A groundbreaking study published in Science reveals that the first eukaryotes emerged no more than 1.8 billion years ago, evolving gradually into a stable diversity of life. This research, conducted by the Polytechnic Institute of the University of Virginia in collaboration with scientists from Russia, China, and several U.S. universities, utilized a comprehensive catalog of fossilized bones and shells to analyze ancient marine eukaryotes, organisms whose cells contain a nucleus.
The study provides the most detailed examination of Proterozoic diversity to date, covering a period from 2.5 billion to 539 million years ago. This era, characterized by the predominance of small organisms and sponges lacking mineralized skeletons, left fewer fossils for study. The researchers employed advanced graphical correlation techniques to achieve greater temporal resolution, revealing significant fluctuations in species diversity.
Notably, the findings indicate that although ancient species evolved more slowly, their evolution accelerated following global glaciations. The analysis suggests that eukaryotic species may have taken longer to evolve compared to later species. The research highlights a critical period, known as the “boring billion,” during which species renewal rates were remarkably low.
After two significant glaciation events between 720 and 635 million years ago, the thawing of ice led to a rapid resurgence in eukaryotic diversity. The researchers emphasize that these glacial periods played a pivotal role in resetting evolutionary trajectories, prompting a swift renewal of eukaryotic species.
This study opens up intriguing questions regarding the slow pace of eukaryotic evolution during the “boring billion,” the factors driving post-glacial evolutionary acceleration, and the possibility of an evolutionary arms race among organisms. The authors believe that this new record will enable future scientists to explore these questions, enhancing our understanding of life’s complex interactions on Earth.