Neo-Darwinism

The dynamic of evolution is based on struggle and competition within and between species for limited resources. Although this process is considered directionless, it is responsible for bringing forth the successive forms of life from single cell organisms to human beings.

This interpretation of evolution has many merits and its simplicity is seductive. However, Neo-Darwinism also has some flaws. It was widely accepted in the 20^th century not because it explained everything perfectly, but because it accounted for the facts better than any alternative, and because it fitted well with the prevailing ideology of materialism in scientific circles. The purpose of what follows is not an attempt to disprove Neo-Darwinism, but rather to show that it is incomplete. Because of this incompleteness, it cannot provide plausible explanations for all the characteristics of evolution and for all the salient paleontological and biological facts. We will argue that, for the same reason, the key terms associated with this view – chance, natural selection, competition, and gradualism – do not appear fully adequate, especially if taken dogmatically, as it has often been the case[2].

Chance

The materialist view is that all the changes in living organisms, from the original single cell to a great variety of species that have existed and currently exist, are the result of accidental genetic mutations[3]. Sure enough, some mutations may be accidental, but the claim that all mutations in all organisms have been random seems improbable for several reasons.

The effects of random mutations may be harmless only in extremely rare cases. They are almost always harmful and incur a loss, not a gain of information and complexity:

The fact that the vast majority of all mutations which have some detectable influence on the functioning of the organism are deleterious suggests that each functional living system is indeed enormously constrained to adaptive changes along only a tiny fraction of all the possible evolutionary trajectories available to it. (Denton, 1998, p.341).

Even if an advantageous mutation occurs, the chances of it spreading throughout the population are very small and the chances against are extremely large. Taking into account the number of mutations that should have taken place, it is highly improbable that they would randomly lead to the great diversity and complexity of life. Chance mutations acted on by natural selection could scarcely account for variations within species (microevolution), let alone for successive variations among them (macroevolution). A blind process on an erratic trial-and-error basis is not impossible, but is incredible. Laszlo concludes:

…A random process could not have produced the kind of order that we meet with in our experience; it could not even have produced the kind of chaos that surrounds us at times. The fact is that pure, unadulterated chance could not have existed in the universe even if it coexisted with strands of order. If a series of chance events had punctuated the developmental process, the things that would have emerged out of that process would have randomly diverged among themselves… Given a process that is subject to pure chance, even previously ordered things would each grow their own way… Evidently, mere chance did not dominate the evolutionary process: there must also have been a significant degree of binding and coordination. (1993, p.18)

A standard response to these challenges to chance is that, given enough time, random mutations would eventually lead to the complex life forms that exist today. However, this does not hold water, especially if long periods of stagnation are taken into account. The rates of mutation necessary are staggering, even within billions of years, considering the cost involved in disposing of the predominant bad mutations. Moreover, for a good mutation to become fixed in a population, all those individuals without the new trait must die. When these considerations are combined with the low rates of reproduction of many animals, there has hardly been enough time for the present species to have evolved. To quote Laszlo again, ‘it is highly unlikely that random processes could have constructed an evolutionary sequence of which even a basic element, such as a protein or a gene, is complex beyond human capacities’. (ibid., p.91)

Adaptation to environmental changes is another reason that makes evolution by chance implausible. A suitable habitat may become less suitable in a relatively short time, and this may threaten the survival of some species. In order to carry on, they have to adapt to new conditions. However, if species changed only by random and gradual mutations, they could not adapt rapidly enough. Yet, many have somehow managed to do so by producing numerous and complex mutations that were just right.

Specific mutations: there are many instances indicating that specific genomic changes can take place under certain con­ditions. For example, both plants and insects can mutate so as to decontaminate the chemicals that enter their environment and develop a resistance to toxic substances. Some experiments (carried out independently by John Cairns and Barry Hall) show that bacteria too seem to be able to mutate only their defective genes. Purely random mutations could never be so specific.

