Video: Ants given a specific job to do are not necessarily the best at it – suggesting that social insects are not as organised as thought

Marked ants reveal that ants with a job to do are not necessarily the best at it (Image: Alex Wild)

It’s tempting to regard an ant colony as the model of an efficient society – everyone has her own specific job to do, and this specialisation keeps the colony running efficiently. Not so: success is down to hard work, not specialisation, new research suggests.

Anna Dornhaus of the University of Arizona, Tucson, videotaped 1142 colour-coded rock ants (Temnothorax albipennis) from 11 colonies as they performed four different tasks, such as foraging for food and nest building.

Unlike leaf-cutter ants or army ants, rock ants – in common with 85% of all ant species – do not have specialisations in body size or shape that would make one individual more suited to a job than another.


No experts

Dornhaus’s team measured the efficiency of each ant by recording the time taken to pick up an object and deposit it somewhere else. They found that the more efficient ants were those that completed the task quickly, so they could move onto the next one.

They also measured how specialised the ants were, by noting how many times each ant performed a certain task. For example, an ant that made 10 trips carrying food back and forth, but only one carrying stones was denoted a food specialist, whereas those ants that carried out the tasks equally frequently were generalists.

It turned out there was no connection between how frequently an ant performs a task and how well it does it. “What is surprising is that a specialist is actually not necessarily very good at what they are doing,” Dornhaus says.

Also, it turns out that ants are not very good at recognising who is the best for the job. “There are individuals who are consistently better than others at specific tasks, but they are not the ones doing the task.”

So if the specialists are not experts, why bother having them at all? Dornhaus thinks it could be beneficial for the colony to avoid the confusion that arises when switching from one task to another.

Time wasting

Mike Kaspari, an ant expert from the University of Oklahoma agrees. “Multitasking is a myth,” he says. “It is inefficient, not because folks can’t learn to do individual tasks better, but because of the constant confrontation with the question ‘what do I do next?’, followed by the gearing up to switch to that task.”

“This wastes time. It is better to be locked in a room to do one thing and one thing only, even if you never get better at it,” he says.

It has long been thought that the success of social insect species, such as bees, termites and ants, stems from the organisation of labour within the group. Dornhaus’ study is the largest so far into the purported benefits of the division of labour. She thinks that the fact that none were found will prompt people to start questioning whether this assumption is valid.

“When we look at animals living in societies it is too easy to think of them in human terms,” she says. “We need to fight that urge. Ants may do things that are non-intuitive to us.”

There could be other reasons why ant species are so successful that are nothing to do with labour organisation, such as an ability one species has to produce a chemical that prevents vegetation from growing on their nest sites.

Journal reference: PLoS Biology (DOI: 10.1371/journal.pbio.0060285)