Darwian Evolution and Intelligence

At the end of the last chapter, the land had been colonized and various mass extinction events had been overcome. Mammals have arrived on the Earth and continued mammalian evolution will dominate the Earth's suface. But how might intelligence arise out of this evolution? Is it inevitable or accidental? The modern idea of evolution was first formulated by Jean Lamarck in the early 1800's. Lamarck published a theory of evolution in 1809 in which he proposed that species arose continually from nonliving sources. These species were initially very primitive, but increased in complexity over time due to some inherent tendency. This type of evolution is called orthogenesis.

Lamarck proposed that an organism's acclimation to the environment could be passed on to its offspring. For example, he thought proto-giraffes stretched their necks to reach higher twigs. This caused their offspring to be born with longer necks. This proposed mechanism of evolution is called the inheritance of acquired characteristics. Lamarck also believed species never went extinct, although they may change into newer forms. All three of these ideas are now known to be wrong.

Evolution came of age as a science when Charles Darwin published "On the Origin of Species" in 1859. Darwin's contributions include hypothesizing the pattern of common descent and proposing a mechanism for evolution -- natural selection. In Darwin's theory of natural selection, new variants arise continually within populations. A small percentage of these variants cause their bearers to produce more offspring than others. These variants thrive and supplant their less productive competitors. The effect of numerous instances of selection would lead to a species being modified over time.

Darwin also recognized several critical facts:

Variability exists within species
Variant traits may be inherited [Darwin did not, however, know how.]
From Malthus' principle of overproduction, many individuals must often die or fail to reproduce. In this "struggle for existence", variants that were slightly better suited to the environment would be more likely to survive.

It then follows logically that certain variants will be preserved over time over other variants and that populations will change over time in their composition. This is evolution by natural selection. The greatest weakness in the theory of evolution by natural selection was the fact that Darwin knew neither how variation among individuals was generated nor how it was inherited.

Biology as a science made its move from an Arisotitlean stage to a Newtonian one with the development of the theory of evolution. About 40 years after Darwin, Gregor Mendel showed that the mechamism for evolution was a change in the gene pool of a population over time. A gene is a hereditary unit that can be passed on unaltered for many generations and which determines the variation of traits within some population.

In order to better understand evolution, it is necessary to view populations as a collection of individuals, each harboring a different set of traits. A single organism is never typical of an entire population unless there is no variation within that population. Individual organisms do not evolve, they retain the same genes throughout their life. When a population is evolving, the ratio of different genetic types is changing -- each individual organism within a population does not change. p> Evolution requires genetic variation. In order for continuing evolution there must be mechanisms to increase or create genetic variation and mechanisms to decrease it. Mutation is a change in a gene. These changes are the source of new genetic variation. Natural selection operates on this principle of variation which is generically shown below:

Now at anytime, random individuals within this population will mate and produce offspring. That mating may or may not produce a different set of characteristics that have a higher survival probability than the original traits of the maters. However, over time, if left undisturbed, an ecosystem will naturally evolve inhabitants that are more adapted to survive in that ecosystem than previous generations. Hence, evolution is a process of statisical adaptation . If any ecosystem can remain unpreturbed for say millions of years, then its possible for the evolutionary process to produce some kind of optimization with respect to that ecosystem. However, on the land ecosystems are subject to large scale catastrophe on short time scales due to climatic, tectonic, or asteroid impact events. Each of these events essentially resets the evolutionary clock Thus, on the long timescales relevant to evolution on the Earth, the role of random catastrophe has been very important in shaping the biodiversity on Earth. Intelligence may be a temporary, accidental outcome of this process.

Galactic Intelligence

If we operate under the assumption that Humans are intelligent then we should consider the question of Galactic Intelligence. For the purposes of our arugment, Galactic Intelligence will simply be defines as a species which is capable of communication through the use of electromagnetic waves . In the case of Humans, we reached this capability about 150 years ago with the development of the telegraph.

