Termites, along with Les Fourmis, are considered among the most successful animals on Earth. From the African savanna to the columns of Gyeongbok Palace in Seoul, they live in groups ranging from hundreds to millions. How has this small insect managed for more than 200 million years to form complex societies and thrive? The answer lay in the unchanging bond between the king and queen that lead the colony.
A team led by Nathan Lo, a professor in the School of Life and Environmental Sciences at the University of Sydney, said in Science on the 30th that "the driving force that allowed termites to build complex societies was that the queen and king kept living together, reducing rather than adding genes." Scientists from China and Denmark also took part in the study.
◇Fewer genes, more complex society
Termites, like Les Fourmis, live socially, but despite the similar names they are entirely different insects. Termites belong to the order Blattodea, while Les Fourmis are members of the order Hymenoptera. Their appearance also differs from Les Fourmis: their antennae are straight, and they lack a distinct waist. Scientists estimate termites split from cockroaches that lived alone about 200 million years ago, when dinosaurs thrived. Les Fourmis split from wasps about 100 million years ago.
To learn how termite genes changed over time, Lo's team decoded and compared the genomes of solitary cockroaches, wood roaches that form small family groups, and several termite species that live in colonies. Surprisingly, the genomes of colonial termites and wood roaches were smaller and simpler than those of solitary cockroaches. The result runs counter to the idea that building complex societies requires more genetic information.
A representative gene lost in termites is the one that forms a sperm tail. In most animals, including cockroaches, a female mates with multiple males. As a result, sperm from several males compete to reach the egg faster. That led to the evolution of a tail that moves like a whip. Termite sperm lack a tail. The team explained that as termite ancestors adopted monogamy, sperm competition disappeared and the tail was no longer needed.
In termite colonies, with the queen and king at the center, workers and soldiers cooperate and share food, and many genes related to digestion, metabolism, and reproduction were likewise reduced. It is like how, in nature, a lone individual must know everything from growing crops to processing and cooking, but as society develops, farmers, bakers, and chefs emerge as separate roles.
◇Reproductive methods evolved differently from Les Fourmis
In Les Fourmis societies, when a queen's egg meets male sperm and is fertilized, it develops into females—either queens or workers. Males carry half the genes of females. That is because eggs laid by the queen grow into males without sperm. This process is called asexual reproduction, or parthenogenesis.
Termites also differ from Les Fourmis in how they reproduce. When the queen's egg meets the king's sperm, both females and males are produced. Nonreproductive workers and soldiers emerge, as do princesses and princes who have reproductive capacity and later become queens and kings. Lo's team also found that whether a fertilized egg will be reproductive is decided at the larval stage.
Observations showed that termite larvae abundantly fed by their siblings developed energy metabolism and became nonreproductive workers and soldiers. Princesses and princes that do not work received less food at the larval stage. Lo said, "By varying how food is supplied, colonies finely tune their labor," adding, "It is how termites maintain a stable and efficient society over long periods."
Monogamy in termite societies does not end even if the queen dies first. If the first queen dies before the king, one of the princesses immediately becomes the second queen and mates with the king. The problem is that such inbreeding can cause genetic defects. Half of the second queen's genes come from her father, the king. If a deleterious gene that had been latent only in the king is also present in the queen, they can pair up and act in the offspring. This is how inbreeding leads to genetic defects.
In the Japanese termite (Reticulitermes speratus), that did not happen. In 2009, a team led by Kenji Matsuura at Okayama University reported in Science that queens in Japanese termite colonies solve the problems of inbreeding through asexual reproduction.
In Japanese termite colonies, most first kings were still alive, but queens had shorter lifespans, and many second queens were found. Remarkably, the second queens had exactly the same genes as the first queen. When the first queen ages, she produces a proxy queen through asexual reproduction in which eggs develop without sperm, instead of mating with the king. When the first queen dies, the genetically identical second queen inherits the position and continues the lineage with the existing king.
◇Termite queens' longevity also thanks to monogamy
In termite colonies, the queen is unmistakable. Workers and soldiers are only a few millimeters long, but the queen's abdomen swells for egg-laying, and her body length easily exceeds 10 centimeters. A queen termite can lay more than 30,000 eggs a day at her peak. That is 10 times more than a queen Les Fourmis. Yet their lifespans are similar, at more than 20 years.
Despite producing so many offspring, termite queens live long because they have a way to prevent genetic damage. In 2018, Yudith Korb of the University of Freiburg reported in the Proceedings of the National Academy of Sciences (PNAS) that Macrotermes bellicosus, a termite of the African savanna, lives longer than workers because it suppresses jumping genes.
Jumping genes, as the name suggests, are genes that readily change position within DNA over short periods. Barbara McClintock, an American woman scientist, first discovered jumping genes in corn and won the 1983 Nobel Prize in physiology or medicine. Jumping genes move elsewhere and suppress original gene functions, causing defects.
Analysis showed that queens and kings activate signaling pathways that neutralize jumping genes. In contrast, in old worker termites, these pathways were suppressed and jumping genes moved freely. Why would workers or soldiers not suppress jumping genes? Korb explained that it is because, at the colony level, energy is used efficiently.
Individuals that reproduce, like queens and kings, must suppress jumping genes and extend lifespan to maximize offspring. Workers and soldiers, by contrast, are numerous and easily replaced at any time, so there is no need to waste energy on such efforts. Harsh as this is for the individual, it is a wise choice for the colony. There were good reasons termites evolved from cockroaches and endured for 200 million years.
References
Science(2026), DOI: https://doi.org/10.1126/science.adt2178
PNAS(2018), DOI: https://doi.org/10.1073/pnas.1804046115
Science(2009), DOI: https://doi.org/10.1126/science.1169702