Are Adaptations "Real?"

AUTHOR: Allen MacNeill

SOURCE: Original essay

COMMENTARY: That's up to you...

In an ongoing thread at Design Paradigm, Salvador Cordova wrote:

“There are many designed features in biology that make no sense in terms of natural selection but make complete sense in terms of design.”

This statement demonstrates a profound misunderstanding of both the concept of “design” and of “natural selection,” a misunderstanding which lies at the heart of the evolution/design debate. What is “design” anyway? Note that I’m not asking the question that Dr. Dembski thought he was answering, i.e. how can we tell if something has been designed. Before one can even ask that question (much less attempt to answer it), one must first agree on what “design” is.

This is not a trivial problem. Michael Ruse, in Darwin and Design: Does Evolution Have a Purpose?, asserts that one of the most important contributions of Darwin’s theory was that it put “design” back into nature (from which it had been removed by the “Newtonians”). To Ruse, “design” is essentially equivalent to “adaptation,” in that adaptations “solve” problems of biological function.

But the problem here is one that Lewontin and Gould addressed almost 30 years ago in their landmark paper “The Spandrels of San Marco...”. Lewontin and Gould pointed out two things: (1) not all of the characteristics of living organisms are adaptations (i.e. some of them are the result of pure “chance,” not necessity), and (2) even the characteristics that are clearly adaptive don’t have to have arisen because they are adaptive, nor will they continue to exist for the same reason. They coined the term “exaptation” to refer to characteristics of organisms that are not necessarily adaptive, but which nonetheless are biologically significant.

I would go much further than Lewontin and Gould: just as Darwin suggested (but did not come right out and say) that there are no such things as “species” (see "Origin of the Specious" in this blog), I believe that in nature there are no such things as “adaptations,” at least not insofar as such "adaptations" are "solutions" to biological "problems." That is, although there are characteristics of organisms that are correlated with relatively high reproductive success (and would therefore be considered by most evolutionary biologists to qualify as “adaptations”), it becomes problematic to decide exactly which of those characteristics are the “real” adaptations and which are merely “accidental.” Indeed, if one is serious about the variation/inheritance/fecundity/differential reproductive success model of evolution (i.e. the genuine article, not the RM+NS straw-man attacked by most IDers), then all of the characteristics of living organisms are “accidental” insofar as their origin cannot be shown to have been “intended” or “pre-destined” ahead of time.

Here is the real crux of the disagreement, as PvM has pointed out: what qualifies as an “adaptation” in biology can only be determined retrospectively, insofar as it has the practical result of causing increased relative survival and reproduction. No characteristics of living organisms can be shown to have come into being because they would eventually have that result; indeed, I would assert that to even make this claim is non-sensical in the extreme. What characteristics of living organisms currently alive will eventually result in their assendance or demise? We have absolutely no way of knowing, nor even of imagining a way of knowing. At some point in the future, we can look back and say “son-of-a-gun, those funny looking scales are correlated with increased survival and reproduction because they allow the animals that have them to fly, and therefore escape predators and capture prey more effectively,” but until this actually happens (and absolutely nothing in nature guarantees that it will), we can’t make any statements about the “value” of any of the characteristics of organisms now living.

This, rather than the rather vapid speculations Salvador cited for the future of genetic engineering, is the real value of genetic engineering to evolutionary biology (and vise versa). We now have the ability to selectively delete individual characteristics from many different organisms. This makes possible something that natural selection does not: the precise determination of the selective “value” of particular characteristics. This has already been done, and the surprising outcome has been that even some gene sequences that were thought to have been very important in selection (due to having been “conserved” over deep evolutionary time) are apparently insiginificant or even useless. We know this because knocking them out of the genome has no discernible effect on the survival or reproduction of the “knock-out” progeny. If one is the kind of “pan-adaptationist” that Lewontin and Gould criticized, this outcome should come as a severe shock, as it should to every IDer. But, if one is a true “Darwinian” (i.e. a devotee to that tradition which questions absolutely all assumptions, including the very existence of “adaptations” and “species”), it should come as no surprise at all.

--Allen

REFERENCES CITED:

Gould, S. J. and Lewontin, R. C. (1974) "The Spandrels of San Marco and the Panglossian Paradigm: A Critique Of The Adaptationist Programme" Proceedings Of The Royal Society of London, Series B, Vol. 205, No. 1161, pp. 581-598.