Portals (Funnels, Bottlenecks) and Convergent Evolution

One of the central features of developmental processes is that they produce emergent constraint. A very good example is the process called convergent evolution, which we have previously also called universal development. In these processes, evolutionary structures and functions of high-utility, like brains, and eyes, are observed to emerge again and again in diverse Earth environments, as special, optimally-adaptive destinations. These destinations are discovered blindly via a mostly evolutionary process, per the 95/5 rule, but once discovered, they persist, and permanently change the nature of the environment. For example, once organisms in Earth’s oceans evolved eyes, a whole new level of defensiveness was necessary for all organisms henceforth on Earth, if they were to survive.

Notice that the level of analysis of the system often determines whether we see evolutionary or developmental process. Evolutionary biologists focus on the changes in the individual organisms, and so they talk about the convergent emergence of brains and eyes in multiple independent locations on Earth as “convergent evolution”. But when we focus instead on the entire Earth or life system, we can just as easily call this process “universal/environmental development.” Both levels offer great insights into biological change.

Developmental processes take away freedoms, they funnel a system through a series of increasingly narrow options into future-determined states. For some physical examples, think of the shapes and types of galaxies, solar systems, and planets, and how similar (“isomorphic”) their various types appear throughout the universe. The laws of physics determine that matter and energy must aggregate into these specific forms, which are individually unique yet developmentally all of a special set of emergent types, just like snowflakes.

In other words, developmental constraints must act like funnels, bottlenecks, checkpoints, or in a term we particularly prefer to use, portals to higher levels of adaptive complexity, waiting patiently in complexity’s “phase space” of physical possibilities, to be discovered by evolutionary search.

In any evo devo system then, adaptation is always a mix of both “blind” evolutionary diversification, and continual funneling of this randomly-created diversity through a hierarchy of constraining developmental portals, which emerge as local complexity builds, just as a developing organism funnels its tissues, organ systems, emotions, mind, and body through a series of developmental phases and stages as it matures from seed, to youth, to puberty, to courtship, to replication as an adult.

Natural selection in evo devo terminology, must always be an irreducible mix of both unpredictable evolutionary selection and predictable developmental selection. Hierarchical portals make up the predictable component of selection. The more hierarchy and portals we can see and validate, both behind and ahead of us, the better our foresight becomes.

The idea that developmental funnels exist in physics, waiting for complex organisms throughout the universe, to find them is a hypothesis of both complexity science and natural philosophy. There are an astronomical number of evolutionary configurations possible as complexity builds. If universal development exists, there must also be a preexisting set of hidden constraints on adaptive configuration space, based on the uniform laws and special initial conditions of the universe. These “configuration space funnels” or “attractors” will pull any evolutionary system operating near them into energetically and informationally preferred bottlenecks (constrained future states), as development unfolds.

Portals are the way we understand, for example, protein folding today. Recall the protein folding funnel graphic we use for depicting development. The picture comes from (developmental) protein folding theory, and helps us understand how proteins manage to reduce their entropy (number of possible evolutionary “configuration states”, which naturally want to keep increasing) by finding the bottom of a funnel-shaped energy landscape in a “random” walk.

Here’s a quote by biochemist (and unfortunately, Intelligent Design-affiliated scholar) Michael Denton on the inevitability of certain kinds of biological macrostructures in protein evolution:

“… [T]here is no doubt that the universe of [potential] protein folds represents a Platonic universe … a universe where abstract rules, like the rules of grammar, define a set of unique immaterial templates which are materialized into a thousand or so natural forms—a world of rational morphology and pre-ordained evolutionary paths … [A]s far as the 1,000 protein folds are concerned, we may be sure that they will be present everywhere in the cosmos where there is carbon-based life, utilizing the same 20 [or so] protogenic amino acids.” (Denton M. et al., The protein folds as Platonic forms, J. Theor. Bio. 219:325-342).

Proteins are guided to the bottom of this funnel not only by the universal physical and chemical constraints Denton sees, but additionally by developmental genes, which have themselves been carefully tuned, self-organized over many past life cycles of the organism, to create these special low-energy funnels in service to the organism’s evolutionary and developmental needs.

Once they’ve made it through any bottleneck, evolutionary developmental systems can and will expand outward again in contingent and unpredictable ways. That is, until further complexification brings them within the attractor field of the next soon-to-be locally dominant portal (developmental bottleneck).

