How Did Life Originate On Earth?
| We all know where babies come from (cause I'm not explaining it!), but how did the first organism come about? Which came first, the chicken or the egg? If everything needs at least one parent, where did the very first parent come from? These are all questions that have no certain answer, and all lead to more questions. This is also the part when Paleontology merges with Chemistry. |
| Before modern science took over, it was believed that a creator, or "God" created all complex forms of life by hand, and other life, such as frogs and bugs, could appear spontaneously in mud. It was one advance when Louis Pasteur proved that life can't just spontaneously appear by itself, not even the simplest of species. Then, once Darwin came up with The Theory of Evolution, it became clear that, all it would take was one living thing to eventually form all of the species we know today. This living this is called the last common ancestor. |
Louis Pasteur
| So, how did the last common ancestor get on Earth? One theory is that life was carried to Earth on an asteroid from elsewhere in the galaxy. Even if this is true, it still doesn't explain how life was formed originally. So we turn to another theory. |
| Let's talk Chemistry. We know that that, in order for something to be called alive, it needs these characteristics: It can turn food into energy, It can reproduce, It has a limited life span, It can grow and move, It produces waste, and It responds to it's environment. We also know that all life forms are made up of and run on, the same chemicals. DNA and RNA to tell the life form how to run itself, and what to pass on to the next generation, amino acids, and proteins. Basically, the building blocks of life are all a bunch of chemicals. Maybe, if the right chemicals got together at the right time, life could form? |
| In the 1950's, Stanley Miller, working at the University of Chicago, did an experiment. He tried to replicate the environment back how it was when life first appeared a billion years ago. He filled the bottom part of a flask with water, to represent the ocean, which he heated, forcing water vapour to circulate. In the top, he tried to create the atmosphere, by adding methane, ammonia, hydrogen, plus the water vapour that was circulating. He then ran an electric charge through all the gases, which was to represent lightning. This caused all the gases to interact. The products of that which were water soluble passed through a condenser into the water. The outcome of the experiment had produced many amino acids, the building blocks of life. He was not able to create actual life, however. |
Miller's experiment.
| If the conditions in ancient times were able to produce amino acids, these could somehow get together to form proteins. If you have all these chemicals of life floating around in the ocean together, probability says that eventually, given enough time (millions of years) the right combination might, by chance, get together to produce a single life form. If this one organism survived long enough to reproduce, it could eventually fill the whole ocean with it's kind. Then, just leave it to evolution to change it into a dinosaur or a human. |
| This is the big theory on how life originated on Earth, even though scientists still question it and disagree with it lots. Remember though, it is just a theory, meaning it is the best we have until it is disproven. Maybe someday we will know for sure, or maybe we will never know. The fact is, somehow, life appeared, it doesn't matter how. You are here. Maybe things were different back then, so we will never be able to figure it out. But somehow, life was formed, so there must be some sort of scientific recipe for life. |
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