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The first cells are believed to have appeared on Earth approximately 3.5 to 4 billion years ago. This timeframe is based on geological and fossil evidence, including the discovery of stromatolites—layered structures formed by the activity of microbial communities, primarily cyanobacteria. The oldest known stromatolite fossils date back about 3.5 billion years, indicating that cellular life was already present by that time.The emergence of these early cells marked a significant milestone in Earth’s history, as they laid the foundation for the evolution of more complex life forms over billions of years. The exact timing and mechanisms of the origin of the first cells remain subjects of ongoing research and debate within the scientific community.