Reconnect With Nature Blog

Sophisticated Tool Use In Brazilian Monkeys

Note from Con Slobodchikoff: This is a guest post by Randall Johnson, who has contributed a numer of posts to this blog and to the Dog Behavior Blog.

In a forest reserve in the savannah-like "Cerrado" biome of Central Brazil, an amazing display of planning, learning, and sophisticated tool use has been documented in a species of New World monkeys. Wild capuchin monkeys (Cebus libidinosus)— a species familiar to many as organ grinders—move along the ground, methodically tapping palm nuts that are produced at ground level to see if they are ripe. Those that pass the test are carried up into trees, where their outer cases are removed and the exposed nuts are dropped on the ground for two or three days to dry.

Then, the aged palm nuts are collected and carried to a separate nut-cracking area. There, the monkeys climb up on top of flat rocks or boulders and, using large stones they have previously selected, they start pounding the hard-shelled nuts, with the stones being used as a hammer and the boulder as an anvil.  After a few whacks, the shells are broken and the monkeys extract the kernels.

The entire process involves several days of testing, harvesting, transporting, and hammering and appears to be a planned activity—a part of the monkeys' culture—that takes place year-round.

This discovery, first reported in The American Journal of Primatology (December 2004) by a multinational research team led by Dorothy Fragaszy, a psychologist with the University of Georgia, is remarkable in that, up to that time, routine tool use in wild primates had been routinely ascribed only to chimpanzees and orangutans and, although there had been anecdotal reports of tool-using capuchins dating back to the sixteenth century, this was the first time such behavior had been scientifically documented.

Furthermore, although the stone hammers had not been fashioned in any way, their use to open encapsulated nuts is recognized as being a complex form of tool use. A number of factors (i.e., material, resistance, friability, shape, and weight) affect an object's suitability to open a hard-shelled nut, with weight being one of the most important. The heavier the object, the fewer strikes are required to crack open a nut.

Fragaszy and her colleagues originally estimated that the stone hammers weighed 16 ounces, but in a subsequent trip, they were found to weigh over two pounds. Given that adult capuchins weigh between 6-8 pounds, they were selecting—and lifting—stones a third and sometime half their own body weight.

The effective use of hammer and anvil is seen only in adults. Although juvenile capuchins are interested in the activity and often play with the procedure, they are not effective at it. It takes years of practice—and maturation—to become effective at cracking open palm nuts with the properly chosen stone.

If you would like to see a video of this extraordinary behavior, go to: http://www.youtube.com/watch?v=-G60UCeXFp0&feature=player_embedded. It's an excerpt from a BBC documentary entitled "Clever Monkey", narrated by Sir David Attenborough. In his closing remark, note his reference to these monkeys as being another intelligent species on Earth.

And if you would like to meet other animals that are known to use tools in the wild, go to: http://www.mnn.com/earth-matters/wilderness-resources/photos/15-remarkable-animals-that-use-tools/handymen

Desert Ants That Count

Note from Con Slobodchikoff: This is a post by guest author Randall Johnson, who has contributed a number of posts to this blog and to the Dog Behavior Blog.

Given that RWNB ended 2009 with a post about ants, it seemed fitting to start the New Year with another post featuring these fascinating insects.

A study done by German scientists, led by Harald Wolf, professor of neurobiology at the University of Ulm, suggests that desert-dwelling ants may have "pedometer-like" cells in their brains that enable them to count their steps and that they use this unique navigational skill to find their way back to the nest after foraging for food.

But why desert ants? Because most ants live in places that allow them to lay a scent trail on the ground that show other ants how to get to food and back home.  Scent trails, however, don't work in the desert; the constantly shifting sand scatters smells almost immediately.

So how do these ants find their way back to their nest with such unerring accuracy? It's already known that ants can use the position of the sun and the pattern of polarized light as a kind of 'celestial compass', but that doesn't explain how they determine distances with such precision.

