Scientists Say They’ve Discovered The Very First Creatures On Earth

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Our planet is home to millions of species of animal, ranging in size and stature. But for years, experts have struggled to pinpoint the identity of Earth’s very first animal. On that note, a group of scientists from the Massachusetts Institute of Technology believed that they’d found the answer in 2016.

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Prior to the publication of that study in February 2016, plenty of experts were of the opinion that the first animals didn’t emerge until the event known as the Cambrian explosion. This was hugely significant, as it marked a time when more advanced organisms started to evolve. The event itself took place over 540 million years into the past.

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However, the MIT scientists uncovered some information that put those long-held views to the test. They were studying age-old rocks for a project, before noting that the stones carried “molecular fossils.” After taking a closer look at the find, the group then made an exciting breakthrough, as we’re about to discover.

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Indeed, one of the fossilized molecules was said to be around 640 million years of age. And given the nature of that molecule, the researchers believed that an animal was responsible for leaving it behind. And they eventually went on to release their fascinating results to the world in 2016.

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Before we dive into those findings, though, let’s cast our minds back to the distant past. Much like with animals, questions about Earth’s first lifeforms have circulated for a very long time. And while the answer isn’t definitive, it’s thought that the latter emerged close to four billion years ago.

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To provide a bit more detail on that front, the New Scientist website suggested that these lifeforms could’ve been created within “undersea alkaline vents.” At some point, it’s believed that both archaea and bacteria started to come to the fore. But the fascinating, monumental developments didn’t end there by any stretch of the imagination.

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You see, Earth experienced a few big and important changes over the following years, laying the groundwork for where we are today. For instance, single-celled lifeforms seem to have emerged around 3.5 billion years ago, ahead of the accumulation of oxygen some time later. From there, the planet’s living organisms continued to transform.

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These major events all led to the Cambrian explosion, which we touched upon a little earlier. This period is said to have spanned for as long as 25 million years, as some existing organisms began to evolve into animals. As for why this happened, it’s claimed that the rise in oxygen levels might’ve had something to do with it.

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Scientists have spent years analyzing fossils which date as far back as the time of this biological explosion. In doing so, they’ve uncovered some of the earliest animals to live on our planet. To give you an example, two experts at the University of Cambridge learned quite a bit about one such organism in 2014.

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The animal in question was called Hallucigenia, due to its mind-bending appearance. It sported a number of spikes on its back and several legs, but that’s not all. Alongside those appendages, the creature had a bulbous-like growth at the end of its body, too. On that note, experts didn’t know what to think after first looking at the remains.

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Indeed, those within the scientific community couldn’t decide if the spikes on the Hallucigenia’s back were actually legs. And on top of that, they struggled with another intriguing question at the time. Given the animal’s unique look, the experts found it tough to confirm if it had any biological successors.

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Some four decades on from those studies, the aforementioned scientists at Cambridge appeared to have an answer. Javier Ortega-Hernandez and Martin Smith claimed that the Hallucigenia bears a striking resemblance to velvet worms. They made their discovery after peering over the former’s remains, noting that its talons were much like that of the worm.

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Smith went into a bit more detail while talking to U.K. newspaper The Independent in August 2014. He told the publication, “We think [the Hallucigenia could] grow a new set of claws before they shed their skins, which they had to do to grow. A very similar feature is found in the claws and jaws of the velvet worms.”

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“No other animal shares this particular characteristic,” Smith added. “It means that the animals do not have to wait for a new claw to form after shedding their skin to grow – they already have one ready formed.” At that point, the scientist then touched upon the Cambrian explosion from his perspective.

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As Smith continued to talk with the newspaper, he looked to put a misconception to bed regarding the biological event. And in addition to that, the expert raised a couple of other interesting points as well. “It’s often thought that modern animal groups arose fully formed during the Cambrian explosion,” he explained.

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Smith then concluded, “But evolution is a gradual process. Today’s complex anatomies emerged step by step, one feature at a time. By deciphering ‘in-between’ fossils like [the] Hallucigenia, we can determine how different animal groups built up their modern body plans.” Meanwhile, another fascinating discovery was made back in 2018.

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After a lot of confusion, scientists were able to confirm that one of the fossils from before the Cambrian explosion did, indeed, belong to an animal. Prior to that, no one could tell if the remains were that of a fauna, flora or something else entirely. In terms of its appearance, the Science journal likened it to a “quilted bath mat.”

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If you’re wondering how the experts finally came to the aforementioned conclusion, it’s actually quite simple. While studying the age-old remains, they found some cholesterol, which clearly indicated that it was an animal of sorts. As for its name, the organism was believed to be a member of the Dickinsonia species.

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However, the Dickinsonia and the Hallucigenia weren’t the oldest animals from our past, as we’re about to find out. A group of scientists from the Massachusetts Institute of Technology revealed that a different lifeform predated both of them – and the Cambrian explosion. Incredibly, that would potentially make it the planet’s very first animal.

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As we mentioned earlier, the researchers were studying old rocks when they found some molecular fossils. Upon closer inspection, the group then identified one of those molecules as 24-Isopropylcholesterol. Otherwise known as 24-IPC, this is a form of cholesterol, meaning that an animal would’ve been responsible for leaving it behind.

