WILLEMSTAD – For decades, scientists have debated how multicellular life on Earth may have originated. Some researchers proposed that single-celled organisms began attaching to one another, while others argued that multicellularity emerged when single cells divided and the resulting cells remained connected. Although examples of both processes had been found before, scientists around the world generally assumed that the origin of multicellular life could only occur through one of these mechanisms.
A new study from Curaçao, recently published in the scientific journal Nature, now shows for the first time that multicellular life can also arise through a combination of both processes: cell division and the aggregation of individual cells.
Several years ago, a new type of colony-forming microorganism was discovered by chance on the northern coast of Curaçao in Shete Boka National Park. These microorganisms, previously unknown on the island, were found in small pools created by splashing seawater. The organisms, known as choanoflagellates, were already recognized by scientists as the closest living relatives of animals. Choanoflagellates are single-celled organisms with a flagellum, a whip-like structure used for movement and capturing food. The organisms in Curaçao were discovered by researchers from the University of California and CARMABI.
Researcher Mark Vermeij, who was involved in the study, explains:
“There are different theories about how complex life on Earth originated, but these theories often exclude one another. In other words, multicellular life was thought to have emerged either through dividing cells that remained attached, or through individual cells that eventually started sticking together. These new discoveries show that the two processes do not necessarily exclude each other and reveal new ways in which multicellular life on Earth may have developed.”
The researchers found that the shape of the colonies changes depending on variations in light conditions and salt concentrations in the surrounding water. Individual cells can come together to form chain-like structures, with their flagella pointing outward, allowing the colony to swim. This transformation, triggered by changing light conditions, demonstrates organized behavior within the colony.
When the surrounding water becomes too salty, the opposite occurs: the chains break apart and return to individual cells. Using advanced microscopy techniques, researchers also discovered that some cells within the chains continued to divide, with newly formed cells becoming part of the existing colony. When salt concentrations became too high, the chains separated again into single cells. Once salinity levels dropped, these individual cells often reconnected.
According to the researchers, these dynamic changes in the colony structure of Curaçao’s choanoflagellates — including the ability of cells to connect, separate, and reorganize, as well as the molecular mechanisms behind these changes — provide important new clues about how complex multicellular life may have evolved from simple ancestors such as choanoflagellates, allowing organisms to better adapt to changing environmental conditions.
The study is available here:
Ros-Rocher N, Reyes-Rivera J, Horo U, Combredet C, Foroughijabbari Y, Larson BT, Coyle MC, Houtepen EAT, Vermeij MJA, Steenwyk JL, Brunet T. Clonal-aggregative multicellularity tuned by salinity in a choanoflagellate. 2026. Nature. Published 25 February 2026.
Study in Curaçao Provides New Insights into the Origins of Multicellular Life on Earth