In the previous chapter we have told of story of the steps needed for the evolutionary process to occur and we have emphasized various potential failure points along that road. Given those difficulties, it might appear that the evolution of intelligence is an improbable event. However, there is a very important difference between improbable and unique. This then begins the question: Is There Anybody Out There?

In the 1960's an astronomer named Frank Drake developed a statistical equation that can be used to estimate the number of civilizations that presently exist in the Galaxy and are capable of communication using electromagnetic radiation (e.g. radio waves). This equation, known as the Drake equation, is:

N_c = R^*f_pn_ef_l f_if_tL

The terms in this equation are the following:

N_c is the number of civilizations that presently exist and are capable of communication. Since we exist, we know that N_c is at least 1.
R^* This is the number of stars that form per year in our Galaxy
f_p is the probability of planetary formation per star. A probability is a number between 0 and 1.
n_e is the number of "Earth-like" planets per planetary system. Earth-like in this respect means a planet with a liquid surface.
f_l is the probability that primitive life forms on a planet with a liquid surface.
f_i is the probability that on a planet with primitive life, intelligence emerges
f_t is the probability that the intelligent civilization becomes technological and develops the means to communicate
L is the lifetime of the civilization in its communicating phase. Note that L for the Earth would be about 100 years, even though civilization has been around for at least 10,000 years.

To get a value for N_c requires finding values for each of the parameters and multiplying the whole string out. Certainly this is guesswork, but we can make some intelligent decisions. Below is one way this equation can be solved.

The Drake equation can be broken up into three parts, an astronomical part involving the terms R^*, f_p, n_e , a biological part involving the terms f_l,f_i , and a socio-economic part involving the terms f_t, L. The most certain part of this equation is the astronomical part. The biological part is fairly unknown although it can be done with a set of reasonable assumptions. The socio-economic part is an exercise in complete speculation. With these caveats in mind, we now offer our preferred solution to the Drake Equation:

The Astronomical Factors:

R^* = 10. This we know, on average 10 stars per year form in the Galaxy.
f_p = 1. This is a statement that planetary formation is a necessary consequence of star formation and therefore that other solar systems are ubiquitous. The recent discovery that many nearby stars have Jupiter mass planets in orbit about them is an important confirmation of this hypothesis. It has also been long known (since the IRAS mission in 1984) that some nearby stars have dusty disks of material around them. Finally, low mass stars like the Sun are observed to rotate very slowly compared to what you would expect based on angular momentum conservation. In the case of our Sun, the initial angular momentum in the interstellar cloud out of which it formed, was converted to orbital angular momentum instead of the rotational angular momentum of the actual star. The formation of a binary star system would also accomplish this.
n_e = 1. This statement says that in all solar systems there is 1 object that is the right distance from the host star such that the temperature is conducive for the condensation of water vapor. The accretion process for planetary formation, briefly described earlier in this Chapter, suggests that planets sweep up zones of debris in more or less random places. In this case, the odds of a planet forming in the habitable zone around a given star are high.

The Biological Part:

f_l = 1. This is a statement that the formation of amino acids on a planet with a liquid surface has a very high probability. This statement seems fairly safe as it's been known ever since the famous Miller-Urey experiment in the 1950's that the synthesis of organic molecules (principally amino acids) from atmospheric chemistry is relatively easy.
At this point our statistical statement is that the Galaxy is teeming with primitive life on planetary surfaces.
f_i = 0.1. This value means that on only 10% of those planets with simple organic molecules does intelligent life arise. Since we know very little about this process, this term could be considerably less than 0.1 and therefore our own existence is improbable. For instance, we know that the Earth periodically suffers mass extinctions of species (most likely due to large asteroid impacts). Perhaps its improbable for a planet to recover from such an event to keep the evolutionary machine moving forward. The one thing that we think we do know about the transformation from primitive to intelligent life is that it takes billions of years. So perhaps all that is required is billions of years of trial-and-error processes in some distant ocean to eventually produce intelligence. If that is the case, intelligence on a planetary surface with a liquid ocean is highly probable.

