What IS biological evolution ?   It is not metaphysical, it is not a philosophical movement, it is not a theory, it is not a belief system.   Educated people know this, but the general public, for a variety of reasons, continually swallows the idea that evolution is a  "world view", a way of looking at things, rather than an empirically-determined fact about the natural world.   What follows is spleen....


“Evolution” is a word precisely defined within the field of biology, but which is often used very loosely by others outside that field.  The word literally means “the unrolling of a scroll”, an image that suggests the gradual revelation of some changing pattern.  Thus, “evolution” is often used very generally by non-biologists to mean “change over time”.

That might seem harmless if a bit vague, but this imprecise language allows “evolution” to be associated in the popular imagination with ideas that are beyond scientific investigation.  For example, many equate “evolution” with naturalism, a philosophical position claiming that you, I, all living things, indeed all of the universe are the impersonal and improbable products of nature. 

To put it bluntly, this understanding of “evolution” is often seen grounds for denying the purposefulness of the Creation and the possible existence of a Creator.  Small wonder, then, that so many sincere people of faith have come to regard the idea of evolution as the biggest of all Big Lies, one designed to deceive the faithful.

It should go without saying that this is not a scientific proposition.  Even a religious skeptic might well reject this argument as appealing to a hypothesis which is non-falsifiable.

This is a very unfortunate state of affairs for the working biologist who routinely observes the fact of biological evolution, which could be broadly defined as a genetic change within a population. Obviously, the frequencies of genes and their various combinations within a group of the same species of organisms will change over time by the addition or subtraction of individuals due to birth, death or migration.  Some come, some go, some stay----and as they do what they do, the total percentage of certain versions of genes (what biologists call alleles) will either rise, fall, or stay about the same.  Evolution, to the biologist, is precisely this continual pattern of genetic change within populations.

Biologists, of course, have no ability to determine how non-biologists use the word, and this even applies to our colleagues: geologists who study “the evolution of the earth” or astronomers interested in “cosmic evolution” are using the term “evolution” in a general way that is not appropriate to biology, which makes a distinction between individual development and changes within a population.


There’s an old idea that seems to never go out of style: the “Great Chain of Being” championed by Aristotle, and rediscovered by those who followed Linnaeus, a connecting thread sometimes depicted as a “ladder of life”, ascending from the humblest slime mold, perfectly situated for its lowly estate, step by step, till you reach that penultimate rung.   There, Aristotle intoned in all seriousness, you would find pachyderms, which according to the sage of Stageira, found “its best purpose” by virtue of being “the beast which passes all others in wit and mind.”

Really?   I kind of thought that the beast that fits that description is human kind, though if we could interview the rest of the animal kingdom, they might demur.   As Elvis Costello has sung, our lot tends to “fills the air with his pride and praise / he’s a big disgrace to our beastly ways.”

But, of course, there’s a reason that Aristotle gives the elephant first billing among the beasts, rather than second billing.   To Aristotle and every one who followed, the “Great Chain of Being” was part of man’s puffed-up sense of self-importance, as humans were placed at the top of life’s ladder, at the Chain’s pinnacle, not one of the beasts himself, but (imago Dei?) set apart to a special station, “one reserved for him, and for him alone.”

So, paradoxically, follows a popular misconception of evolution: the idea that different species are moving in some sort of preordained path towards greater complexity.  In this view, the cauldron of nature boils up products that are superior to the many who perished before, and (as with the “nation of shopkeepers” that produced Darwin) nature’s economy mirrors the ideas of Adam Smith, wherein an “invisible hand” compels the actors on the stage of life toward progress.  Thus, the well-worn and oft-parodied trope embodied in countless cartoons, with a monkey the last to appear, entering stage left, the caboose of a train of progress.  At the front of the train, at the highest run, the clear goal of all this suffering and death: modern man.

Except, of course, that it’s nonsense.   Evolution is simply a change in a population: any change, whether to more or less complex, larger or smaller in size, generalist or specialist.   There is no preordained “direction” to evolution writ large, once you take in a large enough view.  We can acknowledge short-term trends in geological time, but selection doesn’t make an organism better adapted for all the possible conditions of life past, present and future.   Rather, the engines of sex and death that drive populations to both adaptation and extinction tend to fine-tune the local population for the conditions of life at a given time.   As Gould put it, the results of evolution are largely a product of contingency, rather than some sort of manifest destiny.   Given a different environment, our ancestors might not have become bipedal, might not have got such big brains, might never have left Eden, where our mothers never strained to bring our even more sizeable skulls out of their wombs.

Certainly, I’m still with Aristotle in admiring our wit and mind as being even greater than the elephants, but I don’t regard it as an inevitable result of a chain whose parent is necessity, where every step along the way has been part of a preconceived natural order.   Rather, the connection I see produced wit and mind, but it was a chain forged not of one set of links, but of many ever-branching chains.   If Darwin had been an organic chemist, he might even have used the analogy of a chain, but he would’ve asserted that life is more like glycogen than cellulose.   Instead, Darwin was a boy who grew up in the fields and forests of the English countryside, and so the metaphor that he seized upon was entirely natural.

 “The affinities of all the beings of the same class have sometimes been represented by a great tree. I believe this simile largely speaks the truth. The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species. At each period of growth all the growing twigs have tried to branch out on all sides, and to overtop and kill the surrounding twigs and branches, in the same manner as species and groups of species have tried to overmaster other species in the great battle for life . . .As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications.” (from Chapter 4 of the Origin, "Natural Selection").

