s collapse let workers know there ... in favor of “electronic noses,” gas detectors with digital readings, as the BBC reported at the time. In December 1986, Britain ...

they knew to make an even more urgent exit as something had caused the canary to die. The next type of gas detection used was the flame light. One benefit of using a flame light, of course, was that ...

The gas is odorless, colorless ... and they quickly became a metaphor for warning signs – when the canary keels over, it’s time to evacuate the mine before you become the next victim.