canary in the coal mine
矿坑中的金丝雀(指示物种)
There are countless examples of environmental effects on animals that later manifested in humans. The classic example is the "canary in the coal mine". The idea of placing a canary or other warm blooded animal in a mine to detect carbon monoxide was first proposed by John Scott Haldane, in 1913 or later.Well into the 20th century, coal miners brought canaries into coal mines as an early-warning signal for toxic gases, primarily carbon monoxide.The birds, being more sensitive, would become sick before the miners, who would then have a chance to escape or put on protective respirators.
