A Cognitive Toolkit for the Rationalist. 3/6: Neo-Darwinism

Chapter 6: Survival machines

Where did we come from and why are we here?

While the basic mechanism of evolution by natural selection was described by Darwin over 150 years ago in The Origin of Species, the theory has made a lot of progress and accumulated piles of evidence since then. Here’s a very brief recap (which you should feel free to skip over if you’re quite familiar).

Living organisms have descended with modifications from species that lived before them by a process of Natural Selection.

·                     A species is a population of organisms that interbreeds; e.g. homo sapiens.

·                     Individuals of a species have heritable traits in the form of “genes”. These are modified by random mutations and the modified genes are passed onto offspring.

·                     More organisms are produced than can survive and this creates competition for resources

·                     Some modifications afford an advantage to the individual to whom they were passed on. These individuals are better adapted to survive and reproduce in their environment than others, thereby passing on copies of their modified genes to the next generation (“natural selection”).

·                     Meanwhile, the advantageous adaptations are further enhanced by the same process acting on future generations (“cumulative selection”).

·                     Every species occupies a unique ecological niche, in which it makes a living. If it did not, it would be driven to extinction by competition.

While the tenets of the theory of evolution are few and simple, biologists still need to come up with clever, creative explanations for specific traits observed in species. In fact, it was the need for an overarching logic to explain hundreds of such observations that led Darwin to propose his theory.

Some interesting ones:

   ·                  How come cheetahs can run so fast?

·                  Why are some trees so tall? Why as in “how come”.

·                  Why do peacocks (but not peahens) have such spectacular tails?

·                  Why do most species have exactly two sexes?

·                  Why do we die? (Warning: mind-bender!)

https://www.whats-your-sign.com/peacock-symbolism.html 

These and many other observations are explained in terms of quite fascinating concepts like “arms race” and “sexual selection” in Richard Dawkins’ famous book The Selfish Gene, the central idea of which we shall now turn to. Since Darwin, there has been a lot of debate on what is the entity on which natural selection acts, i.e. what does it “select”? Is it the entire species, or groups, or individuals, or something even smaller, something more fundamental? The current thinking is that natural selection acts on genes. But why is this important? Read on…

The fact that humans and apes had a common ancestor (note that apes are our “cousins”, we did not evolve from apes), is well known. But if we trace the ancestor of every known species, it turns out that all life on earth evolved from single-cell bacteria-like life-forms, which are themselves thought to have descended from even simpler, self-replicating molecules (“replicators”). Our genes are the present-day descendants of these replicators. According to the selfish-gene theory, our bodies (i.e. we) are survival machines put together by the coalition of genes that reside in them to aid their survival and propagation. To enforce or encourage behaviour which furthers their goal, our genes have built into our bodies rewards in the form of pleasure (e.g. sweet taste in mouth, orgasm), punishment in the form of pain, and indeed every trait that we find in ourselves, including the most powerful adaptation of all — our minds.

While Evolution is a scientific theory that is relatively easy to understand (compared to say General Relativity or Quantum Mechanics which are highly mathematical), there are a few misconceptions that just refuse to go away.

One of the biggest misinterpretations of evolution is that it describes a “random” process. Without random gene mutations, there can be no design improvement, but the process of selection is not random. It systematically filters the adaptations that are best suited to thrive in the given environment, the filter being death of certain individuals and survival of other individuals (“differential survival”).

Why don’t we “see” evolution happening? The reason is that evolution happens on a geological time-scale. The very first lifeforms appeared on our planet about 3.5 billion (that’s 3,500,000,000) years ago. But our brains are adapted (again, by evolution) to analyse events that happen on much shorter time-scales, nearabout the average human lifespan of less than 100 years. We can only analyse (but not imagine) what is possible on a geological time-scale in terms of abstract models. This is one of the barriers to people’s acceptance of evolution as a fact, other than ideological resistance from religious groups which we will examine in Chapter 8.

It is also critical to understand that evolution is an unguided or “blind” process. It has no predefined goal and no foresight. The replicator replicates not because it wants to, but because it has an inherent tendency to. At a fundamental level, this process is like how hydrogen + oxygen + a spark gives us water + an explosion, though self-replication is a much more complex chemical reaction. The point is, the replicator does not consciously replicate itself any more than hydrogen and oxygen atoms consciously combine to form water. A single molecule (or for that matter, a bacterium) is not complex enough to have a mind — and therefore not complex enough to have intentions, desires etc. We will explore this train of thought further in Chapter 10.

