Imagine for a moment that you travel to a distant planet and discover life there. What kind of life do you think you would find?
Looking up at the billions and billions of stars that fill the night sky, most of us would probably imagine that the plants and animals inhabiting a distant planet would be radically different from the ones we find here on Earth. Few of us, I think, would ever expect to find flora and fauna on a distant planet that would be virtually indistinguishable from that of our own. That is because most of us believe that the formula for life allows for a virtually unlimited number of potential species, and that the particular species that happened to have evolved here on Earth were simply the result of dumb luck.
But, just like the once commonly held belief that the world is flat, the belief in an unlimited number of potential species may also be in error.
For example, if one takes a look at our own planet, one finds standing there a single genomic tree of life from which all plants and animals appear to have evolved. What one does not see, now or at any time in the recent past, is a planet littered with thousands of competing trees of life. And if one looks at the major branches of our lone tree of life, one sees very few branches that contain complex forms of life approaching the level of plants and animals; most of the branches appear, in fact, rather stunted in terms of quality if not in terms of quantity. And if one looks within the kingdom Animalia, one finds only one specie that appears to have ever developed a means of communicating complex ideas in written form: Man. In fact, while Cro-Magnon Man may have been the eventual winner in a life or death competition between it and its closest cousin, Neanderthal Man, nowhere does one observe a far more remotely related specie, such as the octopus, that either developed writing or might have developed writing had it not become extinct through natural selection. So it would appear that Man and his writing ability are unique among all the species that have ever graced this blue planet of ours.
Ultimately genetics is all about combinations. Some genetic combinations are clearly viable, producing life, while other combinations are unable to support life. So one can look at genetics and see it as reflecting a series of random changes that either succeed or fail. And while random genetic mutations can be seen as the wellspring from which the diversity of life actually arises, one can understand evolution to simply be a filtering process that continually refines the set of existing species from the set of all species that, at some point in time, had randomly arisen.
Given what I have just stated, both the formula for life and the formula for Man can be analyzed in terms of mathematics and probability. For example, we know that there must be a set of potential species that is either infinite of finite. Likewise there must be, contained within that set, a subset of intelligent species capable of written communication. And, ignoring the effects of evolution, we can express the probability that such intelligent specie might arise through genetic mutation as a fraction: e.g., 1/x.
The value of x in the previously mentioned fraction is rather important. If x is a real number, such as 4 or 100 trillion, then we can expect to randomly stumble upon an intelligent specie like Man every xth specie on average. However, if x is either infinite or undefined, the probability that one might stumble upon a specie with Man-like intelligence quickly approaches 0. In other words, if x is not a member of the real numbers, the probability of an intelligent specie capable of written communication evolving could very well be the same as randomly selecting an integer from the set of real numbers; clearly it could happen, but it would be akin to a miracle.
One implication of x being a real number is that it is ultimately knowable or measurable. One should be able to actually observe the ratio 1/x in nature.
Another implication is that the existence of such ratio essentially means that there is a fixed ratio between the number of potential species and the number of potential species capable of written communication. The likelihood of such fixed ratio existing is, in fact, extremely good if the number of potential species is finite as it would simply be the result of dividing the number of potential species that, for whatever reason, happen to be capable of written communication (call it p) by the total number of potential species (call it q). But the likelihood of such fixed ratio approaches zero if the set of potential species is infinite and if the value of x is not the result of direct, demonstrable causal relationships that dictate that every xth specie should be capable of written communication.
Superficially, looking at the diversity that surrounds us and the uniqueness of Man, it seems somewhat unlikely that such causal relationships could easily be identified. If we, for the time being, then reject the hypothesis that the set of potential species is infinite and accept it as finite, then we would also have to conclude that the entire set of potential species (including Man) is in fact, much like the atomic and subatomic particles that compose our world, entirely defined by our Universe. Put another way, Man and all other potential species, just like the atomic and subatomic particles, would be inherent to the Universe itself, and, it was only a matter of time before the specie known as Man arose on some planet having the right conditions for its development.
One does not need to perceive the hand of an unseen architect at work in order to appreciate the idea that Man, along with the rest of the living world, potentially was not the result of pure dumb luck but was instead destined to be, that a predictable outcome of the Big Bang was in fact the development of Man. One merely needs to be open to the very real possibility that the set of potential species is, despite appearances to the contrary, potentially finite. And clearly the cosmological implications of Man's potential inherency are nothing less than profound, giving perhaps new relevance to some of the age-old religious tenets concerning Man's origin and primacy among the species.
Of course, the number of potential species could still be demonstrated to be infinite. But then one would, I think, have to explain either (1) why every xth specie should be capable of written communication or (2) how something can randomly occur in nature, such as the ability to communicate via writing, without such occurrence seemingly being governed by definable probabilities (e.g. much like the way the prime numbers occur within the set of integers). This is not to imply that an explanatory model, probabilistic or otherwise, could never be developed that accurately predicts such occurrences; merely that such model's development seems somewhat unlikely given the limited evidence available to us here on Earth.
In all honesty, I think the idea of discovering completely foreign creatures and plants on a distant world naturally appeals to us all. Deep down, we love the exotic. Exotic things drive our imaginations; ordinary things bring us little emotional or intellectual reward. So it would appear that we are all inherently biased in our commonly held belief in the existence of an unlimited number of potential species, and that is something that a truly cautious scientist should take careful note of.
Someday perhaps we will travel to another world and discover the answers we are looking for. I know what I personally am hoping we will find there: something familiar, as I think it would help confirm for us our own special place within the Universe. For me, the alternative, finding nothing there familiar, would be both sad and humbling, as it would reduce Man to being nothing more than a random member of an infinite set of nameless species defined by the probability 1/x.