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The Fly Designs of San Marco

Updated: Aug 2, 2022

No, San Marco is not a person...

Fair warning, this post is geekier than most I write (a high bar already, I know) but if you do choose to read on, you may learn an interesting bit of evolutionary biology and maybe a bit of fly design - or at least I hope!

The Spandrels of San Marco and the Panglossian Paradigm

In 1978, Steven J. Gould and Richard Lewontin, two of the world's best known evolutionary biologists at the time, wrote and presented a paper - an opinion piece really - titled, "The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme". If you take an upper-level or graduate-level course in evolutionary biology or natural history, there is a pretty good chance you have read or will read this paper. And you know Gould and Lewontin are "a big deal" because not many professors get their own Wikipedia pages. And their paper earned not only a Wikipedia page but the term "spandrel" also has its own page. This is all a long about way to say is a pretty damn big deal, among a really small group of us geeks, at least. It is one of those "big ideas" in biology that are argued in the way scientists argue about big ideas.

By Maria Schnitzmeier - Detail of Image:DSCF0077.JPG, CC BY-SA 3.0,

The spandrels purpose is to hold up the dome, in this case in the St. Mark's Basilica in Venice, Italy. And those of St. Mark's Basilica are particularly ornate, as if the building was built to show their beauty. Or as Gould more emphatically and stylistically writes,

"so elaborate, harmonious, and purposeful that we are tempted to view it as the starting point of any analysis, as the cause in some sense of the surrounding architecture."

And this is what Gould and Lewontin will argue against - the spandrels are there because they had to be there. They are not ornate for any purpose other than they had to be there and someone might as well "do something with them". The spandrels are there out of necessity, it just so happens they became something beautiful.

Dr. J's X-legs
Dr. J's X-legs - a fly pattern I am working on. A low floating late summer terrestrial that I have been experimentaing with for the last few summers. Something new and needed or just more wishful thinking?

The essay is a critique of what they call the "adaptionist programme" which, in their view, created "just so" stories that explained the features of organisms as adaptations - shaped by natural selection rather than by chance - genetic drift. They compare the adaptionist prgramme to Voltaire's fictional character, Dr. Pangloss in Candide, ever the optimist despite his quite significant trials and tribulations. Pangloss is contented by his assertion that he is living in the best of all possible worlds. As Dr. Pangloss says,

"Everything is made for the best purpose. Our noses were made to carry spectacles, so we have spectacles. Legs were clearly intended for breeches, and we wear them."

Gould and Lewontin compare this adaptionists views and "just so" stories about why a particular character evolved. They are more or less mocking what they view as other scientists "just so" stories. Maybe you remember a bit of Kipling and his stories, "How the Leopard Got His Spots" and "How the Camel Got His Hump"? Gould and Lewontin use "just so" stories as a pejorative.

Adaptionist Fly Design?

There are lots of "just so" stories about why a fly works, why fish eat our flies, and what different parts of our flies represent. And all of them ignore the parts that don't fit the narrative. Let's start with the thread head which so rarely looks like the head of anything we are imitating - but we need somewhere to tie the fly off, thus there is a thread head. Or that hook that fits into almost no "just so" stories about why fish eat a particular fly.

Milwaukee Leech
The venerable Milwaukee Leech - I have no idea who "invented" it but does it ever work!

What does a woolly bugger represent? I have heard - and presented myself - a number of "just so" stories about why woolly buggers and other fly patterns work. "The fish are taking them as crayfish." Are they? I have no proof of that is why my olive woolly bugger just caught a fish but I like the story. The alternative is that fish are stupid and who knows why they ate it other than they thought it looked like something that the fish wanted to put its mouth on, presumably to eat it. Even that, how often are fish just mouthing something to get it away from them? Lacking arms (yes, that is the hard hitting fish science you come here for), they sometimes use their mouths in place of arms. That is the nature of "bed fishing" for bass or Bluegill or much of the fishing for anadromous salmonids. Truth is, we like to think we know why fish are eating a particular pattern or better yet, why a particular pattern works better than others, but are we just making up "just so" stories?

Dr. J's X-legs, a fly in the making
Another version of a new pattern I am working on - a terrestrial pattern for August and later - that floats with its abdomen in the water. It has taken on many variations. Maybe someday, it will be "just so".

