The Anthropic Oddity of Our Youth

One of the more commonly-debated issues in the philosophy of science and religion concerns the apparent unexpectedness or oddity of the features of our universe. It is very significant, argues one side, that the fundamental laws and constants of the universe seem incredibly fine-tuned to support the evolution of intelligent life. The minutest of variations in the values of some of these constants would render life impossible. What an odd coincidence if all these values “just happened” to be just right. Surely this suggests that they were purposefully designed by an intelligent Creator whose intent from the beginning was for intelligent life to be produced. This is known as the fine-tuning argument.

Not so! argues the other side. For if the fundamental laws and constants of the universe were such that intelligent life could not develop, then we would not be here to debate the issue. The very fact that we exist acts as a filter to select which potential values for these constants we might possibly observe. So surely we cannot consider it odd that they appear to be so fine-tuned for our existence. This is known as the anthropic principle.

Most people would not consider the anthropic principle alone sufficient to remove the sense of oddity that the fine-tuning argument relies on. Its force is considerably strengthened, however, when combined with the possibility that our universe may be only one of billions upon billions of sub-universes, each with its own set of fundamental laws and constants. In this scenario, by the anthropic principle we would naturally expect to find ourselves in one of the tiny fraction of sub-universes that just happened to be fine-tuned for the development of intelligent life. This is called the multiverse hypothesis, and although it remains quite speculative, there are other reasons besides resistance to the fine-tuning argument to think that it might possibly be true. For example, though also quite speculative, string theory seems to suggest that many of the physical laws and constants of the universe would depend on how the various extra dimensions of space happen to be curled up on themselves, so that there could well be an almost incomprehensibly vast number of different sub-universes, each with its own unique set of laws and constants.

I suggest there is another kind of apparent oddity in our universe that is not so easily explained by the anthropic principle and the multiverse hypothesis, however. This is what I will call the anthropic oddity of our youth as an intelligent species. It is the surprising oddity that we find ourselves in as apparently situated almost on the very cusp of the development of intelligent life on our planet.

Consider the incredible diversity of features that evolution has produced and presumably will go on producing on this earth. The most successful adaptations have spread to many different species, either through continued evolution after the adaptation first appeared or through independent development of the same adaptation multiple times. Yet this is strangely not the case for what would appear to be the most successful adaptation evolution has yet produced, namely human intelligence with its orders-of-magnitude greater ability to master such skills as language and math than has shown up in any other species, enabling us to pretty much rule the world without fear of competition from other species. Interestingly, we seem to be not only exceptionally unique among all the species of our planet because of this adaptation, we are also surprisingly living only a brief instant on an evolutionary scale after this remarkably successful adaptation of radically increased intelligence has appeared on the scene.

If intelligence is as remarkable an adaptation as it appears to be, and if evolution is constantly producing intelligent life forms on many planets and possibly even in many universes, then it would seem likely that in most of these cases intelligence would tend to endure a long time after it first appears, though how long before it first appears would naturally vary widely from planet to planet. Therefore, if we were to sample the planets for which intelligent life has already developed, on average we would find that intelligent life has been around on those planets for a long time. So the fact that we happen to live on one of the presumably few planets (by comparison) where intelligence has just developed, and where we are the first species to exhibit it, would seem to be a fairly unexpected coincidence.

We can attempt at best only a very crude calculation of the odds against this coincidence. The first step in such a calculation would be to estimate how long intelligent life would be expected to last on the earth or an average earth-like planet once it develops. For this estimate, I assume that intelligence is generally successful enough as an adaptation that it will probably last until the next mass extinction event. Given that the last such event on earth was about 65 million years ago, I conclude that the expected duration of intelligent life at least on this earth is probably on the order of at least tens of millions of years. By that time, of course, the intelligent beings will probably have diversified significantly compared to their initial form, and they may well comprise many different species instead of just the original one. Also by that time, we might realistically hope they will have developed the science and technology to survive the next potential mass extinction event, so that this estimate of their duration may in fact be far too short, but I will stick with what seems to be a conservative estimate for this calculation.

The next step in our calculation is to estimate where we happen to fall in relation to this expected duration for intelligent life. This is not simply a matter of noting that the development of human intelligence is thought to have occurred around fifty or a hundred thousand years ago. The relevant statistic must also take population into consideration. The question is, if we were to randomly sample intelligent beings from throughout the entire era (past and future) in which intelligence exists on a given planet, how many of them would be as near to the beginning of the development of intelligence on their planet as we are? To estimate this, I will assume (again, conservatively I believe) that the average population of intelligent beings on earth can be expected to stabilize at roughly the current population of human beings today. This means that for the vast majority of the tens of millions of years in which these intelligent beings are expected to exist, there are a few billion of them to sample. The population of humans has only even barely approached this level in the last few hundred years. Therefore, under these assumptions, the chances that a random intelligent being on a random earth-like planet would find himself in our situation—that is, as close to the beginning of his planet’s “era of intelligence” as we ourselves are here on this earth—would be a few hundred in a few tens of millions. In other words, the chances against it would be on the order of 100,000 to one.