The Socio-Economic Part:

f_t = 0.1. This states that on only 10% of those worlds in which intelligence has arisen does technology also arise. This might seem to be an odd statement as many believe that technology is a manifestation of intelligence and is therefore a natural consequence of it. In that case f_t would be 1. However, technology has a definite downside with respect to planetary management in that it creates (and perhaps even demands) non-equilibrium growth and hence threatens the long term sustainability of the intelligent species itself, which is not a very intelligent thing to do. Hence, perhaps it's possible that some intelligent species consciously choose not to develop technology because they are able to look thousands of years in advance and see the consequences. Just because that didn't happen on this planet does not mean that such an outlook is impossible. Note if we combine our estimates of f_t and f_i then we get that only 1% of all planets which host primitive life evolve a civilization that is capable of communication. Again, the number could be much lower than this.
L = 10⁷ (10 million years). How does one arrive at this estimate? Well, we can make the following assumption: 99% of all intelligent civilizations that ever evolve from some primordial ooze are incapable of solving their growth problem and have a technical lifetime of only 1000 years before disappearing. Hence, at any given time in the Galaxy, these civilizations are extremely rare. We then assume that the remaining 1% either solves their growth problem or never has one in the first place and has a lifetime of 1 billion years. One percent of 1 billion is 10 million and that's how we arrive at our value for L . Now, of course, its possible that these "equilibrium" societies never choose to develop technology which is why that can live so long. At the same time, it may will be that out of sheer curiosity these same civilizations develop technology on a small scale in order to achieve communication. Our current use of the Internet is an example of a global communication system that is not particularly resource intensive.

If we now multiply out all of our terms we get:

N_c = (10)(1)(1)(1)(.1)(.1)(10⁷) = 10⁶

Below is a simple calculator that you can use to derive your own estimates. A particularly useful exercise is to determining the combination of parameters that yields N_c =1 when choosing a suitably long lifetime, L. L is important because obviously if you make it short enough, then, at any given time in the history of the Galaxy, only 1 civilization exists (in that window), but that civilization quickly goes extinct to be replaced by another one. This does not seem like a physically reasonable situation so you need to make L sufficiently long so as to allow some probablity that more than one civilizations exists during the same time window. Having done that, then adjust the other parameters to achieve the B>N_c =1 solution thereby specifying what must have uniquely occurred on the Earth and no where else.

One Million Civilizations or Just One

We conclude this Chapter by considering the implication of N_c = one million and give an argument as to why N_c might be just one. To most, one million civilizations capable of communication that exist right now would seem like a very large number. In reality, however, it is a very small number which indicates that intelligent life is rare, very rare, but not necessarily unique to this planet. There are approximately 10¹¹ stars in our galaxy which means, in perspective, that there is only 1 civilization per 100,000 stars. That's rare. When you observe the night sky on a moonless night in a dark location, the number of stars that you can observe with your naked eye is 3-4,000 depending on the quality of your eyesight. Thus, within our naked eye horizon we may well be the only civilization present. But beyond our naked eye horizon is the vastness of the Galaxy, a fact that we can not emotionally appreciate and which biases us towards uniqueness. We are not readily cognizant that we can only interact, in a sensory manner, with an extremely limited volume of the Galaxy and the enormity of what lies beyond our sensory horizon is not something easily grasped.

If we imagine that these 100,000 civilizations are randomly spread throughout the disk of our Galaxy, then the average distance to the nearest civilization is about 300 light years away from us. Even if we could develop a propulsion system that achieves a velocity of 0.1 c, it would take 3000 years to reach the nearest other civilization, presuming we know where it was in the first place. Moreover, although the civilization on the Earth does manifest itself by escaping Television and Military Radar (an ominous combination - perhaps this explains why no one has dropped in to say hello), it has only been doing this for 50 years so we would not expect any civilizations to have accidentally picked up our stray radio wave emissions.

