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Disproving the Notion of Random Chance in Evolution

Lana Goldsmith, Intern

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John C. Avise is Distinguished Professor of Ecology and Evolutionary Biology at the University of California, Irvine.  His new book, Inside the Human Genome: A Case For Non-Intelligent Design, tackles the philosophical question of why humans are imperfect on the genetic level if made by a Creator God.  In this excerpt, Avise asserts that evolution is not random (as Intelligent Design proponents argue) due to natural selection.

Advocates of Intelligent Design contend that complex biological features cannot arise by chance, the implication being that chance equates to sentient forces.  From a scientific vantage, however, the driving force of adaptive evolution–natural selection– is itself the antithesis of chance.  Hereditary factors that promote organismal survival and reproduction in a particular environment tend to be precisely those that proliferate across the generations and thereby come to characterize natural populations.  Whenever genetic variation and differential 9780195393439reproduction exist in nature (as they do in all known species), natural selection is inevitable, both logically and empirically.  Biological traits that emerge from this inexorable operation may have the superficial aura of intelligent artistry, but that appearance is illusory (under a scientific interpretation).  Natural selection can be a highly creative process (given a suitable supply of genetic variation to work from), but it is merely a mechanistic phenomenon– as inescapable and insentient as gravity.

This is not to say that evolution is devoid of important stochastic (i.e. chance) elements.  Natural selection can sift only among the genetic variants available for its scrutiny, and two of the three primary sources of genetic variability– de novo mutation and recombination– occur essentially at random with respect to forging adaptations.  The new mutations and recombinant genotypes that arise in each generation have no biased tendency to enhance either an individual’s genetic fitness (its reproductive success relative to other individuals) or the adaptive needs of a species.  In other words, favorable alleles and more fit genotypes have no known mutational tendency to arise disproportionately when needed.  In this important sense, the genetic fodder upon which natural selection acts can indeed be characterized as stochastic or chancy in origin.

The third source of population genetic variation entails a mixture of “chance and necessity.”  Apart from de novo mutations and recombinant genotypes, the genetic variety available for natural selection in any generation is also a function of historical circumstance, that is, of idiosyncratic genealogical outcomes that have been affected by both stochastic and directive evolutionary processes across all prior generations.  Evolution going forward can work only with the biological substrates–”ghosts of evolution past”– are not supernatural legacies, but instead they are real genetic lineages and real species that have been subjected for eons to the full panoply of evolutionary processes including natural selection (the directive agent of adaptive evolution) as well as idiosyncratic mutation, recombination, and genetic drift (stochastic forces in the sense described above).

The temporal nature of heredity also means that evolution is inherently a phylogenetic process, involving descent with modification.  So, for example, when two or more species share exquisite details in some complex biological feature (such as a long nucleotide sequence for a protein-coding gene), the usual evolutionary interpretation is that these species inherited copies of that trait from a shared ancestor.  The creationist explanation, by contrast, posits that God created such traits independently in each species, starting in each case from scratch.  At least at a superficial explanatory level, evolutionary and creationist scenarios both seem plausible, in principle, for complex traits that perform their functions well.  A more acid test comes from complex traits that are more harmful to their bearers.  …Many complex genetic traits (such as pseudogenes and mobile elements) that often are functionless or even detrimental to the organisms that house them are rampant in the genomes of vertebrate animals, humans included.  Did a Creator God repeat these apparent errors of genomic construction time and time again?  Or are such genomic flaws merely the footprints of phylogenetic history?

Evolutionary processes do not contrive complexity directly from nothing.  Natural evolutionary processes operate on genetic lineages much like homeowners work on their houses– by taking advantage of available construction materials to make individually small but sometimes cumulatively substantial alterations to previously existing structures and functions.  On occasion, fairly extensive renovations may occur rather quickly, but the norm–both for houses and biological lineages–is evolutionary gradualism in which renovated forms closely resemble their immediate predecessors and increasingly diverge from the preexisting entities after longer periods of time and impetus.  In the case of biology, fossils and molecular evidence indicate that most grand evolutionary transitions (such as from ancestral fishes to various derived groups of terrestrial vertebrates) require millions of years and involve many intermediate steps.

The analogy of natural selection to a homeowner can be carried to far, however.  A homeowner presumably has a longer-term plan or intent for her renovations, whereas natural selection renovates biological features without foresight.  The force of natural selection acts as if myopic, unable to perceive the longer-term consequences of its immediate decisions, which are based solely on the fit of available genotypes to current adaptive needs.

At any horizon in time, history-laden genetic lineages both facilitate and constrain what evolution might accomplish going forward.  Natural selection is facilitated in the sense that it need not re-contrive complex biological features ex nihilo in each generation; but it is also constrained because it must operate within the framework of the available (phylo)genetic materials that underlie the existing biological structures and functions in each evolved lineage.  This raises a key point germane to this book.  Evolutionary causation via natural processes leads to a biological expectation not shared by most versions of ID: a routine appearance of suboptimal organic design.