Inter-species consistency (evolutionary convergence): despite the staggering variety of organisms brought forth during the Cambrian period (about 500 million years ago), the species that now populate the Earth exhibit striking regularities both within and among themselves. Some highly specific anatomical features show remarkable consistency among species with very different evolutionary histories. For example, the wings of birds and bats have similarly positioned bones as the flippers of seals and the forelimbs of equally unrelated amphibians, reptiles and vertebrates. Diverse species also exhibit common orders with regard to the position of the heart and the nervous system: in endoskeletal species (those that have a skeleton inside the body), the nervous system is in the back and the heart is in the front of the body, while in exoskeletal species (those who have external skeleton), these positions are reversed. Another example is the eye: its basic structure appears to have been invented independently by about forty unrelated species. Organisms seem to repeatedly arrive at the same solutions to the challenges they face. Even if chance is streamlined through natural selection, the convergence of many highly creative solutions beggars belief.

Natural Selection

There are issues with natural selection too. Even though natural selection can weed out the misfits, it cannot make new things (selection means choosing a few from a greater number). It does not create features but merely selects those that provide a greater survival value, and by doing so only narrows the width of the evolutionary process. Although Neo-Darwinists usually claim that the growth in complexity is the result of adaptation to environment, the appearance of increasingly complex organisms cannot be predicted solely from the operation of natural selection on random mutations.

The classical Darwinian mechanism works mainly to adapt individuals to their existing niches; individual variations do not contribute significantly to the emergence of new and more complex species. Furthermore, many simple organisms are equally or better adapted to environmental variations than complex ones. Only these can be found in extreme conditions. Some unicellular life forms are spread across different environments much more widely than complex organisms (with the exception of humans). Renowned evolutionist Stephen Jay Gould states that ‘…without question, these earliest and simplest cells, the bacteria and their allies, remain the most abundant, widespread, and successful of all living things’ (1988, p.44). If adaptation is the main driving force, evolution should not have progressed from one-cell organisms! This argument can be pushed even further:

If mere survival is the sole desideratum, then it would seem that some rudimentary type of organism would be all that is needed. And there would seem no reason why even a rudimentary type of organism should appear, since it could not hope to rival in longevity the everlasting rocks – but unstable DNA? (Edmunds, 1997, p.159)

Nor can natural selection adequately explain long-term adaptive changes. Some changes have immense consequences, and yet they could not have possessed adaptive advantages when they happened. One example is bisexual reproduction that increases diversity at great cost. Laszlo points out that ‘such a mechanism, while offering an obvious long-term advantage (the more rapid spread of advantageous mutations), does involve an equally obvious short-term disadvantage (the reduced average number of descendants due to males failing to produce offspring)’ (1993, p.169).

Finally, as Karl Popper pointed out, natural selection seems to be based on a circular argument (everything that is adaptive is selected, and everything that is selected is adaptive). So it cannot be refuted, which does not make good science. When natural selection is used to explain everything, even mutually contradictory adaptations (e.g. the indistinctive colours of some insects, as well as very distinctive colours of others), it does not explain much.

Competition

A popular science writer, Robert Hazen, describes evolution in this way:

Charles Darwin proposed that evolution occurs because of the constant struggle for survival. Many more individuals of most species are born than can possibly survive. In the brutal competition for limited resources, individuals with advantageous traits are more favoured to survive long enough to pass those traits on to offspring. (1997, p.197)

Such a dramatic way of interpreting the evolutionary process, using phrases such as ‘survival of the fittest’, ‘struggle’, ‘brutal competition’ and so forth, is fairly typical. This view was already popular in Darwin’s time, possibly as a reaction to the idealisation and glorification of nature by the Romantic movement. His contemporary, the poet Tennyson, famously characterised nature as ‘red in tooth and claw’. However, this outlook is biased. There is no doubt that struggle and competition exist, but cooperation and symbioses within a species and between species is at least equally important[4]. For example, in order to start creating multi-cell organisms, some single-cell organisms must give up their capacity to reproduce –  a striking example of symbiotic cooperation leading to complexity, but contrary to ‘selfish gene’ (or similar) interpretations. It is misleading to use loaded adjectives such as ‘brutal’, even in connection to the predatory nature of certain species. Every organism must die, and the suffering of those individuals who are unfit or misfit would probably be longer and more brutal without predators.

