Despite the lack of evidence to support the existence of extraterrestrial intelligence, many people firmly believe in it. If you are skeptical on this matter you are likely to be accused of being arrogant, anthropocentric or even a religious fanatic. However, to consider the possibility that we might be alone in the universe doesn’t necessarily make you any of those things. You can believe both that humans are rare or unique and at the same time that they are a purposeless arrangement of matter or a curious accident in space-time.

In 1961 the astronomer Frank Drake announced that the number of extraterrestrial civilizations in our galaxy that might contact us could be calculated with the following equation:

N = R fp ne fl fi fc L

Where N is the number of communicative civilizations, R is the rate of formation of suitable stars, fp is the fraction of those stars with planets, ne is the number of Earth-like planets per solar system, fl is the fraction of planets with life, fi is the fraction of planets with intelligent life, fc is the fraction of planets with communicating technology and L is the lifetime of communicating civilizations.

Many people think that this equation actually proves the existence of extraterrestrial intelligence and some even believe that a close encounter of the third kind could be just around the corner. However, the truth of the matter is that there is no scientific evidence to support that intelligent life exists anywhere beyond Earth and the only factor that can be calculated with some certainty in this equation is R the rate of stellar formation (1). Numbers for the other components are the product of the creative speculations of astronomers, SETI researchers and Star Trek fans.

Of course, there’s nothing wrong about speculation (or about being a Star Trek fan). After all, if speculation is based on concrete facts and is not just a wild guess, it’s part of science. However, when it comes to evolution the facts are frequently misunderstood. People, including some scientists, tend to regard it as a linear process instead of as a tree of increasing complexity. Many assume evolution works towards achieving a certain goal, like intelligence. For instance, Lemarchand says “The principle of mediocrity suggests a logical progression: the emergence of life will lead to the emergence of intelligence, which will give rise to interstellar communications technology” (2). In the case of Drake’s equation these misconceptions can lead to fi and fc being hugely overestimated. Carl Sagan, for example, considered a guesstimate of one million possible civilizations in the galaxy “to be conservative” (2).

It is true that wherever life emerges in the universe it’s likely to evolve according to the same rules. However, as Alan Turing explained, incredibly complex and diverse patterns can come into being by following very simple rules. In the same way that there cannot be two identical trees in a forest with the same foliage or number of branches, there cannot be two identical evolutionary histories (unless they exist in some kind of bizarre parallel universe).

Similarly, although there are billions of us, all built from the same DNA instructions, we’re all unique (even identical twins). Just as we can say that you wouldn’t be yourself if a series of interrelated factors and fortunate events (or unfortunate depending on your self-esteem) have not taken place -for instance, your father meeting your mother, your father’s condom breaking, you being born a boy with green eyes, surviving meningitis, developing a twisted sense of humor, deciding to study philosophy, etc.- we may say that intelligence may have never appeared if a sequence of events and a series of factors had never occurred and interacted in the way they did. A single event, like the asteroid that killed the dinosaurs 65 million years ago, can conspire against or in favor of entire species and permanently modify the structure of evolution’s tree. We don’t know, but the number of events that lead to intelligence could be larger than the number of stars in the universe and the interaction of factors necessary for it to evolve more complex than your girlfriend’s moods. Hence, we can say that timing, luck and the interplay of biological and environmental factors are critical aspects in evolution.

Even though it can be argued that intelligence, as the ability to get process and act on information is such a useful and common trait (apparent even in slime molds) that it’s likely to evolve elsewhere, the kind of ability that you need to build civilizations, technology and be aware of it is, in fact, rare. Among the billions of species that have evolved in the planet, perhaps as many as 50, we are the only one that has developed that kind of ability. Furthermore, as Jared Diamond has pointed out, compared to other more successful species like rats and beetles this feature doesn’t seem to be the best way to take over the world.

So, if the same sequence of events is unlikely to play equally elsewhere, if the kind of intelligence you need to build civilizations and technology is rare even in our own planet and if there’s no actual evidence to support the existence of ET intelligence, there might be enough reasons to be a bit skeptical about having an interstellar chat with any space being in the near future.

The problem is that skeptics are often accused of being led by illegitimate motivations such as arrogance, anthropocentrism or religious beliefs. Of course, in some cases that can be true. However, what’s also true is that there are several moral stands and mistaken assumptions behind the “we are not alone” argument and behind these accusations.

On the one hand, there’s a kind of “IQ relativism” based on the notion that “there are many forms of intelligence, all different but equally good, valid and/or complex”. The idea of intellectual diversity is used to sustain that there’s nothing special about us, that intelligence is a standard outcome of evolution and therefore species like ours are likely to evolve elsewhere (yes, this may be the herald of intergalactic political correctness, we should perhaps start calling aliens “intellectually-diverse beings” so that they don’t get mad in case they’re listening).

IQ relativists assume that if you think extraterrestrial intelligence is unlikely, is because you somehow believe humans are superior and, of course, that’s arrogant. However, one thing doesn’t necessarily entail the other. Rarity or uniqueness is not equal to superiority. You can believe that cephalopods are also fascinatingly unique and that doesn’t mean you think they are superior. Moreover, it can be argued that viewing intelligence as an inevitable outcome of evolution is what’s indeed arrogant.

On the other hand, there are the Galileans who react against anthropocentrism assuming that if you are skeptical about the existence of extraterrestrial civilizations you automatically believe humans are the center of the universe. Thus, you may be some kind of religious fanatic or creationist freak who claims that we are God’s favorite creatures or the supreme objective of “Intelligent Design”.

However, there’s a difference between thinking that human-like intelligence could be exceptional and thinking that the heart of the universe is in Alabama or that we are the preferred children of some supernatural being. Again, “unique” doesn’t mean “central”, or “most important”. Exceptions are also part of nature. And, although homo-sapiens could be unique in the universe, so does cephalopods and that doesn’t make them God’s master pieces. What’s more, it could be said that:

• Thinking extraterrestrial intelligence is in some way human-like i.e., having civilizations and technology, is in fact what’s anthropocentric. (By the way, if they are really like us, are they also arrogant and think they are the center of the universe? Maybe that’s why they haven’t bothered to call and that will explain Fermi’s paradox.)
• Believing in extraterrestrial intelligence is as superstitious as believing in God because there’s no evidence of their existence.

In short, to consider the possibility that we might be alone in the universe doesn’t necessarily mean you are arrogant, anthropocentric or irrational. You can believe that humans are both, unique or rare and at the same time a purposeless arrangement of matter, a curious accident in space-time.

References

(1) Shermer, M., 2002, ‘Skeptic: Why ET Hasn’t Called’; Scientific American Magazine; August 2002; www.sciamdigital.com

(2) Lemarchand G., 1998, ‘Is There Intelligent Life Out There?’; Scientific American Presents; Exploring Intelligence; www.sciamdigital.com

(3) Darling, D. The Encyclopedia of Astrobiology, Astronomy, and Spaceflight; www.daviddarling.info/encyclopedia/M/mediocrity.html

(4) Darling, D. The Encyclopedia of Astrobiology, Astronomy, and Spaceflight; Fermi’s paradox