Altruistic ants die alone to protect colony

 

This heroism is the exact opposite of the bumblebee, another social insect. Bees infected by fly larvae move outside the hive where colder temperatures restrict the parasite’s lifecycle. Rather than protecting their fellow bees, Private-Ryan-style, they further their own interests by attempting to extend their own lives.

 

To prove the ants’ desertion is a truly altruistic act, the study had to rule out the possibility of a ‘zombie’ infection manipulating them. Just like the flu makes us cough, the cordeyceps fungus compels ants to climb to the top of a stem to die. From this height, the fungus’s spores are more easily distributed by the wind.

 

The researchers exposed one group of ants to 95 per cent CO₂ to artificially reduce their lifespan. Close to death, these ants exhibited the same behaviour as those infected by fungus – wandering far from their colonies. The zombie factor couldn’t be the explanation.

 

Altruism is seen in elephants, dogs and, of course, humans, but is difficult to measure in controlled studies. In evolutionary terms, it can seem opposed to the theory of survival of the fittest. However, the British Journal of Psychology recently published research suggesting that women prefer altruistic partners. So if it doesn’t kill you, a little martyrdom could go a long way.