Some ants rescue trapped ants, and differences in the activity of nervous system genes may help explain why different individuals respond differently. The results of the study were published in the Journal of Experimental Biology.
Ant colonies depend on workers to perform various tasks, but these workers do not always respond in the same way to the same event. One notable example is rescue behavior, where an ant digs, pulls, or bites restraining objects to help free a trapped ant. Some workers help, while others come close but do nothing.
New research on the desert ant Cataglyphis nigra suggests that this difference has more to do with gene activity in the nervous system than with body size, brain size or energy reserves.
Rescue takes time and energy, may expose the helper to danger, and does not provide immediate, direct benefit. However, it can protect related members of the colony.
“Our study shows that in ants, helpfulness is associated with measurable differences in gene activity,” said study co-author Professor Susanne Fojcik from Johannes Gutenberg University Mainz (JGU). “This is very interesting because rescue behavior has long been associated primarily with mammals, while this type of behavior evolved independently in ants.”
In the winter of 2023, the team collected seven colonies of Cataglyphis nigra from the Tel Baruch sand dunes in Israel. Before testing, 40 working individuals from each colony were placed in separate boxes.
A worker ant from the original colony was held in the center of a sand-covered arena. The researchers opened the entrance and observed the ants for 15 minutes. The rescuer had to get within about 1 to 1.5 centimeters of the captured ant and spend at least five seconds biting, pulling, or digging around it. Ants not engaged in rescue also came close enough to potentially detect a nestmate or its signals, but did not provide assistance.
The rescuers weren’t just quicker or more active. Throughout the arena, both groups moved at similar average speeds, covered approximately the same distance, and covered approximately the same total distances.
The difference appeared near the stuck worker. Rescuers reached the outer area around the fellow about three minutes earlier, and the inner area about four minutes earlier, and then slowed down as they approached it. They also searched much of the surrounding area. Rescuers searched approximately 24 percent more external and 49 percent more internal territory than those who were not involved in rescue efforts.
Next, the team examined which genes were active in different parts of the nervous system. They used RNA sequencing, a technique that measures the number of RNA molecules produced when cells use information from genes.
Tissues from 28 ants were used for analysis, and each sample included tissue from two worker ants from the same behavioral group. The research team studied the antennae, the optic lobes, which are responsible for processing visual information, the rest of the central brain, and the mushroom bodies—regions of the brain that integrate sensory information and help guide behavior.
The strongest signal associated with rescue was found in the mushroom bodies.
“There was increased activity in 15 genes during animal rescues, including genes associated with odor perception, hormonal regulation, metabolic processes and immune functions,” said study co-author Luisa Maria Jaimes-Nino from James Humboldt University.
“Across all the tissues examined, we found a total of nine genes that were more active in ants that engage in rescue than in those that do not,” said Luisa Maria Jaimes-Nino.
The in-depth paper reports nine genes associated with tissue recovery in a simultaneous analysis of all tissue types, with eight genes showing greater activity in patients who experienced recovery of function and one showing less activity.
When each tissue was examined separately, it was found that 15 genes were more active in the mushroom bodies, one in the optic lobes, and no differences were observed in the antennae and the rest of the central brain.
Others have been related to odor processing, juvenile hormone—a chemical messenger that influences insect development and behavior—and polyamines, small molecules involved in control of genes and reactions to odors.
“Instead, our results suggest that differences in the processing of sensory stimuli and in certain molecular signaling pathways may influence whether an ant responds to a threatened conspecific,” says Professor Fojcik.
The researchers also wondered whether the rescuers were physically different. Brain size did not differ between rescuers and non-rescue workers.
In a separate experiment using 10 additional colonies collected in 2025, the team compared 19 rescued individuals with 12 individuals that were not rescued. They measured body parameters, lean mass and proportion of stored fat.
There was no convincing evidence that the rescuers were larger or had more energy reserves. Larger ants showed a slight tendency to help more often, but the difference was not significant enough to be considered significant.
The results do not show that any one “help gene” controls rescue behavior. The researchers didn’t change the genes to test whether behavior would change, so the results show an association rather than a direct cause-and-effect relationship.
The team also couldn’t determine which signal caused rescuers to respond faster. Perhaps smell, vibration, vision, movement, or several signals were involved.
Immunity-related genes also lend themselves to several explanations. Immune system activity can affect the insects’ nervous systems, but rescuers may also be at greater risk of injury or infection because the rescue itself is dangerous.
The RNA analysis was small, and tissue samples from pairs of ants were pooled, reducing the ability to link gene activity to individual behavior. Three planned tissue samples were also lost during processing.
The fifteen-minute experiment created another limitation, as some ants labeled as non-saviors might have helped if the test had gone on longer.
In addition, the research team did not directly measure levels of juvenile hormone, polyamines, immune activity, or the activity of DNA fragments that can move or self-replicate.
Professor Fojcik notes that ants provide a useful tool for studying the reasons why members of the same social group may respond differently.
“Ants are a particularly good model for studying the biological basis of complex social behavior,” says Fojcik. “Our study shows that not only do individual animals in the same colony respond differently, but that these differences are also associated with measurable molecular processes.”
The results obtained do not allow one to equate saving ants with human help or sympathy. Instead, ants offer a simpler biological system for studying how sensory information, nervous system activity, and individual behavior can be interconnected.
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