By Stuart Kauffman
I want us to think about the expansion, via "blind" Darwinian evolution, of the biosphere into an expanding Adjacent Possible, while that Adjacent Possible itself expands due to the expansion of the biosphere into it. So too the econosphere. In both cases, in a supracritical biopshere and economy, what can happen next increases, that is, the Adjacent Possible expands, and this expansion is the result of the previous evolution of the biosphere and econosphere. The world of Possibilities can grow by the very processes through which what is already Actual grows.
Two posts ago, in The Open Universe: Overview, I broached the Adjacent Possible and whether future adaptive opportunities or possibilities are past or present efficient causes. Now it is time to pursue it carefully. If future possibilities afford new ways to adapt and are realized thereby changing the course of evolution of the universe, but these adaptive opportunities are not efficient causes, then the becoming of the universe is not to be explained only in terms of efficient causes.
Several posts ago I discussed supracritical and subcritical economies, subcritical economies are those which cannot expand the range of goods and services endogenously, for example, a subcritical economy like Ethiopia, and supracritical economies like the global economy that explodes in novel goods and production capacities. I think our biosphere, like the global economy, is supracritical, creating niches for new species faster than it is creating new species. There are, typically, ever more ways to adapt into an expanding Adjacent Possible.
The Non-Erogidic Universe
Let's begin with something we know, but rarely think about. How many proteins are there 200 amino acids long? Well, there are 20 types of amino acids, so the answer is 20 raised to the 200th power, or about 10 raised to the 260th power. Now the number of particles in the known universe is 10 to the 80th power. Ignoring the fact that these are far apart and cannot interact, and using the shortest time scale in the universe, the Planck time of 10 to the -43 seconds, if all the particles in the universe did nothing but make novel proteins length 200 every Planck moment, it would take a staggering 10 to the 39th power times the lifetime of our universe to make all these proteins just once!
This means something physical. At levels of complexity about atoms, all of which are made in the universe, the universe will never make all possible proteins length 200, 400, or 1000, nor will it make all possible organisms, organs, or social systems. Above the level of the atoms, the universe is on a unique trajectory, thus can be said to be "non-ergodic". (ergodic means, roughly, that all small regions of a state space are visited proportional to their volume.)
The non-ergodicity of the universe, a universe open indefinitely upwards in complexity, means that history must enter the becoming of the universe.
History, and possible alternative histories, are essential to our story started above.
Recall I defined the Adjacent Possible of a set of 1000 kinds of organic molecules reacting in a liter box, called The Actual, as the set of new kinds of molecules that could arise by single reaction steps from the Actual. This is perfectly well defined for molecules, given a minimal lifetime of a stable molecule in standard conditions.
Now let's imagine life shortly after it started, and today. At the start, let's say there was only one type of "organism" or proto-organism. Clearly, and as shown by the paleontological record, the diversity of species has, with the exception of small and large extinction events, increases as an average, or secular, trend over the past 550 million years since the famous Cambrian Explosion.
Recall that in Breaking the Galilean Spell I spoke of three jaw bones of an early fish evolving by Darwinian exaptations to become the three middle ear bones in you. But then, relational "degrees of freedom" (ie what can vary), matter. Had one bone been in the skull, one in the spine and one in the jaw of the fish, presumably we would not have three adjacent middle ear bones. Then we discussed whether we could prestate all possible Darwinain exapations just for humans, and concluded that we could not. Therefore, we do not know what can happen in the evolution of the biosphere. We do not know all the possibilities in the Adjacent Possible of the biosphere. Then, I said, we cannot make probability statements since we do not know the sample space, nor can we have laws for the emergence of such exaptations.
Turn next to: Can the blind Darwinian evolution of the biosphere open up new ways to adapt or co-adapt? Yes.
Let's return to my example of the humming bird and the field of flowers. Recall that the humming bird, Hannah, inserts her beak into one flower, pollen rubs off the stamen of that flower and sticks to the beak, Hannah grabs some nectar, flies to the next flower swallowing as she goes, and dives for some more nectar in the new flower. And what happens? Some pollen rubs off on the stamen of the second flower pollenating that flower.
Lovely mutualism. Now recall, slowly this time, the question: Can blind evolution stumble upon ever novel ways of co-evolving this mutualism? Yes. Hannah's feeding behavior, and the detailed location of the stamens next to the nectar must coevolve so stamen just brush the beak, and are not crushed by it, or are too far from the nectar they so do not brush Hannah's feeding beak. The flower must synthesize enough nectar for Hannah. And the flower's pollen must co-evolve how they stick to one another just so, and to Hannah's beak, to optimize pollenization. Moreover, notice that Hannah can evolve her feeding behavior so she rubs more pollen off the stamen. The stamen can evolve to be properly situated near the nectar given Hannah's feeding behavior. And I gave the example of the pollen altering its stickiness by evolving either tiny hairs or tiny cups to distribute and hold sticky glycoprotein on the surface of the pollen.
