Oldest Multicellular Organism Discovered
Scientists from the University of Sheffield and the USA’s Boston College may have discovered the oldest multicellular organism. Found in the Scottish Highlands, its discovery has huge ramifications on how we see the evolution of every multicellular organism on earth. It also indicates that life may not have begun in the ocean – but in freshwater lakes.
Oldest Multicellular Organism Discovery
A microfossil was recently discovered in the Scottish Highlands, which contains two distinct cell types. Given an estimated age of 1 billion years old, it is one of the earliest multicellular fossils ever discovered. As such, the teams from the UK’s University of Sheffield and the USA’s Boston College believe it could help provide answers to the missing link of evolution.
The fossil itself provides insight into how creatures transformed from single-celled organisms to multicellular animals. While single-celled creates, such as holozoa, refer to the most basic animals, due to their lack of complexity within their cell makeup, this fossil reveals an organism which is between multicellular organisms (like humans) and their single-cell ancestry.
Scientists have officially given a name to the new organism. Formally referring to the fossil as Bicellum Brasieri in the research paper Current Biology. The name is a nod to the British scientist, Martin Brasier, who dedicated his life to the study of Precambrian (the earliest part of Earth’s history) lifeforms. Sadly, the researcher passed away in 2014, in a car accident.
One of the leading investigators of the research, Professor Charles Wellmen, released a statement earlier this week. In it, he says “The origins of complex multicellularity and the origin of animals are considered two of the most important events in the history of life on Earth. Our discovery sheds new light on both of these.
“We have found a primitive spherical organism made up of an arrangement of two distinct cell types. Which is the first step towards a complex multicellular structure, something which has never been described before in the fossil record.
“The discovery of this new fossil suggests to us that the evolution of multicellular animals had occurred at least one billion years ago. And that early events prior to the evolution of animals may have occurred in freshwater like lakes rather than the ocean.”
Before this fossil had been uncovered, the previous title holder was a fossil from 600 million years ago. These had been found in marine sediments from the Doushantuo Formation in central Guizhou Province of South China.
Why Does the Oldest Multicellular Organism Discovery Matter?
This timestamp of change allows us to better understand not only when the evolution occurred, but where. With the previous understanding of evolution placing the changes in cellular structure within the ocean, rather than lakes. Fossils of the oldest known algae, ancestor to all of Earth’s plants, are also about 1 billion years old.
Lead investigator of the research from Boston College, Professor Paul Strother, says “Biologists have speculated that the origin of animals included the incorporation and repurposing of prior genes that had evolved earlier in unicellular organisms.”
Since cells must form contact with neighbouring cells, in order to work together, the Y-shape formation – shown in imaging – reveals that the cells may have communicated with each other, to exchange chemical information. As Strother states, “What we see in Bicellum is an example of such a genetic system, involving cell-cell adhesion and cell differentiation that may have been incorporated into the animal genome half a billion years later.”
The fossil was found at Loch Torridon in the Northwest Scottish Highlands.
Scientists were able to study the fossil due to the level of preservation. It has managed to hold its structural integrity to an exceptional level. Thus allowing them to analyse it at a cellular and subcellular level. As such, the team in Torrodon now hope to dig a little deeper and discover more of the Bicellum Brasieri. All in the hopes of gaining more insight into the evolution of multicellular organisms.