To try to unravel this mystery, Wolf and his assistant, Matthias Whittlinger, trained two groups of Sahara desert ants to find a food site 10 meters from their nest. While the ants were busy eating, the scientists removed them and divided into three groups.

One group was left alone. The second group had pre-cut pig bristles superglued to each of their six legs, effectively giving them stilts. Ants in the third group had their lower leg segments cut off, thus making each leg shorter. (This part of the experience has since drawn some criticism. It should be noted, though, that in the wild, these segments often dry up and break off naturally without interfering with the ants' ability to walk long distances.)

The ants were then released to make their way back to the nest. The scientists watched to see what would happen. If there really was a step-counting mechanism at work, then the ants whose strides had been altered would have their calculations thrown off.

And that’s exactly what happened.  The normal ants walked right up to the nest and went inside. The stilt-leg ants, using giant steps, walked past the entrance and stopped 15 meters away. The stump-legged ants, using baby steps, stopped short of the entrance by almost 5 meters. Yet, all three groups had walked exactly the same number of steps back from the food site.

Interestingly, when the ants went out again in search of food, the two groups with altered gaits had no trouble judging the correct distance back to the nest.

Of course, this doesn't mean Sahara ants are actually counting their steps as "one, two, three, four, five," and so forth, the way we would. More likely, Wolfe explains, there is a neural mechanism at work that converts the motor excitation caused by each stride into a measure of distance.

Still, it's an ingenious solution to not being able to lay scent trails and it shows there is still much to be learned from even the humblest of creatures.

The Compassionate Ant

Note from Con Slobodchikoff: This is a post by guest author Randall Johnson, who has contributed a number of posts and comments to this blog.

I remember growing up hearing and reading about the proverbial wisdom of ants. If you check the Old Testament, Proverbs 6:6-8 tell us: “Go to the ant, O sluggard; consider her ways, and be wise. Without having any chief, officer, or ruler, she prepares her bread in summer and gathers her food in harvest.”

And let’s not forget Aesop’s fable, “The Ant and Grasshopper”, which depicted the ant as a forward-thinking planner that gathered food in preparation for the coming winter while the grasshopper danced and played his fiddle, seemingly oblivious to future. This fable was, and still is, used to teach the virtues of hard work and saving and the perils of improvidence.

In the realm of ethology, ants have long been known for their complex cooperative behavior, including simple forms of rescue behavior, i.e., sand digging, which date back to 1874. [Belt T (1874) the Naturalist in Nicaragua. London: Murray].

Now, a new study, Nowbahari E, Scohier A, Durand J-L, Hollis KL (2009) Ants, Cataglyphis cursor, Use Precisely Directed Rescue Behavior to Free Entrapped Relatives. PLoS ONE 4(8): e6573. doi:10.1371/journal.pone.0006573, shows just how sophisticated this kind of behavior is.

In a total of 54 tests, the authors experimentally mimicked a natural situation involving an ant restrained by collapsing sand and debris. Hidden underneath the sand was a nylon snare that held the ant in place. If the captive ant was from a different colony or of a different species, the rescue ants ignored it. However, if the captive was a nestmate, the rescuers responded by excavating the sand, exposing the nylon thread, carrying sand away from the snare, and then biting at the snare itself.

These experiments demonstrated that the rescuers were somehow able to recognize what has holding their nestmate in place and direct approach behavior toward that specific object. This shows that rescue behavior is “far more exact, sophisticated, and complexly organized than previously observed,” unlike simpler actions such as digging and limb pulling, which could be triggered by a chemical distress signal.

The tests further showed that rescue behavior is directed exclusively toward a nestmate and it depends on an actively produced eliciting stimulus, most likely a pheromone that contains a component that is unique to each colony. However, pheromones alone don’t explain how the rescuers were able to find the precise location of the nylon thread and target their bites to the thread itself.

The authors distinguish rescue behavior from other types of cooperative acts in that the rescuing ants risk being trapped under the falling sand and there is no reward for the rescuers other than the benefits of kinship relationship.

