Scientists are now saying that complex multicellular life on Earth evolved approximately 100 million years later than what was previously believed. They came to this conclusion by analyzing 635-million-year-old rock fossils.
A study conducted in 2009 by MIT stated that studies conducted on chemical traces that were found in rocks located in Oman revealed that the first complex life on our planet evolved 635 million years ago. They noted that the chemicals (which included steroids) were very similar to those that modern sponges produce.
But now, a new team of experts from The Australian National University (ANU), Max Planck Institute and Caltech have recreated the chemical biomarkers in order to better understand the evolution of our planet. Interestingly, they were able to create the same chemical biomarkers by using algae which was very common on Earth during that time.
While animals became diversified and dominant between 541 and 485 million years ago at the start of the Cambrian Period, some scientists think that according to molecular data, it must have happened at an earlier date. Some believe that animals first appeared between 1,000 and 541 million years ago during the Neoproterozoic Era.
The oldest animal fossils ever found date back between 558 and 552 million years ago during the Ediacaran Period and some others have even been dated as far back as 571 million years ago although experts only have “some degree of confidence” in those records.
While the majority of molecular clocks suggest that animals first emerged between 900 and 635 million years ago (during the Cryogenian or Tonian Periods), new studies had the experts using “biomarkers” in order to better understand and get more answers to the 340 million year gap that remains between the molecular clock and the oldest animal fossils.
According to the new studies, “It brings the oldest evidence for animals nearly 100 million years closer to the present day,” stated co-author Dr. Lennart van Maldegem, adding, “We were able to demonstrate that certain molecules from common algae can be altered by geological processes – leading to molecules which are indistinguishable from those produced by sponge-like animals.”
Dr. Ilya Bobrovskiy explained their studies in further detail by stating, “While it holds true sponges are the only living organism which can produce these steroids, chemical processes can mimic biology and transform common and abundant algae sterols into 'animal' sterols.” “These molecules can be generated in the lab when simulating geological time and temperatures, but we also showed such processes did happen in ancient rocks.”
The research was published in Nature Ecology & Evolution where it can be read in full.