- Peas Be With You
- Evolution Without Mendel
- Darwin without Evolution
- Natural Selection vs. Evolution
- Origin Without Species
- Species Without Origin
- The End of Evolution
- The Principle of Proportionate Causation
- Where Has All the Telos Gone?
- Efficient Causes Without Telos
- That Which Does Not Kill Me Makes Me Stronger
- Revenge of the Stagerite
|Mendel, monk-eying with peas|
Peas Be With You
Mendel chose pea plants partly because they i) had easily identifiable features, ii) could self-fertilize, and iii) were easy to protect from cross-fertilization. But before he could even start, he needed true-breeding plants; that is, plants that when self-crossed would always produce the same phenotype. This took two years of preliminary work. Mendel then spent years making thousands of crosses, discovering that
- traits were inherited whole and
- traits that seemed to disappear in one generation could reappear in another generation
People sometimes wonder where Mendel found the time to do all this, considering his monastic responsiblities. I have even seen it alleged that the abbot shut him down, a nice example of "model-based history"*. But the answer is easy. His research was one of his monastic responsibilities. The monastery had been conducting hybridization research even before Mendel arrived. The Augustinians freed up his time for the research, allocated large plots of land for his research, and built a greenhouse where he could establish a control group for his studies. The Order did not sorta kinda "give Mendel a research grant" to pursue his personal hobby as some historically ill-informed have grudgingly allowed: The research was part and parcel of the Order's program. Mendel himself had trained as a physicist, not a biologist, so this would not likely have been his own personal choice. Mendel was simply doing the scientific research that his Order asked him to do.**
Mendel's results were published in the Proceedings of the Natural History Society of Brünn in 1866. No-one noticed. Over the next 35 years, his work was cited... three times! Oh well. In the early 1900s, Mendel's work was rediscovered by Correns, deVries, and others, and developed into an entirely new discipline within biology -- genetics.
*model-based history. This is where one starts with an idee fixe and deduces "what must have happened" in the light of that prior assumption. This dispenses with the laborious requirement for actual empirical evidence.
** Oddly, Mendel's work and the support from his Order are seldom mentioned during debates about church-science relationships. See first note (*).
+ + +
|Blyth spirit, |
with world-class whiskers
(In Darwin and the Mysterious Mr. X (1979) Loren Eisley gave various reasons why this should not be considered plagiarism. History is always particular and local, and broad generalities about mythic culture heroes seldom stand up to the empirical details. Darwin had read Blyth's papers, although the pages in his Notebooks that would have covered them were later physically removed; and it was Blyth who acquainted Darwin with the works of Wallace. Science is collaborative and cumulative and natural selection was "in the air," a projection of laizzes faire economics onto biology.)
However, two interesting points might be made:
- It might be better to ask how evolution would have fared without genetics than vice versa; and
- Darwin never wrote about evolution.
In the late nineteenth century and early twentieth century, Darwinism was falling out of favour among scientists as an explanation for evolution. One reason was the problem of heredity -- a difficulty that Darwin himself had recognized in the Origin of Species. Darwin had claimed that organisms fortuitously having beneficial traits would more likely survive to pass on the traits; and that enough such new traits would result in a new species. But the prevailing theory of inheritance at the time was that the traits of the father and mother were blended in the offspring. Any new beneficial trait would be diluted out of the population within a few generations, because most of the blending in the first few generations would be with individuals that did not have the trait.
Darwin thus had no explanation for how beneficial traits could be preserved over the succeeding generations. (In fact, given the "consensus science" regarding inheritance, his theory had been "falsified." Fortunately, neither Popper nor Consensus Science were around at the time to mess things up.)
This period is sometimes called the Eclipse of Darwinism, and several authors believed in the 1920s that Darwinism was on its last legs. The eclipse lasted until the Neo-Darwinian Synthesis: that is, until genetics saved the bacon, explained how inheritance actually took place, and put evolution on a more rigorous (and mathematical) footing. It turned out that traits are not blended(!), but inherited whole. And Mendel's mathematical laws of recessive and dominant traits showed how a trait that disappeared in one generation could reappear in the next. Huzzah! Calloo Callay!
Between 1936 and 1947, a number of prominent scientists, notably including R.A. Fisher, J.B.S. Haldane, and Ernst Mayr, salvaged Darwin's original theory by incorporating Mendel's work into it, giving us our modern Neo-Darwinian Synthesis. Wikipedia, that Fount of All Wisdom, claims that the synthesis "showed that Mendelian genetics was consistent with natural selection and gradual evolution."* How fortunate for genetics!
