Occasionally I like to ponder the possibility of intelligent life elsewhere in the universe (given the fact that there's bloody well none on this planet) and so I was intrigued by Stephen Webb's book 'Where Is Everybody?', which covers some of the top reasons why we've yet to encounter ET. My personal favourite is amongst the selection on offer (they have no desire to communicate), but it is an extract from the conclusion that I want to share:
I believe that the Fermi paradox tells us mankind is the only sapient, sentient species in the Galaxy. (We are probably also unique in our Local Group of galaxies, since many Local Group galaxies are unlikely to possess a GHZ. Perhaps we are even unique in the whole Universe — although the finite speed of light means ETCs could now exist in very distant galaxies without us yet being aware of them.) Yet the Galaxy need not be sterile. The picture I have is of a Galaxy in which simple life is not uncommon; complex, multicellular life is much rarer, but not vanishingly rare. There may be tens of thousands of exceptionally interesting biospheres out there in the Galaxy. But only one planet—Earth— has intelligent life-forms.And despite the fact that the universe irritates me in so many different ways, I can't help remind myself, that I'm taking it all, far. too. seriously...
Such a picture is often criticized as violating the Principle of Mediocrity. The picture seems to suggest that Earth, and mankind, is special. Is this not the height of arrogance? Paradoxically, at least to my mind, the expectation that other sentient species must be out there itself smacks of arrogance. Or rather, it achieves the tricky feat of being both self-important and self-effacing at the same time. At the core of this expectation is the belief that human adaptations, attributes such as creativity, and general intelligence, that we think important, are qualities to which other Earth organisms aspire and alien creatures may possess in even more abundance. Allow us a few more million years, so the logic seems to go, and we might evolve into the cognitively, technologically and spiritually superior beings that already exist out there. But the converse of this position is surely false. Give chimps another few million years, so the reasoning goes, and they too will be as intelligent and creative as us. But why should they be? Chimpanzees are good at being chimpanzees; dolphins are good at being dolphins; elephants are good at being elephants . . . Rather than patronizing these species for not exhibiting human characteristics, we should respect them on their own terms for earning a living in a harsh world that cares not whether they live or die.
On the other hand it is undeniable that mankind is profoundly different from every other species on Earth. We alone have language, a high level of self-consciousness, and a moral sense. We are special. But surely our uniqueness could not have arisen by mere chance, by the blind and random groping of evolution, could it? Well, why not?
As Stephen Jay Gould pointed out in a delightful analogy, we can account for any growth in the complexity of living organisms through a drunkard’s walk effect. Imagine a drunk leaning against a wall. A few meters to his right is a gutter. If the drunk takes random equal-sized steps to his left or to his right, then he inevitably ends up in the gutter. No force propels him to his right; he moves randomly, and at any time he is as likely to move to his left as to his right. But the wall eventually stops his leftward motion; over time, there is only one direction in which to move. Eventually, completely by chance, the drunk stumbles into the gutter. The same effect can explain any advance we might observe in the complexity of organisms. At one end we have a wall of minimum complexity that organisms can possess and still be alive. This wall is where life began, and where most life on Earth remains. Over time, evolution tinkers with more advanced organisms; when life itself was young, that was the only available possibility — evolution could not try out simpler designs, because its path was blocked by the wall of minimum complexity. Some of the new designs worked, in the sense that the organisms were adapted well enough in their immediate environments to survive long enough to reproduce. And so evolution staggered on, like a blind drunk, tentatively producing organisms of greater complexity. After almost 4 billion years of random tinkering, we end up with the living world we see today. But there was nothing inevitable about the process; the purpose of evolution was not to produce us. Play the tape of history again, and there is no reason to suppose Homo sapiens — or any equivalent sentient species — would play any role at all.
Many eminent scientists argue that Mind is in some way predestined in this Universe. That far from being the outcome of chance, Mind is an inevitable outcome of deep laws of self-complexity. They argue that, over aeons, organisms will inevitably self-complexify and form a “ladder of progress”: prokaryote to eukaryote to plants to animals to intelligent species like us. It is a comforting idea, but I know of no definite evidence in its favor, and I believe the silence of the Universe argues against it. The famous French biologist Jacques Monod wrote that “evolution is chance caught on the wing.” Even more evocatively, he wrote that “Man at last knows he is alone in the unfeeling immensity of the Universe, out of which he has emerged only by chance.” It is a melancholy thought. I can think of only one thing sadder: if the only animals with self-consciousness, the only species that can light up the Universe with acts of love and humor and compassion, were to extinguish themselves through acts of stupidity.
If we survive, we have a Galaxy to explore and make our own. If we destroy ourselves, if we ruin Earth before we are ready to leave our home planet . . . well, it could be a long, long time before a creature from another species looks up at its planet’s night sky and asks: “Where is everybody?”