When we start discussing Evolution first thing that comes in our mind is Dinosaurs. But evolution is only the story of dinosaurs, no it is not correct. There are many theories of evolution one of them is the very famous "Big Bang" theory. This theory is based on a singular huge explosion. Now you may think, Wow!! we all know this concept. If you know that, very well. Actually, there are many controversies over this topic. Every thinker, philosopher, Scientist gave different theories. Like 'Theory of Special Creation', 'Theory of Special Creation', 'Theory of Biogenesis' by famous Louis Pasture, 'Cosmozoic Theory', and many more.
Now, you may add your theory also, because all these theories are not able to give us the proper idea of evolution. By that time scientist, Oparin and Haldane came into the market. They gave their hypothesis which suggests that life arose gradually from inorganic molecules, with “building blocks” like amino acids forming first and then combining to make complex polymers. After this scientists got a more clear idea about evolution. Then in 1953, S.L.Miller did his very famous experiment (maybe you heard about this in lower classes in your science book, it's boarding actually).
When the earth was formed, the temperature of the earth was very high. There was no oxygen only H2, CH4, NH3, and water vapor. Miller created similar conditions in his lab and performed the experiment and that's why he got success. Now, one question that may arise in your mind what is the ratio of CH4:NH3:H2 gas in his experiment?? So, it is a very common question in every exam if you studied science in your childhood. Every time we (me also) forgot the ratio and every time teacher deducted our marks also : ). Okay, the magic number 2:1:2 is the secret story of some of us.
So, from the very beginning, I am discussing some boarding things. Just try to imagine now at present our earth and 4.5 billion ago earth, both are very much different.
Imagination has no boundary. Almost 3 billion years ago the first non-cellular form originated (microsphere, coacervate). After that first RNA and then DNA and after that a cell and by this way after 1.5 billion years ago free-living eukaryotes appeared. Wow, what a journey!! Many of you also know that first life appeared in the water and then it came to the land. Yeah, by this way slowly we animals and trees came into this planet. If you studied science in class 12th, then you may come across a chapter called "Evolution"(Very much Dangerous questions came in the board exam from that chapter).
Let aside the story, just imagine a few million years ago our ancestors fought with wild animals and we are now chilling with our friends, doing parties and watching Netflix. Actually, toady's lions and 10000 years ago linos were different. Our ancestors were also different than us, actually, this change is called evolution. Like early reptiles and then synapsids then pelycosaurs .... then human ancestors like Dryopithecus... Australopithecus...Neanderthal man...then "WE". So, it is human evolution.
So, evolution is a continuous process, after 4-5k years earth may be changed to a different planet also, which no one can predict. But one thing we cannot ignore is that we are just hosting on this earth. Imagine some guest come to your home and demanding all kinds of stuff and also damaging those, then you will be angry naa!! So, as human beings, we should not use earth in such a way that all things will change on earth and it will be converted to a desert.
Human evolution is very interesting, especially one interesting fact is that human Brain and Language evolved parallelly. It is a very vast topic but I hope you may understand the evolution behind our" Existence". If you want to know more about evolution then, let me know in the comment section, I will definitely explain that.
Thanks for your valuable time.
