Introduction to Evolutionary Theory
Finally we have enough background “pieces of the puzzle” on the table that we can have a semi-responsible discussion of evolutionary theory.
The first thing to note is that “evolutionary theory” has really gone beyond a typical “theory” at this point. At present it has genuinely reached the status of a full-blown Kuhnian paradigm. It acts as the “basket” into which a vast array of other theories deposit their goods, and it holds a huge pile of other theories together. It is important to keep this in mind as we proceed because paradigms have such profound psychological sway that they cannot be “falsified” just by pointing out this or that particular anomaly!
This fact about paradigms is a major reason why it is really an exercise in futility to debate with evolutionists about the data. Religionists interpret “the data” in terms of their paradigm, and evolutionists do the same. So there really is not even one set of “data” that we are all talking about! What “the data” even is, even means, varies wildly due to paradigmatic interpretation. So, the only way to properly talk about “the data” employed in evolutionary theory is to genuinely “get into” that paradigm and make every charitable effort to “see” it as an evolutionist does.
The Big Misunderstanding
One of the most fundamental disconnects that arises in discussing evolutionary theory is in determining/describing what evolutionary theory really claims. The term “evolution” is such common currency now that it is employed everywhere and mostly in contexts that strictly-speaking have nothing to do with actual evolution according to evolutionary theory.
Another problem is that evolutionary theory is often straw-manned by religionists who ought to (and often do) know better. Thus, the contrast is often cast as between so-called “intelligent design” and “pure randomness.” So, I want to side with evolutionists on this one and put a large, firm stake in the ground: Evolutionary theory is not just one grand appeal to “pure randomness.” Yes, randomness is a factor in evolutionary theory, but it is not the primary factor.
The primary factor is “natural selection,” and this factor bears the vast majority of the weight of the theory. This factor is also primarily what differentiates Darwinian evolutionary theory (what we now mean by “evolutionary theory”) from its earlier competitors, such as Lamarckism. Natural selection is the working mechanism of Darwinian evolutionary theory. So when religionists blithely straw-man evolutionary theory by calling it a “theory of randomness” or some such thing, they overlook one of the core components of the theory.
Now, granting modern evolutionists their “natural selection” does not immediately get everybody on the same page about what evolutionary theory really is! The biggest misunderstandings (even among evolutionists) emerge during attempts to get clear about what “natural selection” even is and what power it can actually wield. We will go into great detail on these points as we move forward. However, for the moment, let’s be very clear about one thing: The primary weight of evolutionary theory rests on “natural selection,” so straw-manning evolutionary theory by calling it a theory of “pure randomness” is uncharitable and inaccurate. One implication of this fact is that evolutionary theory must provide a well-defined account of what “natural selection” is and how it really works in the world. We will carefully evaluate evolutionary theory’s efforts to establish these accounts.
The Theory in a Nutshell
Even talking about “the theory” is problematical, as we will detail going forward. But for the moment, we can talk about the “orthodox” view of so-called “neo-Darwinian” evolutionary theory.
Why is modern evolutionary theory called “neo-Darwinian”? Well, “neo” means “new,” which in this context really means “contemporary.” Contemporary evolutionists will say that there were many details of his broad-strokes theory that Darwin did not understand. Because many details have been filled in and “refinements” made to Darwin’s theory, it is a vastly improved version today. So, the “neo” part concerns the improvements and refinements made to the theory as it is today.
The “Darwinian” part concerns the two hallmarks of Darwin’s original theory: Random mutation and natural selection. These two pillars of contemporary evolutionary theory have not changed from Darwin’s original. So contemporary evolutionary theory really is “Darwinian” to its core.
Hence: “neo-Darwinian” evolutionary theory. Rather than to keep repeating the more lengthy phrase, we will continue to use the shortened “evolutionary theory” or “Darwinism” or “Darwinian” and so forth. But please keep in mind that we intend to discuss neo-Darwinian theory, replete with its contemporary refinements, enhancements, and improvements.
This point is important because, again, religionists do often straw-man evolutionary theory by appealing directly to Darwin himself regarding points about which neo-Darwinians would respond, “Dumb argument! We’ve resolved such problems long since Darwin.” So it is critical to be charitable (and truly contemporary) in our analysis of evolutionary theory.
So, what is the neo-Darwinian orthodoxy, otherwise sometimes called the “neo-Darwinian synthesis”?