It is in this respect that natural selection is fundamentally different from artificial selection, the process of selectively breeding domesticated animals and plants for desirable attributes. A French poodle or chihuahua couldn’t possibly survive in the wild. But if artificial selection proceeds by the guiding hand of humans, then “who” guides natural selection? If the answer is “no one” then how can a blind process produce such purposeful design? The answer to this question is not simple and occupies much of Chapters 7 and 8.

Meanwhile, here’s an example of a “blind” process of trial and error that can produce clever and highly effective designs. In oral traditions of boat-building (I was fortunate to have witnessed one), knowledge is passed on to the next generation by word of mouth. Accidental (or wilful) changes to the existing design of boats may turn out to be better in some cases and worse in others. The boats that happen to have the inferior modifications sink, while those that happen to have the superior modifications come back and are copied. After many generations, the boat-makers may not be able to tell us why they make the boats the way they do. But it’s evident that the boats work extremely well. That is, they are fit for a purpose. The analogy with evolution should be obvious but I’ll still spell it out — the ocean is the environment (Nature), the boats are individuals of species, the modifications are gene mutations. Dan Dennett calls this “competence without comprehension” and many more such ideas can be found in his recent book From Bacteria to Bach and Back.

Chapter 7: Something from nothing

A materialistic theory of Origins may be within the reach of science

This chapter introduces some of the theories and concepts that we will need, to be able to assimilate the arguments that follow.

Top down vs bottom up processes: Rather than trying to provide definitions, let me cite some examples of each. A communist economy is a top down economic system. The state owns all productive assets and a central planning authority decides how much of each good or service shall be produced to meet the needs of society in an “optimal” manner. A market economy, on the other hand, is a bottom up economic system. Individual firms and households decide what is best for themselves. Prices act as signals which balance the demand for goods and services against their supply.

Most corporate management is top down — decisions made at each level flow down to the levels below. Open source software communities are bottom up — each individual is free to decide what (and how much) they would like to contribute. Computer languages are developed by a top down process — syntactical rules are synthesized by a few programmers and then adopted by everyone. Human (or natural) languages evolve by a bottom up process. No one intelligently designs a human language.

TL;DR: Bottom up processes are unsupervised (or “blind”). Unlike top down processes, they have no central control. And, coming to the point — evolution is bottom up, Creation is top down. Bottom up is the way of Nature, top down is the way of Humans.

There is a related concept which will also be useful to understand — self-organizing systems. Again, examples will be more useful than definitions here. Crystals and snowflakes spontaneously form into extremely orderly shapes. Birds spontaneously flock and form V-shaped flying formations. Walking trails in the wilderness (“desire paths”) develop as visible trails attract more traffic. Cities and other human settlements spontaneously come up and grow.

All of these are examples of spontaneous order arising from an initially disordered state. “Spontaneous” here has the usual meaning, i.e. not requiring any external control. We are likely to be much more familiar with top down processes because that is how most human institutions function. So when we see order (as in non-random arrangement) we think order (as in decree or command). It’s just one of those biases in our language that inhibit our understanding of how Nature works (more on this in Chapter 10).

By the way, self-organization does not happen in general but only under (very) special conditions. Order cannot always emerge from disorder. In fact the Second Law of Thermodynamics (SLT) says precisely the opposite for an isolated system — the tendency of a system is always towards a more disorderly state or higher “entropy”. But such a statement of SLT applies only to an isolated system — order can emerge from disorder in an open system, i.e. one that can exchange energy or mass with its surroundings. In this case entropy can decrease “locally” as long as total entropy increases.

Emergence: Not an easy concept to grasp but here are some definitions -       


 ·                     When a large collection of simple (and similar) things comes to have properties not present in the simple things themselves

·                     When “more is different” or “the whole is more than the sum of its parts”

·                     When complexity spontaneously arises from simplicity

Emergence cannot be explained in terms of the properties of the simple things but in terms of interactions among them. The number of possible interactions in any system increases exponentially with the number of elements in it — think number of possible handshakes in a group. And that’s how a whole can be more than the sum of its parts.

Here are some examples -

 ·                     Wetness of water: there is nothing “wet” about a single water molecule. Wetness of water is a property that emerges when a large number of water molecules are spread on a surface.

