The Fermi Paradox: Further Reading

There are a lot of good books dealing, in whole or part, with
the overall subject of the search for extraterrestrial
intelligence (the very acronym of SETI) and speculations on
possibilities of success or failure. As such, this particular
listing is merely a sub-sampling of the books that are available
and should not be treated as anything close to a complete listing
of works.

• Extraterrestrials: Where are They?, by Ben Zuckerman (editor) and Michael H. Hart (editor)


• Alien Life: The Search for Extraterrestrials and Beyond,
  by Barry R. Parker


• SETI Pioneers, by David W. Swift



• Paradigm's Lost, by John L. Casti

The Aliens are Among Us Hypothesis

Perhaps the most controversial of all the proposed solutions
to the Fermi Paradox, this hypothesis has generated enough books,
pro and con, to fill several libraries. As such, any sampling of
books is going to be, by necessity, a non-representative sample.
That said, on the pro side, one can find such books as:

• The Day after Roswell, by Philip J. Corso


• Communion, A True Story, by Whitley Streiber


• Alien Contact: Top Secret UFO Files Revealed, by Timothy Good

On the Con side, one can find such books as:

• The Demon Haunted World, by Carl Sagan


• Why People Believe Weird Things, by Michael Shermer


• Scams from the Great Beyond, by Peter Huston

The Apocalyptic Hypothesis

This particular hypothesis is found, as a reoccurring theme, in much of Carl Sagan's works. Perhaps the best (cautionary) example can be found in Cosmos.

Isaac Asimov also dealt with the theme of world-threatening futures in A Choice of Catastrophes : The Disasters That Threaten Our World. Unfortunately, this book is hard to find, but well worth reading if you can find a copy.

The Chariots of the Gods Hypothesis

Like the Aliens are Among us Hypothesis, this hypothesis has been a source of extreme controversy ever since Erich von Daniken published the eponymous Chariots of the Gods. He has since expanded upon the original theme in The Eyes of the Sphinx : The Newest Evidence of Extraterrestrial Contact in Ancient Egypt.



Rebuttals to von Daniken's theories can be found in such works
as Crash Go the Chariots, by Clifford Wilson, and The Space-Gods Revealed : A Close Look at the Theories of Erich Von Daniken by Ronald Story, both of which are somewhat hard to come by. PBS's Nova science series also did a critical report on von Daniken's theories in the 5th season episode The Case of the Ancient Astronauts. Unfortunately, this video is not available for sale from their online store, but a transcript of it can be ordered, for a nominal fee, from WGBH Audience and Member Services at (617) 492-2777, Ext. 5400.

The Dangerous Neighbors Hypothesis

Charles Pellegrino is the primary architect of the DNH. In his opinion, the potential development of relativistic missiles using antimatter drives makes this a very real possibility. He deals with these themes extensively (and technically) in his two works of fiction, Flying to Valhalla and The Killing Star, which are both, unfortunately, currently out of print. Greg Bear also offers a fictional overview of this perspective, using even more esoteric technologies, in The Forge of God and Anvil of Stars.

The First Come, First Serve Hypothesis

This particular hypothesis has received a lot of popularity in recent years, but it remains the brain child of Frank Tippler who first formulated it as part of his eschatological Omega Point Hypothesis in The Physics of Immortality.

A discussion of the Anthropic Principle, which is a major component of the First Come, First Serve hypothesis, can also be found in The Anthropic Cosmological Principle by John D. Barrow and Frank Tippler. A more technical (and expensive) treatment of the Anthropic Principle can be found in The Anthropic Principle : Proceedings of the Second Venice Conference on Cosmology and Philosophy.

The Stay at Home Hypothesis III (a.k.a., The Lotus Eater Hypothesis)

Although this particular example doesn't use virtual reality per our conventional understanding, Greg Bear's Blood Music offers, perhaps, the best fictional treatment of this particular hypothesis. While this title is out of print, I've found that most used book resources have available copies of it.

