They have a reputation for strength, organisation and teamwork. But researchers have now discovered that a key secret to the success of ants is the insect's ability to identify the importance of age in the work place.
A study of Central American leaf-cutter ants has shown that the younger and more vigorous members of the colony are given the toughest job of cutting through the leaves they harvest. Their sharp young teeth do this job efficiently, but as they get older their teeth become relatively worn and blunt.
But rather than being retired or dumped on the ant equivalent of the social scrap heap, the ageing ants are given a new role more suited to their physical abilities. The former chompers become carriers. Instead they transport the leaves back to the colony where they are harvested for food.
'Cutting leaves is hard work,' said Dr Robert Schofield, who led the team of US scientists. 'Much of the cutting is done with a V-shaped blade between teeth on their mandibles. This blade starts out as sharp as the sharpest razor blade that humans have developed.' But over time the teeth become blunter and the cutting job slows down.
Like humans, leaf-cutter ants recognise that older members of the group can still make a worthwhile contribution to societyDr Schofield and his team used hi-tech microscopes to compare the pristine teeth of laboratory-reared pupae with the worn teeth of the wild forager ants.
They found the blade of a cutter ant to be 340 times duller than the pristine blade of a pupa. The study reported in the journal Behaviour Ecology and Sociobiology revealed ants with the most worn teeth, which had less than 10% of the cutting blade, exclusively carried leaves rather than cut them. The team estimated that, because of this age-related wear, a colony spent twice the energy cutting leaves than it would if all the ants had sharp mandibles. Its findings support the idea that wear and fracture can be significant problems for insects as well as larger animals. 'This study demonstrates an advantage of social living that we are familiar with,' said Dr Schofield. 'Humans that can no longer do certain tasks can still make very worthwhile contributions to society.' Leaf-cutter ants live in colonies that have a very developed structure with a strict hierarchy.
2011-01-10 20:34 编辑：kuaileyingyu