A legacy of confusion over biological adaptation

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

In recent papers, I have summarized lectures at CELS (Conference on Engineering in Living Systems) which described the design-based assumptions prevalent in systems biology and which exposed an engineering model for adaptation ( here, here). I will now summarize a third CELS lecture which revealed how Charles Darwin evolved the conventional understanding of biological adaptation as an internal capacity of an organism towards the belief that it is the product of the environment acting on a species from the outside.

Darwin’s positive legacy

Assessing Charles Darwin’s legacy is a complex task. On the positive side, Darwin has helped biologists understand how organisms change over time to better survive in changing environments. Before his views became popular, many species viewed species as static entities, so they did not fully appreciate the historical factors that shape sightings such as diminishing eyes in cave fish.

Additionally, Darwin explained how variation in populations (eg, differences in size and coloring) allowed species to better adapt to their environment. This idea was then incorporated into 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 fields such as virology and environmental science.

On the negative side, Darwin asserted that adaptation is driven by natural selection, which he described as a creative force that has reshaped organisms. This illusion has constantly confused biologists about the true nature of adaptation.

Flip Paley on his head

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

Famous paleontologist Stephen Jay Gould commented in The structure of the theory of evolution:

I was struck by the correspondences between Paley’s and Darwin’s structure of argument (although Darwin, of course, reverses the explanation). Darwin was not exaggerating in telling Lubbock that he had virtually entrusted Paley to memory. Darwin’s style of arguments, his choice of examples, even his rhythms and words, must often reflect (perhaps unconsciously) his memory of Paley.

p. 119

From internalism to externalism

Before Darwin, all adaptation theories focused on how organisms adapt to their environment through internal mechanisms (aka internalism). Temperature regulation is a classic example. Complex animals have sensors that measure their internal temperature. An integrated process sends the sensor readings to analyzers which detect when the internal temperature exceeds a predetermined set point. The analyzers can then trigger mechanisms that release body heat, for example through perspiration. An animal’s ability to adapt to increasing ambient temperature results from internal abilities designed to achieve this goal.

Darwin’s theory of natural selection changed the source of the creative agency of a creator who designed mechanisms internal to the environment that reshaped an organism from the outside (a.k.a. externalism). In the new framework, the environment “tells” a population how to expand its variation and use it to create new innovations. In the process, he exerts “selection pressures” on an organism to “mold” it into passive clay. Biologists Marc Kirschner and John Gerhard explain (here, here):

He accepted the view that the environment directly tells the organism how to vary, and he proposed a mechanism to inherit these changes.

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

The organism was like plasticine, and the reshaping of clay meant that each of the billions of tiny grains was free to move a little in any direction to generate a new shape. … If an organism needed a wing, an opposable thumb, longer legs, webbed feet, or placental development, any of these would emerge under the appropriate selective conditions over time.

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

The central problem with such claims is that the environment is unaware, as described, for example, in the Disney movie. Pocahontas. He cannot select, model, tinker, instruct or perform such actions reserved for intelligent agents. The most astute philosophers of science and biologists have called for the purge of this pseudo-scientific thought from biology. Philosopher Jerry Fodor and cognitive science researcher Massimo Piattelli-Palmarini stated bluntly:

Darwin pointed out the direction of a completely naturalistic – indeed completely atheistic – theory of the phenotype. [trait] training; but he didn’t see how to get it all the way. He killed God, if you will, but Mother Nature and other pseudo-agents [selection] escaped unscathed. We think now is the time to get rid of it too.

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

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

Darwin, quite explicitly, drew this understanding from the underlying motivating force behind the evolution of the actions of plant and animal breeders who consciously choose variant individuals with desirable properties to reproduce for future generations. “Natural” selection is human selection in the broad sense. But of course, regardless of “nature,” it is not a sentient creature with a will, and any attempt to understand how evolutionary processes actually work must be freed from its metaphorical baggage.

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

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

Indeed, the language of neo-Darwinism is so reckless that the words “divine plan” can be substituted for “selection pressure” in any popular work of biological literature without the slightest disturbance in the logical flow of it. argumentation.

Robert GB Reid, Biological emergences: evolution through natural experience, p. 37-38

To fully understand the criticism, just imagine trying to create an evolutionary barometer that measures the selection pressure causing an organism to transform into something different (for example, a fish into an amphibian). The fact that no such instrument could be constructed highlights the fictitious nature of these mystical forces.

Central importance of traits

Any precise analysis of adaptation must shift the attention of the environment to the traits of an organism. The environment simply represents the conditions external to an organism (eg, chemicals present, food available, local predators). The extent to which organisms thrive or perish under these conditions depends on individual traits such as their ability to break down toxins or avoid threats.

To appreciate this change, just read the press articles related to natural disasters. After a hurricane devastates a city, no one examines the surviving houses and states that those that withstood the storm were selected by nature to survive and those that did not resist were selected against. Instead, architects and structural engineers discuss which homes have been designed correctly to withstand flooding and high winds and which ones haven’t.

Often, imprecise evolutionary language does little harm. If an epidemiologist talks about certain bacteria selected for their resistance to an antibiotic, everyone knows the doctor or researcher means that these bacteria have a genetic distinction that allows them to escape the toxic effects of the antibiotic. The real problem arises with the most grandiose evolutionary accounts.

The story that selection pressures caused the brain of an ape-like creature to transform into a human brain to better survive in an unpredictable environment is pure fiction. The neural network patterns underlying such complex traits as human vocalization and language (here, here, here) weren’t hidden under a rock, so Mother Nature taught human ancestors how to slowly instantiate them. over millions of years. Instead, thousands, if not millions of neural connections had to be meticulously designed and integrated into other neural networks in a single instant, otherwise such complex systems would not have functioned at the most basic level. Yet there is not enough time available for mutations and differential survival to generate even a single, targeted mid- and long-range neural connection (here, here). More generally, our ability to adapt to fantastically diverse circumstances was not the result of environmental conditions by chance. It is, on the contrary, the result of our being terribly and wonderfully made.


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