Evolution Strikes Back.
Once upon a time in a galaxy......well right here, we evolved. In fact there is evidence everywhere. So much so that I want to go over it. Not just the evidence for evolution, but a lot of how and why.
I often get the age old question of how life first began. Well I will give you a picture, a good hypothesis, and some examples. The rest is up to you, believe it if you will. Ignore it if you don't.
Primordial Earth was not like today. Not even close. Imagine a world that was void and dark...oh wait that is someone else's story. The Earth was a mass of hot lava and pools of sulfur, hydrogen was plentiful, and there was some water. Nothing we want to drink. Our solar system is still in turmoil with meteors still crashing into the planets. In fact there was no moon yet. Just a hot mass. The earth was cooling though, and stagnating pools of toxic sulfur water lay all around. Nothing was alive here, yet. And then it happened. Life. Now scientists have found nucleotide bases in meteorites. Nucleotide bases are part of your DNA. They have also replicated in strict lab settings, what primordial earth would have been like. Out of that they created amino acids. The substance needed to make protein. In fact they were able to show how it could split easily. Life that would have come first here on earth was not complex. I would have to be simple, and we know that because of the fossil record.
Speaking of fossil record, the makings of a living world came next. We begin finding simple life. Now any single celled organisms were soft and left no trace of being here, but what we do find is suddenly oxygen was here. The world went from being a lifeless blob, to having very simple life. Some of the first sea creatures found are very simple. Yet next we move to trilobites (we have found 50,000 species) and then it seems everyone wanted a shell. Monstrous fish begin to appear in the fossil record. Ones with big teeth, or pincher's. Ones that had many legs and fins. Ones that had many many fins. Huge horrible looking things. Evolution seemed to take off like a shot.
Soon we find fish like Megolodon. He made a great white shark look like a snack. Plants become more varyiated, and so do the species living under the sea. The fossil record shows life was over abundant. By this time the Earth had a moon, and pretty much the orbit we do now. Though the tilt was a bit different. Everything was going along fine, and then, nothing. Something wiped out almost all life on earth, and life had to take off again.
Evolution took off anew and tetra pods formed. This means four legged animals. Now the fossil record shows that first was fish and then fish like land animals. Once tetra pods formed, next was amniotes. This is where mammals split off from dinosaurs.
So from fish to four legged creatures, we began the slow walk through time. Slowly primates evolved from simpler mammals. At some point a common ancestor to the chimp diverged and a few humanoid species were born. First Australopithecus Africanus, then Homo Erectus, Then Neanderthals, and than Homo sapiens. On an island another species of hobbit like humanoids also evolved. Probably from humanoid ancestors who evolved to the environment of the island.
Now evolution has always had a helping hand. That is mutation, speciation, and gene flow. Mutation means a small change has happened somewhere in the DNA. Now that mutation does not always benefit the species and it does not survive. Other times it is just what the species needs to thrive. This can mean a longer beak, longer legs, and in humans becoming erect.
Speciation means over time as two similar mammals begin moving in two directions they often get more and more distant from each other. As they get more distant it becomes harder and harder to interbreed. Until finally due to environment and biological changes, the two can no longer interbreed, and are separate.
Gene flow is a species migrating from one place to the other, spreading out as it goes. As the genes flow from one place to the next, a new environment might mean some slight changes, and result in a new species.
It is through subtle changes that humans came to be. We currently have six thousand fossils of human evolution. Not to mention a complete fossil record of horse evolution. We have dinosaur fossils that lead us to modern birds including feathers. We have plants and microbes found in glaciers. The amount of evidence for evolution is astounding. Though we may not know what sparked the first life, since then there has been a long trail of fossils leading to modern day. As we learn more we find how close and yet far we are from those creatures of the past. After all DNA holds the whole story. In four letters it spells out the code for a long line of change, and while we may lose a few genes off our switches, we still hold an entire history wound tight in a code that takes up ten books. One tiny strand that tells so much about the history of the whole planet.