The Transcendent Hypothesis

The concept of the Singularity is very popular in the Extropian movement, although not all Extropians agree with this particular interpretation of the singularity. For a good overview of transhumanism (which is a superset of the Extropian movement), I would recommend Great Mambo Chicken and the Transhuman Condition : Science Slightly over the Edge, by Ed Regis, as well as The Extropian Home Page.

The science fiction writer Vernor Vinge has been the primary advocate of the idea of the technological singularity as transcendent event. This idea was a central plot point in his novel Marooned in Real Time which is, unfortunately, currently out of print but, again, well worth searching for. Critiques of Vinge's concept of the Singularity can be found here.

The Fermi Paradox: Conclusion

Ever since our species came to realize that other species could be out there, we have had a driving curiosity to know whether they are out there. An initial sense of optimism, where many people thought that our own solar system would be full of intelligent life, has crashed into the real world. The solar system not only lacks intelligent life, but it seems to lack any life other than our own, potential Martian fossils and speculations for life in the Europan ocean notwithstanding. SETI, likewise, has failed to turn up a single unambiguous signal from the stars.

Many people are still optimistic that other intelligences may exist that are able and willing to communicate with us, but against the very real silence and emptiness that we have encountered, Fermi's profoundly simple question has become a very pertinent one to those holding such hopes. The fact that it may only be possible to gain a definitive answer to the question by actually going out into the galaxy and making a comprehensive search hasn't prevented us from suggesting answers. Indeed, as such proposed solutions to the Dangerous Neighbors, the Apocalyptic, and the Lotus Eater Hypotheses show, such speculations may be pertinent not only to our curiosity but to our future as a species.

So we wait, and we ponder, and we listen with keen ears for the faintest indication that we may not be alone in the universe. As Carl Sagan stated on numerous occasions, any answer to that question is one that is well worth knowing.

The Fermi Paradox: The Transcendent Hypothesis

The Transcendent Hypothesis argues that technological development is exponential and that such development eventually leads to a period of asymptotic development with culminates with a technological "Singularity" at the asymptote. The TH suggests that when a species reaches this singularity, it "transcends", meaning that it either moves to another plane of being inaccessible to us (e.g., to another dimension), or that it becomes something so utterly alien that pre-singularity cultures are incapable of recognize it, much less comprehending it.

Critics of the TH complain that it is so utterly speculative as to be worthless. Even if we grant the notion that civilizations eventually reach some sort of technological singularity, the notion that they "transcend" is spiritual mumbo-jumbo thinly disguised by a science-fictional gloss. Lacking an actual mechanism to support the notion that civilizations can "transcend", it ought to be dismissed out of hand. Supporters of the TH contend that the notion of a singularity is firmly ground in real-world extrapolation and that the notion of transcendence is nothing more than a restatement of Clarke's Third Law, "Any sufficiently advanced technology is indistinguishable from magic". As such, any attempt to deal with the Fermi Paradox from a level of our own technological development is simply naive and we should expect advanced civilizations to be fundamentally incomprehensible.

The Fermi Paradox: The Stay at Home Hypothesis III (a.k.a., The Lotus Eater Hypothesis)

The third SAHH suggests that, as species discover and develop virtual reality simulations, they eventually become so immersed in the simulations that they lose all interest in the external world. In such a scenario, the period between the development of radio communications and the rudiments of space travel, and the development of addictively immersive virtual realities is so short as to preclude the development of interstellar travel. Likewise, the potential period of communication would be so short as to make it unlikely that we would intercept a communication from another species before they turned permanently inward.

Critics argue that it is unjustifiably pessimistic to suppose that any species would choose to live in simulated worlds to the exclusion of the real world and that, even if we suppose that some might, it's unreasonable to suppose that all species would be so prone. Supporters of the third SAHH counter that it is reasonable to presume that all species are subject to pleasure and pain stimuli. Furthermore, they insist that it is equally reasonable to suppose that a world tailored to species' preferences is going to be far more capable of stimulating the pleasure of that species than the mundane universe. As such, permanent virtual addiction seems inevitable for all but those few species that eschew virtual reality at a very early stage in its development. They note that our own species seems to be tumbling down that path without any sign of slowing.

