Question No. 22
- Evolutionary theory attacked: a debate in need of quantitative arguments? (on whether the responses of evolutionists to creationists are persuasive)
- Answered 6 March 2008.
Question author: friend.
Asked 19 January 2008.
1. Three arguments
One of the well-known creationists' arguments (we understand "creationism" broadly here, including "intelligent design" and not going into the fine systematics of the notion) is that of the so-called irreducible complexity. It is argued that complex features and mechanisms of the living organisms, like eye or brain or any other, could not have evolved by small mutational "steps", because such mechanisms only make sense as a whole. That is, if you build a car, it will only add to your performance when fully ready, as it will not move until fully accomplished. But to occasionally accomplish the whole car in a series of numerous small operations is improbable, if these operations are undertaken at random without the ultimate goal to build the car and some prior knowledge about it. Hence, biological complexity could not have evolved by itself, but would have needed a designer.
Recently a good friend sent us an e-mail with three excerpts written by prominent evolutionists. The texts are apparently meant to discard the above argument as implausible. The friend asked "think as if you were a creationist. Would you be convinced by these arguments?" The logic of the three excerpts is briefly outlined below.
The first text (A.G. Cairns-Smith "Seven Clues to the Origin of Life" as interpreted by R. Dawkins in "The God Delusion", p. 156) discusses a stone arch. Take any of the stones away, and the arch will collapse. This is interpreted as an analogy to irreducible complexity (remove one wheel from the car, and it will not move). Yet, as it is further argued, we all know that this stone arch did not arise as a whole, but was built in a series of small operations. Originally there were some subsidiary constructions which supported the arch while it was built and which were removed after it was ready.
Essentially it is said that those structures that are currently perceived as irreducibly complex, evolved occasionally from other structures that, at those times, performed different functions. Namely the change of functions and possible reduction of some of the original components make the observed structure to look irreducibly complex.
The second text (B. Charlesworth, D. Charlesworth. Evolution, a very short introduction, 2003, Cambridge University Press, Chapter 7 "Some difficult problems", pp. 110-112) discusses car manufacturing. It would be a mistake to assert that the existing structure arose as a whole from something non-functioning like a broken car. Instead, it was gradually perfected from more primitive yet fully functioning structures, like the ancient cars of the end of the XIXth century were, in a large series of consequential engineering efforts, transformed into modern cars. Some organisms, even unicellular ones, possess primitive eye-like structures allowing them to discern some light. In the higher animals these primitive structures have been perfected.
Finally, the third text (R. Dawkins "The God Delusion", p. 156) presents the most general argument. If one sees an extraordinary, highly professional magician trick, which mechanisms one naturally does not know, it is no reason to abandon scientific thinking and involve some divine force to accept the existence of this trick. That is, the fact that we do not understand how something has happened does not mean that it could not happen without an external designer (creator).
Given these three arguments, do creationists lose or win at this point of the debate? They lose, because they have originally put themselves in an unfavorable position of the side arguing that something CANNOT HAPPEN (irreducible complexity). To assert that something CANNOT HAPPEN is the strongest possible scientific statement. Only some very major, absolutely fundamental discoveries were able to sustain claims of this type. The discovery of Energy Conservation Law showed that energy CANNOT arise out of nothing. Einstein's theory of relativity stated that NOTHING CAN move at velocities exceeding that of light. Everything else, not precluded by such major laws, can happen.
To give an example, with the development of quantum mechanics it was found that material objects have properties of both particles and waves at the same time, which was very difficult to imagine and accept. Yet this firmly established fact formed the basis of a most successful physical theory, which yielded lots of confirmed predictions. Similarly, however 'unbelievable' some features of the organisms may look, this is not a scientific argument to question their evolutionary origin.
2. Major problems of modern evolutionary theory
There is only one way to scientifically make the point that something cannot happen (besides discovering a fundamental law). It is to use quantitative probabilistic estimates. In other words, to show that the probability of something to happen is below any reasonably accepted value. Arguments of this type are accepted in the court, for example, when the issue is about genetic tests of parental identity.
Let us imagine, for conceptual simplicity, that speciation occurs when an organism acquires a new advantageous feature formed in a series of small steps, like the above three texts propose. Natural selection works on individuals in the population, which carry those mutations ("small steps"), which ultimately lead to the appearance of the new feature, according to the conventional evolutionists' picture.
It is clear then that the greater the number of mutations in a species occurring per unit time, the more frequently such a species will be producing new features and, hence, evolve. Using the above analogy with car industry, a large company employing many bright minds and many workers to test the ideas of those bright minds will sooner produce a new car model than a very small, slowly-working provincial factory.
We now perform some elementary calculations. Consider a typical mammalian species with the overall number of individuals in the order of N ~ 109, reproduction time T ~ 1 year, and genome size of the order of G ~ 109 nucleotide pairs. With the mean mutation rate in the order of ? ~ 10?10 mutations per nucleotide pair per replication event (this rate is broadly universal across all of life except the RNA-based viruses), and the number of cell divisions in the germ line of mammals in the order of n ~ 10, we obtain that the mammalian species produces V = NGn? /T ~ 109 new genetic variants per year.
