When Jeannette Whitton and I hatched the idea of writing a paper on species concepts in 2016, we had no conceptual agenda and, thank goodness, no deadline. We had three motivations: each of us knew that their view of species was unfinished, despite many years of occasional contemplation; we had an invitation from Matt Haber to a special workshop; and our different but overlapping backgrounds made us a good team. Jeannette is a speciation and population biologist who grew up (academically) alongside taxonomists; I am a taxonomist and systematist raised alongside varied evolutionary biologists. Jeannette’s curiosity was provoked by the structuring of biodiversity that she saw on the landscape, wondering what are these forms with distributions and distinctive traits. My curiosity came from memories of exciting (contentious? vicious?) discussions by systematists in the 1970s and 80s, as well as conversations over many years about species taxonomy with my brother David. Also, I had some unfinished business: I had touched on species concepts tangentially in my 1997 gene trees paper, but hadn’t returned to develop the ideas. We didn’t think the literature had answered our curiosities. Despite the progress made by Mishler, de Queiroz and others, the questions already well answered were not the questions we were asking.
Our paper is out (https://doi.org/10.18061/bssb.v2i1.9358)! I want to tell the story of how it developed because it is a good example of the importance of patience and courage. The patience allowed for Slow Science. That mattered. The courage helped us work with collaborators (each other) with different inclinations and different (initial) perspectives. Indeed, I should have said “how it developed from my vantage point”, because Jeannette’s journey and mine were, of course, different. (Jeannette tells her story here.) The story will be long, though not as long as our journeys or our paper!
My starting point, as Jeannette and I began working together, was philosophical and abstract. I assumed that species weren’t real (in some deep sense), that alternative constructs would serve different purposes, and that a detached pluralism was going to be the solution. I expected our paper would outline a menu of alternative tightly-defined species concepts, from which each biologist could choose their favourite. I imagined we were going to propose definitions centred on utility to biologists, almost as if we were at best ignoring Nature, at worse telling it how to be, taking control of it.
Jeannette’s starting point, as I (too slowly) came to appreciate, was different. She saw species as objects untamed, sovereign, with their own agency and their own reality independent from the contemplation of any biologist. Our different inclinations stemmed not from an irresolvable conflict of worldview, but, I suspect, from the different acuities of our conceptual eyes. Jeannette is stronger than I am at grasping complex dynamic entities, and so it’s comfortable for her to see them more completely, in their wholeness. (I think her ability comes from the patience and attentiveness with which she integrates information.) I am good at conceptual reductionism, but that means I have to break things into pieces, and if I get the first cut wrong, I can get stuck. Well, as it turns out, I did get stuck.
The question we were asking was, what is a species? Biologists have given many different answers to this question, and there’s a reason for it. The world of species concepts is a shapeshifting nightmare, full of the ghosts of perceptions and possibilities. Species are genes and bodies tumbling through time, rivers of descent with trickles of mixing. The bodies have forms and actions and potentials and interactions. They live in a complex ecology. Their genes have a past, a present, and (many of them) a future. And, everything is changing, generation by generation, with feedback. It’s a labyrinth in 6 dimensions (more likely 1000, but let’s be shy and just say 6). It is riotous. It’s a wonder that there could possibly even be something “simple” inside the labyrinth that we might want to call a species. Biologists try to find a place to stand, and a direction to face, to view this “simple” thing. It’s like the blind men and the elephant. Each biologist finds a slightly different point of view and strains to interpret the 6 dimensions in a simple way. Whatever simplicity they see might as likely be an illusion imposed by their predefined focus as an aspect of reality. It’s a scary place. If it weren’t, species concepts would have been resolved long ago.
In the first few months of pondering together, Jeannette and I took some tiny steps forward toward a common view involving reproductive communities, feedback processes, and the chain of cause and effect from cohesive processes to genealogies to traits. We wrote a talk for Matt’s 2017 workshop, and gave it. In retrospect, the ideas we had then seem hopelessly incomplete.