Obviously, the ‘wise’ ant holds onto more secrets and surprises that might inspire new proverbs and fables.

Note: The PLoS ONE article includes two videos of these experiments.

RECONNECTING WITH NATURE…THROUGH AESOP’S FABLES?

This is a post from Guest Author Randall Johnson, who has contributed a number of guest posts and comments to this blog.

Reconnecting with nature may take some unexpected twists and turns along the way, but who would have thought Aesop’s Fables would turn out to one of them? That’s right. The ancient Greek story-teller credited with collecting such timeless fables as “The Tortoise and the Hare” and “The Boy Who Cried Wolf”, each with a moral lesson at the end, may also have been a keen observer of bird behavior.

In “The Crow and the Pitcher”, a thirsty crow comes across a pitcher with water at the bottom, beyond the reach of its beak. After failing to push the pitcher over, the crow drops in pebbles, one by one, until the water rises to the top, allowing the bird to drink. (The moral of the story: Necessity is the mother of invention.)

Well, it turns out that this is more than just an old fable. Researchers Christopher Bird of the University of Cambridge and Nathan Emery of Queen Mary University of London have reported in the current issue of Current Biology that rooks, another corvid and a relative of the crow, are able to use stones to raise the level of water in a plastic container to reach a floating worm.

Bird and Emery experimented on four rooks by presenting them with a clear tube partly filled with water and a worm floating on top, and a nearby pile of stones of varying sizes. The birds spontaneously dropped stones into the water and seemed to estimate how many stones would be needed. They also quickly learned bigger stones worked better than smaller ones.

Although some species of crows have been proven to use tools in the wild, rooks do not. They don’t have to as they have easy access to food, like carrion. But in an experimental situation like this one, they easily figured out how to use the stones to reach the worm.

Says Mr. Bird, “It was a remarkable combination of some understanding of the task with really rapid learning.”  In the summary of their published paper, Bird and Emery state, “This behavior demonstrates a flexible ability to use tools, a finding with implications for the evolution of tool use and cognition in animals.”

The more we take time to watch animals, the better we see how much we share in common with them, including brain power, and how this common thread firmly and solidly connects us to the natural world that supports us all.

Now, I seem to recall Aesop also told a story about the goose that laid golden eggs. Well, if such a fabled fowl should also exist and find its way to my door, that’s one story you won’t read about in Current Biology. I’ll keep that one all to myself.

As Below, So Above

For several days now, as I have been taking my dog for a walk around a pond at the local state park, I have been assaulted by a deer fly (family Tabanidae). The fly always starts buzzing me in the same 30 meter (100 feet) stretch of path, where the acacia trees provide some shade and the winds blow gentle puffs of air.

The fly seems to have a very circumscribed territory. Once I get out of that 30 meter stretch, he breaks off his attack and disappears, only to reappear during my next circuit on that path.

I try to put myself into the world of this fly. I am guessing that his world is encompassed in a plot of land that has a diameter of 30 meters. This is all that he knows. This is all that he sees. At random unpredictable times, potential meals move into range, triggering a hunger response. Outside that range, potential meals vanish, as if they never existed.

With my superior vision, I can see the whole pond, and I can think that it is very quaint that the fly cannot realize that simply going outside his 30 meters would give him more potential meals. He is limited by his perception, in ways that I am not.

But then I think, how much are we humans limited by our perception? Many years ago, I met a farmer who had not traveled more than 20 kilometers (12 miles) from where he had been born 70 years previously. Now many of us travel around the globe fairly effortlessly, and we can use electronic means of perception to see what is happening anywhere in the world.

But our solar system is huge, our galaxy is larger, and our universe is larger still. We can’t see anything of what is happening there, with a few paltry exceptions of Hubbell telescopes and rockets sent to other planets.

Like the fly, our world is circumscribed. We can see much more than the fly, but in the larger scheme of things, our perception does not extend out much more than his, in terms of cosmic distance.