See complexity scientist James Crutchfield’s cartoon depiction above of how genotypes may be constrained to evolve in search “basins” in “genospace,” and to occasionally find and transition through “portals” (constraining bottlenecks) between different evolutionary fitness environments. How many such bottlenecks exist in real genospace is unknown at present. Such portal attractors clearly must exist for simpler structures, like galaxies and stars, which are so isomorphic (similarly shaped) in our universe. Proving or refuting their existence in more complex systems, living and beyond, is a major goal of complexity science.

The better we understand development in any of these complex systems, the more often we find self-similarity in how developmental processes occur in many different types of complex systems. For example, cosmologists have recently shown that the same density fluctuation models and math used to explain power law mass scaling (Zipf’s law) in galactic development can be used to explain power law population scaling in city development. Cities, and corporations, are additional complex adaptive systems we have left off of this starter list. Many developing complex systems share other spatial scaling laws and frequency distributions (such as the normal and log-normal distributions). We won’t go into these topics too deeply in this Guide, but they deserve mentioning for those who are mathematically inclined.

Convergent form and function in placental and marsupial mammals. This is one famous example of “convergent evolution,” or rather, convergent evolutionary development.

As we move up the complexity hierarchy from physics to chemistry to biology, to society, our list of potential evolutionary fanouts and developmental portals rapidly grows. At the level of physics, the first of the five universal hierarchies, we can see developmental physics in the motions of the planets, which are highly future-predictable, as Isaac Newton discovered. Other physical processes, such as the production of black holes in general relativity, the acceleration of entropy production, and the acceleration of complexification in special locations also appears to be predictable and universal. Other physics by contrast, such as quantum physics, looks highly evolutionary and unpredictable, fanning out into local diversity.

At the level of chemistry, organic chemistry may be a portal, the easiest statistical path by far, to producing autocatalytic molecular species most capable of VCRIS-driven learning and adaptation. Earth-like planets may be the only easy portal to produce living cells. DNA and proteins may be the only easy portal to producing cells (this hypothesis is now becoming partly testable by simulation). Oxidative phosphorylation redox chemistry may be the only easy portal to high-energy (energy-dominant) cellular metabolism.

At the level of biology, think of life’s convergence, on multicellular organisms, bilateral symmetry, eyes, skeletons, jointed limbs, land colonization, wings, opposable thumbs. On Earth, we see these structural features, such as eyes, emerge and persist independently in various separate evolutionary lineages and environments, because they are so valuable to acquire. Developmental forms and functions are those that will be more adaptive at each particular stage of environmental complexity, in more contexts and species. Think of two eyes (binocular vision) for a predator, over three eyes or one eye.

Excellent Intro to
“Convergent Evolution”
(envir. development),
McGhee (2011).

For another fascinating example, consider all the body form and function types that converged in the evolution of placental and marsupial mammals (see picture right). Australia separated early from the other continents, producing a natural experiment, parallel evolution in separate yet similar Earth environments. This evolution produced marsupial mammals very similar to the placental mammals on other continents, plus a few new ones, like the kangaroo. This process of arriving at the same endpoints via different paths is sometimes called parallel evolution or convergent evolution, but its best name is evolutionary development. Evolution seems destined to randomly, contingently, and creatively discover these optimum forms and functions. But once discovered, they stay dominant for their time and place, and they eventually lead inevitably to the next portal pathway.

See theoretical biologist George McGhee’s lovely book, Convergent Evolution (2011) for a great introduction to convergent evolution, and his earlier work, The Geometry of Evolution: Adaptive Landscapes and Theoretical Morphospaces (2006), for examples of convergence in geometric and functional morphospace, using adaptive landscapes to show the predictable increase in fitness of various convergences.

Adaptive (fitness) landscapes were introduced by the great geneticist and evolutionary biologist Sewall Wright to visualize and quantize fitness in multidimensional parameter spaces. Morphospaces and fitness landscapes are a rigorous and valuable way for scientists to approach the topic of developmental portals. Unfortunately, very few scholars explore convergent evolution today, as mainstream science still largely rejects, and thus is biased against, the teleological (developmental) perspective on biological, social, technological, and universal change. Only in physics and chemistry is developmental portal work fully accepted today.

Nevertheless, a number of biological “developmentalists” continue to explore the ample evidence for convergence in the form (morphology, geometry) and function of biology. Listen to paleontologist Simon Conway Morris in Life’s Solution: Inevitable Humans in a Lonely Universe, 2003 (p. 309) talking about convergence:

“The phenomenon of evolutionary convergence indicates that … the number of alternatives [for adaptive biological form] is strictly limited … the vast bulk of any given ‘hyperspace’ not only will never be visited during evolutionary exploration but it never can be. These are the … wildernesses of the maladaptive, the 99.9% … of biological space where things don’t work, the Empty Quarters of biological nonexistence.”

