A defining feature of our world is life. To our current knowledge, Earth is the only planet that has that.
Despite the destruction of the environment, life is still present in every corner of the world, even in the most extreme places imaginable…
For all we know, Earth is the only planet with life. But how did it start? (Illustration image: PxHere)
But why is that? How did life begin on Earth? What sequence of events led to the emergence of birds, insects, amoeba, and humans?
In fact, figuring out how life began on Earth is much harder than filling in the missing chapters in the world history book. This question also leads to other big questions: How rare is life on any given planet? What is the probability of life appearing on any planet?
Unfortunately, we don’t have all the pieces of the story of the origin of life. But what we do know shows that this story has a very wide scope, and it also takes us on an adventure back to the original time of the world.
It all starts with water.
1. Where does the water on Earth come from?
There is no clear answer to the question of where Earth’s water comes from. (Photo courtesy: Flickr/Andrea Della Adriano)
To find out why there is life on Earth we have to start with water, because it is the only thing on Earth that all life needs. Different life forms can survive on wildly different food sources, but no species can survive without water.
But it is strange that scientists still do not fully understand how water has covered two-thirds of the world’s surface and created the first conditions necessary for life.
The problem is that when the Earth was forming, it was extremely hot. Therefore, the water that surrounds the surface of our planet will at first be evaporated.
Lydia Hallis, a planetary scientist at the University of Glasgow, told Unexplainable’s Noam Hassenfeld: “So how do you get so much liquid condensate on the surface of a planet that should be very, very much? hot?” .
Scientists may have thought of several possible explanations. Could water have been delivered from comets that collided with Earth? Or, more strangely, do we only have water due to an extremely random event of the planets, such as Jupiter moving toward the Sun from the outer edge of the solar system? Or was the water somehow buried deep inside the early Earth?
2. How did life begin on a water-filled globe?
Even single-celled organisms can be incredibly complex. So how did life first form? (Artwork: Flickr/FWC Fish and Wildlife Research Institute)
Once water appeared, life was probably also present. Therefore, it is possible that life did not begin on Earth at all.
But if scientists doubt it, it’s justifiable.
For decades, scientists have been trying to recreate in the laboratory the conditions of the Earth when it was first filled with water. The idea is that, if they can mimic the conditions of the early Earth, perhaps they will eventually be able to create something similar to the simple cells that first formed on their planet. billions of years ago. From there, they were able to assemble a story about how life began on Earth.
This direction of research has demonstrated some amazing successes. In the 1950s, scientists Harold Urey and Stanley Miller showed that it was possible to synthesize the amino acid glycine – that is, one of the most basic building blocks of life – by mixing a number of gases was filled with the atmosphere billions of years ago, with simulated temperatures and lightning.
Since then, scientists have been able to create blobs of lipids that look a lot like cell membranes. And they made RNA molecules form, just like simplified DNA. However, scientists have not yet been able to get all the ingredients of life created in the lab and assembled into a single cell.
So what’s in the way?
What if scientists really succeeded and created life in a bottle? They can uncover not only the story of the origin of life on Earth, but also come to a shocking conclusion about how common life is in the universe.
3. So what is life?
We still cannot define life. (Artwork: Pexels)
No matter how life began, we know today that it is pervading the Earth. We recognize life when we see it. But do we know what life is basically all about?
The answer is no.
Carl Zimmer, science reporter and author of Life’s Edge: The Search for What it Means to be Alive, says: “No one has been able to define life yet, and some will tell you it does. is impossible”.
We have no shortage of efforts to define life. “There are hundreds of definitions of life that scientists themselves have published in the scientific literature,” says Zimmer.
The question of what is life sounds easy, like something a fifth grader could answer. “It seems like an easy question because we feel life,” says Zimmer.
Our brains are actually tuned to recognize things like biological movement. We have the hardware to detect life. But that doesn’t mean we’ll know what it is.”
The problem is, for every definition of life, scientists can think of an exception that makes that definition wrong. For example, NASA’s definition of life: “Life is a self-sustaining chemical system capable of Darwinian evolution.” But this definition would exclude viruses, as they are not “self-sustaining” and can only survive and multiply by entering a host.
On the one hand, the definition of life will be very useful when we look for signs of it on other planets and moons. But on the other hand, how do we know that we have found life? Because as Zimmer explains, we probably can’t define life at least with current knowledge.