On the other hand, for a species of tiny eukaryotic unicells, which are vastly more numerous than the huge mammals, the characteristic values of the same parameters would be N ~ 1018, T ~ 10?2 year, n = 1 and G ~ 107 n.p. (here we take a conservative estimate). It follows that the unicellular species produces V = NGn? /T ~ 1017 new genetic variants per year, i.e. one hundred million times a greater amount than mammals do. (We do not consider bacteria here, including them would increase this difference to hundred billion times.)
In other words, recalling the analogy with automobiles, an average species of unicells is one hundred million times larger a company working on producing new cars than an average mammalian species is. In text 2 there is another analogy, comparing mutations with steps along the hillside. So, the unicells make hundred million of times more steps per unit time. Should not they be making it to the top more frequently than mammals, and by the same amount? In other words, one can predict from this evolutionist logic that unicells should speciate hundred million of times more frequently than mammals do. Given that unicells speciate once in several million years, mammals would never do.
However, the available paleoevidence shows us that this is not the case. The mean time of species duration and hence, frequency of speciation, does not depend on species abundance, varying around several million years for any lineage, from marine diatoms to large mammals. Another observation is that the genetic distance between related species (i.e. the relative number of different nucleotide pairs in their genomes) does not depend on species body size or abundance and is in the order of a few per cent for close species, be those close species of bacteria or of primates. These observations unambiguously exclude the possibility of intraspecific mutations being the trigger of the speciation process in the biosphere.
In a New York Times article "Inferior design" (1 July 2007), a renowned evolutionist Richard Dawkins attempted to dismiss an argument of similar kind by saying that "if mutation, rather than selection, really limited evolutionary change, this should be true for artificial no less than natural selection. Domestic breeding relies upon exactly the same pool of mutational variation as natural selection." Thus, it is concluded, it would have been the same impossible to make new breeds as to observe new species.
The second sentence of the quote, which is critical for the argument to stand, is incorrect. Although Charles Darwin made no difference between the mechanisms of natural and artificial selection, the information that has become available in the more than century of post-darwinian work is enough to enable contemporary people to meaningfully re-think this issue. A tiny portion of the several million species inhabiting the biosphere exhibits exceptional variability of somatic traits, which appear to be usable by humans for their own needs. The absolutely dominant majority of extant species resist any attempts to be artificially selected, yet all of them have speciated.
The artificially selected breeds are inferior to their wild parents in viability and fertility (remember the catastrophic rate of cancer in pets). Artificially selected plants, as soon as the artificial selection pressure is lessened, return to the wild form. Should evolution be based on the same principle, we would have witnessed recurrent appearance of one and the same species (reversed evolution), which is never observed. Artificial selection of poorly viable monsters occasionally liked by humans has nothing to do with the evolutionary appearance of a novel species capable of existing morphologically unchanged in harmony with its environment and with other species of the ecological community for millions of years. In an implicit yet firm recognition of this fundamental difference, the science of systematics has never granted the status of 'species' to any artificially selected breed of animals or sort of plants.
Dawkins remarks that artificial 'speciation' occurs nearly instantaneously, so, following this 'artificial' logic, one could then expect the appearance of not only new breeds of dogs, but of new families and orders of artificial animals during the thousands of years of artificial selection. Yet all one can see is the endless variation of one and the same dog (cat, pigeon etc.), which shows once again that choosing among defective individuals of the species (which, in those very few species that allow for being selected, can indeed be quite different from one another in appearance, as symptoms of various congenital diseases are) has nothing to do with evolution and speciation.
It can be thought that if, instead of trying to forcefully persuade the public that the evolutionary theory petrified free from any major problems more than a century ago, its advocates would openly confirm the existence of such and the need to resolve them in a free scientific investigation, such a statement would only gain respect to evolution. It would also serve as an impetus to young scientists to test their abilities in solving teasing and exciting problems. Theoretical physics, a most successful science, has always openly recognized its problems. Many of them were later solved in an astonishingly elegant way; the others still persist and are under consideration. Science goes forward; new knowledge always arises in a single number and goes against the previously established consensus from which it is by definition missing.
3. How the problem resolves
Those readers, who are interested to know how the enigma of equal speciation rates in the biosphere can be resolved without involving a creator or whatever mystic forces, yet demanding the accepted evolutionary paradigm to be revised, are referred to the documents listed below.
- Does the process of speciation occur today, and can one observe it?
- Chapter 11. Evolution in Gorshkov et al. "Biotic regulation of the environment: Key issue of global change", Springer, 2000 (PDF, 1.5 Mb).
- Makarieva A.M., Gorshkov V.G. (2004) On the dependence of speciation rates on species abundance and characteristic population size. Journal of Biosciences, 29, 119-128. Abstract. PDF (0.1 Mb). Copyright Indian Academy of Sciences.