Planet Earth is around 4.5 billion years old. Various interstellar turmoils and the constant interplay between dark matter and other matter in space that took place millions of years after the Big Bang formed this planet we call home. What was the first thing on the third rock from the Sun?
Well, the answer is exciting as your imagination allows it to be: rocks are the structures that shaped first after Earth was no longer a hot ball of lava floating in space. However, not only are the stones we walk on today old, but they are also most commonly a home for fossils that are millions, or even billion years old.
There are numerous findings across the planet that tell us the stories of how old the rocks are, and how old were some of the first life forms that appeared on Earth. For example, some fossils found in Australia suggest how they are actually the remains of something that had the capacity to use the energy coming from the Sun, nearly 3.5 billion years ago.
The so-called microbial fossils from Downunder, are not even the oldest we have dug up. In Greenland, scientists have found fossils of cyanobacteria. Although these are very small, and indeed elementary forms of life, they have formed colonies in the form of stromatolites 3.7 billion years ago. In 1996, some evidence was found on something that could be at least a hundred million years older, but it is still a mysterious microbe.
First Life Forms
As there is more evidence being found every year in rocks and fossils that continue to stretch how old first life forms really were, it is hard to give a definitive answer when did first life forms appear.
The different bacteria types mentioned above already started to form more complex structures, but possibly the first thing that could be considered as an organism were prokaryotes. Scientists suggest how prokaryotes appeared 4 billion years ago as simple microorganisms of a single cell.
One thing you have to remember is how different the conditions were on both the surface and the atmosphere of Earth. It was scorching for millions of years, the last Ice Age finished just 12,000 years ago, and the amounts of oxygen were nowhere near the levels we have today. With that in mind, the Hadean Eon was a tough time to be alive, when even the meteorites were still flying around and crashing into the surface.
Water did appear relatively quick on the surface, but only due to the effects of the vaporization of everything that was on the surface. The atmosphere was unfriendly, or at least it would have been for us back in the day, as it mostly consisted of carbon dioxide.
While we still search for answers, it is worth noting how there is already substantial evidence of zircon crystals forming 4.4 billion years ago. This suggests how the conditions in the Earth’s earliest days were maybe not so adverse, relatively speaking, and that those zircon crystals are Earth’s oldest friend. Or its first creation, if you wish.
About the Author
Antonia is a sociologist and an anglicist by education, but a writer and a behavior enthusiast by inclination. If she's not writing, editing or reading, you can usually find her snuggling with her huge dog or being obsessed with a new true-crime podcast. She also has a (questionably) healthy appreciation for avocados and Seinfeld.
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