Termites are counted among the most successful animals on Earth along with Les Fourmis. From the African savanna to the pillars of Gyeongbok Palace in Seoul, they live in groups ranging from hundreds to millions. How has this small insect formed a complex society and thrived for more than 200 million years to this day? 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 in Australia, said in Science on the 30th that "the driving force that allowed termites to form complex societies was that queens and kings kept living together, not adding genes but instead reducing them." Scientists from China and Denmark also took part in the study.
◇Genes shrink as society grows complex
Like Les Fourmis, termites live socially, but despite the similar names they are entirely different insects. Termites belong to the order Blattodea (cockroaches), while Les Fourmis are members of the order Hymenoptera. In appearance, unlike Les Fourmis, their antennae are straight and they have no distinct waist. Scientists estimate that termites branched off from cockroaches that lived alone 200 million years ago, during the heyday of dinosaurs. Les Fourmis split from wasps 100 million years ago.
To see how termite genes have 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 social termites and wood roaches were smaller and simpler than those of solitary cockroaches. The result ran counter to the idea that more genetic information is needed to build a complex society.
A representative example of what disappeared in termites was the gene that forms a sperm tail. In most animals, including cockroaches, a female mates with multiple males. As a result, sperm from different males competed to reach the egg faster. That led to the evolution of a tail that moves like a whip. Termite sperm have no tail. The team explained that as termite ancestors adopted monogamy, sperm competition vanished and the tail was no longer needed.
In termite colonies, workers and soldiers cooperate and share food around the queen and king, and genes related to digestion, metabolism, and reproduction were also greatly reduced. In nature, living alone requires all the knowledge from growing crops to processing and cooking them, but as society advances, it's like having separate farmers, bakers and chefs.
◇Reproductive methods evolved differently from Les Fourmis
In Les Fourmis societies, when a queen's egg meets a male's sperm and is fertilized, it becomes either a queen or a worker, all female. Males have 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 their reproductive method. When the queen's egg meets the king's sperm, both females and males are produced. Workers and soldiers that cannot reproduce emerge, and princesses and princes with reproductive capacity also appear and later become queens and kings. Lo's team also found that whether a fertilized egg can reproduce is determined at the larval stage.
Observations showed that termite larvae supplied with abundant food by their siblings developed energy metabolism and became nonreproductive workers and soldiers. Princesses and princes, who do not work, received less food at the larval stage. Lo said, "By varying how food is supplied, they finely tune the colony's labor force," adding, "It's how termites maintain a stable and efficient society over long periods."
Monogamy in termite society 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. That is because the second queen's genes are half from the king, her father. If a harmful gene that was latent only in the king is also present in the queen, it can pair up and act in the offspring. This is how inbreeding causes genetic defects.
In the Japanese termite (Reticulitermes speratus), that did not happen. In 2009, a team led by Kenji Matsuura of Okayama University in Japan reported in Science that queens in Japanese termite colonies solve the problem 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 the same genes as the first queen. When the first queen ages, she does not mate with the king but produces a proxy queen through asexual reproduction in which eggs grow without sperm. When the first queen dies, the second queen, a genetic replica, inherits the position and continues the lineage with the existing king.
◇The longevity of termite queens also owes to monogamy
In a termite colony, the queen is unmistakable. Workers and soldiers measure only a few millimeters in body length, but the queen's abdomen swells for egg-laying and her body length easily exceeds 10 cm. A queen termite can lay more than 30,000 eggs a day at her peak. That is 10 times more than a queen ant. Yet their lifespans are similar at over 20 years.
The reason a termite queen can give birth so profusely and still live long is that there is a mechanism to prevent genetic damage. In 2018, Yudith Korb of the University of Freiburg in Germany reported in the Proceedings of the National Academy of Sciences (PNAS) that termites (Macrotermes bellicosus) living in the African savanna live longer than workers because they suppress jumping genes.
As the name suggests, jumping genes are genes that can easily change position in DNA over short periods, as if leaping. 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, suppress the original gene's function and cause defects.
The analysis showed that queens and kings activated a signaling pathway that neutralizes jumping genes. In contrast, in old worker termites, this pathway was suppressed, allowing jumping genes to move freely. Why don't workers or soldiers suppress jumping genes? Korb explained that it is because energy is used efficiently at the colony level.
Individuals that reproduce, like queens and kings, must suppress jumping genes and extend lifespan to increase their offspring. In contrast, workers and soldiers are numerous and can be replaced at any time, so there is no need to waste energy taking such measures. From the perspective of the individual, it is a harsh decision, but for the colony, it is a wise choice. There were reasons termites evolved from cockroaches and have 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