Since the beginning of our journey on this planet, humans have been fascinated with our origins, why we are living, and what the purpose of our life is. With Life developing 3 billion years ago from the simplest forms of cells into the complexity we’ve reached today, the question of how we got here still exist. Here’s a look at 5 theories of how we came to be.
1. Protected by Ice
Ice may have been covering the earth’s oceans 3 billion years ago, the layer of ice that could have possibly been hundreds of feet thick, would have helped molecules survive longer, allowing reactions to take place. Also the ice might have shielded fragile organic compounds that were in the water from ultraviolet rays and cosmic impacts.
2. RNA world
The RNA world theory proposes that RNA molecules aided in creating DNA and proteins that were necessary to form how we are today. RNA still performs several roles in the processes that translate genetic information from DNA into protein products. It is generally accepted that current life on Earth descends from an RNA world, the question of how RNA got here still remains with some scientists believing the molecule spontaneously arrived on Earth, while others think it was unlikely to have happened.
3. Simpler Start
As opposed to the complexity of the RNA world, some scientist believe life might have begun with smaller molecules interacting with others in cycles of reactions. These molecules could have been contained in capsules akin to cell membranes that over time evolve into more complex molecules.
4. Deep Sea Vent Hypothesis
The deep sea vent theory posits that life began at submarine hydrothermal vents, where hydrogen rich fluids emerged from below the sea floor. The rocky nooks of the vents would concentrate these molecules together and provided mineral catalysts for key reactions. Even today these vents, rich in chemical and thermal energy, sustain vibrant ecosystems.
This proposes that life didn’t begin on Earth, but was brought from somewhere else in space distributed by meteoroids, asteroids, comets, planetoids, and by spacecraft, that were harboring microscopic life forms that can survive effects of space. When these life forms meet ideal conditions on a new planet’s surfaces the organisms become active and begin the process of evolution.