When did the first eukaryotes emerge?

The emergence of the first eukaryotes is estimated to have occurred around 2 billion years ago. This time frame aligns with significant developments in the history of life on Earth, particularly during the Proterozoic Eon, when the conditions supported the evolution of more complex cellular structures. Eukaryotes, characterized by their membrane-bound organelles and nucleus, represent a major evolutionary leap from prokaryotic organisms, which include bacteria and archaea.

The timeline for the appearance of eukaryotes is supported by both fossil evidence and molecular data, which suggest that more complex life forms began evolving shortly after the Great Oxidation Event, approximately 2.4 billion years ago. This event marked a significant increase in atmospheric oxygen, which would have allowed for the evolution of aerobic respiration and the development of complex life forms, including eukaryotes.

Understanding the timing and conditions that allowed for the emergence of eukaryotic life is crucial, as it set the stage for the evolution of multicellular organisms and the biodiversity we see today.