New fossils discovered in the Gaoyuzhuang formation of Northern China suggest that complex living organisms capable of organizing itself into large cellular colonies emerged on Earth more than 1.5 billion years ago, or nearly one billion years earlier than previously believed.
However, the findings, which were the work of a team of US and Chinese researchers and have been published in the latest issue of the journal Nature Communications, have divided members of the scientific community, according to AFP reports. Some have praised the research, the news organization said, while others are not convinced by the paper’s claims.
As BBC News and the Daily Mail explained, fossils large enough to be visible to the naked eye first became common between 541 and 635 million years ago. However, the study authors wrote that macroscopic eukaryote fossils found in the 1.56 billion-year-old Gaoyuzhuang formation are two to three times that age, and are likely the oldest multicellular organisms ever discovered.
As Maoyan Zhu, a professor at the Nanjing Institute of Geology and Paleontology and one of the researchers involved in the study, told AFP, “Our discovery pushes back nearly one billion years the appearance of macroscopic, multicellular eukaryotes compared to previous research.”
Other scientists divided about the study’s claims
Zhu’s team found 167 measurable fossils at the Gaoyuzhuang formation that were preserved as carbonaceous compressions and which were up to 30 centimeters long and nearly 8 centimeters wide. One-third of the fossils were irregularly shaped, including some which were linear, some which were wedge-shaped, and some which were oblong – a sign of complexity.
Furthermore, detailed analysis of some of the fossil specimens revealed that they were made up of a tightly-packed arrangement of individual cells measuring approximately 10 micrometers in length, or about the same size as the width of cotton fibers, BBC News noted. These eukaryotes were described as marine organisms, somewhat similar to algae, that used photosynthesis.
The stone where the fossils were found. Credit: Maoyan Zhu
While the authors noted that some of the fossils could simply be different parts of a single type of organism, they are confident that tongue-shaped ones they discovered are unique. They added that the fossils provide circumstantial evidence for at least limited cell differentiation, one of the key stages of evolution, but they have been unable to link these eukaryotes to any other group of organism, living or extinct, according to BBC News and Daily Mail reports.
Zhu told the AFP that the research team’s findings provide “compelling evidence for the early evolution of organisms large enough to be visible with the naked eye” and that it “totally renews current knowledge on the early history of life.” Phil Donoghue, a professor and paleobiologist at the University of Bristol, agreed, calling the discovery “a big deal” and adding that these fossils “are certainly the oldest demonstrably multicellular eukaryotes.”
Others were more skeptical, including Jonathan Antcliffe, a senior researcher in the University of Oxford’s department of zoology, who told the news agency that there was no evidence to suggest that the organisms were eukaryotic and not single-celled organisms such as bacteria. Likewise, Abderrazak El Albani of the University of Poitiers in France told AFP that there was not enough detail in the paper to back up the authors’ claims that the organisms were multicellular.
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Image credit: Maoyan Zhu
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