At the level of society, think of our niche-dominant social brains, and the predictive and imitative behavior that led to those brains. Think also of humanoid forms, with their runaway language and tool use. We will discuss human forms and human civilization in the next section.

At the level of technology, think of four wheels as the dominant form for a car, over two, three or more than four wheels. Four wheeled cars are going to be the dominant morphology for cars on all Earth-like planets, because they are the minimum configuration for simple stability, and because all car-using species will also make flat roads to go with their cars, to maximize their social value as a densification and dematerialization device.

At perhaps the deepest level, think also of our social and mental convergence, through science, on particular set of validated maths, models and explanations for the universe, discussed in Chapter 7, and as well outlined in Peter Watson’s Convergence: The Deepest Idea in the Universe, 2016. At a certain point, our science on a particular subject decelerates. It funnels in on a particular set of maths and explanations, as the most evidenced and accurate. Possible alternative models evaporate, and a growing universality and constraint on our thinking emerges as one set of models increasingly wins the competition for explanation. After a while, though it is still heresy among scientists to say it, the useful science in that area begins to end. Our minds move on to new frontiers.

For us to scientifically understand developmental convergence in the complex substrates of biology, society, and technology in coming years, we will have to develop a vastly better quantitative understanding of how the next adjacent opportunities for increased fitness, in a universe of ever growing complexity, constrain evolutionary processes into a exploring a vastly reduced developmental subset of potential evolutionary parameter space.

Developmental portals, for their part, can obviously be nowhere near as plentiful as evolutionary experiments, since development is a funneling in, a rarity in dynamical systems, and evolution is a contingent branching out of variety, always occurring in parallel with development, to the extent that development allows it. Nevertheless, in a universe as complex as ours, there are surely millions of portals for us to discover, in various environments.

All such portals are statistically destined to emerge via evolutionary search on all Earth-like planets, given the special initial conditions and laws of the universe. Each of these developments may be destined to become optimal or dominant, for their time, in environments in which accelerating complexification and intelligence growth are occurring.

We must now say something about Simon Conway Morris, a scholar I have cited on this page, and with respect to the intersection of religion and science in Chapter 12 (Visions and Challenges). Conway Morris is a Christian and a believer in the idea of theistic evolution, the compatibility of scriptural religious beliefs and the practice of science. I’m a believer in the compatibility of figurative spiritual beliefs and science, but not of literal versions of those beliefs.

Conway Morris is sometimes classified by others as a scholar of Intelligent Design, though I doubt he would agree to that label. Many Intelligent Design scholars, are rightly considered unscientific and dangerous by mainstream science, as several are not able to separate their religious beliefs from their scientific work. What’s worse, their religious beliefs have led some in these communities to advocate for such heresies as “equal treatment” of their theistic views in public high schools, along with evolutionary theory and other fully naturalistic world views. As a result, most of the scholars who identify with the intelligent design community are not accepted by mainstream science. This treatment is as it should be, in my view.

Conway Morris is entitled to his personal religious beliefs, yet we as consumers and evaluators of science should strive to know the religious and spiritual positions of any scientist, and to understand how those beliefs might bias them in unscientific ways. We should also be mature enough to investigate the evidence and argument presented by any scientist, regardless of their beliefs. I cite Conway Morris because his work on evolutionary convergence appears first-rate, in my view. In all his publications, Conway Morris presents a carefully constructed and compelling evidence-based case for the inevitability of many forms and functions of biological organisms in Earth’s history, including such complex functions as intelligence, emotions, and morality.

In Chapter 12, we discuss some of the dangers of scriptural and supernatural religious beliefs in our section on Scriptural Futurists. We also offer a perspective on Responsible Spiritual Foresight, in which we argue that while having personal spiritual beliefs is actually necessary in a world with such primitive science, and that there is no credible evidence for supernaturalism in either our scripture or the universe at present. We also argue that science is increasingly offering us both evolutionary and developmental perspectives and guidelines on responsible spiritual practice.

We have a ways to go before science and spirituality can live well together, and at present, a rocky road to walk. So let’s walk carefully, and help others walk toward a more evidence-based view of the world, a view that still lets us talk about such issues as universal intelligence, purpose, and (self-organized) design, in each case from a fully naturalistic, scientific, or prescientific (systems theoretic) world view.