*gradual. It is not clear why evolution must be gradual; and modern genetics is discovering that it need not be. Species tend to appear abruptly relative to geological time, and then gradually develop and elaborate.
2. Darwin without Evolution
These were the meanings current when Darwin did his thing. Darwin, who knew that the English country squire was the pinnacle of evolution, rejected the term "evolution" both because of its association with the French Terror (according to Michael Ruse) and its inherent teleology (according to Etienne Gilson). He did not use it until the sixth (and final) edition of the Origin, much preferring either "natural selection" or [his favorite] "descent with modification."
The public mind, however, prefers short terms to longer phrases, and quickly conflated Darwin's natural selection with Spencer's evolution, to the great distress of both men. Spencer objected that his principle was much broader than a mere scientific law, and published a widely-translated pamphlet making his (ultimately futile) case for priority. Darwin, who seldom bothered responding to any disagreement (and seems to have regarded Spencer in person unfavorably) detested philosophy on principle and resisted using the term "evolution" until he finally threw in the towel in the sixth edition of Origin.
Natural Selection vs. Evolution
The result was confusion between evolution and natural selection. Many Late Moderns confuse Fact and Theory and seem hold that if a theory is well-supported it "graduates" to a Fact. But a Theory is a story we tell ourselves that "makes sense" out of a body of facts -- the mathematical Laws may be deduced from it and the empirical Facts predicted. From this point of view, falling bodies are facts, and gravity is a theory proposed to explain them. Physicists have considered a number of theories regarding gravity, which is how scientific progress is made. Similarly, the evolutions of species are facts and natural selection is a theory proposed to explain them. Biologists have considered a number of theories regarding evolution (Lamarck, Darwin, Kimura, Shapiro, etc.).
For so long as the universe was regarded as eternal, there was no reason to suppose the furniture was not also eternal. After all, Darwin knew all the same animals that Aristotle did. But the Judaeo-Christian notion of the universe as a created thing with a beginning in time undermined this notion -- and disenchanted the universe, as well. There were no dryads in the well, no nymphs behind the trees. The stars were not actual gods, but "just another created thing." But if the universe had a beginning in time, there was no reason why individual species would not also have beginnings in time.
Genesis states that God told the sea and the land to bring forth the living kinds and that the sea and the land obeyed by bringing them forth. St. Augistine of Hippo wrote a millennium and a half ago that this must be interpreted causally. Nature had been given the power to act immanently in obedience to laws the Creator had laid down. Thomas Aquinas, who believed in a beginning in time, supposed that new species, "if any such appear," would be "produced by putrefaction by the power which the stars and elements received at the beginning." IOW, by powers inherent in nature. He did not suggest they would "poof" into existence. In Contra gentiles, he regarded a multiplication of species in space and time as a positive good: finite matter participating in the infinity of God. So for theological reasons, there ought to have been new species replacing old.
This remarkable groundwork was obscured when medieval scholasticism was abandoned, and it is significant that the wacky new ideas that arose -- of all species created at the same time and directly by God the Efficient Cause, of design being evidenced by the improbability of dead matter coming together by chance, and so forth -- were all themselves products of the Modern Ages.
The notion that matter is dead and must be "pushed" from without, while defensible as regards inanimate matter and physics, is less so when dealing with living matter and biology. Living things -- more or less (some more, some less) possess the principles of their own motion, as Aristotle wrote. (And Darwin, after reading The Parts of Animals regarded the Old Stagerite as far above Buffon and his other near contemporaries.) But the successes of the Early Modern Age in physics led to an attempt to apply the metaphysics underlying Modern physics to biology, with mixed success.
Origin Without Species
One of two difficulties with the Origin is that Darwin did not believe species were real things in the world. He wrote in the Origin that "I look at the term species as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling each other..." But resemblance is in the mind of the beholder, so the origin of a new species is when human biologists decide a set of individuals no longer resembles an old species. This would not make for a very exciting theory, however, and Darwin himself sloughed over it.
But it does illustrate the philosophical incoherence of nominalism. If grass is green and a frog is green does that resemblance put them in the same species in the Science of Green Stuff? A realist philosopher like Plato or Aristotle would note that there is something actually in the "set of individuals" by virtue of which we note a resemblance. It is instructive to realize that the biogenetic study of species reveals clades that more or less correspond to the common sense groupings people have given to living things in the past. IOW, when a child says "Horsey!" upon seeing a zebra in the zoo, she is grasping something real about horses and zebras.