To paraphrase a Hermetic saying, “As below, so above.”  We and the fly have much in common. We both can only see a very small portion of reality. And as we delve into quantum physics, we are not very sure what really is reality. Perhaps there are intelligences greater than ours who think that it is very quaint that we cannot realize that by simply going beyond the limits of our current perception we can see a greater reality. Or perhaps not.

I don’t know if the fly worries about such questions. Current scientific thought would suggest that he is not capable of such thoughts.  And perhaps we too are not capable of thoughts that would transcend our reality, allowing us to see a larger world.

So what to do? In my case, I am simply going to enjoy my moment in Nature, and even though the fly wants to suck my blood, I am going to enjoy his buzzing, even as I wait for my steps to take me out of his range.

A Conversation On Anecdotal Evidence

This is an email conversation between Randall Johnson and Con Slobodchikoff on the value of anecdotal evidence in biology.

Randall Johnson:
I've submitted a new Dog Behavior Blog comment (http://www/dogbehaviorblog.com) in response to your latest entry, "A Dog's Concern for a Cat". Focus: anecdotal evidence as a useful source of information.

Comment on Dog Behavior Blog: This incident joins a long list of other reported observations that clearly show that dogs are capable of feelings we associate with empathy and sympathy and that they extend these feelings toward other species.  If we had only a handful of stories like this one, then we could say this is anecdotal evidence, but when there are hundreds of stories reporting similar behavior, we no longer have anecdotal evidence, but rather a solid body of observational evidence. Since the human environment is the dog’s natural habitat, then these reports can also be considered as field observations, which is a respected source of data-gathering. I don’t know if anyone has decided how many anecdotes it takes to cross over to the realm of observational field data, but if this hasn’t been done yet, it’s high time some kind of marker was devised. And, in defense of anecdotal evidence, Hungarian ethologist Vilmos Csányi of the Eötvös Loránd University, who has devoted more than a decade to investigating dogs’ cognitive abilities, has used anecdotes on many occasions to inspire more formal experimental investigations.

Con Slobodchikoff:
Thank you for your insightful comment, which I published on the dog behavior blog.  As you know, "anecdotal evidence" can sometimes be used as a convenient way to sweep inconvenient evidence under the proverbial rug. There surely has to be some kind of standard for how much anecdotal evidence constitutes proof, but I don't know of any standards. However, if you go back to the papers in biology journals of 60-70 years ago, much of what was presented there was in the form of anecdotal evidence. Where would science be today if we discounted such evidence?

Randall Johnson:
While writing my comment, I was pretty sure there was no standard for anecdotal evidence. You raised a good point about this kind of evidence having played an honorable role in science in the past.
Somewhere along the way, it was stripped of some of its original credibility and we need to get it back or devise some clear guidelines for its use as a source of evidence.

I am submitting a brief comment in response to the "Are We Unique?" essay on the Reconnect With Nature blog. (I'm surprised this one hasn't generated more responses.)

Con Slobodchikoff:
First, thanks for your comment on Are We Unique. As usual, a great comment! I have posted it, and I hope that it raises some discussion or at least some thoughts on the part of the readers.

For the anecdotal evidence part, it seems to me that biologists have bought into the idea that experimentation is the only way to obtain valid biological data. This is fine for lab studies, but experiments are often difficult to do in nature, under field conditions, and a lot of the time we are left with observations that cannot be quantified or even repeated. In my mind, this does not make them any the less valid. I think we need to come back to a point where a certain quantity of similar observations is accepted as proof of the validity of a particular behavior or biological circumstance.

Randall Johnson:
My question, at the beginning of this discussion, was: At what point does an observed behavior stop being treated as anecdotal evidence and be recognized as observational data? Most definitions I’ve looked at stated that anecdotal evidence is limited to one or a small number of cases, but no one, so far, has said, “Well, if you have 10 cases of “X” behavior, it’s anecdotal, but if you have 11 cases, it’s observational data.” Maybe it’s not all that important, but considering science strives for precision, there’s a big fuzzy area here that’s calling out for better definition.