For the next couple of years, I took the lead on the writing, partly because Jeannette was focused on other projects, partly because I had more practice in writing in a theoretical voice. As I wrote, I tried to expand the ideas Jeannette and I had developed for the workshop, tried to carry on with the threads from my gene tree paper, tried to remember things I’d thought about decades ago, tried to catch up on the literature. I was trying to see species as synchronic things, defined only in this moment, but at the same time thinking that rank had to be set by long term forecasting, while also remembering that in 1986 I was convinced that retrospection was the only viable approach (see Note at end). This brawl between the present, the future, and the past swirled in my mind. I sought a truce by writing, paragraphs and paragraphs, but I couldn’t resolve the battle. I worked on it only occasionally; I had other projects also.
Every so often, I thought that the pieces were almost coming together, that I could see an almost complete picture, that we had shone the light almost everywhere in the labyrinth. I knew there were still murky conceptual regions that I hadn’t faced. I hoped they were just small corners rather than whole rooms. But, whenever Jeannette and I would talk about the paper, I could tell that she had her own flashlight and was standing in a different room that I hadn’t explored, one of living lineages enduring through time. I couldn’t yet see what she saw, though.
If you’re thinking, “How hard can it be for two biologists to share their insights?”, then go read Kuhn about paradigms. Each of us inhabits our own worldview that constrains what we are able to see and hear. Not only did each of us not know quite what we wanted to say to the other, we struggled to hear the other as well. A collision of two worldviews, each half muddled, is as likely to yield all muddle as all clarity.
The difficulty of understanding other worldviews applies even within myself. Our eventual framework is so obvious to me now that it’s really hard for me to understand and describe what the Wayne of 3 or 4 years ago was thinking, how his conceptual landscape was structured. I recall it as poorly as a town I visited in a dream — I can’t relate its signposts to those I see now. Our paper is not a map drawn stroke by stroke. The lines changed and dissolved and reformed as paradigms shifted, as we sketched with two confused hands. Any narrative that used today’s eyes to describe the drawing of the map, and tried to tell a story of Jeannette and me adding lines one after another, would be false.
Rather than mislead you with a false tale of linearly accumulating ideas, I will tell you instead about how our collaboration unfolded to my eyes. Jeannette and I tried to compare notes occasionally, but it didn’t lead very far in the first few years. I muddled along with my flashlight as she muddled with hers. Our ideas simmered slowly, often separately, Jeannette’s in her readings and teaching and cogitation, mine in my readings and writings and sketching.
An important contributor to the paper has been our co-teaching the basic evolutionary biology course at UBC. Jeannette gives the lecture on species concepts. Each semester, she and the students would collaborate, they providing willing and curious ears, she finding anew the words to explain species to them. I was there to eavesdrop. Each semester I’d hear her lecture, and some of her thinking would find its way into my mind. I swear, I was taking more notes than the students.
Bit by bit, we made progress. Text that Jeannette wrote in early 2021 — a snippet is “if we choose to look carefully, species will reveal their natures” — clashed with my perspective then, but a year later that same text not only made sense to me but had become central to our developing theme. Jeannette’s vision was seeping into my resistant brain (and perhaps mine into hers), and my shattered image of species was starting to become whole. By the start of 2022 we had achieved a hazy version of the final plot. We might have published at that point, but we knew there were still unlit corners big enough to house logical demons ready to take all of our thinking back to zero. The map was still only 70% drawn.
By late in the summer of 2022, something in the simmering pot had jostled around the ideas and the courage. Jeannette found greater clarity in her vision of species and in how to express it. I, finally, was fully ready to hear her concept of species waiting to be seen. (Remember that I’m telling this story from my perspective. She may say the converse, that I found my voice and she found her ear.) A fundamental shift in my thinking had happened: I had been seeking what we call “closed” species concepts in our paper — those that specify criteria for species status that are necessary, sufficient, and invariant — but I needed to let go of that completeness and universality. I needed to allow for an open species concept, that only partly defines what species are, leaving the rest to nature. In just a few months, our integrated picture came in sharp focus. Light flooded the formerly-dark corners. Many of the auxiliary issues resolved. We found confidence. I must confess, I was a bit giddy with excitement.
