Study Shows Ants Have Group-Level Personalities

Researchers at the University of Tours (L'Université François-Rabelais de Tours), in France, have discovered that ants display personality traits, joining the company of other insects like cockroaches and damselflies.

The study, spearheaded by entomologist Raphael Boulay, had 27 colonies of funnel ants taken into a lab, where queen ants reared new workers. This lab-rearing assured that all the ants within the experiment were young and inexperienced workers, giving them a completely untouched "slate" to study potential personalities.

Researchers then waited and observed the ants as they explored new areas and foraged for food. They kept track of the numbers of ants that were sent out to forage, how many went to explore, and how many stayed within the "hill" hiding during certain set periods of time. These numbers where then compared to measure boldness, adventurousness, and willingness to forage within each group.

The scientists measured risk-taking within the foraging group by increasing the temperature of the foraging areas from 26°C (78.8°F) to 60°C (140°F). Ants that ventured out in any temperature above 46°C (114.8°F) were considered as "risk-takers," according to Science Magazine.

The researchers then compared the results from each colony, finding that different groups had varying levels of risk-takers, and that boldness, adventurousness, and willingness to forage also varied. The colonies with shy and fearful groups were less inclined to forage at higher temperatures, compared to the more bold colonies.

Eleven weeks later, the team performed the same tests, and found that these traits persisted over time, showing that the ants did display group personalities. As reported by Science Magazine, "more than half of all variation between colonies fell into distinct categories known as 'behavioral syndromes.' These syndromes - similar to personality types among humans - are present across the animal kingdom and include categories like 'proactive' (animals are bold, aggressive, and risk-prone) and "reactive" (animals are shy, calm, and risk-averse)."

The researches also found that when two groups were forced to share a foraging area, the bolder of the groups would display more aggressive behaviors toward the other ants, and were more efficient at collecting food. The scientists concluded that despite this, the aggressiveness could result in a higher mortality rate, resulting in a bit of a tradeoff between the two behavior patterns. 

A study done in 2014 with rock ants confirmed colony-level personalities, further supporting the idea that ants do develop personalities on the group-level.

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