Nothing, of course, begins at the time you think it did.
I listened to a fascinating podcast a couple of days ago. It had to do with evolution, and the transition on Earth of living forms from fishes (of the water) to creatures who lived on dry land. Perhaps you, like I, have come across some pictures in the media in this regard that try to illustrate the concept in a easy to follow manner. The illustrations could include a body of water on one side and dry land on the other, and show a series of creatures emerging from the water onto the dry land, with the nature of the creatures changing form as you sequence them from the water on to the land. At one end of the sequence you will find a fish. At the other end you will find a human being. Here is an humorous example.
Of course, the pictures do not represent anything close to reality. The transition from fish form to human being took place over hundreds of millions of years and not in single picture frame – obviously. The process was also very complex, and impossible to capture in pictures like this. Also, if I understand correctly, there were simpler forms of life on earth before the fish. Nevertheless…
When scientists study evolution, they try to find evidence of the transitions from one kind of life form to another. This is the realm of the paleontologists. This is a fascinating subject, especially when you are dealing with the study of fossils/skeletons of lifeforms that existed hundreds of millions of years ago. It seems that we know enough about the geology of the earth and the ancient land forms that used to exist in those days, including the mountains, rivers, and oceans, to have some idea as to where to look for pieces of evidence of life from those times. And, surprising to me, there are such land forms, from those times, that are accessible to us easily. For example, there was a section of the Pennsylvania turnpike that was built by blasting a path through a mountainside that revealed rocks over 350 million years old. These rocks revealed preserved fossils from that period of time. (Human beings are capable of destroying our sources of knowledge without even a second thought in our quest for progress and all things “modern”, including mindless and unlimited convenience and speed.)
The reader will surely agree that, as part of the evidence of the evolution that took place, it would be great to find the lifeforms that represent the transition from a form of life that existed solely in the waters to one that lived solely on land, i.e., the fish to tetrapod transition. You may be surprised to learn that the first of this evidence was only discovered in 2004. This life form was given the name Tiktaalik (for reasons you will discover if you follow the links I am providing). The scientific process in this case allowed the scientists to narrow down the time-frame of possible existence of the kind of creature they were looking for, and then look for places where they could access the right kind of rocks of that particular period of time in order to search for the creature. They were successful in their quest.
My blog includes only a small part of the things I learnt from the podcast that I listened to. There is no way I, with my limited understanding, can do justice to the subject matter in a blog. Hopefully, I have stirred your curiosity, and motivated at least one or two of you to also listen to the podcast. Science is fascinating!