·                     Social insects: Ants, bees and termites live in humongous colonies comprising of thousands (sometimes millions) of individuals. The entire colony behaves in an apparently goal-driven, purposeful manner, achieving amazing feats of organization. But each individual ant, bee or termite possesses very low intelligence; and yet all this is achieved without any central control.

·                     Heat: It was thought till the mid-1800’s that heat is some kind of invisible fluid which flows from hot to cold bodies (the “caloric” theory). We now understand heat in terms of the kinetic energy of the molecules of a body.

·                     Life: It was around the same time that living organisms were thought to contain some invisible “substance” or “force” that was absent in inanimate objects (“vitalism”). The modern conception is that the chemistry of life is not fundamentally different from other chemistry.

What is the importance of the last two examples? It is this — if a behaviour (or property) can be explained in terms of another known property (or explained as an emergent property), then there is no need to assume a new fundamental property. Occam’s Razor favours this.

Of course, just explaining a phenomenon as “emergent” from this or that does not by itself add to our understanding of it. The mechanism by which the macro behaviour (e.g. of the ant colony) emerges from the interactions of individual units (e.g. ants) needs to be explained in sufficient detail.

Abiogenesis: This is the theory of how life could have (actually, must have) emerged from non-living matter. The most popular theory, advanced in the 1960's says that the first self-replicating molecules (“replicators”) may have been RNA molecules which catalysed the production of more RNA molecules (the RNA world theory), though this is now increasingly in doubt. The Miller-Urey experiment in the 1950’s tried to simulate the “primordial soup” in the lab — the conditions that were thought to exist on earth about 3.5 billion years ago. They found that more than half of the 20 amino acids common to all life had formed spontaneously within just a week. Once the first replicator formed, evolution by natural selection would have kicked in… we know the rest from Chapter 6.

Recent research in physics suggests that the tendency for random collections of atoms to form replicators may be explained by thermodynamics (recall earlier reference to SLT). Any system that receives energy from an external source (e.g. Sun) and can expel heat into a surrounding “bath” (e.g. ocean or atmosphere) will tend to dissipate increasing amounts of heat over time via self-replication — a process referred to as dissipation-driven adaptation. The implication is that the appearance of replicators, far from being a chance happening, could have been inevitable given the conditions on a young earth.

Flat Universe: The observation that the universe has exactly enough matter (including dark matter) to slow down its expansion but never quite stop it. While this is a statement of how the universe will end, it has another implication — the universe has a “net energy” of zero, with gravity constituting negative energy. That means, according to Quantum Mechanics, it is a universe that could have come out of nothing. This logical leap assumes familiarity with several quantum physics concepts which I would not like to go over. Fortunately Lawrence Krauss explains the idea of the flat universe quite nicely, so we can now move on.

Chapter 8: The myth of creation

What kind of answers do we find satisfying?

We are now in a position to summarise what we have as the elements of a purely materialistic answer to the question of “how the world came to be” -

1.           The idea of a Flat Universe implies that our universe could have come into existence out of “nothing”

2.           The process of Abiogenesis describes how the earliest life could have emerged from nonliving matter

3.           Evolution takes over from there to explain how the vast variety of complex life that we now see could have come from the first self-replicating molecule

Of course, we cannot claim that each of these theories stand on equally firm ground. In fact the first two statements are, at this point, fairly speculative and it wouldn’t be fair to even call them theories. Evolution, on the other hand, is a theory so firmly established that it is regarded as scientific fact. The important thing is that each of these theories is evidence-based. While religions of the world provide their own creation myths, these are inconsistent with each other. You believe the one you grew up with. But there is one thing common to all creation myths and that is intent (more on this in Chapter 10). What we have from science is not one more creation myth. Over time, as more evidence accumulates, it will seem as “obvious” as the fact that the earth goes around the sun — a theory that took more than a thousand years to establish from the time it was first proposed by Aristarchus of Samos.

Even setting aside #1 and #2 and accepting #3 (evolution), the conclusion is inescapable — we have effectively eliminated the need for assuming an intelligent creator of life on earth. People who continue to believe in a creator must do so for reasons other than wanting to know the truth about “how things (we) came to be the way they (we) are”. That question has already been answered and the answer has no place for a creator. The myth of creation could be just that — a myth.

While we can assert that there is no need to invoke a creator, we cannot prove its non-existence (we know why from Chapter 2). And neither can we appeal to evidence: For two reasons — first, we already saw in Chapter 4 how beliefs are immune to (contradictory) evidence. And second, eventually every debate which cites evidence is bound to turn extremely technical. There is a limit to how much evidence and counter-evidence even a Rationalist, given the time and inclination, can go over. Instead here are my a priori reasons for choosing the materialistic worldview -

·                  It is a bottom up explanation; i.e. it explains limitless complexity starting from extremely simple beginnings. The mechanisms are described in Chapters 7 and 8.

