On an outing, a couple of companions mentioned that they were reading Beaver Land by Leila Philip. They remarked about several curious facts about beavers, including a claim I found dubious: that beavers could direct the trees they felled. That is, the beavers could decide then execute a plan that would make the tree fall in a direction they chose. Of course, to anyone who does this, as I do, that’s obviously crap.

Think about how beavers chew away at a tree—they chew away at tree until the top portion of the tree either falls over or is connected by a dull point of the connected fibers of the heartwood. These beavers aren’t directing the fall at all; they are merely taking what comes to them.

Along with this claim was that beavers have some sort of special hearing that allows them to hear the tree fibers cracking so they know when it’s going to fall, and they can escape safely. Anyone who has been in this situation knows that you don’t need special hearing, and you don’t even need to be particularly close. The fibers snapping is loud.

So, I went to look for the research, and I found the distressing article The Orientation of Beavers (Castor canadensis) when Cutting Trees (OHIO J SCI 103 (5):143-146, 2003).

This entry isn’t about beavers; it’s about the idea that you can have an idea of beaver behavior without ever looking at one, or putting forth a way to predict what would happen.

Again, science is the art of prediction. Can I observe the world, detect patterns, and make correct predictions? In this case, given a tree, can I predict to a high degree where a beaver will stand?

I suspect you can’t. I suspect the beaver stands wherever he was when he encountered the tree, and the direction of travel is much more predictive than anything else. I also expect that beavers don’t really have a plan; they act compulsively and randomly. But it’s up to someone else to prove through a mountain of evidence that that’s not true.

Beavers die

One of this group’s assertions was that beavers had a special power to avoid being hurt by trees. Of course, that’s stupid and false:

The idea that beavers can control the direction of a tree’s fall is now out of favor based on two types of observations: 1) many trees get caught in the foliage of other trees, and 2) falling trees sometimes kill beavers

But this statement is similarly stupid. That a tree gets caught up doesn’t mean that the beaver didn’t control the direction. In a dense forest, any direction is likely to cause a hang-up. And, that falling trees sometimes kill beavers doesn’t mean beavers didn’t control the direction. That can be “shit happens”, that there are stupid beavers (choosing a bad direction is still choosing), or nothing at all.

There’s nothing here that comes from actual observations of beavers, and as such, saying anything about how beavers orient themselves to the trees is just the bunk.

The elephant and the three blind men

In the parable of the three blind men and the elephant, three different people feel different, select parts of an elephant then tell others what an elephant looks like, having never touched all of an elephant. And, as the parable’s situation forces, having never seen an elephant.

So, let’s suppose that we want to discover if beavers employ a plan and execute it with skill to repeatedly and consistently succeed. What’s the first thing we’d want to do?

If I were designing this experiment, I’d want a bunch of graduate students, volunteers, and field workers to observe beavers and record what they do. I’d interview as many people as I could about beaver behavior. If I could, I’d ask beavers what they are up to.

This paper goes in a different direction. It ignores the beavers and looks at the tree stumps.

Wait, what? How is a tree stump going to tell them anything? Here’s the glaring red flag that shows that the authors not only don’t know anything about beavers, they don’t know anything about trees.

Directional felling

In the world of forestry, “directional” felling refers specifically to making the tree lay over in a direction against its prevailing forces. For example, suppose the tree in front of me leans to the left. Can I fall it to the right instead?

To accomplish that, you can’t do what beavers do: chew away the tree until the remaining fibers fail. Most forestry directional felling is going to maintain some of the tree’s fibers and use those fibers to constrain the tree from falling in the disfavored directions. This is the “hinge”, and typically it’s about 80% of the diameter of the tree and slightly in front of the center of the tree.

Even during the fall, the hinge is intact until the face-cut aspects meet, stopping the free fall of the tree and causing the momentum of the falling weight to rip the hinge apart. This typically happens when the angle of the bole (the main part of the tree) is around 45 degrees to 30 degrees to the ground, in which case the direction of fall is a fait accompli. Indeed, in some falls, these fibers never completely fail because the tree’s branches hold the bole off the ground.

But, I don’t think the people involved in this paper have ever had to cut down a tree, or at least one large enough they might lose their life if they did it incorrectly.

The stump is not the tree.

Earlier, I wrote about indirect measures and that most science is not actually a serious attempt to add to human knowledge. That is the case here as well. There is nothing in this paper that increases our understanding of beavers. We already know the paper did not observe any beavers. They also didn’t observe any trees that were still standing.

Instead, their indirect measure was the disconnected stump left over and the orientation of surrounding trees. From that, and only that, they try to work backward to what the beaver was thinking and what the beaver did. They use a plumb line to measure the angle of the trunk compared to straight up, and assume that they know something based on that. If you’ve ever worked in a forest, you know this is complete bullshit. Trees do all sorts of crazy things, and knowing what the stump looks like doesn’t tell you about the bole. The angle at knee height is useless. But it is something that you can measure.

Consider, for example, how the weight is distributed in the canopy. A tree leaning to the right might have its center of gravity to the left because there are more or heavier branches on the left. These things matter, but aren’t part of the data.

One of the curious things about this paper is that they don’t mention the tree type. But why would you if a tree is just a tree? Some trees, like birch, are thin and tall without branching, so canopy asymmetry doesn’t matter as much as it does with a pine. The Ohio Department of Natural Resources says the forest is a mix of beech and maple.

With all of this, the paper lacks any science (predictive power) and any investigation of the beaver’s intent. If all the trees are leaning toward that marshland or pond, the beavers might not have any agency at all in the direction that the tree falls.

But there’s this nonsense:

Far from the shore, the trees tend to be fairly symmetrical and vertical (Loehle 1986). Thus, trees should fall in the direction from which they are cut.

This is stupid beyond belief; it’s unsupported, has no observational evidence, and is a completely broken syllogism.

It is there only to lead to the next statement:

Therefore, beavers trying to control the direction trees fall should cut from the side nearest the water to minimize the distance the trunk or branches need to be dragged.

How they could have done

They could have recorded beavers chewing on trees and watching them fall. They wouldn’t have to measure 452 stumps, make large unsupported logical leaps,

But the acknowledgements give it away:

This research was funded by the Howard Hughes Medical Institute Undergraduate Biological Sciences Education Program grant to Ohio Wesleyan University.

This is a vanity project to keep students, who are short-term workers, busy. They didn’t care to get to the truth; they cared about a short-term project that could satisfy a grant and be completed by temporary workers.