The Fermi Paradox: The Stay at Home Hypothesis II (a.k.a., The Economic Impasse Hypothesis)

The second SAHH suggests that the technological factors that restrict interstellar travel and communication, (e.g., the speed of light, interstellar dust, and so forth) simply make in uneconomical for any species to invest in such activities on any but the smallest scale (e.g., probes to local solar systems and broadcasts only to the very nearest set of stars). As such, intelligent life may be common in our galaxy, but travel and communication would be so restricted that we should never expect to encounter any evidence of it.

Critics of the second SAHH argue that this hypothesis presumes that current limitations on technology can reliably be imagined to apply to future technologies. Proponents of the second SAHH counter that neither can one simply presume that a sufficiently advanced technology will be able to circumvent the known laws of physics.

Critics also complain that applying economic principles to extraterrestrial intelligences is patently anthropomorphic. Supporters of the second SAHH reply that economics isn't merely a human convention, but a universal description of how limitations on resources have an impact on actions. They point out, for instance, that many of the principles of economics apply directly to the evolution of biological systems.

The Fermi Paradox: The Stay at Home Hypothesis I (a.k.a., The Reluctant Traveler Hypothesis)

The first SAHH suggests that it is anthropomorphic to simply assume that other species are either interested in interstellar colonization or communication and that our own desires to do so represent a rarity in the cosmic arena. If other species do not find either of these subjects to be of any interest, we should expect to find ourselves in a silent universe.

Critics of the first SAHH suggest that it stretches credibility to presume that no other species have any interest in these things and that we are unique. They note that this is particularly hard to accept since you only need a single colonizing species to arise in order for the presence of intelligence to become quickly ubiquitous (see the First Come, First Serve Hypothesis). Supporters of the first SAHH counter that, even in our own case, we have only made the most furtive efforts at broadcasting our presence and that merely colonizing our own solar system has been something we haven't even attempted due to a profound lack of interest. As such, a reluctance to take up the challenge of colonizing the galaxy may well be the norm and that interstellar species may be so rare that our galaxy has yet to produce one.

The Fermi Paradox: The Dangerous Neighbors Hypothesis

The Dangerous Neighbors Hypothesis suggests that intelligence may be common but that communicative intelligence is rare. The reason for this is that those species that do communicate their presence tend to be obliterated by their neighbors, leaving only those species that maintain a strict cosmic silence alive. Charles Pellegrino, in particular, has come up with "The Three Laws of Alien Behavior", which he contends apply to all species:

1. Their survival will be more important than our own survival. If an alien species has to choose between us and them, they won't choose us. It is difficult to imagine a contrary case; species don't survive by being self-sacrificing.
2. Wimps don't become top dogs. No species makes it to the top by being passive. The species in charge of any given planet will be intelligent, alert, aggressive, and ruthless when necessary.
3. They will assume that the first two laws apply to us.

The rationale is that, in recognizing that other species represent a potential threat, and given that the survival of one's own species is of primary important, the most rational thing to do when encountering another species is to destroy them before their potential threat is transformed into a real threat. In the meanwhile, because you can assume that other species will do the same to you, your best option is to remain absolutely inconspicuous (e.g., no open radio broadcasts).

There are two major objections to the DNH. The first is to argue that it is presumptuous to simply assume that all other species will be automatically aggressive to the point of acting with paranoid abandon. Supporters of the DNH note that even if we do presume that some species are altruistic, such species will still be in jeopardy from species that embrace the rationale of the DNH. Over time, a sort of cosmic natural selection would weed out the altruistic species leaving a galaxy full of dangerous neighbors.