However, the larger issue is still related to the credibility of anecdotal evidence. In the late 19th century, it fell under some heavy criticism, largely because George Romanes, Charles Darwin’s protégé and an eminent biologist in his own right, relied heavily on anecdotal methodology to develop his theory of comparative psychology and, to this day, there still seems to be a lingering ‘cloud of doubt’ hanging over it.

Then, the other day, I came across a news item from 2005 on the Science Week web site that I found particularly insightful. In discussing numbers and counting in chimpanzees, the writer pointed out that one problem with investigating non-human primates is that experiments can’t be done on large populations because such populations either don’t exist or are prohibitively expensive to maintain. The result is that reported experiments are often "anecdotal", i.e., experiments involving only a few or even a single animal subject. The writer then stated: “But anecdotal evidence can often be of great significance and have startling implications: a report, even in a single animal, of important abstract abilities, numeric or conceptual, is worthy of attention, if only because it may destroy old myths and point to new directions in methodology.”

The debate continues. Although I’m not a gambling man myself, I’m willing to bet that, in the end, anecdotal evidence will regain its former luster and that the academic / scientific community will universally recognize it as a valid—and valuable—source of data. Let’s face it. There are still lots of old myths out waiting to be slain.

Con Slobodchikoff:
Yes, it is true that many experiments cannot be done on multiple animals because of the cost or the lack of animals. I was talking just the other day to someone about Alex, the parrot (see earlier post: A Tribute To Washoe And Alex), and the person I was talking to pointed out that we can’t generalize from only one parrot to say that parrots might have language-like abilities or the cognitive skills to count and identify colors and shapes: Alex might have been a genius among parrots, a feathered Einstein. That might very well be true, and Irene Pepperberg is doing careful experiments with other parrots to test for this possibility. However, Pepperberg’s extensive experiments with Alex show that not all parrots are incapable of complex cognitive skills.

Unlike Pepperberg’s work with Alex, many observations cannot be repeated on command. Does that invalidate them? I guess it depends on the credibility of the observer and the relative novelty of the observation.  If I say that I saw my dog burying a bone in my back yard, no one would question this anecdotal observation. However, if I say that I saw my dog surfing the internet on my computer, lots of people would probably discount that as pure fantasy, because it does not fit the current dogma of what dogs are capable of doing and no one else has reported this (and no, my dog does not surf the internet).

But we have to be careful about discarding observations that do not fit our preconceived notions. If an observation comes from a credible source and can be documented, then that observation can have the seeds of changing our thinking about the world around us.

As William James once said, you need only one white crow to disprove the assertion that all crows are black.

A New View of Dog Domestication: Human-Canid Co-evolution

Note from Con Slobodchikoff: This post is written by guest commentator Randall Johnson.  Once involved in river dolphin research and preservation, Randall Johnson lives in the Brazilian state of Minas Gerais, where he works as a Portuguese-English translator. His household includes three dogs, two of which were adopted off the streets, and he's active in a local group that rescues stray dogs and works to find them good homes. For another post by Randall Johnson on a difference between wolves and dogs, see the Dog Behavior Blog at http://www.dogbehaviorblog.com

     For millions of people around the world, their dogs provide not only an important source of companionship, but also offer a daily way of reconnecting with nature, if for no other reason than they force us to get off our backsides and take them outside for a walk. The intense bond between humans and dogs is an old one, perhaps going back as far as 135,000 years, and we may well ask how it all got started.