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9 Responses to “Disproving the Notion of Random Chance in Evolution”
  1. Well, as any good Creationist will tell you, “suboptimal organic design” is simply more evidence for the existence of the Divine. Like refrigerators and cars, the good Lord has ensured that humans have built-in obsolescence (BO). It’s a sure-fire recipe for disaster if the Creator sets us up for going forth and multiplying but doesn’t have a mechanism to control the upper limit. So what might be seen as “poor design” turns out to be a smart move by the Grand Architect. When the Good Lord said “three score years and ten” He really meant it. Hence all the nasty little things that can go wrong with the human body post 70 years of age.

    The argument for BO may smell a little but I’m sure the promoters of ID are quite happy to use liberal amounts of that new fragrance – “Obfuscation.”

  2. [...] Disproving the Notion of Random Chance in Evolution [...]

  3. Jim Buck says:

    A ‘routine appearance of suboptimal organic design’. Presents no problem to ID. Microsoft is an inteligent designer, but every version of Internet Explorer turns out to be suboptimal. Creativity’s drive towards “perfection” is asymptotic.

  4. RickK says:

    Nothing found in nature could ever “present a problem” for ID, because ID isn’t a rational scientific theory. It’s a religiously-driven political advocacy movement. If rainbow-striped pigs with huge golden wings appeared out of nothing over Trafalgar Square and flew in complex geometric patterns, ID “theory” could “explain” it. If a dog gave birth to a cat, ID could “explain” it.

    There are scores of ways evolutionary theory could be disproved. Why isn’t it? Because (1) species evolve, and (2) based on every example we have ever explained, natural phenomena have been caused by natural effects.

    “Intelligent Design” is useful in politics (google “Wedge Strategy”), but it has no explanatory usefulness whatsoever in science.

    That’s why people like Stephen Meyer direct their great ID tomes at the general public in the religion section of Borders Books, and not at the biology or mathematics community via conferences, papers, journals and academic lectures. As Russell Cross said – the goal is obfuscation, not science.

  5. [...] Disproving the Notion of Random Chance in Evolution is an Oxford University Press blog entry. The first paragraph: Advocates of Intelligent Design contend that complex biological features cannot arise by chance, the implication being that chance equates to sentient forces. From a scientific vantage, however, the driving force of adaptive evolution–natural selection– is itself the antithesis of chance. Hereditary factors that promote organismal survival and reproduction in a particular environment tend to be precisely those that proliferate across the generations and thereby come to characterize natural populations. Whenever genetic variation and differential reproduction exist in nature (as they do in all known species), natural selection is inevitable, both logically and empirically. Biological traits that emerge from this inexorable operation may have the superficial aura of intelligent artistry, but that appearance is illusory (under a scientific interpretation). Natural selection can be a highly creative process (given a suitable supply of genetic variation to work from), but it is merely a mechanistic phenomenon– as inescapable and insentient as gravity. [...]

  6. mmm says:

    “In this excerpt, Avise asserts that evolution is not random (as Intelligent Design proponents argue) due to natural selection.”

    Strawman. I have never heard any ID proponent arguing that evolution is random. But there may be confusion about the terminology. The term “chance” has many meanings. ID proponents’ question has been: are we products of blind evolution (that means pure “chance” alternative) or are we products of intelligent actions (purpose or “intelligent design” alternative). For example ID advocate Michael Behe believes that design was done in evolutionary process (he favors the theory of common descent).

    The question has been “By Design or by Chance” in the metaphysical level: what is the last explanation: design or chance?

    The appearance of suboptimal organic design may be expectation also from ID perspective. If one doesn’t know, what is purpose and plan of designer, it is impossible to know, whether the design is optimal or not. Appearance of suboptimal design (seen from human perspective) is ID’s expectation.

  7. [...] Disproving the Notion of Random Chance in Evolution Advocates of Intelligent Design contend that complex biological features cannot arise by chance, the implication being that chance equates to sentient forces. From a scientific vantage, however, the driving force of adaptive evolution–natural selection– is itself the antithesis of chance. Hereditary factors that promote organismal survival and reproduction in a particular environment tend to be precisely those that proliferate across the generations and thereby come to characterize natural populations. Whenever genetic variation and differential reproduction exist in nature (as they do in all known species), natural selection is inevitable, both logically and empirically. Biological traits that emerge from this inexorable operation may have the superficial aura of intelligent artistry, but that appearance is illusory (under a scientific interpretation). Natural selection can be a highly creative process (given a suitable supply of genetic variation to work from), but it is merely a mechanistic phenomenon– as inescapable and insentient as gravity. [...]

  8. Jim Buck says:

    Rainbow-striped pigs with huge golden wings appearing out of nothing over Trafalgar Square and flying in complex geometric patterns, is no big deal these days; and the first thought of any sane and rational person would be that such phenomena were the products of intelligent design (Like ‘Avatar’ is for example).

  9. [...] This post was mentioned on Twitter by Rebecca and BelgradeSummerSchool, Ben Sykes. Ben Sykes said: #design Disproving the Notion of Random Chance in Evolution : OUPblog http://bit.ly/aJbVbP [...]

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