The second objection is to question the technological feasibility of destroying another species in a first strike, particularly without opening oneself to a counterstrike. Unfortunately, this is a very technical topic and it would be impossible for me to give a fair representation to the points and counterpoints that have been made over this contention. Suffice it to say that both sides do have arguments for their respective positions.

As a final note, the DNH is, perhaps, the only solution to the Fermi Paradox that directly impacts upon our own survival as a species. If the DNH is true, our radio broadcasts are placing us in grave danger and should be curtailed as soon as possible.

The Fermi Paradox: The First Come, First Serve Hypothesis

The FCFSH is a variation of the Cosmic Isolation Hypothesis that does not rely on the proposition that intelligence is intrinsically rare. The FCFSH uses the Weak Anthropic Principle in an attempt to demonstrate that if you are an intelligent species then you should expect to find that you are the first intelligent species to arise in your home galaxy. The reasoning behind the FCFSH is thus: even if a species disperses through its galaxy at a mere 1% the speed of light, the amount of time that it would take such a star-faring species to colonize every star in an average galaxy (e.g., our own) would be a mere 10 million years. While 10 million years seems like an extremely long period of time compared to our own history, it's an eye-blink in terms of evolutionary time. The FCFSH further hypothesizes that such widespread colonization would tend to preclude the development of additional intelligence. Therefore, the only intelligence likely to develop within a galaxy will be the one that first develops within a galaxy. Ergo, if you are an intelligent species, you are automatically going to be the first.

Critics of the FCFSH complain that it makes a number of hidden assumptions, the most prominent being the supposition that existing intelligences automatically preclude the development of new intelligent species. It also supposes that interstellar colonization is the de facto behavior of intelligent species (see the Stay at Home Hypotheses). Supporters of the FCFSH suggest that these criticisms violate the Copernican Principle which states that, unless we have empirical evidence to suggest otherwise, we should always assume that there is nothing unique about our status in the universe (e.g., we aren't at the center).

One bit of data that may support the FCFSH is the recent observations that our Solar System is probably among the first generation of systems that have enough complex elements (e.g., carbon) to support life. If intelligence is something that evolution has difficulty producing, we may well be among the first intelligences in our galaxy, if not the first.

The Fermi Paradox: The Cosmic Quarantine Hypothesis

The Cosmic Quarantine Hypothesis resembles, in many ways, the notion of the Prime Directive as found in the Star Trek series of science fiction shows. The hypothesis proposes that advanced species with interstellar capacity may well be common but that they are deliberately shielding their existence from us for one reason or another, e.g. to protect our cultural development. Many variants of the CQH add the additional hypothesis that we will be granted access to the galactic community once we obtain a sufficient level of development.

Many people find the CQH to be an example of paranoid thinking in as much as it indicates a conspiracy of silence by vast powers beyond our reckoning. They note that not only would there have to be a quarantine against visits to our world, but that there would have to be a perfectly enforced quarantine on radio communications and other detectable manifestations of extraterrestrial intelligences, including ones from species near our own level of development. Supporters of the CQH tend to reply that such a "conspiracy of silence" would represent no more effort than setting up a duck blind for a sufficiently advanced species or set of species.

The Fermi Paradox: The Cosmic Isolation Hypothesis

Perhaps the simplest solution to the problem of why we seem to be alone is to suggest that this is because we are, in fact, alone. This hypothesis proposes that life (or, at least, intelligent, communicative life) is extremely rare and that the density of intelligence in the universe is so low that we should never expect to find anyone else out there.

One pertinent argument against this hypothesis is the observation that life got an extremely early start on Earth. Practically as early as life could have started, it did. This would suggest that life needs minimally favorable conditions in order to start and to thrive. The upshot of this argument is that we should expect life and, hence, intelligence to be very common and not the product of a Great Accident.

