Ants apparently know exactly when they'll die, and when the insects are closer to death they choose to do more risky jobs like foraging for food far from the nest. Many scientists had observed that older ants tend to take on risky tasks, but had postulated that this was just a function of age. But a group of researchers in Poland, led by Dawid Moron, published a spooky article in Animal Behavior demonstrating that every ant knows when it will die, and the closer it gets to death, the riskier its behavior gets. Moron and his team exposed ants to carbon monoxide, which shortens their lifespans considerably, and discovered that the damaged ants started doing risky things at a young age, implying that they realized they were soon to die despite their relative youth.
This implies that ant workers adjust their threshold for engaging in risk foraging according to their life expectancy.
Knowing when you'll die sounds like a nightmare, but ants have managed to turn it into functional altruism. Knowing when it will die lets each ant make a rational decision to face danger that could benefit the rest of the nest. After all, it's going to die pretty soon anyway, so it might as well do a bunch of potentially fatal things beforehand. Image by Bill Hails.
A Story of Ants, Ageing, and Altruism [via The Independent]