Notice, though, there is no reason to believe that the branches at the top are superior to those of the past, nor is any particular part of the canopy singled out for praise over the rest.   It is the whole tree, “ever-branching”, which is the object of wonder and even adoration, not any particular primate.


In his book, ‘The Evolution-Creation Struggle’ (2005), Michael Ruse claims that the term ‘evolution’ has at least three meaning: evolution as fact, evolution as a theory, evolution as a belief system.

Strictly speaking, evolution itself is not a theory.  By itself, evolution is a fact, whether we are talking about the changes in the frequency of some gene within a living population,  or about the dramatic changes so vividly established by the fossil record in rocks of different ages.   While we may not have the blow-by-blow description of the latter, geneticists in the last century were able to show how the large-scale patterns of change (macroevolution) are easily extrapolated from the summation of innumerable tiny changes (microevolution).

Still, sometimes people speak of evolution as a theory, or (with less precision) “just a theory”, which not only gets the biology wrong, but also betrays its speaker as someone who doesn’t understand the nature of science.   Saying that any idea in science is “just a theory” is like saying, in effect, that the idea is just an incredibly powerful and useful model that has passed many critical tests, a model that has been widely-adopted by the scientific community.”   This is a curious way to argue, and can only be excused on ignorance of how the scientific usage of the word ‘theory’ differs from a hunch or wild speculation.

If evolution is simply the pattern of genetic change in a population, then it is no theory, but a fact!  If it is fact, then, why refer to “evolutionary theory” or “the theory of evolution”, as so many writers on the topic do ?  The answer is that these phrases are often chosen by men who should know better out of laziness or a desire to oversimplify the matter for lay people.  Such phrases are really seen as being a convenient shorthand for something like the following: “The Evolution of Life Through Natural Selection and Other Related Processes”. 

Take a look at that last phrase.  It is long-winded and inconvenient, perhaps, but close examination should make it clear that neither evolution or natural selection (two distinct concepts!) are in way the theory itself.  What is theoretical is the exact nature of the past relationship between natural selection (and other processes) with the fact of evolution.  There is nothing theoretical about evolution itself----it has occurred, and is occurring all the time!  There is nothing theoretical about natural selection----it has been observed, and is continually being confirmed by new observations, to the point where its action is trivial.   Testing whether or not a population will change genetically over time is not a good way to win a Nobel Prize, any more than dropping a hammer is likely to lead on its own to a published article in Physics A.  Our present and its immediate, unfolding future are jam-packed with confirmation of the facts of evolution, of natural selection and even those particular cases where it can be directly shown that natural selection leads to evolution, rather than some other phenomena.

It is not the present, or the future, which troubles so many, but rather it is the past.  This is where we can speak of the “Theory of Evolution Through Natural Selection and Other Related Processes” and know that any current model is at best probable rather than certain.  Simply put, we weren’t around in the past to directly measure genetic changes.  Genetic relationships in fossils typically must be inferred from morphological similarities and dating techniques, though some advances have been made in extracting DNA sequences from the long-dead.  Without direct measurement of the actual genetic changes and with limited knowledge of the precise environmental conditions in which the long-vanished fossil life forms flourished and died the scientist is left not with supposition, with a strongly-supported inference, but hardly the certainty and narrowed focus of the results obtainable with present-day populations.

So evolution properly speaking is a fact, and people often use the word by itself as shorthand for Darwin’s theory, but evolution itself is not in any way theoretical.   When is it appropriate to consider evolution a belief system?   Ruse, for one, acknowledges that “the term can mean the whole metaphysical or ideological picture built around or on evolution---strictly speaking, this is called evolutionism.”  This is ‘evolution’ with a capital ‘E’: in general, when you start hearing sentences that begin with ‘Evolution does this’ or ‘Evolution does that’, as if it were some being with personality, you’re really talking about ‘evolutionism’ or (and some people treat this as if were the same thing) ‘Darwinism’ !  To Michael Ruse and others who make the same distinction, this understanding of ‘evolution’ loads the terms with values that can not be supported by the science, and leads the advocates of evolution to, without even realizing it, “competing for space in the hearts and minds” of religious believers.

These last two terms open up a can of worms.  Evolution’s critics, especially the supporters of intelligent design, love to use the word ‘Darwinism’ as a substitute for ‘evolution’ or ‘evolutionary biology.’  To further the confusion, many legitimate scientists still use these terms as shorthand for “evolution by natural selection”, as when Dawkins remarks that “Darwinism is widely misunderstood as a theory of pure chance” (Climbing Mount Improbable, pg. 70).

What a mess!  One word, three different meanings in popular usage, but only one of them is really accurate.    I am not an “evolutionist”, I am not a “Darwinist”, and I do not consider evolution or natural selection to be either theoretical, or items in a belief system.   I will go further: well-educated people who understand the science and still make those sorts of claims are simply unprincipled liars who are exploiting the general public’s ignorance on these topics.   A plague on their houses.

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1 comment:

R. Moore said...

A very good post.

You note that "educated" people accept evolution, while the masses do not, but surely the masses are mostly educated.

We know that a majority rejects evolution, not on its own merits, but because it contradicts a more dearly held theory: that God exists, and is responsible for Creation.

Education has little impact in such a contest. Instead, the popularity of an idea ultimately changes the mind -- slavery, subjugation of women, discrimination of gays -- these ended not because of an enlightened population, but an embarrassed one.

Most young people today accept evolution and natural selection not because they understand in any deep way -- the evidence, or the logic behind it -- but because the ridicule engine known as the Internet opens one up to ridicule at light speeds. Their addiction is there downfall, so to speak.

And others cling to creationism by simply avoiding engagement, and therefore ridicule. Churches make very good fortresses of the mind.