To my surprise — actually, astonishment — we ended up not with detached pluralism, but a strong recommendation about the nature of general-purpose species in biology. But, it’s not a tightly-defined species concept. It is a statement of two necessary conditions of a general-purpose species concept (it must embed cohesive processes, and it must be retrospective). It leaves the rest to Nature and biology, and perhaps, to each clade, as different groups of organisms may have different ways to be species.
We don’t yet know how the biological community will respond to our paper, but for me it’s been a lovely journey. We were just climbing upward. We hadn’t expected to find ourselves suddenly at the top of a mountain, but we did. It feels like an answer, which I had never anticipated. I won’t try to argue for its novelty. It is just a step away from other published species concepts. It feels to me that biologists were already seeing it, some directly and some out of the corners of their eyes, and we just brushed away some fog, focussed attention on it, and articulated it.
I attribute our progress (for ourselves, if not for the field) to the two things I mentioned at the start, patience and courage. We had the patience (and opportunity) to let our ideas simmer slowly. Heat and cool ideas too quickly, and you get committed to the wrong choices, you get glass, brittle. Heat and cool them slowly, and you get crystals of great size and strength. (Materials scientists, please don’t complain that glass can be stronger than crystal. Just go with the poetry.) I believe deeply in the value of letting a conceptually-difficult project drift in and out of consciousness over many months, not rushing its growth. Perhaps I want to believe that only because of my introverted and cautious nature, but also, I’ve experienced remarkable success with simmering in the past (especially, with Mesquite). I recognize, though, that such patience is rarely possible in modern science.
Our courage was to work with someone who didn’t see things my/her way, and therefore had the most to teach me/her. That balance between the necessary and the as-yet-unknown, the momentary and the enduring, the dissected and the whole, the tamed abstract and the untamed reality, is the balance between my starting point and Jeannette’s. It would be wrong to say that I contributed the one half and she the other, because both of our respective conceptual universes extend to both sides, but she had greater strength on the one side, I on the other.
I feel as if I came to this project trying to paint a portrait of species with blue, violet and ultraviolet paints, and a bit of yellow for highlights. Cool, abstract, and prescriptive. It wasn’t working. I got stuck conceptually, unable to form a complete image. Jeannette brought a vision of a complex, integrated system, whole and dancing with life — a different set of paints, red, orange, and green. My colours were synthesized; hers belonged to nature. It wasn’t until we combined our colours that our palette was complete. We could finish the painting. Its new understanding could not have been achieved by either one of us alone. On this journey I have been (and I feel as if I have been) Jeannette’s student, and perhaps she has been mine, and that is what makes a good collaboration.
As much as we have learned from working together, I think that Jeannette and I will continue to lean in different directions. I find the cool abstract ideas more interpretable, but I think that Jeannette, with her greater patience and ability to see complexity on its own terms, not moving so quickly to dissect as I do, sees the living reality, the reds and oranges, as more real and visible, the blues and violets as oversimplified or even partially invented. The challenges we faced in this project were as much about navigating our own minds and biases, and becoming open to others, as they were about evolutionary theory or organisms. It’s made me better aware of my own bias, and I think that of much science, toward dissected and sterilized ideas. Jeannette’s paint colours are harder to work with, and harder to communicate, but because they touch the blood of reality, we need to pay more attention to them (and to Nature), not less.
The scientific process must be lit by the harsh glare of evidence and logic, but it must be accompanied by grace: an offering of open attention towards Nature. The reductionist programme would have us believe that all understanding comes from shattering into pieces and parameters. I might accept that ideas, as they mature, should resolve towards crisp logical abstractions, but we cannot forget that they are our brass rubbings, not nature’s original art. As nature is being explored, as possibilities are being conceived and tested, science must dare to look outward to the untamed, to look beyond our inner dialog, to listen rather than to speak. This is natural history. Science would be barren if it looked only inward to our mental constructs. It would be impoverished if it did not take advantage of the old and deep ability that humans have (some more than others) to grasp flow and collision, form and movement. By taking a stance of listening to nature, with patience and deference, one is put into a different mode of attention, open to surprises. What is heard while listening guides, or at least should guide, what path is chosen. Even after science finds and follows a path of shattering and quantification, our ears and eyes should remain always open, lest we succumb to the hubris of artificial certainty. Science is always both exploring and testing, back and forth, nature and ideas tumbling through time.