I consider these to be very remarkable odds. It’s as if our odometer as an intelligent species shows a reading of 000000. We seem to be very surprisingly young indeed! What are we to make of this apparent coincidence?

One explanation that naturally suggests itself is a little sinister. Perhaps our assumption that intelligence is generally a successful adaptation is not true after all in the long run. Perhaps it is actually a very poor adaptation, in that it has a built-in tendency to destroy itself. Even if intelligent life is indeed evolving all the time on many planets and in many universes, if in the majority of cases it soon ends up destroying itself and its planet almost as quickly as it develops, then it would not be odd at all that we find ourselves in the position that we do. We would expect to find ourselves in that narrow window between the first development of intelligence on our planet and our planet’s total destruction by that intelligence, since for most life-supporting planets there would only be that tiny window in which intelligence exists.

Whether or not this is a reasonable conclusion is difficult to say. Certainly with the development of nuclear weapons (among other things) one could argue we are almost compelled to ponder the possibility that intelligent life may have a self-destructive tendency. On the other hand, even if that unfortunately turned out to be true, we might question whether the destruction would likely be so complete as to put an end to all life altogether on its respective planet, or whether there would more likely be at least a few survivors. And even if the only survivors were cockroaches, could we not expect evolution to go on and eventually produce intelligence once again? If this latter possibility is deemed more plausible than the absolute destruction, then the natural expectation would be that most life-supporting planets would develop intelligent life many times over in their histories. The fact that we are the first on our planet would still therefore be somewhat of an oddity, though admittedly not as much as our initial rough calculation would suggest.

If we do not find any such sinister explanations to be plausible, perhaps we should bite the bullet and say the oddity we’ve been discussing is just a coincidence. Maybe it’s true that there are millions of long-enduring intelligent life forms in the universe or multiverse, and maybe we do indeed “just happen” to be one of the few who only recently cropped up on our planet, even though the majority can look back at a long history of intelligence in many different species on their respective planets. Odd coincidences do happen, after all; there is nothing unscientific about them. Besides, every intelligent life form that is now old must have been young once, so why should we consider it surprising that this is where we happen to be?

I think we have good reason to consider this surprising, however. I doubt that we would have so easily dismissed other, similar apparent coincidences that hypothetically could have arisen but did not. For example, if our calculations of the big bang had initially predicted that life-sustaining conditions would persist in our universe for quadrillions of years, I think we would have suspected something was wrong. It would have been just too strange a coincidence that we happened to be in first 10-20 billion years of the possible range if we could have just as easily found ourselves a quadrillion years farther in (or a quadrillion plus a billion, or a quadrillion plus two billion, etc., etc., etc.). To our relief, since our calculations in fact show that life will be impossible after “only” another few tens of billions of years, it’s not statistically strange at all that we find ourselves somewhere in the broad middle of that range.

There remains yet one additional possible implication that the anthropic oddity of our youth may be pointing us toward. Perhaps we need to bring in the question of teleology. Even if our situation is a genuine statistical coincidence, perhaps it is not a metaphysical coincidence, but was rather in some sense designed into the system from the beginning. If we interpret the laws of the universe (or meta-laws of the multiverse, if there is one) as working in perfect accordance with a specific purpose or goal for which they were designed, and if we are so audacious as to believe that this specific purpose or goal might have been the creation of human beings, then there is no longer any mystery to the coincidence. Then we would naturally expect to find that the evolutionary factors in the universe tending to the development of intelligence might well be so precisely balanced with the extreme rarity of favorable conditions that intelligence appears not millions of times or zero times but exactly once, exactly in the form of us. This is not a scientific conclusion, of course, much less a provable one. It is just a philosophical hypothesis that may or may not be correct. But neither is it non-scientific; it is entirely compatible with science in every possible way. It simply attempts to make sense from a philosophical perspective of what may be a genuine coincidence from a scientific perspective (and again, genuine coincidences do occur). And it does so in a way that is not specifically tied to theism, yet seems to me to harmonize rather nicely with that view.

Update [added 8/23/2014]: A year and a half after writing this essay, I learned that the statistical oddity it refers to has been noticed and written about before by several scientists and philosophers, including Brandon Carter and John Leslie. Rather than exploring the possibility that it might imply teleology and a one-off development of intelligence as I suggested, however, it appears they all have used it strictly as an argument that humanity is likely facing a doomsday scenario. I do not know if any of them considered the point I raised that even if intelligence tends to be self-destructive it would still seem statistically unexpected that we would be the first species to develop this capacity on our planet, since even a doomsday scenario would likely not put an end to the planet altogether. For more information, see Doomsday Argument on wikipedia.

This page copyright © 2013 Edward A. Morris.  Created February 27, 2013.  Last updated February 28, 2013.

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