Evolution is one of those common ideas so often discussed that you cannot grow up without learning about it. In a nutshell, it’s the idea that beneficial mutations are selected by fitness competition, allowing a species to gradually adapt better to its environment. The concept is not that a species keeps getting better and better, but that it becomes better suited to the environment it lives in, so it can survive and reproduce better. It has nothing to do with the generation of greater intelligence, except so far as intelligence is a general tool that helps organisms with it to survive and reproduce. For a species that is living in an environment with a wide variation of attributes, seasonal or otherwise, intelligence is useful in changing behaviors to match the changes in environment, but it is by no means the only way genetics can arrange for that.
If we are trying to figure out if an alien civilization can arise on various planets around the galaxy, it would be good to understand as much as possible the role of evolution, as life originates in a very simple form, and there are perhaps millions of mutations that have to be successful if someday, something produces a starship. The simple idea of mutation and selection seems reasonable in the abstract. Consider some scenarios. There is a population of a billion aliens. In one of them, a mutation happens which does something beneficial. Does that mutation spread through the population? Just to get started, did the mutation happen in an alien already near the top of the heap and likely to reproduce anyway? If the number of offspring is set by the society in which the alien lives, this mutation provided no benefit whatsoever. The next generation will have the same number of copies of the particular alien’s genes whether or not the mutation happened, and whether or not it has noticeable beneficial effects. So social conventions can completely override the fitness effect.
Suppose it actually does have some effect on the reproductive rate of the alien in which it arises. Instead of the societal standard of 3.0 offspring on the average, this mutation raises it to 3.1 . So, if the mutation happens ten times, there might be some small percentage change of its population in the society. One more alien out of a billion has a new gene. Exactly how many generations will it take before it becomes widespread? This depends on the social conventions, the degree of luck in reproduction, the existence of other genes that also are competing, and much else, but perhaps a hundred or a thousand generations later some scientist might see some measurable effect.
Let’s just consider one other factor: competing genes. Instead of a population with identical genes, suppose there is a wide diversity. Then, in the particular alien we were discussing before, after a mutation happens, all his genes, whatever they are, are simultaneously competing in the fitness completion, if there is one in his society. After a hundred generations, which of the thousand diverse genes he has comes out a winner in the population count game? Could be any of them. With a diverse set of genes and a large population, there is no way for a single mutation to rise to the top. There is too much stochastic variation in the generation-to-generation sweepstakes.
Consider a contrary situation. In the beginning of the hunting grand transition, aliens are living in small groups, with largely homogeneous genes. Now, when a mutation happens that has a noticeable effect on either survival or reproduction, it has a chance to compete in the fitness race and win, and then the incidence rate of the new gene in the small group can go up. If this happens enough times, so that there are several positive-acting new genes over some period of time, the group might be so successful that it divides, and now there are two groups with the improved genes. In small groups, with fairly homogeneous genes, mutations can in a few generations become widespread and begin to infect the whole population. But in large, genetically heterogenous masses, the statistics are against it. Too many competing genes make the selection of any particular one much less likely. So also do the memes of society, which might dictate who reproduces and how many offspring they have.
This seems to imply that evolution is a great thing for producing initially intelligent creatures, but then when this intelligence allows them to pass through the agricultural grand transition and start to hugely grow in numbers, and form large cities with very heterogenous genetic mixtures, it stops working. The genetic pool stops improving, and what benefits that existed in it earlier may or may not remain. The upshot of this is that only if there is something that might be thought of as societal momentum, or inertia, will the society continue to improve. Genetics via evolution just about stops working after the hunting grand transition, and intelligent design doesn’t become available until after the genetics grand transition. This means there are many years, perhaps thousands, in which the alien civilization is stuck with the genes they managed to develop before all this civilization started. If those genes and the gene pool that they are enmeshed in are enough to push technology all the way to the genetic discoveries that allow intelligent design to step in where evolution failed, then we might see an alien civilization develop star ships. If instead, it doesn’t make it, then the fallback position is idiocracy, which is the inevitable result of a situation of relative affluence, meaning fitness isn’t eliminating anyone, and a negative correlation between intelligence and reproductive rate. Understanding the limitations of evolution to pull an alien species out of the primitive, non-rational morass that all species evolve in, into the post-Baconian period where technology is moving forward at jet speed, will help us understand if it is likely that we will find alien species at least as smart as we are, and possibly more advanced.
Once the genetics grand transition gets going, then besides technology rocketing forward, intelligence and other beneficial genetic and memetic phenomena will also, and there will be a feedback effect from intelligence into technology development. This implies that the final grand transitions might be completed very fast, and after that, the alien civilization will in short order transform itself according to the rules it sets for itself, likely, efficiency and other ones similar. Since these transformations will be rocking society, it is hard to see that they would simultaneously be doing much in the space travel arena. Perhaps that gets put off in most alien civilizations that hit the jackpot until after asymptotic technology wraps up. This makes sense in another way as well, as space travel is an expensive enterprise, so why not wait until technology is finished before starting projects in this area?
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