By Joshua Van Laan

Psychology professor Dr. Jeffrey Wilson is a recognizable face around the halls of Olin. Known for his upbeat attitude and his fascination with earthworms, Dr. Wilson has become a staple of the third floor Psychology Department at Albion College. Recently, I was lucky enough to sit down with Dr. Wilson and ask him what it is that make earthworms so special.

The Pleiad:  How did your earthworm research start?

Wilson:  Well, that’s a good question. I did undergraduate work with rats,  and graduate school with rats and mostly cats. After grad school, I got my degree in 1983 for what, 25 or so years after I worked almost exclusively with rats. Rats are really expensive, for one thing. A single rat cost $30, and it takes a lot of animals to do any given study, so that’s an issue, and if I have students do a project with animals there’s a limit to how many projects we can run, given the cost. Rats are also heavily regulated, as are most vertebrates. It becomes too difficult to do research with vertebrates but that’s not insurmountable. It’s easy to overcome those problems. You just have to make sure you’re treating them ethically and properly.

But about four years ago, I felt like my rat research had hit a dead end. It wasn’t going to go anywhere else, and for reasons that still aren’t clear to me, I decided I would try earthworms. In part because the behavior is so constrained, there’s so little they can do, and yet they can do stuff. So, it might make it easier to try get at the neuroscience. It might make it easy to get at what’s going on in their nervous system that allows them to behave the way they do. So I changed my direction about four years ago, and it looks like it’s going to work.

So what have you found?

What I’ve been able to do is overcome some instrumentation problems. There is about a 100 year history of people working with earthworms doing behavioral studies with them and learning studies with them and looking at what’s going on in their nervous system. The problem with most of those behavioral studies is that people watch the animal and say, “Yes it moved far enough,” or “No it didn’t move,” and that’s fraught with issues of subjectivity and in science we like things to be objective, to be measurable, to be quantifiable, and if my behavioral measure I say, “Yes I think the worm moved far enough” and if I know what I’m hoping will happen there is all sorts of opportunity for bias. So there’s a long history of people doing earthworm research in which they observe the animals and determine if the particular animal made a response that way.

The other issue is that for a long time there was a history of the question of whether earthworms could learn that their responses have effects. People who study learning studies study two types of learning, classical conditioning which is like Pavlov’s dog learning that bell means food. It does learn to salivate to the bell, but the response is irrelevant. It’s learning to link two different stimuli. The other kind of learning is instrumental learning, which is,  for example, Skinner’s rat learns that pressing a lever produces food. And, in that case, you’re learning about a response.

A little over 100 years ago, there was research by a very famous comparative psychologist who showed that earthworms could learn instrumental learning. They could learn a very simple maze. If I go left, I get shocked. If I go right, I get to a nice, dark, mostly dirty place, so I like that. A lot of people replicated that work, and then it was discovered in the ‘70s that if you shock a worm, they spit out a chemical that they and other worms find repelling, so those worms probably weren’t learning at all. Once they got shocked, they stayed away from that chemical, and when people redid that study properly, making sure that chemical couldn’t have an effect, there was no evidence of learning. So from the 1970’s on, no one did that kind of  instrumental learning with earthworms. I decided to try that again, because I’m convinced they should be able to do that kind of learning, but I couldn’t use electric shock because I didn’t want the chemical to be an issue. And I also wanted an objective measure of their behavior. So I set up earthworm running wheels where it’s a slow process, but you put a worm in a wheel like a hamster in a wheel, if you design the wheel properly, the wheel will turn as the worm crawls and then you can monitor the worms position and get an objective measure of how much the animal moved. So we’re currently setting up a setting where we can look at and to avoid the issue of chemicals being omitted from the worm when it gets shocked we’re using bright light as the stimulant that worms don’t like. Worms don’t like bright light. That’s why, on a sunny day, you don’t see them out so well. They try to avoid bright light. So we have it set up where if a bright light is turned on and if the worm crawls far enough in the wheel, the light turns off. The worms can learn to do that. They also learned the opposite, if I crawl, a light comes on. And those worms learn not to crawl. So we’re showing worms can learn about their response. But we’re doing it in a way where there’s no chemical being spit out by the worm and there’s no observer bias, it’s all computerized, a computer watches the wheel, turns on the light turns off the light. So the main thing I’ve done to this point is demonstrate that despite the early problems with people thinking that worms can learn this instrumental learning and it being problematic with the chemical, worms can in fact learn instrumental learning and responses and I’ve also come up with this system of objectively measuring the behavior. Where we’ll go from there is looking at what’s going on in the nervous system during learning. So I’ll have students this summer depending on FURSCA funding looking at the roles of two different neurotransmitters in the worm’s nervous system and how those neurotransmitters play a role in learning and memory of these particular tasks.

What makes the worms’ nervous system unique?