Furthermore, if competition is the only driving force, one would expect that super-bacteria, super-plants or super-animals would have developed well before the appearance of humans and would have taken over the whole eco-system. Every competition eventually ends up in monopoly. Yet, a delicate balance in nature that allows development to go on seems to be permanently preserved. In rare cases, when a particular type of species starts to dominate to the extent that they prevent further evolution, they are conspicuously wiped out. For example, as many researchers have argued, mammals and thus humans could not have evolved without the demise of the dinosaurs[5]. No doubt competition matters but, it seems, only up to a point.

Gradualism

If the theory of evolution is completely right, life should be subject to a process of gradual transformation that allowed it to move from simple forms to ever more complex ones in small steps. Early life consisted of tiny unicellular organisms living in water, and every other form, extant or extinct, should be connected by an unbroken chain of intermediate species to these first ones. This is not exactly the picture that one gets from the available fossil evidence. If evolution had been gradational, there should be greater variations between fossil specimens reflecting every small step in the process. However, this does not seem to be the case. Although there is an abundance of fossils of fully formed species, there are few contenders for their transitional forms (hence the phrase ‘missing link’). For example, there are no traces of the evolutionary ancestors of the trilobites in the rock layers beneath where the trilobites are found[6]. It seems that trilobites, with their sophisticated optical systems, appear in the geological record relatively suddenly. These occurrences cannot be fully accounted for by the incompleteness of available data.

Mounting paleontological evidence suggests that ‘speciation’ (the emergence of new species) can be a rapid process. Species seem to change in relatively swift bursts, without leisurely transition periods[7]. These episodes of fast speciation are separated by fairly long spans during which no significant alterations can be detected. In other words, species appear abruptly, often in quite different forms, and remain substantially unchanged for millions of years – a condition of stasis at odds with Darwin’s model of continuous change. Then, just as quickly, they become extinct and are followed by other very different species[8]. The fossil record demonstrates abundantly that each episode of extinction was followed by a period when new forms proliferated, filling the ecological niches emptied by the old. Not only individual species but entire genera make their appearance in relatively short time. Probably the most spectacular example is the so-called Cambrian explosion about half a billion years ago, the sudden emergence, in the span of a few million years, of a great variety of the bigger animals that now populate the earth. It is significant that every new cycle is not comprised of species at the same level of complexity, but more advanced ones.

We should hasten to say that this does not refute the continuity of the evolutionary process, nor does it imply that an external force directly interferes with it, as creationists (or proponents of intelligent design) would like to believe. Punctuated equilibrium, strictly speaking, is not saltationism (radical large mutational changes from one generation to the next or discontinuous appearance of new species), so it does not contradict organic evolution. Slow, continuous change (within species) may be the norm during periods of environmental stability, while rapid speciation may occur during periods of environmental stress. When the milieu changes and existing niches disappear, some species die out. Then the ‘peripheral isolates’ (species that live in relatively small numbers) invade the centres of dominance and take over as the new main species. There are also some creative ways of moving forward that may not require intermediaries. For example, the difference between prokaryotes (cells without organelles) and eukaryotes (cells with organelles and other structures) is striking, and yet no intermediaries have been found. There are many living samples of each, but none of those in between. A very likely possibility, put forward by the above mentioned biologist Margulis, is that eukaryotes appeared as the result of a symbiosis of two different prokaryote species

However, even when the above hypotheses are taken into account, conventional Darwinian mechanisms do not seem fully adequate to explain the stops and starts observed in the fossil record (why species appear so abruptly and why they persist so long without changing). These punctuations are too radical to allow for solely Neo-Darwinian interpretation. Moreover, there is not always evidence of environmental stress – quite the opposite: an evolutionary change sometimes causes ecological upheavals (the appearance of photosynthesis-capable organisms being an example). Explaining the reverse is also a problem. As science writer Richard Kerr puts it, ‘what would maintain the equilibrium… keeping the new species from evolving in spite of environmental vagaries?’ (1995, p.1421-1422).

