Saturday, May 7, 2016

Intelligent Design and Evolution

In a previous post, the situation where an alien civilization becomes smart enough to conquer the challenges posed by genetics and other biological intricacies, and becomes able to design complex life forms and bring them into existence was discussed. For that civilization, evolution was the old way of life forming, and served just as a database from which they can unlock some secrets of genetic coding.

It is quite possible that the same or a similar alien civilization would take on a much more difficult and much more tenuous project, that of seeding life on a previously lifeless planet. This is the most extreme seeding scenario that an alien civilization could undertake. More moderate ones might have them tampering with the genetic codes on some planet where life had already originated and progressed, up to some plateau. The alien civilization could be the way that life on that planet overcomes the plateau and leaves it behind. But surely the most difficult situation of all is one in which a lifeless planet is chosen by some alien civilization as a new home for life.

In another post, alien civilizations were divided up, parameterized so to speak, into categories that related to what their goals were for space travel. They ranged from colonizing sweet spot planets with their own civilization all the way to colonizing lifeless planets with life of some sort. Also included was the null goal of doing no space travel at all. Recall that the question of why a particular alien civilization would want to do this is not answerable by logic and reason, but only by accident of history. Alien civilizations all find out they have no destiny, except what they set for themselves. Some may choose spreading life around the galaxy.

We on Earth are very, very far from understanding if this goal is even possible, but that does not prevent us from thinking about it. Is it possible that an alien civilization could start life on a lifeless planet, one that would, except for their intervention or that of some other alien civilization, never have even the simplest single cell biological organism living and reproducing on the planet. In other words, are there planets which could sustain and evolve life, without ever having been able to originate it? If the origination process is really a fluke of one or more rare events happening, then it could certainly be possible for life to continue where it could not start.

In this blog, the early life origination hypothesis was discussed, in some detail. This involves the changes in a planet that might happen if there was a planetesimal impacting it, at the right time in its age, at the right mass, speed, center of mass distance and direction of motion. The composition of the planet and planetesimal have to be right, and of course the planet has to stay in the liquid water zone (LWZ). Suppose there is such a rare combination of conditions that has to exist in order for life to originate. If the planet were never impacted, but simply continued to orbit its star in the LWZ, it might have enough free energy its oceans from volcanic activity to provide energy for some chemotrophic cell, and have enough chemical resources in the ocean for reproduction as well. Maybe some special regions or areas, such as mudflats or the vicinity of sea vents were necessary for life to survive and reproduce. If an alien civilization could predict such conditions, and scan their nearby exo-planets to find some planets that had them, they could send over a simple probe able to inject such cells into the right areas, and then go and plop into the ocean and rust to bits.

If you were tasked with doing this project, you would want to know as much about the target planet as possible. In yet another post, what could be seen with a large spaceborne telescope, or an array of them, was investigated. Quite a lot can be seen, but the limits were drawn on the wrong side of the pre-existence of life question. It would likely not be observable from remote distances whether or not there were already chemotrophs floating around in the seas of the target planet, enjoying themselves and making themselves busy with evolving into something even better.

If life cannot originate without having a large moon still hanging around the planet, this would make the problem simple. Something like a large moon would be easily observable. So, if the impact hypothesis is correct, and conditions are so stringent that an orbiting moon has to be left in place in order to have origination of life, then they would know.

If there was no moon, then they would have to face the question of their own uniqueness. If the galaxy had lots of alien civilizations like them, looking for planets to seed with life, they wouldn't know if their chosen target planet had already been visited a hundred million years before by a seeding probe from another alien civilization, which was successful. Since the transition from chemotrophs to photosynthetic cells takes that long, there would be no observables left over for them to see.

They could decide to send an initial probe, able to take samples from whatever location was the known habitat of chemotrophs, and then send messages back to the home planet saying that the planet was pristine, or somebody had already gotten there first. However, this would be a waste of resources. Such a communicating probe, with such investigatory powers, would probably be much more massive than a simple seeding vessel, so the most efficient and economical path forward would be just to send the seeding vessel outwards. Nothing would be lost. They could not expect to find out if their seeding venture worked, because working involves a very long wait time. Evolution has a scale of a billion years, and if things go wrong after the first two or three hundred million, the target planet reverts to lifelessness, just as it had been before the seeding venture. So the benefit to the seeding alien civilization is not the self-congratulations for a job well done, life started anew, but instead in knowing that they took a gamble on preserving life in the galaxy, and maybe it took.

There is no hope for the home planet to be able to predict their own success at seeding. A billion years is so long in terms of galactic events, and even stellar and planetary events, that stochastic effects swamp any attempt at prediction. Just consider trying to predict if a supernova was going to go off within lethal range of the target planet. Type 2 supernovas come from stars with short lifetimes, and the gas clouds in the Milky Way would make such a star, and then it would move around relative to a circular motion around the galaxy with some additional random velocity, interacting with both the general gravitational field of the galaxy, which is not uniform, but also with the gravitational attraction of other stars. Where it would wind up when it was ready to blow its top is totally unpredictable. Even the location of type 1 supernovas wouldn't be predictable. The same holds for many other perils. Thus, the alien civilization is not in the seeding game for glory in its own lifetime, but for the sense of trying to do what the thing they should do, according to their own memes.

There are a lot of pieces to the puzzle of whether such a venture could be undertaken with a good chance of success, or whether it is simply close to impossible. Perhaps we can, at some later date, figure out some of the options. Until then, we have to still consider we might have been the target planet. If some alien civilization took an intelligent design for a single celled organism and deposited here on Earth some millions of years ago, rather millions of centuries ago, and then depended on evolution to produce us, we should thank them for the gamble.

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