I would argue that it’s not unique, that’s the reason I want to study it. Neurons are highly conserved throughout evolution; any animal that has a neuron has a neuron like a neuron in another animal. There are species differences but for the most part once evolution found out how to use neurons to communicate it’s a good idea they kept them. So when people study neurons or the nervous system in a very simple animal like an earthworm what seems to be true about that nervous system is also true about more complicated nervous systems like in mammals. A lot of knowledge in neuroscience has come from studies of relatively simple invertebrates and then when people figure out how to ask the same question in a more complicated nervous system they find out that it works the same way. So if we can study learning and memory in the relatively simple learning system of the earthworm and it is different from ours, there are far fewer neurons it’s arranged differently, it’s a different neurosystem, we can study learning and memory in that very simple nervous system and find out something interesting about how it’s happening it might suggest how learning and memory is happening in our more complicated system.

So it can apply to larger things?

That’s the hope. But to be honest learning how an earthworm learns is sort of cool too. Even if it has no application. But people like to know applications, it would be foolish of me to suggest that what happens in an earthworm isn’t going to happen in the rest of us. Earthworms can’t do as many things of course they’re limited to what they can do. But my guess is whatever mechanism is going on in their nervous system that allows them to learn is going to be a mechanism that’s similar that allows you to learn.

How long does the average earthworm live?

Well I can’t tell you for sure. There a lot of different kinds of earthworms, something like 1,600 different species, I don’t remember the exact number, I’d have to Google it to be sure but it’s a huge number. But typically, when you think of earthworms, you think of the big juicy night crawlers that you see after a rainstorm. And those are a species, people call them Canadian night crawlers typically, that’s one of the most commonly studied species, they can live on the order of 4 years, maybe longer. I’ve worked with those, I also work with smaller worms some people call them Red Wrigglers, they’re the kind that are used in compost bins. The advantages of those is that they can be maintained at room temperature so they’re really easy to keep in the lab. The problem with those though is that they’re much smaller than the big night crawlers, so when I do a running wheel for the little worm it’ harder to do the wheel because the worm can crawl all the way around the wheel and sometime it’s not heavy enough to actually turn the wheel. So I switched over last summer to the night crawlers because they’re bigger but they require refrigeration. I have a specially modified freezer where I house those animals. In both cases though I have one initial expense for the worms, and I still have worms. So I can maintain them in the lab, I know that my Red Wrigglers, the compost worms, were reproducing, I have an unlimited supply of those probably for the indefinite future. But I’m probably not going to work with them very much because they’re smaller. The larger Canadian night crawlers not convinced yet that they’re reproducing. I’m convinced I can maintain them in the lab I’ll have to count again this summer a year after I got them in to see how many I have, and see if there are more than I put in initially.

What else do you like to do?

I do photography, I’ve always done photography since high school days back in the days of film of course now I do digital like most people do. I have kids I enjoy playing with my kids and teaching my kids. Read but I mostly read nonfiction I rarely read fiction. Give me a lab and worms and I’m happy at least 8 hours a day.

So you’re pretty fond of worms then?

I’ve become fond of them. Here’s the little trivia knowledge that you want to throw in because you’re going to be amazed by this and your readers will be amazed by this. Every worm you see here in Michigan is an invasive species. No worms were left after glaciation. The Ice Age wiped out all the worms in North America, North of where the glaciers came in. So every worms you see is from European settlers. In plants, all the worms you see. You dig up earth out here you’re going to see worms they weren’t here before Europeans came over. One way people know that is they know how far down the glaciers went they know what species are south of the glaciers and they can calculate how far they move in a year and there hasn’t been enough time since the glaciers for those earthworms to have moved north. There are areas of north America and Canada where the ecosystem has seriously been disrupted by earthworms. We tend to think of them as good animals, but what they’re very good at doing is breaking down decaying leaves and decaying vegetables. There are forests in north America where there are a lot of plants that thrive on very slow decaying leaf litter then earthworms come in and eat up that leaf litters and those plants lost their ecosystem. So there’s parts of Canada that actively work to keep earthworms out. Who thought that earthworms weren’t native?

I’m happy my students get to work with worms. I was worried that when I got rid of rats students would say, “Oh I don’t want to work with worms, I want to work with fuzzy animals.” But it hasn’t been an issue there are plenty of students who want to work. I like it and I think it’s providing opportunities for my students. Also in the teaching lab it makes it easier for a student to do a project. When I worked with rats each student would propose an individual project and I would pick one or two that the class would do as a whole for time expenses and mostly for monetary issues we couldn’t afford every student to have 20 or so of these rats. It’s no an issue for a student to have 20 earthworms to study with. It allows us to do a lot more in a research setting and in the teaching laboratory that they wouldn’t be able to do otherwise.

How much are earthworms?

When I was buying the night crawlers I started maintain my own colony they were $3.50 for 18 and the last summer I bought a box of what was suppose to be 500 but there was 615 in the box, I counted. And that was $50.00 or something but I still have those worms and like I said I hope that they’re reproducing. The wrigglers I got, the compost worms, they were on the order of $50.00 for a thousand or 1,500 and they’re reproducing and I have them so the cost is negligible, and they eat garbage. I bring in my vegetable waste from home and feed them to the worm so there’s no expense associated with that. So it’s the year of sustainability I’m helping to sustain the campus and provide compost.

Photo courtesy of Dr. Jeffrey Wilson

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