The usual "biological definition of species" is not much help. Two individuals are of the same species if they can mate and produce fertile offspring. That means that my great-grandmother and I are of different species! Facetious, but it does indicate that biologists have a way to go to catch up with physicists in the matter of operational definitions. For one thing, many different groups are given distinct species names even though they are interfertile. Dogs and wolves, for example. Ring species, in which populations A and B are interfertile, B and C are interfertile, but A and C are not, indicate that the definition is not "well-defined." Botanists have sometimes complained that the species definition is "animal-centric" and does not fit as well on plants. Then, too, the definition wholly is inapplicable to asexual species. As a result, one sometimes sees a suite of as many as four entirely different definiions of what a species is. But any good metrologist will point out that different definitions of a measurement define different qualities.
*taught to deny formal causes. At this point they use "emergent property" as a scientific way of saying "then a miracle happens."
Species Without Origin
The second difficulty is that Darwin did not describe the origin of species. His engine only works if you already have a species to begin with. What he described was the transformation of species.* He has explained a mechanism by which a subset of species A can change into species B, but has not explained the existence of species in the first place. No skin of his nose. Newton did not explain where gravity came from, either, and explicitly disavowed any effort to explain the nature of gravity itself.
So it is no criticism of Darwin to say his theory did not explain something it did not set out to explain. Only that the book should have been titled differently. ;-)
* transformation. Note: trans-form-ation. That formal cause stuff again.
The End of Evolution
|The end of an arrow|
One of the key concepts lost during the Scientific Revolution was the concept of τελος, or end. It is almost impossible to point this out to a Late Modern or (worse) a Post Modern, as they will load up the term with the preconceptions of people who had no first-hand experience with the concept. One person commented:
There is nothing any more teleological [in evolution] than when a river carves a path through the lowest contiguous sections of land. “It’s amazing! Look at that river strive to flow downhill! How did the river know those bits led to the sea? It must be struggling to reach the ocean!"This displays a profound ignorance of telos, confusing it with consciousness and purpose in order to create, wittingly or not, a "straw river." He cites no examples of rivers flowing uphill. Elsewhere on that same board another commenter said that
"When I want to understand something scientific, I go to experts on the subject– not [to] self appointed experts on invisible beings."To be consistent, he would then no doubt to understand telos go to experts in Aristotelian natural philosophy - not [to] experts in the metrical properties of physical bodies. In the absence of such an expert, I will attempt to answer.
The first quoted person is wrong on two counts.
- There is telos in physical systems. Systems move toward attractor basins, toward equilibrium manifolds; chemical reactions run to completion, then stop. The equilibrium state may be an orbit or a resonating reaction, but this is still a "finality" to the physical process. An inanimate system tends to minimize its potential function, even if it does not intend to do so.
- The evolution of species is more teleological than a river "seeking" the lowest attainable gravitational potential. Living beings have an integrated wholeness and possess inner principles that inanimate bodies do not. A petunia is a bag of chemicals; but it is not only a bag of chemicals. For so long as it is alive, it does things that a bag of chemicals cannot do. This is why biology at one and the same time "is not a hard science" like physics and chemistry, and also "a much harder science" than physics and chemistry.
- "the end." The process simply stops. The reaction is complete. The fingers have reached their final length. The telemeres have divided for the last time.
- perfection. The process achieves all that is achievable of its nature. The tiger cub grows into an adult tiger, at which point it possesses all the attributes of tiger-hood. It can become no more tigerish.
- purpose. This applies only to conscious beings. The wolf sets out in search of prey. The salmon swims upstream in search of the spawning grounds. A bird selects a twig to build a nest. (Notice that even here, the purpose need not be self-conscious.)
- Natural selection.
- Struggle for existence.
- Striving to reproduce.
Adaptation necessarily points beyond itself. Ad-aptus: "toward being fitted to a purpose." A species adapts =to= something. When Darwin (who first used the term adapt in a biological sense) wrote that species "strive to the utmost to reproduce," he did not mean that two petunias decide to get together to make lots of little petunias in order to ace out the violets in the struggle for sun and water. But he meant that there was an inner drive in organisms that pointed toward something outside the organism; viz., toward reproduction. He wrote also that there was a remorseless struggle for existence. Again, no conscious intent is invoked; but only an inner drive of the organism to continue living by seeking water,* seeking food, seeking shelter, seeking escape from predators, and so forth.
It is often said that these terms are just metaphors; but metaphor is the business of literature, not of science. No one has yet successfully "cashed out" terms like adaptation for non-teleological expressions. (Dawkins' supposed example in The Selfish Gene, which purports to show how unguided natural selection can lead to a particular English sentence Methinks it is like a weasel is inherently teleological (and guided by an intelligence!). The end is the sentence he uses as a goal.)
