Search Here

Boosting dopamine levels turn passive worker ants into aggressive warriors, according to a new study.

Scientists linked the ritualized fighting behavior of the Indian jumping ant (Harpegnathos saltator) to increases in dopamine levels. The latest findings reveal that a boost in dopamine levels trigger dramatic physical changes in the ants without affecting their DNA.

Researchers from North Carolina State University, Arizona State University and the U.S. Department of Agriculture found that the dramatic changes undergone by Indian jumping ants are triggered by on or off genes, depending on social and environmental factors.

Researchers explain that when a queen ant dies, the female workers take part in ritual battles to establish dominance. In the end, a group of 12 workers tend to establish dominance to transform into a cadre of worker queens or "gamergates."

While the gamergates look like ordinary worker ants, researcher shows that they undergo extreme internal changes. Their brains shrink by a fourth in volume, their ovaries expand to fill their abdomens and their life expectancy rises from about six months to years.

"We wanted to know what's responsible for these physical changes," lead researcher Dr. Clint Penick said in a news release. "The answer appears to be dopamine. We found that gamergates have dopamine levels two to three times higher than other workers."

Researchers in the latest study removed a group of workers from a colony (Colony A) from their gamergates. This triggered the ritualized battles to establish dominance in the removed group so that workers can effectively form their own colony (Colony B).

Penick and his team them removed and analyzed winning workers in Colony B. They found that these dominant ants had started producing elevated levels of dopamine, which researchers noted were more than other workers, but less than full-fledged gamergates.

Later, researcher placed the dominant workers back into Colony A and found that the regular Colony A workers identified the changes in the dominant workers and showed "policing" behavior by holding down dominant ants. Researchers found that the dominant ants turned back into regular worker ants within 24 hours as their dopamine levels dropped to original levels.

"This tells us that the very act of winning these ritual battles increases dopamine levels in H. saltator, which ultimately leads to the physical changes we see in gamergates," said Penick. "Similarly, losing these fights pushes dopamine levels down."

Researchers said the findings also provide insight into other social insect species.

"Policing behavior occurs in wasps and other ant species, and this study shows just how that behavior can regulate hormone levels to affect physiology and ensure that workers don't reproduce," Penick explained.

The findings were published in The Journal of Experimental Biology.