Certainly the most active (and vociferous) proponent of the neo-Darwinian synthesis today is Richard Dawkins. And in this brief lecture on YouTube (about 5 1/2 minutes), Dawkins illustrates the key defining points of Darwinism: random mutation “filtered” by natural selection, which together produce an “accumulation of small changes” that ultimately produce new species. Dawkins himself sums up these points in the opening of Chapter 3 of his seminal book, The Blind Watchmaker, quoted here:
How then, did they [apparently “designed” living things] come into existence? The answer, Darwin’s answer, is by gradual, step-by-step transformations from simple beginnings, from primordial entities sufficiently simple to have come into existence by chance. Each successive change in the gradual evolutionary process was simple enough, relative to its predecessor, to have arisen by chance. But the whole sequence of cumulative steps constitutes anything but a chance process, when you consider the complexity of the final end-product relative to the original starting point. The cumulative process is directed by nonrandom survival. (emphasis in original)
Notice some key points that emerge just from this one brief passage:
* Randomness produces small mutations, the “new genetic information” of change
* Natural selection “directs” which of these mutations “make it” and which do not
* Survival-enhancing mutations “survive to fight another day” and thereby breed
* The whole process is slow, gradual, and step-wise in tiny increments
The points can be summarized into one famous line emerging all the way from Aristotle’s time: Natura non facit saltus, which is Latin for: Nature does not make leaps. And this principle is the driving force behind Darwinism even today.
We can thus apparently contrast “Darwinism” with other contemporary theories of evolution, such as Gould’s and Eldredge’s theory of “Punctuated Equilibrium,” that has often been held up in contrast to “Darwinism” insofar as it could be called a theory of “saltation” (or, in Latin, leaps or rapid changes). Now, both the late Gould and Eldredge have called themselves “Darwinian” in principle. Their theory was designed to explain the long periods of “stasis” (no change) observed everywhere in the fossil record that are “punctuated” by “short” periods of relatively “rapid change.” And both Gould and Eldredge denied that theirs was a theory of saltation!
So a pressing question immediately emerges: Just how “slowly” must a series of changes “accumulate” in order to be consistent with Darwinian theory, and how “rapidly” must a series of changes take place in order to count as a “leap” and thereby indicate a theory of saltation?
The hallmark of Darwinism is the slow accumulation of changes in tiny increments, which distinguishes this theory from theories of saltation that accept or embrace at least “small leaps” at times. How “big” of a “leap” is a leap? And how big of a “leap” would demonstrate that Darwinism is an inadequate account of how evolution really works?
Notice in that last question that we are not asking: “How big of leaps would it take to falsify evolutionary theory?” That is a question that can well be asked, but we are not here asking that question!
Both neo-Darwinism and Punctuated Equilibrium are theories residing firmly in the evolutionary camp, and, as we have noted, both Gould and Eldredge often emphasized that their theory is “Darwinian,” as they postulated that entirely “Darwinian” principles worked during the “brief” periods of change indicated by the fossil record. So, within certain bounds, evolutionary theory can absorb the idea of “leaps” in nature, or at least of “faster than expected” tiny, incremental changes that “quickly” accumulate.
No, what “saltation” really means is nature taking such large leaps that the tiny, incremental process of accumulated random mutations cannot account for the quick-amassing of enough genetic information to produce “sudden” and “large scale” changes. And no evolutionist today believes that the evolutionary process involves saltation in this sense. Thus, there is indeed a hard dichotomy between Darwinism and saltation, where demonstrated saltation would indeed be a falsification of Darwinism.
Gould and Eldredge postulated Punctuated Equilibrium to salvage Darwinism from the fundamental problem observed in the fossil record: The fossil record appears to demonstrate saltation, or big leaps between species! So, Punctuated Equilibrium is not itself a theory of saltation; it is designed to interpret the saltation evidenced in the fossil record. Now, back to the question we said we were not asking: “How big of leaps would it take to falsify evolutionary theory?” Actual saltation would be a falsification of Darwinism, and the fossil record does indicate saltation. So, Punctuated Equilibrium is a Darwinian interpretation of the fossil record in an attempt to keep apparent saltation from falsifying Darwinism.
In summary, Darwinism states that tiny, occasional, random changes appear in the genome of some living things, and such changes are “allowed” or even “directed” to accumulate over time by the force of natural selection. Over time and with accumulation, these changes produce demonstrable, observable differences between organisms within the “same species.” These differences begin to differentiate among these organisms to the degree that organisms of “one type” become isolated from organisms of “another type,” ultimately making the divide between the types sufficient to result in a new species emerging. The occurrence of such a divide is called a “speciation event.” And the occurrence of many, many such speciation events defines the outworking of Darwinism throughout the history of life on Earth.
Going forward, we will analyze the details of how both random mutation and natural selection are supposed to work together to produce speciation events. And we will examine what the term “speciation event” really means.