Evolution Icon Evolution
Intelligent Design Icon Intelligent Design

Darwin’s Theory of Natural Selection Has Left a Legacy of Confusion over Biological Adaptation

Brian Miller
Photo: Cave fish (Phreatichthys andruzzii), by Hectonichus, CC BY-SA 3.0 , via Wikimedia Commons.

In recent articles, I summarized lectures at CELS (Conference on Engineering in Living Systems) that described the design-based assumptions prevalent in systems biology and that outlined an engineering model for adaptation (herehere). Now I will summarize a third CELS lecture that revealed how Charles Darwin shifted the conventional understanding of biological adaptation as an internal capacity of an organism to the belief that it is the product of the environment acting on a species externally. 

Darwin’s Positive Legacy

Evaluating the legacy of Charles Darwin is a complex task. On the positive side, Darwin helped biologists to appreciate how organisms change with time to better survive in shifting environments. Before his views became popular, many saw species as static entities, so they did not fully appreciate the historical factors shaping such observations as diminished eyes in cave fish. 

In addition, Darwin illuminated how variation in populations (e.g., differences in size and coloration) enabled species to better adapt to their surroundings. This insight was later integrated with genetics and mathematics in one of the great scientific achievements of the 20th century, known as population genetics. The resulting set of tools has proven invaluable in such fields as virology and environmental science. 

On the negative side, Darwin asserted that adaptation is driven by natural selection, which he portrayed as a creative force that reshaped organisms. This illusion has consistently confused biologists over adaptation’s true nature.

Turning Paley on His Head

The problem originates with Darwin’s fascination with natural theologian William Paley. He was deeply impressed by Paley’s argument that life demonstrates clear evidence for design, pointing to an all-powerful Creator. Paley famously compared the design of living structures to the intricate complexity of a watch. Darwin mimicked Paley’s logic and style in his own writings, but he replaced the Creator with natural selection. 

Famed paleontologist Stephen Jay Gould commented in The Structure of Evolutionary Theory:

I was struck by the correspondences between Paley’s and Darwin’s structure of argument (though Darwin, of course, inverts the explanation). Darwin did not exaggerate when stating to Lubbock that he had virtually committed Paley to memory. The style of Darwin’s arguments, his choice of examples, even his rhythms and words, must often reflect (perhaps unconsciously) his memory of Paley.

p. 119

Internalism to Externalism

Before Darwin, all theories of adaptation focused on how organisms adapt to their environment through internal mechanisms (aka internalism). Temperature regulation is a classic example. Complex animals possess sensors that measure their internal temperature. An integrated process sends the sensors’ readings to analyzers that detect when the internal temperature rises beyond a predetermined set point. The analyzers can then trigger mechanisms that release body heat as, for example, through sweating. An animal’s ability to adapt to increasing environmental temperature results from internal capacities that were designed to achieve that goal.  

Darwin’s theory of natural selection changed the source of creative agency from a Creator who engineered internal mechanisms to the environment that reshaped an organism externally (aka externalism). In the new framework, the environment “instructs” a population on how to expand its variation and use it to craft novel innovations. In the process, it exerts “selection pressures” on an organism to “mold” it as passive clay. Biologists Marc Kirschner and John Gerhard explain (herehere):

He accepted the view that the environment directly instructs the organism how to vary, and he proposed a mechanism for inheriting those changes.

The Plausibility of Life: Resolving Darwin’s Dilemma, p. 3

The organism was like modeling clay, and remolding of the clay meant that each of the billions of little grains was free to move a little bit in any direction to generate new form. … If an organism needed a wing, an opposable thumb, longer legs, webbed feet, or placental development, any of these would emerge under the proper selective conditions, with time.

The Plausibility of Life: Resolving Darwin’s Dilemma, p. 31

The central problem with such claims is that the environment is not conscious, as depicted, e.g., in the Disney movie Pocahontas. It cannot select, mold, tinker, instruct, or perform any such actions reserved to intelligent agents. The most astute philosophers of science and biologists have called for the purging of such pseudoscientific thinking from biology. Philosopher Jerry Fodor and cognitive scientist Massimo Piattelli-Palmarini bluntly stated:

Darwin pointed the direction to a thoroughly naturalistic — indeed a thoroughly atheistic — theory of phenotype [trait] formation; but he didn’t see how to get the whole way there. He killed off God, if you like, but Mother Nature and other pseudo-agents [selection] got away scot-free. We think it’s now time to get rid of them too.

Jerry Fodor and Massimo Piattelli-Palmarini, What Darwin God Wrong, p. 163

Many have traced the confusion back to Darwin’s mistaken analogy between artificial breeding and undirected evolution. Geneticist Richard Lewontin commented:

Darwin, quite explicitly, derived this understanding of the motivating force underlying evolution from the actions of plant and animal breeders who consciously choose variant individuals with desirable properties to breed for future generations. “Natural” selection is human selection writ large. But of course, whatever “nature” may be, it is not a sentient creature with a will, and any attempt to understand the actual operation of evolutionary processes must be freed of its metaphorical baggage.

Richard C. Lewontin, “Not So Natural Selection,” New York Times Book Review

Others have pointed out that evolutionists’ employment of the term “selection pressure” is often equally misleading and intellectually vacuous. Evolutionary biologist Robert Reid stated:

Indeed the language of neo-Darwinism is so careless that the words ‘divine plan’ can be substituted for ‘selection pressure’ in any popular work in the biological literature without the slightest disruption in the logical flow of argument.

Robert G. B. Reid, Biological Emergences: Evolution by Natural Experiment, pp. 37-38

To fully comprehend the critique, one simply needs to imagine attempting to craft an evolutionary barometer that measures the selection pressure driving one organism to transform into something different (e.g., fish into an amphibian). The fact that no such instrument could be constructed highlights the fictitious nature of such mystical forces. 

Central Importance of Traits

Any accurate analysis of adaptation must change the focus from the environment to an organism’s traits. The environment simply represents the conditions external to an organism (e.g., chemicals present, available food, local predators). The extent to which organisms flourish or perish in those conditions depends on individuals’ traits such as their ability to degrade toxins or avoid threats. 

To appreciate this shift, one simply needs to read news articles related to natural disasters. After a hurricane devastates a town, no one examines the surviving homes and states that those that withstood the storm were selected by nature to survive and those that did not were selected against. Instead, architects and structural engineers discuss which homes were designed properly to withstand flood waters and high wind velocities and which were not.

Often, imprecise evolutionary language causes little harm. If an epidemiologist speaks about certain bacteria being selected for resistance to an antibiotic, everyone knows that the doctor or researcher means that those bacteria have some genetic distinction that enables them to evade the antibiotic’s toxic effects. The real problem arises with the more grandiose evolutionary narratives. 

The story that selection pressures directed the brain of an ape-like creature to transform into the human brain to better survive in an unpredictable environment is pure fiction. The schematics for the neural networks undergirding such complex traits as human vocalization and language (hereherehere) were not hidden under some rock, such that Mother Nature instructed human ancestors on how to slowly instantiate them over millions of years. Instead, thousands, if not millions, of neural connections had to have been meticulously engineered and integrated into other neural networks in a single moment, or such complex systems would not have functioned at even the most basic level. Yet, the available time is insufficient for mutations and differential survival to generate even one mid- to long-range targeted neural connection (herehere). More generally, our ability to adapt to fantastically diverse circumstances did not result from the happenstance of environmental conditions. It is, instead, the result of our being fearfully and wonderfully made.