*seeking water. One plant in the desert of South Africa has sunk a taproot hundreds of feet into the earth in search of water
The Principle of Proportionate Causation
One argument against telos in nature is that evolution doesn't necessarily point to humanity as its end. That is irrelevant. It doesn't point to humpback whales, either. That is because evolution [by which we must understand "natural selection"] is a universal cause and humans and whales are particular effects. Thus they are on different causal levels. The end or telos of natural selection in general is suggested by the title of a well-known book: the origin of [new] species. That is, natural selection "points toward" the emergence of new species.
For a particular species in a given situation, the end of natural selection for that species is not a longer beak or a shorter beak, but simply greater fitness for whichever niche it occupies [resulting in greater
reproductive success]. But there is a hint here of another principle, which we will look at shortly.
Where Has All the Telos Gone?
Long time passing. That telos is as natural as efficient causes was perfectly evident to Aristotle and those who came after him for the next 2000 years. So why did the Modern Agers shut their eyes to it? There are two reasons: i) it is useless and ii) God.
1. Telos and Usefulness
The essence of the Scientific Revolution was a shift in scientific focus from the contemplation of the beauty of nature to the enslavement of nature to man's dominion over the universe. No fooling. The worth of science would henceforth be judged not by the greater understanding of nature it provided but by the useful and profitable products that could be derived from it. This was ably set forth by Francis Bacon in The Masculine Birth of Time, by Rene Descartes, and others. You hear echoes of this 'tude in repeated plaints that science works! or "look at all the technology that science has gifted us with." Insight into nature is seldom touted; only its practical spin-off. Significantly, Darwin himself was not one of these, as we see in his famous "this view of life" passage. In many ways he was still an old-fashioned pre-Cartesian natural philosopher.
Bacon agreed that telos existed in nature as a matter of empirical fact; he just didn't think it would help men dominate the universe the way efficient causes could. After all, to know that a bird's wing is "for" flying may be interesting, but to know how the wing produces flight might lead to airplanes and strategic bombing and all sorts of useful stuff. Descartes went further. Since that which was not metrical and controllable was invisible to the new methodology, such things do not exist. This is a bit like the man whose only tool is a hammer claiming that the world consists only of nails. But in any event, since the new science focused on practical technology, telos fell by the wayside. This was a grave error, as we shall see in a moment.
Furthermore, to reject telos because Thomas reasoned his way from telos to God makes no sense. Thomas reasoned his way to God from motion in the world and from efficient causes. But unless the Post Modern Age is about to give us the New Zeno, no one is so atheistic as to deny the reality of motion. Nor (save for Hume and al-Ghazali) do they generally deny efficient causation. Indeed, they place their faith in a subset of efficient causation; viz., mechanical efficient causation.
Empedocles thought that mechanical causes were all that was needed to understand nature, so we mustn't suppose this is a new controversy. Aristotle contraverted him, because to the Old Stagerite, it was not an either-or proposition.
The telos was "the cause of causes." An efficient cause A would not entrain B "always or for the most part" unless there was something in A that "pointed toward" B. So the natural selection of a particular population of finches in a particular situation would not entrain longer beaks (let us say) unless there were something in the [natural] selection that "pointed toward" longer beaks. IOW, telos grounds efficient causation, which would otherwise descend to mere correlation or coincidence. It explains why A causes B specifically, and not C, D, E, or nothing at all. Thus, while Empedocles said "mechanical causes, and no telos," Aristotle said "mechanical causes and telos."
Edward Blyth, who described natural selection twenty years before Wallace and Darwin (but who did not call it by that name), proposed it as the engine that maintained the species type by de-selecting variants that were not up to snuff. Remember that a currently existing species is already well-adapted to its niche, and Blyth thought that natural selection would tend to preserve the existing species as-is. He thought natural selection (by whatever name) was an argument in favor of fixity of species! This is the main reason why, when Darwin finally broke down and admitted that had had predecessors in the field, he took note of Wallace and others, and even had kind words for Lamarck, but in this context made no mention of Blyth. That is because Lamarck, though grievously astray as regards the efficient cause, was in the same camp as Darwin regarding the metaphysical issues.
Now it is easy to see that Blyth was correct. Most mutations are harmful and natural selection will tend to weed them out and thus maintain the type. It is less easy to see that Darwin was also right, and telos is necessary to do this. The rescue comes from a most unlikely quarter: Jean-Baptiste Pierre Antoine de Monet, Chevalier de la Marck.
|Lamarck, acquiring a characteristic|
By the last edition of the Origin, Darwin had spoiled the elegance of his original insight by adding other more nebulous mechanisms. He was even taking a new look at Lamarck and allowed how there might be circumstances in which the Lamarckian mechanism would work. The error was to swallow Lamarck whole rather than only his central insight. Darwin had apparently begun to sense that the two mechanisms were in some way complementary.