·                  It explains the unknown in terms of the known. In other words, it does not invoke undefined agents which are left to the imagination.

·                  It does not rest on moral judgments or contain any specific cultural references. In other words, it is universal.

·                  It is self-consistent. Physics explains chemistry which explains biology which explains neuroscience…

The second point needs a bit of elaboration. It may seem that science explains the unknown only in terms of more unknowns. After all, quarks and quasars (or neutrons and nucleic acids) hardly feature in the layperson’s image of the world. Which is why we would like to decide what “kind” of theory we like when it comes to explaining the natural world, believing on faith that the evidence for it is strong. We will revisit this theme in Chapter 11.

Meanwhile creationists continue their efforts to discredit evolution, substituting ideologically motivated pseudoscience like Intelligent Design in its place. Intelligent Design assumes that all life was created by an intelligent entity (God) and uses the notion of “irreducible complexity” to argue against evolution — the teleological argument or Paley’s Watchmaker. While there is no evidence in favour of Intelligent Design, the many design flaws in the human body are evidence against it. The human eye, for instance, has a blind spot not present in the eyes of the octopus.

Several detailed arguments against creationism and in defence of evolution can be found in Dawkins’ second book The Blind Watchmaker. And here’s a very concise encapsulation of the core logic, by Steven Pinker (the full article is hyperlinked in Chapter 12):

Natural selection… explains one of the greatest mysteries in science, the illusion of design in the natural world. The core of natural selection is that when replicators arise and make copies of themselves, (1) their numbers will tend, under ideal conditions, to increase exponentially; (2) they will necessarily compete for finite resources; (3) some will undergo random copying errors (“random” in the sense that they do not anticipate their effects in the current environment); and (4) whichever copying errors happen to increase the rate of replication will accumulate in a lineage and predominate in the population. After many generations of replication, the replicators will show the appearance of design for effective replication, while in reality they have just accumulated the copying errors that had successful replication as their effect.

Evolution by natural selection is the kind of “rule” that emerges in the absence of top-down order. Consider this somewhat simplistic analogy. Streets in Indian cities are notoriously difficult to cross, especially for people who have grown up in the West. If you were to stop someone on the street and ask them “Excuse me, what’s the rule for crossing the street here?” you would get this “If you see a car approaching, don’t cross. If no car is approaching, then cross”. But you were looking for a rule like this “If the light is red don’t walk, if it is green then walk”. But that kind of rule would exist only if it was put in place by a traffic authority. Whereas the first rule is an “emergent” rule — it does not need any external agency to put it in place.

Now, we would like to move on to a different question, one that science was thought to not have any answers to — “Why are we here” or “What is the purpose of our existence”?

The only ‘purpose’ of a survival machine (us) is to survive and pass on its genes to as many offspring as possible while trying to ensure their survival as well. This much should be clear from Chapter 6. It is the only meaningful answer to the existence question. Why do we find this answer so hard to accept? Why do we cling to fantasies instead (heaven and hell, eternal soul, rebirth, moksha…)? While this may sound like a rhetorical question, it is not and we will actually try to answer it in Chapter 10.

Here’s another question that science is not supposed to have an answer to — “why is there so much suffering in the world?”. And here’s a possible answer, apart from the obvious fact of predation. Evolution, being a blind, unguided process of trial and error, must produce many individuals with slightly different traits and wait to see which ones turn out to be the fittest i.e. best adapted to survive in the environment in which they find themselves. While each individual must strive to survive and prosper (the desire for self-preservation itself being an evolutionary trait), not all will be able to. If there were no competition, all new traits (via gene mutations) would be passed on to the next generation and would be equally prevalent in the gene pool. One eye would be as good as two. Our well-adapted, purposeful traits are therefore a direct result of the suffering and premature death of millions of individuals who left no offspring.

Isn’t there a way for the same good designs to come about (or be “brought about”) with less suffering? Maybe there is, but who will see to that? There is no one in charge, no one running the show and therefore no one to negotiate with or appeal to! In the next two chapters we will explore the question of how we came to believe that there is someone in charge.

Written by Ambar Nag.

ambarnag@gmail.com

(Continued in Part 4)