And so, we centred our species concept at the balance between abstraction and nature’s reality: our abstraction requires process and retrospection, but Nature retains control over the fullness of its living realization.
Although I’ve emphasized the differences in our approaches, I learned better over this journey how much they are alike. Jeannette and I share, by inclination, a common belief in both logic and listening. Even though I suggested I lean toward abstract dissection, and she toward attention to the whole, both of us have strength in and commitment to both. Jeannette’s logic is fierce. I have long listened to the spiders. Both of us have sought to find the edge between what to control and what to let go. That shared balance is what drove this paper.
What came together in this paper wasn’t just Jeannette’s worldview and mine. It was also two halves of me. For so much of my career, theoretical Wayne and the practicing taxonomist Wayne didn’t speak much to each other. The latter already lived in a worldview of lineages much like Jeannette’s, alive and breathing. That Wayne already saw and painted spider lineages in all the colours of light, but he didn’t have much of a voice, didn’t have much to say except in the language of spiders. In effect, Jeannette helped him find a broader voice, perhaps just as I might have helped Jeannette’s theoretical half strengthen her voice.
I feel lucky, not only to have had the luxury (yes, it is a privilege) to spend 7 years on a paper, but to have a collaborator who was also willing to spend that long, and who was willing to work with someone (me) who was (and is) still learning how to listen to untamed ideas and untamed Nature. To Jeannette: Thank you.
Note at end:
About retrospection, I’m referring to some verbal comments I made at a conference in a discussion session about behaviour and species, in 1986. My comments were included in the published transcript (cited as “Maddison in Vlijm, 1986”) in the proceedings volume. I don’t remember why I spoke up about species concepts, given that the discussion wasn’t supposed to be about species concepts, but in 1986 it wouldn’t have been surprising for the discussion to veer in that direction. Because the proceedings are not available electronically, and likely only (now elderly) attendees have them, I will give here the full text of my part of it. I correct two errors, “potentially” to “potential” and “vieuwing” to “viewing”, and add a comma.
Wayne Maddison remarks, with respect to the biological species concept vs. the phylogenetic species concept: “The biological species concept might be thought of as prospective or viewing the future, in that potential interbreeding might predict whether populations now separate might later recombine. Units so delimited might behave to some extent as evolutionary units, since they would be like ropes that become unbraided occasionally, yet would rebraid and so maintain a cohesiveness. While such units seem relevant to evolution, they may be inappropriate for use in testing theories about evolutionary processes. To test process theories we need to determine what has happened in evolution, and to do this we reconstruct changes by looking at how characters vary within and among units (species). This reconstruction of history would best proceed if our units reflected history, that is if they were phylogenetic (monophyletic) species. Dreams of the future will not help us; since all of our data are of the present and past, our units by which we interpret these data must also be strictly historical. That is, we need monophyletic species, which are not necessarily biological species. Of course, this argument may be irrelevant to the question of ethological vs morphological distinctions since we use ethological characters either to reconstruct phylogeny or as evidence for reproductive isolation and likewise for morphological characters.”
From: Vlijm L. 1986. Ethospecies. Behavioral patterns as an interspecific barrier. Actas X Congreso Internacional de Aracnologia 2:41-45.
I don’t know whether to be proud or embarrassed that my views have changed so little. The 1986 argument isn’t fully correct to my 2023 eyes — monophyly isn’t enough; we can test some process theories with data of the present; species serve for purposes beyond testing process theories — but it anticipates one of the core arguments in our paper.
Reflections on a Spider's Eyes 