However, proponents of the CIH note that, although life on Earth got a very early start, it took four and a half billion years to produce sapience. Furthermore, if it weren't for a number of bona fide accidents (including the extinction of the dinosaurs) the Earth would probably still be barren of intelligence. This would suggest that intelligence is something that natural selection doesn't produce easily and that it may, in fact, constitute such a rare accident as to drive down the density of intelligent life to the point where the Fermi Paradox would be satisfied.

It should be noted that "low density" is a relative term. If the density of intelligent life is so low that there is only an average of one intelligence in ten galaxies, there are good reasons to believe that we would always be out of the communication range of fellow intelligences even though the observable universe would contain approximately one hundred million sapient species in it.

The Fermi Paradox: The Chariots of the Gods Hypothesis

Similar to the Aliens are Among us Hypothesis, the Chariots of the Gods hypothesis is that aliens aren't currently here, but that they were here at some point in the past. The COTGH suggests that evidence of this can be found in the mythologies of the world and in the help that they lent to ancient cultures in building large and complex structures, such as the pyramids.

Critics of the COTGH complain that mythological "evidence" isn't empirical evidence and that the structures the proponents of the theory point to could have been built by so-called primitive cultures. They further suggest that, had aliens visited us in the past, we should expect to have found some bona fide artifacts by now. Supporters of the COTGH respond that, even among human cultures, only a fraction of the artifacts of our cultures survive even a few thousand years and that, if the aliens were only here a comparatively short time, we shouldn't necessarily expect to find physical evidence. They further note that mythology can provide real evidence of historical occurrences, as the myth of the fall of Troy has demonstrated.

The Fermi Paradox: The Apocalyptic Hypothesis

One of the more ambiguous parameters of the Drake Equation is f_L, which is the fraction of the duration of a planet's existence during which communicating civilizations exist. In other words, this is the average "life span" for an intelligent species. If f_L is a low number, this would indicate that most intelligent species have a very short period of existence and that, consequently, the average density of intelligent life for any given period of time would be low enough to satisfy the Fermi Paradox. One possible mechanism that would promote this would be the development of self-destructive technologies. Our own species appears to be passing through a period of its development where there are any number of ways that we could bring about our own destruction, including nuclear holocaust, environmental collapse, biological warfare, and so forth. Nor does the future appear to be getting any safer as is seems that such "horizon technologies" as nanotechnology will offer us even more paths towards self-destruction that are even easier to take.

Critics of the AH argue that it is an extremely pessimistic premise and that there is no good reason to suppose that "technological adolescence" has a particularly high mortality rate. They note that we seem to have cleared many of the hurdles that have faced us and that, for the time being, it would even seem that we are moving away from the brink of disaster. Proponents of the AH agree that it is a pessimistic hypothesis but point out that this does not dismiss its potential viability. That note that, unless we have cause to believe that other species are wiser than us, a dangerous period of technological adolescence seems to be practically unavoidable, particularly given that there seems no end in sight of the deadly hurdles that a species must clear.

The Fermi Paradox: The Aliens are Among Us Hypothesis

One potential answer to the question of "Where are they?" is "Right here!"

The AAAUH hypothesis suggests that, contrary to the opinions of skeptics, aliens are visiting the Earth and that they are being detected, albeit not in ways that the orthodox scientific community is willing to accept. Supporters of this hypothesis point to the large number of reported sightings and close encounters of various types.

Detractors of this hypothesis note that, in spite of the large number of sightings, no empirical evidence has been forthcoming. More so, attempts to account for this lack of empirical evidence often tend to cross the threshold into the realm of outright paranoia (e.g., in contending that the governments of the world are deliberately suppressing information). Proponents tend to dismiss such accusations as being either myopic or deliberately obtuse.

The Fermi Pardox: Introduction

Before Unstructured Musings, I had a website called The Lair o' Lias. One of the sections of the site was dedicated to the Fermi Paradox. Thanks to the Wayback Machine, from the Internet Archive, I've been able to salvage the content of it. I thought it would be a good idea to post it to the blog. I'm breaking it into sections starting with this, the introduction.

