Life is a mystery. We don’t know how it started, we don’t know what it means. Though we may try to convince ourselves of its meaning by making up wonderful stories, reality seems mostly hidden. We have no clue how life took that first little step, eventually persisting and evolving over millions of years that followed. So, here we take a tiny glimpse of the history of the planet earth which has bore and nurtured this delicate entity that we call life.
Rewind 4.5 billion years: the solar system has just formed from a cloud of dust that collapsed. Most of the collapsed mass is at the centre of the system and has formed the Sun, around which revolve hundreds of rocky masses. These are constantly colliding, sometimes clinging to one another and forming larger rocks, and at other times shattering into tinier ones. Such repeated processes eventually lead to the formation of larger masses called planets. Our Earth was one of them, but it was nothing like how it is today.
The surface of the earth was but a sea of molten rock. It’d take some time until the surface cools and solidifies. Even after the cooling, there’s a lot of heat trapped beneath it, which often erupts out in the form of volcanoes. The gases from these eruptions will form the first atmosphere of earth. But still, there’s no water, no oxygen, and no chance for life to thrive.
It was the icy meteors which entered the earth from outer space that introduced water into our atmosphere. With clouds formed, there was rain. And the earth harbored water on itself for the first time. But the presence of water only facilitates life; it does not necessarily imply the origin of life. Then how exactly did life begin?
As we said before, we don’t know how it all began. Different people have guessed different explanations. Some say it was the lightning bolts from the skies, some say it was the deep sea vents underneath. Some even say that the comets that brought the water also brought the first microbes and life evolved. And some say it all happened in the most natural manner – inch by inch, molecules got more and more complex, with repeated reactions, going from single atoms to single cells to complex multicellular organisms capable of reproduction.
The bacteria that so formed turned the sunlight and the carbon dioxide that was available to them into oxygen (a process we now call photosynthesis). They produced oxygen in such large amounts, that newer life forms that evolved thereafter, based their existence on the consumption of oxygen. With the stage now set, life evolved, becoming increasingly advanced, and from what began as the complexity of our universe came about a system just as complex within every single one of us.