Some questions on evolution

[Anomalocaris]

Hi , I have only a layman's knowledge of evolution and have a few questions that nobody has ever been able to answer, hoping some knowledgable folks here might help me out.

1. I know that the exact mechanism of how life started is not yet known. What seems certain though is that it started surprisingly soon after the earth got created, life was just busting out all over. My question is this: obviously conditions must still be OK for life, otherwise we would be a dead planet. So why is new life not busting out spontaneously all over so we can see it happening?

There are two reasons.

1. Time scale - earth is 4.6 billion years old. If new life busts out somewhere on earth once every 1 million years, it would still have had done so 4600 times in the life of earth. But modern science is only 300 years old. The chance of it having happened once to be observed during the existence of modern science is 0.03%. The chance of it having happened where science happen to have been looking is much less still.

2. Opportunity - any life to just bust out is almost necessarily the least well adopted life that could possibly be called life. Any survivor from any previous busting out of life would have had a lot time to improve its adaptation to the environment. So one would expect once a single instance of life busting out have succeeded, its descendants would rapidly gain an insurmountable accumulation of evolutionarily advantages over any future life to come. So unless some environmental catastrophe were to be so complete as to wipe the slate completely clean, we would expect very few, possibly only one, instance of life busting out to leave any descendants. All subsequent instance would be overwhelmed and wiped out by the better adapted descendants of this one instance almost as soon as they arise.

2. It seems to me that there is a sort of drive towards more complexity. Why is this so? Or am I wrong? I mean, Viruses and Bacteria and Archea are successful ubiquitous organisms. What made them develop into more complex forms of more and more complexity, inventing sex and self awareness, intelligence along the way and all, until eventually we get to Mila Kunis?

I think that's enough to be going on with.

Uh, no.

1. The overwhelming majority of life on earth consists of simple one called organisms without cell nucleus. This has been the case since shortly after life we recognizes first arouse, and continue to be the case today. Whether you measure by the number of individuals, or by total biomass, the vast, overwhelming majority of life on earth has not gotten nearly as more complex as you might imagine. The dominant theme of life on earth, once we get away from our egotistical focus on what we can see through our naked eye, is one of conservatism. Only some plant and animal flotsam upon the vast ocean of conservatively simple bacterias have gotten steadily more complex.

2. In so far as life on earth have gotten more complex, complex often, but not always, pays in evolutionary competition. Complexity allows division of labor, and allows more focused, as well as more sophisticated, adaptation. As a result, complexity allows organisms to become better able to survive specific environmental stresses. So long as some complexity pays some times, some organism will steadily get more complex.

3. But complexity do not always pay, even for organisms that have gotten more complex in the past because complexity have paid in the past. As a result, there are numerous examples of formerly more complex organisms losing complexity. Take for example the sea squirt. So even for the complex flotsams floating upon a sea of simplicity, there is no steady progress towards greater complexity. Some become more complex, some stay conserved, some become less complex. So as a net result, Some did get more complex until, let there be Steven Hawkins or mila kunis. But many stays chimpanzees. Some, like the sea squirt, regressed back to bing Kirk Cameron's or Ken Ham.
So there is chance and opportunity allowing, but not drive towards, complexity.