Current events (E.O. Wilson saying that scientists don’t need to be good at math) give me a great reason to introduce what might be my favorite scientific paper.
I have three reasons for choosing this paper to share with you. One minor reason is that, from one ant man for another more illustrious ant man, I’d like to be one of the few scientists to publicly say something nice about E.O. Wilson this week without any kind of caveat.
Second, the content of this paper, and the fact of its existence, frames Wilson’s message about science and math that dovetails with my recent writing on how to design a research program.
Last, since this paper was published it has been a source of inspiration to me as a scientist.
Without further ado, here’s the paper:
Wilson, E.O. 2005. Oribatid mite predation by small ants of the genus Pheidole. Insectes Sociaux 52: 263-265. There is a paywall – email me if you’d like a copy.
Here is the abstract of this three-pager in its entirety:
Using “cafeteria experiments” with forest soil and litter, I obtained evidence that at least some small Neotropical species of Pheidole prey on a wide array of slow-moving invertebrates, favoring those of approximately their own size. The most frequent prey were oribatid mites, a disproportion evidently due in part to the abundance of these organisms. The ants have no difficulty breaking through the calcified exoskeleton of the mites.
What is the deal with this, and why is it inspirational? Please humor me by reading on if I haven’t lost you already.
This paper was published in the year 2005. In 2003, after several decades of effort, Wilson had published a monumental revision of the most species-rich genus of ant, Pheidole. Any taxonomist can appreciate the sheer enormity of this effort that had Wilson’s attention over the years. Clearly, it’s a work of love. Most Pheidole are tiny in size. They’re charming little ants, if nondescript, and not really different from one another in obvious ways that could account for their richness.
Like most years, 2005 was a good year for Wilson. He wrote three PNAS papers, two with his long-time friend and colleague Bert Hölldobler. He also wrote a controversial paper in Social Research arguing that altruism doesn’t principally arise from kin selection, a precursor to Wilson’s now full-fledged group selection posture. He had a book chapter come out, oh, and also he published a big book introducing the concept of gene-culture coevolution. And then there was this little paper, one of my favorite papers ever, in Insectes Sociaux.
If you want to understand and measure the diversity of ants, the first place to start is to sample the leaf litter. A whole book has been written about how to do this, actually. That’s where the action is, in terms of functional and taxonomic diversity. Pretty much wherever you go on the entire planet, the most common thing that you’ll find in the litter is Pheidole. They’re cosmopolitan, if not sophisticated. If the importance of a taxon is measured by its diversity, abundance and distribution, then Pheidole are the most important ants. (I guess you could argue for carpenter ants, too. But why? They’re so boring.)
Wilson has argued time and time again that ants are really important, they rule the world, they have the same biomass as people, and all that stuff. So, since Pheidole are the ants that rule among the ants, then we’ve got to really have figured out these ants, right? After all, they’re easy to find, they show up at baits, they’re easy to work with.
So what can we, as the community of ant biologists, tell you about the natural history, life history and habits of these Pheidole that live in leaf litter? Here’s a quick list of features:
That’s only a slight underexaggeration. Okay, so, I can at least tell you what they eat.
No, I can’t.
Actually, I can. Why? Because E.O. goddamn Wilson, at 79 years of age, after reaching the pinnacle of his career twenty different times and receiving every honor you could invent, decided to do the little experiment to figure this out. He wrote it up as a sole authored paper in a specialized journal.
It turns out they love oribatid mites. Now you know.
(This is not insignificant, actually, for the field of chemical ecology. Two years after the Wilson paper, Ralph Saporito sorted out that mite alkaloids end up in ants, which end up in poison frogs as their chemical defenses. The frogs also eat the mites directly, too.)
Wilson had spent decades slowly churning on the revision of Pheidole. After spending all that time at the scope and in the museum sorting out the genus, he can’t be blamed for thinking, “what do we know about these ladies after all?” Instead of just wondering, he did the experiment. You gotta love that spirit.
It’s rare for a midcareer PI of a typical lab to do a little experiment of one’s own like this and take the time to write it up. And then there’s EO Wilson doing his own experiments, among a string of high-profile papers, books, gala appearances and being a reliable stand-up mentor to junior colleagues. This communicates an unabashed love for these ants, for discovery, for natural history, and for answering unanswered questions wherever they lead you. Wilson is the consummate tinkerer.
This paper is by no means an outlier. Studies like these pepper his CV, sandwiched with his major theories and findings. To me, these are the actual meat of the sandwich. (Or tofu or something. I don’t eat meat.) To those of us who study ants, that’s what makes Wilson a rockstar. He’d be super-awesome without any of the books and big theories formulated by collaborations with mathematicians. His productivity, keen sense of natural history, an eye for observation and an interest in discovering questions as well as answers has been a trademark of his ant-centered work. The man loves ants, and it shows.
When this paper had come out, I had been working on the ecology of litter-nesting ants in tropical rainforests for about ten years. There were many ideas that I was pursuing, and I’m proud of what I’ve done and excited about what lies ahead. This has been rewarding because so little is known about the biology of these animals, despite their abundance and diversity.
After ten years, if you had asked me, so what do they eat? I wouldn’t have been able to tell you. How many zoologists do you know who can’t tell you the diet of their study organism?
Isn’t that odd that I didn’t know what these ants eat? That nobody knew, at all? Hell yes, it’s odd. Wilson saw it was odd. And he did something about it. The publication of this paper was but a speck, if a speck at all, on the face of his career. For those of us who study litter ants, this was very important. Any one of us could have done it. But you know what? We didn’t, while Wilson did.
That’s what badass science looks like, in my book. And it doesn’t require partial differential equations.
Footnote: You might be wondering, by the way, how can you not know what they eat if you work with them all the time? The answer is, essentially, that these are really small ants. A massive colony fits in a microcentrifuge tube, and a smallish one can fit in a 2 cm piece of straw. You won’t see what’s between their mandibles in the wild, and can’t make out the refuse in nests, either.