Intriguingly, growing evidence suggests that extinctions follow relatively regular periodic patterns[9]. The statistical chance of these patterns being a random occurrence is very small. Some of them may have been caused by physical factors (e.g. slight variations in the Earth’s orbit over long periods, leading to a climate change). Nevertheless, it is conspicuous that different, and as a rule, more complex life always follows relatively soon after. Such occurrences certainly add weight to the argument that traditional evolutionary mechanisms may not be the only factors at play.

The increase of complexity

It is a real challenge to explain why more and more complex organisms have steadily appeared throughout evolution, if every life form is supposed to be a result of accidental changes in the genetic material. The second law of thermodynamics demands that in any closed system, entropy increases. Energy tends to disintegrate into simpler forms, rather than integrating into more complex ones. In other words, a system inevitably moves towards the state of maximum randomness and disorganisation. Life, of course, is not a closed system, so an increase in complexity does not violate the second law. Nevertheless, it seems strange that at every level there is a tendency in evolution to produce something new and more complex, going persistently against that law – from relatively simple and crude forms to complex and refined ones. Polanyi and Prosch (1975, p.167) comment:

Another unsolved problem arises from the continuous quantitative increase in DNA chains from those of bacteria to those of man – from about twenty million DNA alternatives to about twelve billion. DNA does not behave naturally. It moves from a lower energetic level to the higher, because it moves towards a higher complexity, which cannot be explained by DNA itself. There is no chemical model available to explain this enormous growth or the chemical explanation for this fundamental fact of the system, just as we have no chemical explanation for the historical origin of DNA or for its capacity to produce media that apparently anticipate the continued development of the embryo.

An argument that all life could develop from a hypothetical first cell as all new life develops from a single fertilised cell doesn’t hold water. A cell can develop into a complex organism only because the ‘instructions’ are already contained in the original cell. For large scale evolution, mutation must add new information. It has been already demonstrated many times with detailed probabilistic analysis that this is extremely unlikely (most classic textbook cases of mutations cited in favour of neo-Darwinian evolution are, in fact, losses of information). Hence, it is incongruent to conclude that random mutations on their own can account for an increase of complexity.

Even if we accept that gradual incremental steps may in some cases accidentally lead to more complex structures, they could not do so in all instances. Let’s draw a comparison with horse-drawn carts and motor cars. Carts and cars have some similarities (e.g. four wheels) and the same purpose, but cars did not gradually evolve from carts. Throughout centuries, carts had been steadily improved. However, the making of a car required a leap involving the concurrent addition of a few completely new components. Even the simplest functional motor needs several parts that do not exist in the most advanced carts. And if just one of these components were missing, the motor would be nothing more but extra weight that the cart would be better off without. Similarly, the survival of a new species is dependent on all the necessary mechanisms (in at least a rudimentary form) being present to begin with. The problem is that one gene mutation is obviously insufficient for more complex adaptation. However, if just two mutations are required at the same time to produce at least a slight advantage, the chance that this will happen accidentally decreases dramatically.

An example from Dawkins’ book The Blind Watchmaker (1986, p.97-99) may be a case in point. Weakly electric fish use electric fields to navigate in muddy waters. However, this remarkable ability is of no use unless the body of the fish is absolutely rigid. To make up for this, the fish has developed one long fin, so that the rest of the body can remain still. Even with this fin, the movement of the fish is rather slow, but this is compensated by its ability to detect electric fields in water. So the navigation system is useless without the fin, and the fin is maladaptive without the navigation system. Their appearance had to be synchronous, but they require very different sets of genetic mutations (not to mention that these mechanisms must also be controlled by an appropriate nervous system and brain). Sometimes many simultaneous mutations are necessary, which makes chance, as their main cause, improbable. Considering that the vast majority of mutations are lethal anyway, it stretches belief that numerous beneficial mutations  can accidentally occur at the same time.

