The road not taken – for me, and for ecology

Everyone knows Robert Frost’s poem The Road Not Taken:

Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;

Then took the other, as just as fair,
And having perhaps the better claim
Because it was grassy and wanted wear,
Though as for that the passing there
Had worn them really about the same,

And both that morning equally lay
In leaves no step had trodden black.
Oh, I marked the first for another day!
Yet knowing how way leads on to way
I doubted if I should ever come back.

I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I,
I took the one less traveled by,
And that has made all the difference.

I thought of this poem a couple of times when reading this week’s issue of Nature.

The first time was for personal reasons, while reading a very nice profile of Bob Paine. The profile emphasizes that he’s been influential not just through his own work, but indirectly via all the very successful and influential ecologists who trace their “academic ancestry” back to him. This sort of thing is fun, if always a little arbitrary (most ecologists have more than one mentor during their careers, and so can be said to be “descended” from more than one person). Reading this reminded me that when I was first looking for graduate advisers, I really wanted to join the Paine “family tree”, either by joining his lab or the lab of his former student Bruce Menge. For various reasons, I went in a different direction in the end. But I’ve occasionally wondered what the road not taken would’ve been like. In some ways I might have ended up rather the same. Bob Paine, Bruce Menge, and Peter Morin (with whom I actually ended up doing my PhD) are all big believers in manipulative experiments for instance, so I’d probably still have ended up as an experimentalist myself. And they all encourage their students to develop their own projects, so I’m sure I’d have learned to think for myself no matter where I went. They’re alike in little ways too. For instance, like Bob, Peter never puts his name on student papers unless he really has made a sufficiently substantial contribution to have earned co-authorship. But on the other hand, they work in different systems and their interests and approaches differ in other ways too. I’d surely be doing different experiments and thinking for myself about different stuff had I joined the Paine or Menge labs. And while my own interests and approach have diverged from Peter’s in some ways over the years, presumably I’d have diverged from my supervisor in some different fashion had my supervisor been Bob Paine or Bruce Menge instead. Anyone else ever wonder about this? Wonder what would’ve happened if you’d chosen some other supervisor?

I also thought of the Frost poem because of the juxtaposition of the Paine profile with a piece by Drew Purves and colleagues. Brian isn’t the only one calling for ecologists to do more predictive modeling, and to take their cues from the data- and computationlly-intensive successes of fields like meteorology. In their piece, Purves et al. call for ecologists to develop “general ecosystem models” (GEMs; awesome acronym!). GEMs would be analogous to climate scientists’ general circulation models (GCMs). Purves et al. recognize that such models will be very challenging to develop, but argue that it’s feasible if we take the right modeling approach and get serious about collecting the right data. For instance, they suggest that GEMs, like GCMs, will need to be explicitly mechanistic and process-based, as opposed to purely statistical or phenomenological. They also suggest that, like GCMs, GEMs will need to aggregate or otherwise simplify a lot of underlying detail, such as lumping species into coarse trophic groups like “herbivores” and “carnivores”, and using body size allometries to estimate unmeasured parameter values. Purves et al. are speaking from experience–they’ve built a prototype GEM that produces promising results. And they rightly emphasize that if ecologists were to get serious about building GEMs, much of our data collection effort (both observational and experimental) would have to be redirected, towards obtaining whatever data are needed to reduce the most important uncertainties in the GEMs. So there’d still be place-based field research–but it would be whatever place-based field research was needed to support GEM development. I found the piece a very good and thought-provoking read from some ecologists who clearly are not hypocrites when it comes to forecasting the effects of climate change.

As I said, I found the juxtaposition of the profile of Paine with the Purves et al. piece striking, and it made me think of Frost’s poem. To the extent that ecologists ought to redirect their efforts to building, or supporting the building of, the sort of predictive models Purves et al. call for, they’ll need to direct their effort away from the sort of experiments that made Bob Paine and many of his students so influential. And indeed, the profile of Paine touches on this near the end, noting that some of his “descendants” have moved into the sort of science Purves et al. call for. Bruce Menge for instance has moved away from the sort of field experiments individual investigators can run and into large-scale, standardized data collection by big, coordinated teams. It’s the sort of data that one needs to parameterize GEMs–but also the sort of science that leaves little room for individual investigators to think and work independently. It’s very centrally-coordinated science. And while it’s science that undoubtedly raises some interesting fundamental, conceptual questions, it’s very policy-driven science. As his own “descendants” like Jane Lubchenco note, Bob Paine doesn’t have much use for “relevant” or centrally-coordinated research.

I don’t want to exaggerate here. I highly doubt that we’ll ever see a world in which literally every ecologist does the sort of work that Purves et al. call for and no one any longer does the sort of curiosity-driven, fundamental work that made Bob Paine famous, or vice-versa. But there clearly is a trade-off here, two roads diverging in a wood. And while some ecologists will always go down each road, the field as a whole–perhaps as indexed by the road more ecologists take–does seem like it may face a choice in the not-too-distant future.