     Although a number of theories have been advanced, Austrian ethologist Wolfgang Schleidt, a disciple of Konrad Lorenz, offers an elegant view that emphasizes companionship and cooperation over human domination (see Schleidt, W.M.and Shalter, M.D. Co-evolution of humans and canid: An alternative view of dog domestication: HOMO HOMINI LUPUS? Evolution and Cognition 9(1) 57-72, 2003.). Instead of perpetuating the traditional view that dogs are the products of our ancestors’ ingenuity, Schleidt proposes that the initial contact between humans and gray wolves—from which dogs descended—was mutual and that the impact of the wolves’ social ethics on our own may equal or surpass our impact on their having become dogs. He sees the various changes that occurred both in humans and wolves as a process of co-evolution.

     One of the most intriguing aspects of Schleidt’s scenario is that wolves had a powerful influence on the social ethics of the early human groups through a kind of ‘lupification’ of human behavior or, to put it another way, the ‘humanization of the ape’. Wolves, as pack animals, survive by cooperation and teamwork. They hunt together, raise pups together, share food, and share risks. On the other hand, the social life of chimpanzees, our closest biological relative, is opportunistic, almost Machiavellian in nature, with chimps looking out for ways to get the better of each other. If we look for the biological roots of those traits we value as being especially humane, like group loyalty and cooperation for the common good, we don’t find them in apes. Instead, we find them in the social canids, like the gray wolf.

     At some point after humankind separated from a chimpanzee-like ancestor around six million years ago and spread across Eurasia and into North America, the sociality of human groups stopped completely resembling the primate model and began reflecting elements of the canid model. Based on new paleontologic, biogeographic, and genetic evidence, Schleidt suggests that this shift coincided with the time humans came into close contact with wolves after moving into their domain. Wolves were not only top predators, but also nature’s first ‘pastoralists’, living off of vast, migrating herds of ungulates, e.g., reindeer and bison. During the last Ice Age, these human groups learned how to co-exist with wolves, adopting their pastoralist lifestyle and even some of their pack behavior (learning to cooperate as a group, share risks, extending relationships beyond immediate kinship, etc.). This was also the period during which early humans (i.e. Neanderthals) gave way to modern humans and dogs began separating from wolves.

     Of course, this is an extremely simplified version of one facet of a richly-detailed theory. For those who want to see the ‘big picture’, I urge them to visit the following site and read the full article: www.uwsp.edu/psych/s/275/science/coevolution03.pdf.

--Randall Johnson

Animal Language Institute

This week marks the opening of the online Animal Language Institute.

The Animal Language Institute (ALI) is a website designed to promote interest in animal communication research, especially where it touches upon the cognitive capabilities of animals. With the Internet extending past barriers of geography, politics, and economics, the Animal Language Institute is an ideal way to bring together researchers, students, and curious laypeople from around the world to share ideas and information that will deepen our understanding about the communication systems of other species.

The Animal Language Institute website hopes to be the most extensive and easily accessible repository of information about research into the communication and cognitive abilities of various species of animals. Towards this end, ALI is amassing a core collection of outstanding scientific papers, that will be available to any registered visitor.

The Institute website currently has four major sections: 1) A database of papers published on animal communication; 2) A listing of people who are doing important work in the field; 3) Equipment and software reviews; 4) Interactive tutorials.

ALI will maintain open access to the webpages of the Animal Language Institute for the next month, so that anyone can access any page without registering. After that, ALI will ask people to register in order to access some parts of the website. Registration is free, and can be done at any time. ALI is asking people to register so that it can keep track of how many people are using the resources of the site.

ALI’s website is: http://www.animallanguageinstitute.org. Its mission statement is expressed in detail on its home page, and all doors to other sections are currently open. Go to the website, wander around the pages, and see what you think. If you like what you see, go ahead and register so that you can continue to get access to the site.

A Tribute To Washoe And Alex

They were pioneers, and they died within a few weeks of each other. Like all pioneers, they pointed the way to new discoveries and new ways of thinking. And like all pioneers, they bore the brunt of skepticism from the naysayers, the folks who do not want our vision of the world to change.

They did not ask to be pioneers. That job was thrust on them by others. But during their lives, they showed the world a different view, a different perspective, a different reality from the comfortable one that has lasted for thousands of years.

