When I come around

I tend to dwell a lot on everything that concerns being human. I mean, what combinations of minor and major evolutionary processes have led us to this character state defined as a Homo sapiens? Things like this can easily keep my nights sleepless. You know the saying if a tree falls in the forest and no one's around to see or hear it, did it ever occur at all? If you say no, then did the world really exist before your first memory? Even better: did the world exist before the one and only "I think therefore I am" species (i.e. us) came along?

If you leave out philosophy and creation myths that place humans in the center, then yeah, there was something here before us. Actually, there were a lot of things here before us. Some, like liverworth are still here today but more species that you could ever imagine have walked and inherited the earth in thousands (or millions!) of years before us, until some cryptic event made them head towards extinction. If you dig around in the earth's crust you may come across some fossils, but we will never ever be able to know all the creatures that have existed (or that will exist in the last million years of this planet, but that's another question).

Predating the waters of the Cambrian period was a strange little being named Opabinia regalis, belonging to a group of animals that have no decendants living today. The fossil record claims that it was up to 7 cm long, had five eyes and a really remarkable feeding part of its body (which makes me think of the offspring of a trilobite, elephant and a vacuum cleaner). The Cambrian period flourished with life forms in many, many versions but this period ended with the greatest mass extintion ever, leaving behind a fraction of species that later evolved into the various life forms we are today.

I may add that the fossil record is based on fewer than twenty fossils. Now, think about a present species that's fairly abundant in our world and have been so for a couple of hundred thousand years. Imagine that only a fraction of these were fossilised and only 15 of these were discovered by some future creature that has a bias for investigating the world's history. Will that say anything about all the other species that exist today? Not really... More fossils of other species might give more but we will never know it all. And that's what's keeping me up at night. Maybe it's a weird extension of being a control freak, but it really bugs me to know that I will never know how things have been before I came around.

Sources:

Evolution. An introduction (Stephen C. Stearns and Rolf F. Hoekstra). Second edition.

http://en.wikipedia.org/wiki/Opabinia