Musings on reading older literature (UPDATED)

It’s common for senior ecologists to complain that ecologists these days don’t read the older literature enough. But of course, like many problems with kids these days, the “problem” may be one of perception rather than reality. I have no idea if ecologists these days read the older literature any more or less than they used to (anyone have data on that?) But I do have some thoughts on why one might want to read the older literature–or avoid it!

Probably the best and most common reason to read the older literature is that otherwise you can’t understand the current literature. Think of foundational papers for instance.

Here’s another clear-cut reason to read the older literature: you need to read all that’s known about some specific topic. Meg has a good post on this.

UPDATE: Can’t believe I forgot a third reason: some classic papers are so rich in insight that you can keep returning to them over and over. Meg has a good post on this.

But in other circumstances, it’s not so easy to decide what to read. Tradeoffs and opportunity costs are everywhere. Time spent reading old stuff is time not spent reading new stuff, or doing something else worthwhile. So you can’t just bemoan how nobody reads the older literature anymore unless you also say what everybody should be doing less of, so as to free up time to read more older literature. Especially if by “older literature” you mean “stuff that was new when I was a student.” 🙂

There’s a difference between reading older papers and evaluating them. It’s possible to have both too little and too much respect for older papers. Obviously, if you’re ignorant of the history of your field, you’re at serious risk of reinventing the wheel, or making a big mistake that someone who knew the older literature would never make. But less obviously, if you have too much respect for the older literature, you’ll be too quick to dismiss novel work that actually advances the field. For instance, zombie ideas persist in part because of reflexive citation of “classic” papers that have since been refuted or superseded. I think the way to square this circle is to read critically. So that familiarity with the older literature doesn’t shade over into excessive respect for the older literature. (You should read new papers critically too, of course)

Following on from the previous thought: novelty is a matter of degree. There’s a continuum from “that’s already been done” to “that’s totally novel”. At the former end are things like rediscovering known proofs of mathematical theorems. If you’re unaware a theorem’s already been proven, and so prove it again in the same way, you’ve wasted your time. At the latter end is stuff like Einstein’s work on relativity. But most new work falls in the mushy middle–building on, refining, extending, or revisiting older work. So that the newness of the new work becomes a contestable judgment call.

Part of what makes those judgment calls difficult is that it’s often very easy to read modern views back into older literature. As modern readers, we tend to notice, and be impressed by, old passages that sound modern. Even if the passage is a brief sketchy version of something that’s now much more fully worked out. And even if the apparent modernness of the passage represents a misreading on our part. Darwin’s Origin is a good example. It’s very easy to misread Darwin as having a correct, modern understanding of how isolation and divergent selection contribute to speciation. He didn’t (at least, I don’t think so–feel free to push back in the comments). And although we see Darwin as hugely original, remember that back in his own time some people accused him of being unoriginal. Claiming that the notion of natural selection was already in Blyth, or Wells, or Matthew, or Hutton. And that the notion of evolution was already in his grandfather Erasmus’ poetry, or Buffon, or the classical Greeks. Critics of Darwin’s originality were wrong. But that they existed at all is an illustration of how slippery a concept “novelty” is.

I now think one of my own papers is an example of excessive attention to, and respect for, older literature that has since been superseded. Fox and Olsen (2000 Oikos) takes as its starting point a somewhat famous but frankly rather strange theoretical paper of Robert MacArthur’s from 1955. It’s on the relationship between a food web’s “complexity” or “diversity” and its “stability”. As a grad student, I found the paper intriguing. I tried to figure out what exactly MacArthur (1955) meant and how it related to other things I’d read. Eventually, I thought I’d figured it out sufficiently well to have a testable hypothesis. But it’s not a method of hypothesis development that I’d choose again. My time would’ve been better spent focusing on more recent papers.

I’ve heard that in some scientific fields, there’s a culture of reading and citing older papers, and a collective sense of the field as a lengthy, ongoing conversation that you can’t join unless you’ve fully caught up on “earlier episodes”. This sort of culture has advantages and disadvantages (at least I’d think so; what I’m about to say is speculation on my part, informed by conversations with Brian and others). A culture of reading and citing older papers ensures that nobody reinvents the wheel. But it also risks closing the field off to worthwhile input from outsiders. Both input on the current topics of conversation, and input that would shift the conversation towards different topics. At its worst, you can imagine this kind of culture might deteriorate into navel-gazing and gatekeeping. (Note that I have no idea if any field actually is like this; I’m just raising possibilities). This sort of culture isn’t unique to scientific fields, and doesn’t arise solely from an appreciation for old scientific papers. There are bits of the blogosphere/twittersphere, including the scientific blogosphere/twittersphere, that have the feel of an ongoing private discussion among insiders. Those insiders sometimes react pretty harshly to any newbie who tries to join the conversation without first having spent an inordinate amount of time getting up to speed. I hope that the conversation at Dynamic Ecology is both an ongoing conversation that people will want to keep following and participating in, but also a conversation that newcomers feel free to join. Would welcome feedback on this.

Discussions of the value of reading older literature sometimes mix up the value of reading the older literature with the value of reading broadly. They’re orthogonal. Personally, I worry less about people not reading the older literature (though I do worry about that), and more about people not reading sufficiently broadly. I worry that in future, increasing use of filters like Google Scholar recommendations and social media won’t just cause people to read more narrowly, but will cause them to unconsciously redefine what I would consider narrow reading as broad reading.* I’d say you’re not really reading broadly unless you’re reading a fair bit of stuff that has nothing to do with anything you work on. Brad Anholt for instance once told me that he reads the introductions of every paper published in various leading ecology and evolution journals. It’s how he keeps up with current thinking in the field as a whole. That’s reading broadly. Even if you fall short of that ideal, I suggest reading outside your field in cognate fields dealing with conceptually-analogous problems. For instance, any community ecologist studying species coexistence should be at least passingly familiar with the population genetics literature on maintenance of genetic diversity. Not because of the possibility of eco-evolutionary dynamics, but just because “coexistence” is ultimately the same problem, whether it’s coexistence of species or coexistence of alleles.

So I dunno. Do we read enough older literature these days? Do we read broadly enough? You tell me. Looking forward to your comments.

*Note that my worry hasn’t come to pass yet. Judging by this poll, people currently use social media and other newfangled ways of finding papers to read as a supplement to, rather than replacement for, old school methods.