Tool use and cognition, Part 2: Can water be a tool?

I promised that there would be actually spider monkey tales in here...


When I was studying the spider monkeys at Brookfield Zoo (summer 2007), Rita, the youngest of the group, did something really fascinating. She was trying to reach a food item (some kinda of leafy vegetable) that had fallen into the tapir's pool. So, using her spider monkey assets, she did what any spider would do: Anchor her tail to a support, and swing out to try to reach it. However, despite that long tail and long arms, and several swinging attempts, she could not reach out. Looking frustrated, she gave up. She sat there, gazing at the pool and the leaf for a couple minutes. And then, she got up, went to another spot closer to the leaf (that lacked supports for tail-anchoring). She was still to far to reach it, but she paddled the water, floating the leaf closer until she could pick it up and reach it.

Regardless of what to call it, this was a fascinating example of problem-solving. But, it got me thinking of whether manipulating water could be consider tool use. If water can be considered a detached object, it would meet the definition for tool use. But, given the weird and amorphous properties of water... I'm really not sure.

However, there's a couple studies that have specifically looked at water as a tool. In Raising the Level: Orangutans use Water as a Tool, Mendes, Hanus, and Call specifically investigate the use of water as a tool, and the orangs utilize water to float a peanut to the top of a tube. Similarly, in Rooks use Stones to Raise the Water Level to Reach a Floating Worm, Bird and Emery provide use inspiration from Aesop's fable "The Crow and the Pitcher," testing whether rooks can use stones to float a worm to the top of the container. The result is that rooks quickly figure out that they need to add stones to access the worm. You can watch these trials here, thanks to YouTube.

Based on these studies, it sounds like water does qualify as a tool. Furthermore, it really is a more impressive tool, since the animals need to understand water's properties. While the orang and rook studies involve using water to float and object to the top, it would be really interesting to see some studies that investigate the use of water to move an object horizontally closer, the way that Rita got the leaf. And perhaps we should being doing more of these cognitive studies with spider monkeys, so they can show off how smart they are :)

This is "Science" news?

The headlines (and the articles themselves) at LiveScience are so absurd some times, I have to wonder... If this is labelled as science news, no wonder so many Americans are skeptical of science.... at the fact that this can pass as science journalism is a testament to the fact that science education in our country is truly poor...

Mermaid Sightings Claimed in Israel

Facebook Can Insight Jealousy

High-fat Diets Make You Stupid and Lazy

Men Not Choosy in One-night Stands

Great student quote...

From one of my student papers, about an article by Barbara Smuts on male-female friendships in baboons...

"The article was very clear and not confusing, other than why someone would want to spend every day for 16 months watching baboons in Kenya."

Umm... my answer would probably be 1)because they are terrestrial and easy to see and follow and 2) because they're feces are WAY easier to collect. But I guess that doesn't apply to that study, considering that she wasn't collecting fecals, and probably wouldn't make any more sense to my student... I guess they just think that following monkeys around all day is weird... perhaps I need to remind students that watching monkeys is much like watching reality TV... only less cheesy and more scientifically important :)

Tool use and cognition, Part 1: Thumbs not required

In my Anth 200 class, I have my students read an article by Craig Stanford entitled "Got Culture." It's from his book Significant Others (2001) so after 8 years, obviously there's been a lot more research that's come out on culture and tool use among animals. But he brings up one question:

"If tool use and other cultural innovations can be so valuable to chimpanzees, why have they not arisen more widely among primates and other big-brained animals?" He later concludes, "So to be a cultural animal, it is not enough to be big-brained. You must have the anatomical prerequisites for tool cultures to develop. Even if these are in place, there is no guarantee that a species will generate a subsistence culture in the form of tools."

I would disagree. As I caution my students, since this article was written, a lot more reports of tool use have come about, in a variety of animals. Furthermore, a lot of them lack the anatomical prerequisites (dexterous fingers, grasping hands, opposable thumbs). Tool use has been observed in elephants (which do have a dexterous trunk, with finger-like appendages), crows (which use their beaks to hold tools), dolphins (who once again, use their "beaks"), and spider monkeys (who have a reduced thumb that is pretty much just a little stub).

So why don't we see tool use more often among other large-brained animals? I suspect that first, it has a lot to do with a) observation time, and b) what we're looking for. Chimpanzees are incredibly well-studied in the wild, as compared to a lot of other species. Furthermore, observations of tool use among orangutans, bonobos, and gorillas were not made until well-after long-term studies had been initiated. Thus, it might take a lot of time to catch these observations, particularly if it's rare behavior. Additionally, if you're not looking for and expecting tool use, you might miss it. In the first field study conducted on spider monkeys back in the 1930s, Carpenter (1935) observed that spider monkeys engaged in directed branch-dropping at observers. This does fulfill the classic definition later articulated by Beck (1980):

‘‘the external employment of an unattached environmental object to alter more efficiently the form, position, or condition of another object, another organism, or the user itself when the user holds or carries the tool during or just prior to use and is responsible for the proper and effective orientation of the tool."

However, this behavior has gone overlooked, and there's some debate whether it counts as tool use. The question is whether it is intentional and directed: personally, given my own experiences nearly being concussed by a branch dropped/thrown by a spider monkey (thanks to one of my field school students last summer, I was warned just in time), I suspect it is--but conclusively demonstrating intentionality and directedness is tough to do. Furthermore, there is even one paper in which an author argues that when capuchins branch-drop, it is directed and intentional, but when spider monkeys or howler monkeys do it, it's not. But clearly, that sounds like a very capuchin-centric double-standard. Furthermore, behaviors like fur-rubbing don't seem to even be included in reports of tool use, even though they also fit that definition (and once again, could be subject to debate).

I think this is because, if a chimpanzee does something with an unattached object, it's more likely to be accepted as tool use. If another animal uses it (especially if it's not an ape or capuchin), it's likely to be questioned--is that really tool use? or should it be classified as object use, or substrate manipulation? Is it really intentional and directed? Do they understand what they are doing? Does it count if they use a tool to modify an aspect of themselves, other individuals, or an "object" such as "water" or "vocalizations?" While all of these are important questions, it's important that we apply the same criteria to evaluating if a behavior meets the definition of tool use. And I think, if researchers studying animals were looking for, or at least considering, that certain behaviors may be tool use, or cultural traditions, they may be more likely to actually take note of them and document them as such. While we still need to be exploring whether the behavior is intentional and directed, and whether the animals understand the properties of what they are using, that doesn't mean we should discount such observations, or reclassify them under another definition (unless, of course, they don't meet the standard criteria).

Anyway, I will write more on this subject later on. But for now, here's a few links and references:

Orangutans use leaves as a tool to modify their vocalizations

Cultural transmission of tool use in bottlenose dolphins

And of course, our recent paper on tool use in spider monkeys . . . You can read the media interpretation here, or read the paper itself:

Lindshield, SL, Rodrigues, MA. 2009. Tool use in wild spider monkeys (Ateles geoffroyi). Primates 50(3): 269-272.

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