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Are we alone in the universe?

This is one of the greatest mysteries of our age. Clearly our intuition suggests that we aren't alone. It's hard to look up at the sky and to contemplate those hundreds of billions of stars in our galaxy alone without thinking that there simply must be intelligent life out there somewhere — probably life that we could communicate with if we only knew where to look and how to listen. Certainly this has been one of the great themes in Science Fiction. Over the last century, ever since H.G. Wells wrote The War of the Worlds, our media has been flooded with speculative stories that reflect our hopes (and fears) for the existence of alien life.Venus

In 1961 the noted astronomer Dr. Frank Drake came up with an equation, later to be known as the Drake Equation, which set definite parameters on how many extraterrestrial civilizations should exist. The Drake Equation asks several questions:

• How many stars are there in the galaxy?
• What fraction of those stars have planets around them?
• What fraction of those planets are capable of sustaining life?
• What fraction of those planets actually have life?
• What fraction of that number have intelligent life?
• What fraction of intelligent life forms are able and willing to communicate?
• How long do such intelligent, communicating species live (on the average)?

The beauty of the Drake Equation is that if you plug in numbers to all of its variable, you get a good estimate of how many intelligent, communicative species should exist in the galaxy at any one time. Unfortunately, this is easier said than done. Some variables, such as the number of stars in the galaxy, are easy to come by. Some, such as the number of stars with planets, can be only be approximated from educated guesses. Some, such as the fraction of biospheres that develop intelligence, are the subject of raw speculation. In spite of this, the Drake Equation generated a great deal of hope in those who wanted to believe in the existence of extraterrestrial intelligences for the simple reason that all but the most pessimistic estimates indicated a galaxy that was absolutely teeming with vocal ETIs.

SETI, the Search for Extraterrestrial Intelligence, was founded on the basis of that optimism. If you had asked the attendees at the first SETI conference to guess how long it would take before we discovered a signal, I'm confident that most would have guessed that we would do so within the space of a few years. I'm equally confident that none would have dared suggest that we would never find such evidence. Forty years later, we find ourselves confronted with a lingering silence, punctuated by several false or unconfirmable signals, and a muted sense of optimism. Most people still believe that we will find other intelligences, but there is the deep question of why, if life is as common as we suspect it is, we haven't found it yet.

The great physicist Enrico Fermi was one of the first people to ask this. Certainly he was the one who put it most succinctly: "Where are they?"

More formally, if intelligent life is as common as the Drake Equation tends to lead us to believe, why isn't its existence so obvious as to be unmistakable? Indeed, why isn't it already here?

This is the Fermi Paradox: If extraterrestrial intelligence is as common as we believe it should be, its presence should be obvious and unmistakable. It isn't. Hence the paradox.

It is a question that bestrides the question of our place in the universe. Where are they? There is a certain temptation to resist asking it, to dismiss it as premature and unworthy of consideration.

And yet… and yet…

Its presence casts a pall over any discussion of alien life. As much as we want to ignore it, as much as it acts as a damper to our enthusiasm, we are compelled to address it. It is a question that many people have contemplated, and it is one that has generated numerous potential answers.

A Proposed Solution to the Fermi Paradox

I am sure that it says something about me that one of my hobbies is the Fermi Paradox. More precisely, it says that I'm a hopeless nerd who could really stand to get out more often. Be that as it may, the Paradox is something that engages and delights me.

A while back, the great physicists Enrico Fermi (one of the key players for the Manhattan Project) came across some of his colleagues discussing the question of whether or not there was life in the universe. Fermi pondered the question for a bit and then said (and I paraphrase), "Where are they?"

Like many profound questions, it's deceptively simple. Fermi's point was that if life did, indeed, exist and was, in fact, common (as is often believed), why haven't we seen any evidence for it? Indeed, why aren't they already here.

