Paper wasps that can recognize faces are more cooperative

A new study from Cornell University reveals that paper wasps possess the ability to recognize individual faces, a skill that seems to enhance their social cooperation and potentially their cognitive abilities. 

The research offers compelling behavioral evidence of an evolutionary link between individual recognition and social cooperation.

Social interactions and intelligence 

Study senior author Professor Michael Sheehan noted that the research delves into the relationship between social interactions and intelligence in animals.

The findings are particularly significant as they suggest that the ability to recognize individual faces may not just be a trivial aspect of wasp behavior but a fundamental feature that influences their social dynamics and cognitive development.

Genomic adaptations 

Through genomic sequencing, the researchers discovered that populations of paper wasps capable of recognizing each other exhibited recent adaptations in brain regions associated with cognitive abilities, such as learning, memory, and vision.

Distinct wasp populations 

The research was focused on two distinct populations of paper wasps (Polistes fuscatus): one from Louisiana, with more uniform appearances, and another from Ithaca, featuring diverse color patterns on their faces. 

“The evidence for strong recent positive selection on cognition, learning and memory is much stronger in the northern populations compared to the southern populations,” said Professor Sheehan.

Behavioral differences 

Experiments indicated a stark behavioral difference between the two groups of paper wasps. Unlike the southern wasps, the northern population displayed the ability to recognize individuals and showed greater social cooperation.

Interestingly, the study highlights the role of facial color patterns in these behavioral differences. Southern paper wasps exhibit similar red color patterns on their faces, whereas northern ones have varied black and yellow patterns. 

“As you go further north, you find the individuals become more variable in their color patterning, such that roughly around the Carolinas, they start becoming substantially variable and continue to be more variable as you go further north,” said Professor Sheehan. In the Ithaca population, every individual was pretty distinct, he said.

Aggression levels 

During lab experiments, aggression levels were recorded as wasps from both populations were introduced to strangers. 

Northern wasps showed aggression towards strangers but were less hostile towards wasps they had previously met, suggesting recognition. 

By contrast, the southern wasps treated all individuals similarly, indicating a lack of individual recognition.

Social cohesion

The ability to recognize individuals appears to make northern wasps more selective in their interactions, leading to more stable social groups. 

On the other hand, the southern wasps, with less individual recognition, tend to have less consistent and cohesive social interactions.

“Individuals in the southern population treat everyone the same,” said Professor Sheehan. “They don’t show any evidence of changing their behavior as a result of previously meeting that particular individual, which suggests they’re not recognizing them.”

Study implications 

While further research is needed, Professor Sheehan said there’s some indication that wasps from the northern population have more stable nesting groups, whereas the southern wasps had high turnover of members when they occasionally made nests.

The data suggests that being able to recognize individuals makes northern wasps more selective and better able to manage their social profiles, whereas the more homogenous-looking southern wasps interact more indiscriminately and have less consistent, cohesive social interactions, Sheehan said.

The study was funded by the National Science Foundation and the National Institutes of Health. The findings are published in the journal Current Biology.

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