Humans have always been fascinated by the possibility of life on other planets. We love shows like Star Trek because they fill gaps in our knowledge of extraterrestrial life forms. But many scientists and astronauts believe that to delve into extraterrestrial life, we must first look at Earth.
How the Earth evolved could give us clues about what kind of life form was there – if any – and how it came to be. Earth is home to thousands of plant, animal and even microbial species, all of which have one thing in common: their energy needs. Yes. The primary reason for nearly every living thing on Earth—from bacteria to humans—is to gain energy.
You’ll find both the smallest and most abundant organisms at the most fundamental levels of life: bacteria and single-celled microbes. Bacteria can live anywhere—deserts, jungles, inside and outside of people, even on frozen mountains where nothing else can live—because they eat everything. If any object has stored energy, bacteria will find a way to use it up. Case in point: the sunken World War II battleship currently lying on the seabed is covered in iron-eating bacteria.
Elsewhere on Earth, the Hang Son Doong cave complex in Vietnam sees hardly any light, but lush vegetation grows on the cave floors, consuming all the energy they can get. As you get to know more complex creatures, a camel might seem alien if you’ve never seen it before. But like bacteria and burrowing plants, camels are built to survive. They have wide teeth to help them eat, and a fat-filled hump to conserve energy for long periods of time.
Life forms found on Earth have adapted to their environment. Maybe this happens on other planets too. But how did life on Earth begin? For billions of years, microbes lived side by side, eating everything — including other microbes — until one microbe ate the other without digesting it. The two merge and become mitochondria — also known as the cell’s power plants.
This changed history. These simple organisms evolved into something more complex and, while interconnected, began using oxygen for energy. After another two or three billion years, they evolved into humans.
The Earth can evolve in many different ways, but the way it eventually evolved made the Earth and everyone on it the way we are today. As for extraterrestrial life forms, it is unlikely that another planet like ours will emerge.
So if we encounter aliens there, they might be quite unusual. No, we won’t encounter two-legged Vulcans like Mr. Spock, but we might encounter simple life forms like bacteria and other single-celled microbes.
Directed by: Nat Sharman