Other physicists have emphasized this last question by noting that the time it takes to get to the farthest star in the galaxy is the same duration that it takes to get to every star in the galaxy since you can send out a multitude of ships in every direction. Since the farthest star, from us, is about 100,000 light years away, this means that if we were expanding through the galaxy at only 10% the speed of light it would take one million years to completely colonize the galaxy. At a mere 1%, you could do it in ten million years. Even at a glacial tenth of a percent, you could still manage the task in 100 million years.

These may seem like long durations but, when you consider that the galaxy is approximately 10 billion years (or 10,000 million years, if you prefer British notation) old, even 100 million years isn't a very long time. If alien colonizers had developed just 200 million years ago at the farthest galactic point from us, they would have already gotten here well before the dinosaurs went extinct (aided by the fact that the stars, themselves, are in orbit around the galactic center).

So where, in fact, are they?

That's the Fermi Paradox. It cuts to the very core of our place in the universe and it has no easy answer. This isn't, however, to say that answers have not been proposed. On one side, you have the bleak proposition that we are, in fact, likely to either be alone or so isolated as to make no difference (see, for instance, Rare Earth by Ward and Brownlee). On the opposite extreme, you have the contention that aliens are, in fact, already here and that they've been here since the dawn of history (as the infamous Chariots of the Gods suggests). In between these extremes, you have diverse propositions including Zoo hypotheses that suggest that we're in a kind of cosmic wildlife preserve (where we mustn't be disturbed!), economic models that suggest that interstellar colonization is just too damned expensive to make it worth the effort, and such disturbing suggestions as the theory that intelligence is self-limiting and always results in its own extermination before it gets out of hand.

I will be the very first to admit that, right now, the Paradox is basically a philosophers game. A less kind way to put it would be to call it mental masturbation. In truth, the only way to solve the Paradox is to go out there and to actually take a comprehensive look around. I think that it's fair to say that this won't happen for a very long time, if ever. Be that as it may, even if there's no value to be had in considering the question, right now, it doesn't change the fact that it is still an important question as well as a good way to stretch one's mind. We certainly don't criticize the ancient Greek philosophers for thinking about the nature of the Cosmos (even though their answers were typically wrong and often amusing). In the last resort, it's harmless fun and I see no risk in indulging myself.

The first challenge for any attempt to address the Paradox is that it must account for the existing data. If alien intelligences are out there, their presence is not obvious. We have (tabloids and UFO enthusiasts to the contrary) not found any solid evidence that we are being visited. We have found no artifacts, much less anything as telling as a piece of advanced machinery recovered from the Carboniferous. Diligent sky surveys have also failed to yield anything above natural cosmic noise and a single, unrepeated "Wow Signal" that's more likely than not just an artifact of the equipment that detected it. The universe is eerily quiet. This is a challenge not only to the UFO crowd, but also to the Sagan's and Drake's of the world who imagined a universe brimming with life.

My personal hunch is that intelligence is, for one reason or another, rare. I also suspect that we are near the beginning of the fertile age of the universe and that we may well be among the first to look out upon the universe with wondering eyes. Might there, however, be some way to preserve the notion that life and intelligence are common while, never the less, accounting for the silence?

I don't have much confidence in the theories of Intelligent Design that are currently being offered as a popular alternative to the Theory of Evolution. I distrust any theory whose ultimate support rests upon the proposition that, at some point in time, a miracle happened. Appeal to miracles has always struck me as lazy, even when I was a theist. I no longer believe in any gods but, even if there did exist something godlike, I think that I would have less respect for it if it had to prop up crucial elements of its creations with supernatural buttresses. I think that a truly consummate deity would only need a single miracle to start the universe, if that many, leaving a creation that could look after itself from that point forward. Call it an aesthetic preference for Deism if you like.

