A study published in Current Biology shows that the way ants distinguish nestmates from outsiders is more flexible than previously thought. The researchers worked with clonal raider ants (Ooceraea biroi), which reproduce asexually so scientists can create genetically identical lines and mix them for experimental colonies.
Chemical analyses found that colonies share the same set of waxy compounds, but they combine these compounds in different ratios to make distinct colony scents. Baseline tests confirmed that ants usually behave aggressively toward foreign genotypes.
To test learning, the team placed young ants with faint chemical profiles into foreign colonies. After one month of prolonged exposure, those ants chemically resembled their foster colony and no longer faced aggression when tested separately. But some limits remained: ants separated from genetic kin at the egg stage still accepted individuals of their own genotype. Learned tolerance was fragile—if contact stopped, aggression returned in about a week, while brief, occasional encounters were enough to maintain tolerance. Tolerance persisting after five days of separation suggests a longer-lasting olfactory memory rather than short-term desensitization.
Difficult words
- clonal — produced without sexual reproduction, genetically identical
- genotype — the genetic makeup of an organism or groupgenotypes
- compound — a chemical substance made of different partscompounds
- scent — a smell that comes from an animal or placescents
- aggression — hostile or violent behavior toward others or outsiders
- tolerance — acceptance of individuals or signals from others
- olfactory memory — memory related to smell and odor recognition
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Discussion questions
- How do you think learned scent tolerance might help or harm an ant colony? Give one reason.
- Have you observed animals using smell to recognise others? Describe a short example.
- The article says tolerance is fragile but can be kept by brief encounters. How could this idea apply to human relationships or groups?
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