An Inverse Great Filter – Predators

Great Filters are events or processes which are very rare, when considered across all planets where they might have happened.  They are one possible answer to the question, “Where are the aliens?”  There are many other answers that do not involve a rare event.  For example, it may be that aliens do not see any point to coming here.

Another possible set of answers to that question involve the inverse of a Great Filter, which we can call an Inverse Great Filter, rather than being creative about nomenclature.  This is an event or process which occurs on every one of the possible planets where it could happen, except a very few and it is the lack of the occurrence which makes it possible for intelligent aliens of those very few planets to emerge and begin their voyaging across the emptiness of space.  Very few may be zero. 

This blog post does an example of an Inverse Great Filter.  Consider the evolution of life from the first self-replicating virus or whatever the first self-replicating thing was, up to the creature that is just about to begin tool-using.  We consider tool-using to be the start of the evolution of intelligence, a major turning point, although it is an assumption.  Suppose the creatures live in an environment like a forest or a savannah or a coastal bay or anywhere else on the planet.  They eat the plants there, or perhaps they catch smaller creatures and eat them.  The smaller creatures could be animals, insects, bottom-dwelling water creatures, fish, birds, or something else mobile.  They do this because they are part of the ecology now, and have not yet begun to differentiate themselves from other creatures.  There is no agriculture.  There is no tool use, even of stone or sea shells or sticks, as that is still in the future. 

In the same ecology, there are other creatures that do the same.  They eat mobile creatures, by catching them, except they do not catch fish or birds or insects.  They catch soon-to-be-intelligent creatures and eat them.  These predators are efficient, and they are numerous, probably eating many other creatures as well.  They are adaptable, and when their hunting ground is encroached by some new creature, they adapt to eating it.  Let’s refer to them as Top Predators.  There is a balance here, as the hunting ground is full of things for creatures on the next level of predation to consume, so if this hunting ground becomes depleted of food for the Top Predators, it isn’t long before some other tasty creature moves into it to take its chances in a food-rich environment, unfortunately inhabited by Top Predators. 

Suppose it is pretty easy for Top Predators to evolve to becoming more capable of catching creatures, and not so easy for the next rung to evade them.  A balance exists, or over a longer period, the Top Predators exterminate their favored prey frequently by driving their numbers below the critical mass needed to maintain the population.  The exterminated prey is replaced by another prey, which has been there previously, but now has more food choices because the exterminated prey is not nourishing itself on the next rung down.  So years go on. 

Any intelligence that involves in the creatures does not evolve in the Top Predators, which doesn’t need tools for any purpose, but have a successful existence catching second level prey.  It evolves in the second level prey, but just as the intelligence genes begin to spread though the population of second level prey, they get exterminated in their environment and evolution’s roll of the dice throws craps.  Predators in the environment of the potentially intelligent creatures eat them.  Maybe there are multiple predators, and maybe the intelligent creatures get a break now and then for some period of time measured in centuries but get exterminated anyway.  In short, intelligence never gets to develop even to the tool-using phase because of the efficiency of the predators which exist at that time.

Now, this is a snapshot, and the same thing must go on continually over the whole period in which the potentially intelligent creatures keep trying to evolve to become smarter.  Perhaps once they get to a certain stage of intelligence they can protect themselves against the predators, or evade better.  Perhaps in most worlds, they can’t get there.  Intelligence doesn’t do enough to save them.  Speed might have, or fur that was a disguise, or tree-climbing ability, or hiding in caves ability, or something else might have, and this might have militated against any advantages that intelligence gave so that intelligence becomes a non-chosen trait.  Other types of traits which promote predator avoidance become the selected ones.  Talking or communicating with grunts which might have led to an iota of intelligence improvement turn out to be signatures that the predators listen for. 

So, predators are a potential Inverse Great Filter.  As far as we know, on Earth from before the period of the dinosaurs to nowadays, there have been predators looking for a meal, independently of how smart it was.  They are evolving constantly, as are all species, and under the Predator Inverse Great Filter hypothesis, on most inhabited worlds in the galaxy, they are successful enough to preclude intelligence from getting a handhold and starting to kill the Top Predators off.  Perhaps there are many varieties of Top Predators on most alien worlds, and specializing, using intelligence, to avoid one of them makes the creature more vulnerable to others.  Five Top Predators?  Ten?  If we ever find some of these alien worlds we can take a count.

Since we have passed through this Inverse Great Filter, it would be one possible explanation why we are sitting here alone and out of contact with any other civilization.  If it is the one single explanation, meaning that there are no other Great Filters and no other barriers to star-traveling, then we can go forward when we wish to do this, provided we spend the money on building the ships and the money and decades or centuries to figure out how to build the ships.  It also means we can become the galaxy’s premier anti-environmentalists.  If we somehow become suffused with the over-arching meme to promote intelligent life on other planets, we can go from inhabited planet to inhabited planet, killing off the Top Predators there and allowing intelligent life to spring into existence over the next tens of thousands of years, provided no new Top Predators emerge very early.  Perhaps hunting expeditions should occur every ten thousand years.