More to the point, however, is that our estimate of N_c = one million is based on a very long average lifetime per civilization. In fact, for reasonable probability values, N_c is more strongly dependent on L than any other term. This means that each one of these civilizations are considerably more advanced than us and have already gone down the pathway to be included in the Galactic Club. This perhaps is the most significant conclusion that one can draw from this statistical argument: civilizations with short lifetimes do not matter and have only a very small window of detection in the Galaxy. To claim our place among other intelligent civilizations in the Galaxy requires that we adopt a different system of planetary management such that we achieve sustainability. Perhaps then, we will even be invited to apply for membership in the Club.

So far we have considered this hypothetical collection of one million civilizations to be static in nature. That is, they occupy their planet in an equilibrium state. However, perhaps curiosity causes them to develop space travel. Would it be possible for one of these civilizations to essentially colonize the entire Galaxy. Let's consider the following scheme:

One day, some civilization decides to use its resources to launch 1000 inhabited space ships in random directions.
Each spaceship is capable of a propulsion velocity of 0.1 c.
99% of all spaceships are destroyed before reaching another planet
Upon arriving at another planet, on average 10,000 years later, the surviving members of the civilization spend 10,000 more years on that planet converting its resources into 1000 more spaceships to repeat this exercise.

How long would it take to reach all 10¹¹ stars in our Galaxy if this scheme were rigorously followed. For instance, in the first step, one civilization eventually reaches 10 new planets. Twenty thousand years later, the resources of those 10 planets have been converted into 1000 more space ships per planet and now there are 10,000 exploratory space craft randomly cruising the Galaxy for new planets. The later timesteps in this sequence are summarized in the following table:

Year	Number of Planets Colonized	Number of Spaceships launched
1	1	1000
10⁴	10
2 x 10⁴	10	10⁴
3 x 10⁴	100	10
4 x 10⁴	100	10⁵
6 x 10⁴	1000	10⁶
10⁵	10⁵	10⁸
4 x 10⁵	10⁷	10¹⁰
10⁶	10¹⁰	10¹³
2 x 10⁶	10¹¹	10¹⁴

From which we find that the entire Galaxy can be colonized in just twenty million years via this scheme.

So, where are they?

The colonization argument presented above has been used to suggest that, in fact, N_c = 1 and that we are it. Earth. That's it, the sole keeper of the question marks in the Galaxy and perhaps the Universe. This is a disturbing thought as it implies an awesome responsibility on us earthlings. If we extinct ourselves we extinguish the very questions that the Universe has used to become self-aware. One resolution to this dilemma is simply that interstellar travel may be a lot more difficult than the above scheme suggests. Clearly, the average time of 10,000 years to reach another planet requires a multi-generation committment. The individuals that get on the spacecraft are not the same ones that get off 10,000 years later. Perhaps this is impossible. Then again, perhaps advanced cryogenics would make interstellar travel feasible. It's difficult to know.

What we do know is that we are unmistakably here and we are observers of the Universe. Our knowledge of the Universe may be primitive, but if so, this is a reflection of the primitive nature of the questions that we ask. But we have been investigating the nature of the Universe for only about 10,000 years. In this flyspeck of time we can't hope to have gained fundamental knowledge. The challenge for us, which stems from the study of Cosmology, is to preserve our civilization and our species so that we will be able to make inquires about the nature of the Universe for millions of more years. Only then can we acquire wisdom and truly understand our connection to the Cosmos and whether or not we are alone.

Chapter 7: Is There Anybody Out There?

Darwian Evolution and Intelligence

Galactic Intelligence

Drake Equation Calculator

Number of communicating civilizations currently existing in the Galaxy:

One Million Civilizations or Just One