single-celled to multi-celled
When did multicellular life first evolve? That's a good question, and its own which geobiologists may now have an answer to. A fossil of a 600 million-year-old multicellular organism displays unexpected evidence of complexity
When did multicellular life first evolve? That's a good question, and its own which geobiologists may now have an answer to. Researchers have found evidence in the fossil record that complex multicellularity appeared in living things bout 600 million years ago, which is nearly 60 million years before skeletal animals appeared during a huge growth spurt of new life, called the Cambrian Explosion.
In order to examine the appearance of multicellularity on Earth, the researchers examined phosphorite rocks from the Doushantuo Formation in South China. They discovered preserved multicellular fossils that showed signs of cell-to-cell adhesion, differentiation and programmed cell death. These are all qualities of complex multicellular eukaryotes, such as animals and plants.
"This opens up a new door for us to shine some light on the timing and evolutionary steps that were taken by multicellular organisms that would eventually go on to dominate the Earth in a very visible way," said Shuhai Xiao, one of the researchers, in a news release. "Fossils similar to these have been interpreted as bacteria, single-cell eukaryotes, algae and transitional forms related to modern animals such as sponges, sea anemones or bilaterally symmetrical animals. This paper lets us put aside some of those interpretations."
The findings actually shed light on when multicellularity first appeared. Single cells began to cooperate with other cells and created a single, cohesive life form. The complex multicellularity that was found in the fossils is inconsistent with simpler life forms, such as bacteria and single-celled life. This seems to show that multicellularity appeared far earlier than previously expected.
Currently, the scientists plan to focus on a broader paleontological search in order to reconstruct the complete lifestyle of the fossils. This, in turn, should tell researchers a bit more about the origins of life on Earth.
The findings are published in the journal Nature.
In order to examine the appearance of multicellularity on Earth, the researchers examined phosphorite rocks from the Doushantuo Formation in South China. They discovered preserved multicellular fossils that showed signs of cell-to-cell adhesion, differentiation and programmed cell death. These are all qualities of complex multicellular eukaryotes, such as animals and plants.
"This opens up a new door for us to shine some light on the timing and evolutionary steps that were taken by multicellular organisms that would eventually go on to dominate the Earth in a very visible way," said Shuhai Xiao, one of the researchers, in a news release. "Fossils similar to these have been interpreted as bacteria, single-cell eukaryotes, algae and transitional forms related to modern animals such as sponges, sea anemones or bilaterally symmetrical animals. This paper lets us put aside some of those interpretations."
The findings actually shed light on when multicellularity first appeared. Single cells began to cooperate with other cells and created a single, cohesive life form. The complex multicellularity that was found in the fossils is inconsistent with simpler life forms, such as bacteria and single-celled life. This seems to show that multicellularity appeared far earlier than previously expected.
Currently, the scientists plan to focus on a broader paleontological search in order to reconstruct the complete lifestyle of the fossils. This, in turn, should tell researchers a bit more about the origins of life on Earth.
The findings are published in the journal Nature.