This issue is even more striking in relation to macroevolution, the emergence of new (usually more complex) species from earlier ones, especially if we take into account that intermediary forms are often not found, and that breeders have not ever managed to produce one species from another. Let’s take one example. No transitional fossil structure between scale and feather is known. This is not surprising, considering that a half-feather is  likely to be a disadvantage rather than an advantage. A feather has a quite complicated structure that is light, and yet wind-resistant. This is possible because of the complex system of barbs and barbules. Barbules on one side of the barb are rigged, and on the other have hooks. It is hard to imagine that chance mutations could produce this precise cross-linking of the barbules to make a connecting lattice. Even if the chance mutation of a ridge/hook occurs in two of the barbules, it also needs to be translated to the rest of the structure. Moreover, if this lattice were not lubricated, the sliding joint made by the hooked and ridged barbules would soon fray, which means that the wings would be useless. Many other adaptations are necessary to have birds that can fly (forward-facing elbow joints, navigating tail, strong wing muscles, hollow bones, etc.). Even if all of them have developed gradually, each step had to be synchronised and the new must be so great an advantage that it compensates for the losses of fully functional forelimbs or strong bones. Moreover, not only must each modification have sufficient survival value, but the related genes must also be dominant in order to pass it on to successive generations. Of course, once this transformation has occurred, natural selection will select the better wings from the less workable wings. Darwinian natural selection clearly plays a role, but it seems mainly in perfecting changes that have already occurred by different mechanisms.

The problem of complexity resides not only in the remarkable number of components that are sometimes necessary, but also in the fact that life forms are such highly integrated systems that their components cannot be changed independently. Any functional change would require specific compensatory changes in the interacting subsystems. For instance, a change in protein structure would necessitate many complex simultaneous changes throughout the molecule to preserve any biological function.

There are, of course, possible mitigating factors for the above. For example, some components may have been adapted from existing structures that had a different faction (e.g. feathers may have first developed as a protection from cold, and later adapted for flying). Irreducibility may also diminish on a molecular level. For instance, the genomes of all organisms are clustered in a relatively small region of DNA sequence space forming a tree of related sequences that can all be inter-converted via a series of tiny incremental steps. So the sharp discontinuities between different organs and different types of organisms greatly diminish at the DNA level. What looks very different on the macro level, may not be so different on the DNA level:

…in DNA sequence space it is possible to move at least hypothetically from one adaptation (position) to another in DNA space via functionless or meaningless intermediate sequences. This is because a DNA sequence does not have to be functional to survive and be passed on through the generations. In fact, the greater part of all the DNA in nearly all the cells in higher organisms, although it is copied faithfully at each cell division, is never expressed… It is very easy to imagine how an evolving DNA sequence might be passed silently down through several generations before being expressed… [this] means that new sequences and hence new evolutionary innovations can be generated, at least hypothetically, via functionless intermediates. Thus, new organs and structures that cannot be reached via a series of functional morphological intermediates can still be reached by change in DNA sequence space. (Denton, 1998, p.278-279)

In short, the sequence specifying the future of evolutionary events may be stored in noncoding DNA that is passed on from one generation to another. So, some genetic changes, especially in higher organisms, could have been a matter of rearranging pre-existing genes rather than the emergence of new ones. This still does not explain though, the enormous increase of the DNA chain throughout evolution, and even if it is assumed that these dormant genes are the key, the question remains why they are passed over to the next generations when they are not needed, and – even more importantly – why they become active just when they do. 

All the above leads to the conclusion that Neo-Darwinism is incomplete – but are the alternatives better?