Week 3 - History of Life

 This is my third entry for the third week. This week, I started learning a new topic, "History Of Life". When talking about history of life, I would imagine dinosaurs, huge tress, hawks and some wild extinct creatures. But in this topic, I think I learn beyond my imagination. Primitive Earth is not only about dinosaurs, yet I am sure there is must be something that even scientists cannot explain. Anyway, this topic capture my heart most because it is history about "life". I am emphasizing life as I would really want to know, how did life begin. The Earth's age was about 4.9 billion years! So, within a very long time, what had happened on this Earth? At first, was there fully equipped with all our basic needs and when did humans start to inhabit this Earth? Tonnes and tonnes of questions drive me to know more about history of life, Most of my questions, had the answer revealed in this topic we were learning.

 The Earth was just a desert once. There was only small inorganic materials such as carbon dioxide, nitrogen gas and water but then chemical evolution had took place and organic molecules formed. Then, biological evolution happened which contributes to life. That was only the rough idea of how life begin pathway. Organic molecules sprung from inorganic matter through a natural mechanistic process on pre-biotic Earth called chemical evolution. It was divided into two ideas. First is the organic molecules could have formed from smaller molecules present on primitive Earth either very slowly within a long time or rapidly before the Earth cooled down (Prebiotic Broth Hypothesis). second, asteroids may have brought them from outer space. But then, Miller and Urey made an experiment and proposed that organic materials formed near Earth's surface.

The very new information that I have got is, RNA is the first genetic material and not DNA! I always think that DNA is the starter of all this genetics matter, but not after knowing RNA World theory. Why RNA is the first to come? Because it can copy themselves in solutions containing nucleotides without enzymes. Then we learnt about protobiont evolve that lead to a modern cell. Basically, protobionts are aggregates of artificially produced prebiotic molecules .  I have encountered an exciting fact that the first protocell was only a sac of water and RNA. The look of protocell must be very cute and simple!  Successful protobionts will grow and split, and passed down their heredity. But only then, the natural selection has picked DNA over RNA because of the stability of DNA.

Lastly in this topic, we learnt about systematics, taxonomy and classification. I think that we should say million thanks to Caralus Linnaeus because he was the first to develop and publishthe first comprehensive and consistent classification system for both plants and animals. He makes our work easier and arranged.