They were Washoe the chimpanzee and Alex the parrot.

Washoe showed that a chimpanzee can learn a number of signs in American Sign Language and use those signs to communicate with people.  Not only that, but she showed that she could teach these signs to other chimps, and could communicate with other chimps, using the signs.

Alex showed that he could tell the differences between shapes and colors, and could use perfectly-enunciated words to communicate these differences to the people around him.

Washoe and Alex were both taught by careful scientists who went to great lengths to remove subjectivity from their analyses. But neither Washoe nor Alex was merely a “lab subject,” taken out just for experiments but otherwise ignored. The people around them cared deeply about their welfare.

As pioneers, both Washoe and Alex showed that animals have the cognitive capacity to use language in meaningful ways.  Because the scientists were very careful with their studies, it is difficult for the skeptics and naysayers to discount the results, although it appears to be the nature of skeptics and naysayers to keep trying.

And as pioneers, Washoe and Alex pointed the way to a different world. A world where we humans acknowledge that animals could have sentience and cognitive capacities that could include language. A world where we see animals as intelligent beings, rather than as objects that exist merely for our convenience. A world where animals are no longer considered as things to be used, but fellow creatures to be respected.

Do Ants Think?

Sometimes the days are gorgeous, balmy and calm with the sky a cloudless soft baby-blue. On such days, I am often stuck in a dark windowless auditorium, lecturing to about 100 university students in my animal behavior class. The pull of the day affects us all. I am somewhat less enthusiastic in talking about the computer-generated slides that I am showing, and the class is restless, anxious to get outside to enjoy what is left of the day.

At such times, I switch into discussion mode. I start asking the class questions that can stimulate a conversation and bring out some opinions. The students usually perk up, particularly if the subject is one that really interests them.

One of my favorite topics is the question: do animals think? I start off by asking, how many people believe that humans think? Usually all the hands go up, except for a few contrarians who are not convinced that anyone is capable of thought.

Then I ask, how many people believe that their dog thinks? About half the hands go up. How about cats? Interestingly, perhaps a third of the hands go up. Somehow, dogs seem to have more followers than cats in the thinking category.

Next I ask: how many believe that an ant can think? Almost no hands go up. Virtually everyone seems convinced that ants cannot have any thoughts.

And finally, I ask: how do you know? This generates a lot of discussion that usually revolves around the difficulty of proving that anyone, human or animal, can think. The argument usually follows along these lines: I know that I can think, so by extension, I am willing to concede that perhaps other humans can think. Can I prove it? No, not really. I can provide a battery of problems to solve that seem to require thought, but I cannot conclusively rule out a stimulus-response explanation that would not require thinking. But, because I am human, I am willing to give the benefit of the doubt to my fellow humans.

So why are many people not willing to give the benefit of the doubt to their fellow animals? The students in my class who have dogs usually tell stories of their dogs doing things that seem to require thought. Can they prove that their dogs think? No, not really. But they can identify with the world that dogs live in and the problems that dogs face, and are willing to give them the benefit of the doubt.

But almost no one is willing to give the benefit of the doubt to ants. My students cannot imagine the world of an ant or the problems that ants might face, and are willing to accept that ants do not think. Can they prove it? No, not really.

And here is the key. We are willing to accept that people think, without much proof. We are unwilling to accept that other animals think, also without much proof. Where we can put ourselves into the mind of another animal, we are much more willing to accept that the animal thinks. Otherwise, we assume that there is no thought.

The assumption that animals do not think can be dressed up with all kinds of alleged scientific evidence: The brain is too small, there is no cerebral cortex, the cortex is too small, there are no frontal lobes, and so on.

But the bottom line is, how do we know that an ant does not think? The answer is, we don’t. Unless we are willing to argue from definition. We can define thinking as only a human property, and then we can sit back in great satisfaction that we have solved the problem of animal thinking once and for all.