When did life begin to form on Earth? And how did that life transform into multicellular organisms? Experts have a deduction based on observational evidence, but a new study claims the old estimates could be wrong by a difference of 100 million years.
Based on a study of chemical biomarkers, scientists claim that complex multicellular life evolution dates, deducted by a 2009 MIT study, might be incorrect. The new study was carried out by The Australian National University (ANU), Max Planck Institute and Caltech.
The MIT study posited that complex life first evolved 635 million years ago. Their observation was based on trace chemicals found within rocks from the period in Oman. The chemicals even included certain steroids, and most chemicals were similar to those produced by modern sponges. Therefore, the scientists associated with the study postulated that this was a sign of complex-life evolution.
Now, a team has recreated similar biomarkers in a lab with help of algae. The organism, very abundant on the planet today, is presumed to have been even older that period. The Cambrian period (541–485 million years ago) is considered to be when complex animals became prominent, dominating the majority of ecosystems of the planet. But based on molecular data, scientists believe complex animals may have risen quite a long time before this.
But a large section accepts that Cryogenian or Tonian periods, within the range of 900–635 million years ago, as the origin timeframe, based on molecular data. But the range of 340 million is quite large with no exact confirmed time. This is why the 2009 MIT study became a milestone because it confidently hypothesised 635 million years as the breaking point with evidence of sponge-produced biomarkers.
However, the new study says the basis of the theory is flawed as the compounds could be created by many other mechanisms and didn’t necessarily originate from sponges. “It brings the oldest evidence for animals nearly 100 million years closer to the present day,” said one of the co-authors Dr Lennart van Maldegem. They successfully attributed the chemicals to algae and geological processes. Algae is considered the precursor of complex life.
Another co-author, Professor Jochen Brocks noted that the importance of the previous study was the steroids found in rocks which are generally considered to be only found at ocean-bed. This raised a question; if sponges were so abundant, why didn’t they leave fossils? According to Daily Mail, the lead author Dr Ilya Bobrovskiy claims to resolve this mystery by lab recreation of these biomarkers. Their conclusion – sponges weren’t the only animal capable of producing such steroids which suggest the previous estimates are wrong.