Lamarck's central insight was this:
"Great alteration in the environment of animals leads to great alteration in their needs... Now, if the new needs become permanent, the animals then adopt new habits which last as long as the needs that evoked them.... Every new need, necessitating new activities for its satisfaction, requires the animal, either to make more frequent use of some of its parts which it previously had used less, and thus greatly to develop and enlarge them; or else to make use of entirely new parts, to which the needs have imperceptibly given birth by efforts of its inner feeling."Leave that "inner feeling" crap out of it and what we see is that an organism is an active participant in its own evolution. Natural selection sculpts a species toward greater fitness to its niche; but what Lamarck almost saw was that the animal's own habits, derived from its needs, help define that niche.
So a finch, let us say, entering a new environment will, in response to its inner drive to maintain itself, will begin to "make a living" in whatever way it can, using whatever nature has provided. Perhaps it will try to crack nuts. At that point, that "job description" of nut-cracker will put a new direction upon the natural selection process, and finches with beaks better suited to nut cracking will tend to be more reproductively successful than those less well endowed. Meanwhile, some other group of finches, making its living differently, will find itself being selected according to different criteria. IOW, it is the finality toward which that particular population of finches moves that turns natural selection from Blyth's mechanical grim reaper maintaining eternally unchanging species to Darwin's creative engine sculpting the emergence of new species.
This is somewhat in line with Kimura's theory of neutral selection, by which "mutation happens" and, provided it is not actually fatal, the organism makes use of it in some way. IOW, there is no such thing as a "beneficial" mutation as such. All traits and features are "spandrels." It is the organism's use of the feature that makes it beneficial.
The panda's "thumb" is an example. The protruding wristbone did not evolve in order to strip leaves from bamboo cane; but the wristbone protruded and pandas learned to use it to strip leaves from bamboo cane. The "advantage" is posterior to the mutation. (And objections to evolution by natural selection based on the unlikelihood of hitting such a target become moot. The panda's wristbone did not hit the target, the panda painted the target around the wristbone.)
|The swift-evolving lizard of Croatia|
Italian wall lizards introduced to a tiny island off the coast of Croatia are evolving in ways that would normally take millions of years to play out, new research shows. In just a few decades the 5-inch-long (13-centimeter-long) lizards have developed a completely new gut structure, larger heads, and a harder bite, researchers say. ... Pod Mrcaru, for example, had an abundance of plants for the primarily insect-eating lizards to munch on. Physically, however, the lizards were not built to digest a vegetarian diet. Researchers found that the lizards developed cecal valves— muscles between the large and small intestine—that slowed down food digestion in fermenting chambers, which allowed their bodies to process the vegetation's cellulose into volatile fatty acids.It's unclear why they thought it would "normally take millions of years," since modern genetics is discovering that molecular machinery can result in changes that are massive, specific, and sudden, and we now know that epigenetic factors can affect when and how a gene realizes during morphogenesis.
"They evolved an expanded gut to allow them to process these leaves," Irschick said, adding it was something that had not been documented before. "This was a brand-new structure."
Shapiro: The exstence of cellular biochemical activities capable of rearranging DNA molecules means that genetic change can be specific (these activities can recognize particular sequence motifs) and need not be limited to one genetic locus (the same activity can operate at multiple sites in the genome). In other words, genetic change can be massive and non-random.
You can run, but you can't hide!
Basically, we have seen several major threads coming together: Mendel's genetics, Darwin's natural selection, Kimura's neo-Lamarckian neutral selection. In an article that I have long lost, these factors were summarized as follows:
- The genetic factor: the tendency to variation resulting from constant small random mutations in the genetic code; i. e., a variety of differing individuals within a species capable of transmitting their differences
- The epigenetic factor: the tendency of interbreeding population to reproduce itself in a stable manner and increase in numbers; i. e., the maintenance of type
- The selective factor: natural selection by the environment which eliminates those variants which are less effective in reproducing their kind; i. e., the agent determining in which direction species-change will take place
- The exploitative factor: the flexibility of living things by which they are able to occupy new niches in the changing environment; i. e., a feed-back mechanism which guides the selective process toward a new type which can exploit new environmental possibilities
- Material cause
- Formal cause
- Efficient cause
- Final cause