Why Do Ants Live in Colonies? A 60-Year-Old Theory May Be Wrong
Why do ants, bees and wasps live together in colonies where most individuals never reproduce? For about 60 years, many biologists pointed to one special genetic trick. A new study in Current Biology, from Arizona State University and published in August 2026, shows that this explanation does not hold up as well as we thought.
The old theory
In ants, bees and wasps, females hatch from fertilised eggs and have two sets of chromosomes. Males hatch from unfertilised eggs and have only one. This system is called haplodiploidy. One result is that sisters are more closely related to each other than to their own daughters would be. The theory went like this: if helping your sisters passes on more of your genes than having your own young, working for the colony pays off. That would explain why social colonies arose in exactly these insects.
What the new study found
PhD student Sachin Suresh and Timothy Linksvayer used data on tens of thousands of insect species. Social colonies do appear more often in haplodiploid insects, but almost all of that comes from one group: the stinging wasps, bees and ants. Haplodiploid insects outside that group became social about as often as normal insects. So the genetic trick alone does not explain it. "It has more to do with environmental factors and the life-history traits of insects," Suresh says. Things like having a sting and building and defending a nest seem to matter more.
What this means for ant keepers
You can see haplodiploidy at work in your own colony. A queen decides whether an egg becomes a female or a male, simply by fertilising it or not. That is also why workers in a queenless colony can still lay eggs: they cannot mate, but their unfertilised eggs grow into males. If you ever see winged males appear in a colony that lost its queen, this is the reason. The study also fits what keepers see every day: a colony is built around a safe, well-defended nest, which is exactly why a good setup matters so much. Read more about how a colony works in our post about the ant colony.
Sources
Suresh, S. and Linksvayer, T., 2026. Current Biology.
ScienceDaily, 2026. A 60-year-old theory about ants, bees and wasps may be wrong.
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