The fact that a hook is intended to hook and hold fish creates a bit of a spandrel - our flies have to conform to this limitation. It makes our flies particularly rigid and the hook is almost always quite evident. For centuries fishes have continued to hit our imitations despite that "steel hemorrhoid". Odds are pretty good they will continue to do so for decades to come. Anyone remember Waterwisp flies which were dry flies tied backwards and upside-down to better hide the hook and mimic the naturals? While an interesting idea, it did not seem to go very far as they were more of a pain to tie and they solved a problem that did not really exist. Trout simply do not seem to see the hook as we do - or at least it is not a negative trigger - so hiding the hook bend seems to do nothing. A lot of new fly patterns solve problems that do not really exist.

Fettuccine foam divers
Fettuccine Foam - an interesting material that lets you play around with some new ideas.

There are two reasons to design a new fly in my mind; 1) to solve a real need and produce a fly does a better job of catching fish than what is currently available, and 2) to make money and/or get "famous", in the way any fly designer is "famous". Points one and two are not mutually exclusive, I suppose. However, there are fly bins and Instagram feeds full of flies that are more designed more for #2, than #1. That is not to say that there are not a lot of great new fly patterns out there. However many new patterns are either not very new or they do not really do much to solve a problem. Many new flies are created to sell flies. Now part of this is my personal bias - I will take a simple fly I do not mind losing over a complex tie most any time and I like patterns that have movement built into them.

Clouser Deep Minnow
A Bob Clouser tied Clouser Deep Minnow - sometimes new materials (dumbbell eyes) open up new possibilities for the tyer.

It is HARD to come up with a truly new pattern as we are limited not only by our imaginations - a pretty significant limitation - but also by materials and the fact they need to be put on a hook. Let's face it, most new patterns borrow very heavily from existing patterns. There are only so many materials and so many ways they can be applied to a hook to imitate something alive.

Close Carpet Fly
The Close Carpet Fly - a bit of wicked cool innovation and a bit of burrowed ideas - that seems to be true for most new fly patterns.

To borrow another idea from Stephen Jay Gould - punctuated equilibrium or the idea that little new happens for long periods of time (stasis) but then a new feature comes along and we see rapid evolution. Niles Eldredge and Gould wrote that we see little evidence of gradualism in the fossil record - the model most of us think of - that small incremental changes add up over time. Instead they argue that we see little change in fossils often over millions of years and the evolution of few new species and then - BOOM - drastic changes and speciation. Fly tying can be much the same, if we looked into pattern books, we would see lots of the same for generations. Catskill dry flies have some variation but they are largely the same - hackle fiber tails, a body, a split upright wing, and a traditionally wrapped hackle. There are a lot of variations on this general theme. Then, every once in a while, something comes along and changes everything. I would offer a few examples - beadheads, dumbbell eyes, parachute posts and patterns, articulated shanks, and other such inventions and fly tying takes a new direction. And if we were to look through the fly tying fossil record, we would see an explosion of patterns using these new materials and new techniques - and for the most part, we do. Though not always - parachutes date back much further - to the 1920's and '30's - but the 1970's and '80's started to see an explosion in these patterns. This is comparable to the evolutionary biology idea, adaptive radiation, of which "Darwin's Finches" is the classic example - from 1 came 14 species. Chichlids of African rift lakes laugh at the paltry speciation of Galapagos finches.

To wrap this up, truly new and innovative flies are rare because we are constrained with the materials available to us, the techniques available to us, and the fact that these materials and techniques have to be wrapped around a hook. I do not mind the "just so" stories, in fact they are part of the fun of fly fishing and fly tying. Sure, most are about making us feel smarter than a trout (or bass, musky, bonefish, tarpon, etc.) but some days we need that boost.

If you want to

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Brian Larson
Brian Larson
May 30, 2022

pictures are a bit messed up size wise and print very small.

Jason G. Freund
Jason G. Freund
May 30, 2022
Replying to

Brian, it is the same template as always so it must be either on Wix's end or yours. For the font size, you can control that on a PC with a control+scroll bar. For the photos, the first one is not very good (it's an open source image) but if the rest are messed up, for me that usually means clearing my cache.

I suspect it is on Wix's end, it happens on occasion for me too. Clearing cache and simply coming back later seem to clear it up.

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