That said, if there is one thing about humanity that strikes me as verging on the miraculous, it is the invention of writing. More specifically, it's our very capacity for being able to invent it and use it in the first place. Every other element of our biology and our cognition has developed through evolutionary time, including the explosive development of our brains over the last two million years. Even tool making, which has been seriously proposed (with little contention beyond stick using Chimps) as one of the few things that genuinely distinguishes us from the other animals, has an evolutionary pedigree.

Writing is not like that. Writing relates to language, of course, but language was shaped into our throats and our brains by selective pressure. Even if language is only as old as this more recent (and lonely) branch of the Hominid family, it had time to be forged by evolutionary pressures. Writing, by contrast, is too recent. Much too recent.

The earliest proto-writing extends back a mere 7,000 years, or so. Most humans were not introduced to writing until the last few centuries. Many people, throughout the world, remain illiterate. Despite this, if you were to take any random child from any random part of the world without any concern about selecting a child of the proper race or lineage, you could teach that child to write with as much facility as any other randomly selected child. What's more, if you were to apply a specific sort of lesion to a literate person's brain, you could destroy their ability to either read or write or both. This means that although we didn't evolve literacy, the structures that allow us this feat are present in every single person on the planet barring only those who have developmental handicaps and those who have suffered particular forms of neurological trauma.

I said that I would consider this to be something that verges on the miraculous. I do not mean that literally. Clearly, the skills that allow us to become literate must be co-opting existing neural structures. PET scans and MRI bear this out. Our ability to read and write is closely tied to our ability to speak and comprehend. It is, in practice, little different from being able to use a heavy wrench to drive a nail. Was it, however, an inevitable adaptation?

Is it possible that our easy facility with the written word is a fluke? Could it be that there's something particular about our own neural architecture that allowed us to adapt existing linguistic skills to the novel solution of literacy? We know that intelligence alone does not guarantee literacy. If a person misses a certain magic window, between the ages of four and seven, their ability to become literate, at some later point in life, is compromised even if their overall linguistic development is not impaired. It is not that far-fetched that there could be a species, out there, that has strong linguistic skills but no innate ability to learn how to read and write. From there, we only need to take the further step of supposing that our own species is the exception rather than the rule.

Imagine what it would mean for an entire species to be illiterate. Imagine what would happen to our own species if we were to suddenly lose the ability. Literacy is more than a form of communication, it's a way of distributing intelligence. Instead of each person having to hold everything they know in their own heads, they can offload part of the burden of memory to paper freeing up space to more efficiently use their overall intelligence. Consider how much more difficult the task of constructing a large building would be if the foremen were forbidden from using blueprints. For that matter, think of how much more challenging it is to do long division without a pencil and paper.

Literacy also gives us history. Oral histories are notoriously unreliable over any sort of long term. There is a reason that our understanding of the past changes sharply once you pass the point where we had developed any systems of writing. Once you go past that terminus you literally have to start digging history out of the ground and piecing it together in the form of pot shards and other durable artifacts. This is the reason that we know next to nothing about European history beyond a mere two thousand years ago. Literacy hadn't reached that far, yet, and more the pity.

If literacy is rare, so, I believe, must be technology. Without an ability to record a reliable history, innovations don't tend to accumulate at anything but a glacial pace (again, I use that term literally). More so, the overall level of innovation that you can achieve is limited to the population's ability to hold their entire store of knowledge in their own brains. It is not, I think, outrageous to suppose that a truly illiterate species could not achieve a high technology, much less an interstellar one.

So there is my proposal. Let's call it the Rare Readers hypothesis.

Now, do I believe that this is likely to be the case. No. I suspect that once you achieve brains that are capable of complex symbolic manipulations and abstract associations (that is, language), it's probably that the tools for literacy are already in place and only waiting to be discovered. Even if literacy requires particular neurological features, I think that it's probable that there would be selective pressures towards developing those particular features. I would not be surprised if there were a few intelligence species out there that were stranded in islands of illiteracy, but I am doubtful that this would constitute a norm.

So what was the point of all this. Well, it's fun to think about. At least if you're the kind of nerd that I am.