(Mirror Daily, United States) – The latest MIT study suggests that sea sponges were the first animals on Earth. It seems that the sea sponge evolved long before the Cambrian explosion when scientists believed that life started to proliferate on our planet.
The study conducted by a team of MIT researchers was published in the “Proceedings of the National Academy of Sciences” journal on the 22nd of February 2016. The main conclusion of the paper was that sea sponges were the first animals on Earth.
Recently a team of paleontologists unearthed a great number of well-preserved fossils that dated from roughly 540 million years in the past. These findings were the basis of the MIT team’s study.
The universally acknowledged theory of the Cambrian explosion dictates that life on Earth rather exploded at a certain point in the past when single celled organism evolved into multi-cellular beings. The geological spam in which the evolution took place was significantly short.
In order to establish what the very first multi-cellular animal that evolved on Earth was, the MIT researchers focused their attention on molecular fossils. These are the molecule traces that are left behind by a decaying animal.
According to the lead author of the study, David Gold, an MIT postdoc in the Department of Planetary, Earth and Atmospheric Sciences, the scientific community was convinced that multi-cellular animals evolved long before the Cambrian explosion.
In order to prove that theory, Dr. Gold, and his team analyzed the 24-isopropylcholestane, also known as 24-ipc. This is a lipid molecule, a sort of modified version of the much more popular cholesterol.
In 2009, a team of researchers managed to confirm the 24-ipc’s presence in a rock sample that dated from around roughly 640 million years in the past. This was the first evidence that indicated the presence of life so far back into the past.
In order to find the original multi-cellular organism, the scientist first had to determine the gene that produces the 24-ipc molecule. After answering that question they then had to trace down the organisms that are capable of carrying these genes and finally study how that specific gene evolved over the years.
Present-day sea sponges and a couple types of algae are capable of producing the 24-ipc molecule. The team analyzed approximately 30 organisms including fungi, sea sponges, algae, and even plants. They searched for a specific kind of sterols that are associated with the 24-ipc producing gene.
Fast forwarding to the major discovery. The researchers found that the sterol methyltransferase gene was responsible for the production of the specific sterols they were searching for.
After comparing various types of genetic trees they concluded that the SMT was first developed by the sea sponges roughly 640 million years in the past. This means that the sea sponges were the first animals on Earth.
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