How many ways are there to alter the beak's shape, so as to brush the pollen grains? Well, typically there are many major and minor gene mutations that affect beak shape in a host of different ways, all of which can mold it more or less to the same shape. This contribution by many genes to a trait is called "polygeny". Many genes can alter the location of the stamen near the nectar. The viscosity of the nectar can change, altering Hannah's feeding behavior. The new hairs and new cups can alter shape and size and distance apart to alter pollen stickiness. Just the advent of hairs versus cups shows that evolution can blindly stumble upon novel ways the mutualism can adapt.
Of course my "hairs" and "cups" are my imagination, but they suffice to firmly make my point. Evolution can indeed open up new ways to evolve the mutualism between Hannah and her friends, let alone insects, and flowers.
But this is crucial. A "new way to adapt" is, perforce, a new adaptive possibility that did not exist before the hair or cup emerged.
Are we forced to use "modal" language like "possible?" I think the answer is "YES". The situation is simple, an adaptive "step" will not happen unless it is possible. If no hair or cups exist, then no adaptation by tuning hair or cup structure or locations can happen.
For something to happen, trying hard to use a language only of Actuals, we fail, for we must be able to talk in terms of what can happen. If something cannot happen, eg perpetural motion machines, it will not happen.
But there is more: Let's parse, "There is an opportunity to adapt" to "the adaptation is possible. It may or may not occur. If it occurs it will tend to be selected to fixation in the population." "Fixation" means all the members of the species have the new trait, it may be too strong of a condition.
Notice first that "tend to be selected" is a "dispositional term". The achievement of this selection will be by efficient causes. But can we give the necessary and sufficient set of efficient causes such that the adaptation comes to be selected? Typically, no. But then we can have no law for how the trait comes to be selected, we can have no compact description of the regularities that would be contained in the necessary and sufficient efficient cause conditions that we cannot state.
Now how can the new way of adapting, for example, the evolution of hairs, come about? Well an acausal, on the Copenhagen-Born interpretation of quantum mechanics, quantum random event might occur which causes a now classical mutation bringing the hair on the pollen, or the cup on the pollen into existence in the universe. Or a hair might arise in one flower and a cup in another of the same species of flower, opening two new ways adaptation can go, each of which might progress in a variety of detailed ways, polygenically for each small step, opening yet further new avenues for adaptation.
Note, as required above, the opportunity itself is a possibility that might or might not occur.
So the emergence of new ways, or opportunities, to adapt can be quantum-acausal. But the achievement of the adaptation can also be quantum-acausal by further mutation events induced by quantum acausal events. Again, as required above, the adaptation may or may not be achieved, and if quantum-acausal on Copenhagen, it "just happens".
Thus, the biosphere stumbles into an Adjacent Possible that can expand: two ways or more to adapt improving the mutualism by modifying cups or hairs in multiple ways.
The number of ways to adapt depend upon the number of "features" of a member of a species , the complexity of those features, and all members of all species with which it interacts in its ecosystem, including all its relational degrees of freedom ways of interacting, plus all - relational degrees of freedom - ways it interacts with its abiotic world as well.
As species become more complex, and as features per species become more numerous and more complex and diverse, the ways of adapting become more numerous.
One can show in a simple analytic model that an economy with the diversity of goods on the X axis and production capacities on the Y axis can be subcritical or supracritical. In the latter case, it generates an exploding diversity of new goods and new production capacities. In brief, the economy generates more than one new economic niche for each new good it produces, so the very diversity of the economy is a major factor in economic growth. Data now support this.
The biolgoical analogue of a good is a trait of a species member. The analogue of a production function includes a functionality in a mutualism, for example, the beak of Hannah rubbing off pollen grains from one flower and transferring them to the next flower. We need novel theory here. My strong intuition is that the biosphere is now supracritical: each new trait, or "task", ie good or production capacity, that the biosphere engenders, creates more than one new adaptive opportunity for the involved species, so adaptations explode into the Adjacent Possible, invade the Adjacent Possible, and create ever new adaptative possibilities as this expansion happens. Thus the Adjacent Possible itself expands.
Strikinglly, we do not know all the possibilities in this Adjacent Possible, for we cannot prestate all possible Darwinian exaptations just for humans. The supracritical biosphere is evolving ever more ways of becoming and doing so in ways that it seems we cannot entirely say. The biosphere is creative in its becoming, but not mystical. There is nothing "spooky" going on, and no laws of physics are violated.
There may be a general law, however: The biosphere may, as an average trend, tend to increase the growth of its Adjacent Possible as fast as it sustainably can.
Now the ontological bite: Can a future possible adaptation opened up and achieved by quantum-acausal processes be a past or present actual efficient cause of an adaptation? No, no it cannot. But then the opening up of new ways of adapting that can change the course of biosphere evolution can and do change the course of evolution, hence change the becoming of the universe. Possibilities cannot be causes, so the becoming of the universe is not only due to efficient causes. Instead it is also open to the emergence of novel possibilities of becoming.
We are a long way from Laplace's Demon knowing the entire future and past of the universe given the positions and momenta of all the particle in the universe and Newton's laws.
All this means we must begin to think about how possibilities for becoming themselves come into existence. And we have to think about whether the adjacent possible of the biosphere is ontologically real. We have not asked these questions before. They seem fundamental, and yield a new view of an open universe.
I thanks Harvard theologian Gordon Kaufman, and Swarthmore philosopher Alan Baker for useful discussions.