Evolution Paused for a Billion Years After the First Complex Life Appeared
Geologists Reveal a Quiet Period in the Earth's History
A new study suggests that the evolution of complex life on Earth paused for about a billion years after the first eukaryotes appeared.
For billions of years, life on Earth consisted of simple, single-celled organisms. Then, about 2.7 billion years ago, eukaryotes evolved. Eukaryotes are more complex cells that contain a nucleus and other membrane-bound organelles.
The evolution of eukaryotes was a major turning point in the history of life on Earth. It paved the way for the evolution of all multicellular organisms, including humans.
But a new study suggests that the evolution of eukaryotes was not a smooth and steady process. Instead, there was a pause of about a billion years after the first eukaryotes appeared.
The study, which was published in the journal "Nature Geoscience", was conducted by a team of geologists from the University of California, Riverside.
The team studied the geologic record of the Earth's oceans over the past 3.5 billion years. They looked for evidence of biological activity, such as the presence of fossils or the chemical signatures of life.
The team found that there was a period of about a billion years, from about 1.8 billion years ago to 800 million years ago, when there was little evidence of biological activity in the oceans.
The team believes that this period of time represents a pause in the evolution of eukaryotes.
The team's findings are significant because they suggest that the evolution of complex life on Earth was not a linear process. Instead, there were periods of rapid change and periods of relative stasis.
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