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The key factor in all this analysis was the age of the rocks. Indeed, they dated back some 640 million years, well before the Cambrian explosion. So, keeping all of that in mind, the team were of the opinion that the molecules belonged to a sea sponge, as they’re known to give off 24-IPC.

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To explain more, a member of the group spoke with the MIT News website in February 2016. David Gold said, “We brought together paleontological and genetic evidence to make a pretty strong case that this really is a molecular fossil of sponges. This is some of the oldest evidence for animal life.”

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Sea sponges are fascinating creatures, ranging in shape and size under the sea. While they don’t have any organs or cellular tissue, the animals eat very small portions of food when it comes their way. They don’t actually move in the water, as they’re stuck on the same surface over their lifespan.

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Furthermore, it’s believed that there are up to 10,000 types of sea sponges living today, proving how large their group is. And unlike other animals, they’re able to survive in wildly different conditions around the world. For instance, you’re just as likely to find a sea sponge in tropical waters as you would near the North and South Poles.

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Going back to the study, a professor named Roger Summons offered his thoughts on the findings. He worked alongside Gold as they traced the molecular fossil back to the sea sponge. But as it turned out, this project had ties to the past at MIT, with Summons recognizing that in his comments.

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“This research topic has a 20-plus-year history intimately connected to MIT scientists,” Summons told the MIT News website. “Now, in 2016 David Gold has been able to apply his skills, and the new tools of the genomic era, to add a further layer of evidence supporting the ‘sponge biomarker hypothesis.’”

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With that being said, you’re probably wondering how Gold and company were able to prove that sea sponges had left the 24-IPC behind. After all, who’s to say if they were even capable of making that molecule millions of years ago? Unsurprisingly, the MIT researchers had the same thoughts at the time.

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So, in an attempt to figure it all out, Gold and his colleagues produced a checklist of sorts moving forward. To begin with, they wanted to identify the genetic strand which creates 24-IPC. The group eventually got their answer after studying several lifeforms, honing in on a gene called sterol methyltransferase.

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Otherwise referred to as SMT, this strand of genetic code can’t make 24-IPC alone. In fact, an animal has to carry multiple “copies” of the gene for the molecule to be present. Once the team found that out, it made the search a bit easier, as we’re about to discover.

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Gold’s team realized that algae and sea sponges housed the correct amount of SMT, so they moved to the next phase. The scientists drew up something called an “evolutionary tree,” which charts the changes in recorded remains. At that stage, they tried to spot when the genetic strand emerged in the two organisms.

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In the end, the group from MIT confirmed that sea sponges were ahead of algae on that front. Thanks to the data, they estimated that the former had been creating 24-IPC for about 640 million years. That number obviously coincided with the age of the rocks that were being looked at previously.

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Following that in-depth study, Gold and his colleagues posted the results in an issue of the Proceedings of the National Academy of Sciences journal. It also garnered plenty of attention online, with outlets like the Business Insider website covering the story. And The Independent website shared the fascinating findings, too.

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On that note, Gold then pondered some intriguing points about the sea sponges from millions of years ago while speaking to MIT News. Alongside that, he admitted that researchers still need to find out more information regarding past biological lifeforms, as well. And his thoughts on the subject didn’t conclude there.

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Gold told the website, “[These findings] bring up all these new questions. What did these [sea sponge] organisms look like? What was the environment like? And why is there this big gap in the fossil record? This goes to show how much we still don’t know about early animal life.”

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“[It also shows] how many discoveries there are left,” Gold continued. “And how useful, when done properly, these molecular fossils can be to help fill in those gaps.” Keeping those words in mind, another stunning story emerged in 2019, when a group of researchers saw some significant markings in China.

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With a Virginia Tech professor named Shuhai Xiao leading the way, the researchers uncovered the remains of an old animal on land. They also caught sight of its fossilized “trail” in the ground, too. It was believed to be around 550 million years old, which again predated the Cambrian explosion.

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Speaking to the Virginia Tech website in September 2019, Xiao went into a bit more detail about the findings. He said, “This discovery shows that segmented and mobile animals evolved by 550 million years ago. Mobility made it possible for animals to make an unmistakable footprint on Earth, both literally and metaphorically.”

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“Those are the kind of features you find in a group of animals called bilaterians,” Xiao added. “This group includes us humans and most animals. Animals and particularly humans are movers and shakers on Earth. Their ability to shape the face of the planet is ultimately tied to the origin of animal motility.”

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That discovery actually tied into something else that Gold mentioned back in 2016. He claimed that there were more complex lifeforms living on the planet before the Cambrian explosion than you might suspect. The scientist also admitted that it was tough to tell if they evolved beyond that, but the molecular fossils could be a big help.

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Gold told MIT News, “There’s a feeling that animals should be much older than the Cambrian [explosion], because a lot of animals are showing up at the same time. But fossil evidence for animals before that has been contentious. So people are interested in the idea that some of these biomarkers and chemicals, molecules left behind, might help resolve these debates.”

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