NATURAL SCIENCE:IMAGINE A culture so cold and rational that the oldest individuals are forced to take on society's most dangerous jobs. The calculus is simple: when young, you get the safe jobs; when you have a limited amount of time left, however, you get put on landmine clearing.
Such is life for many social insects, including several species of bees and ants. The prime of life is spent feeding the queen, caring for newborns and tending to the nest or hive. But with age comes a switch to foraging: strenuous and risky work that often ends in fatal injury or death by predator.
Polish scientists conducted a study subjecting young and middle-aged ants to two kinds of treatment to shorten their lifespan.
Irrespective of their age, the ants whose life expectancies were reduced in these ways soon found themselves foraging, suggesting that the genetic shift to more dangerous work is prompted not by an internal clock that measures age but rather by an ant's mysterious ability to sense when its life is almost over, the researchers report in the journal, Animal Behaviour.