Canine Comprehension of Complex Communications

No question about it, canines are smart and adaptable. In recent posts, we’ve featured a dingo who cleverly figured out how to use a table as a tool enabling him to reach tempting food, described research suggesting that dogs may be so in tune with our feelings that they can catch yawning bouts from us, highlighted evidence that humans and dogs may be undergoing cognitive convergent evolution with each other based on our close social relationships over the millennia, and even noted a study pointing to canine self-awareness based on their recognition of their own, er, yellow snow.

Also, dog owners frequently describe how smart their cold-nosed friends are, how they know the words for large numbers of toys and other objects, and how they understand and sometimes obey numerous commands. (Good dog!) However, while there have been many studies investigating the linguistic abilities of primates, cetaceans, parrots and certain other species, there has been surprising little formal research into the verbal comprehension of dogs. Dogs have been tested for their understanding of specific words and commands, but there has been an absence of research into whether they can understand and distinguish the constituent parts of complex sentences that refer both to objects (e.g., “ball,” “stick” or “newspaper”) and to actions (e.g., “fetch,” “roll over,” or “point”).

Until recently, that is.

Chasing Down Linguistic Meaning

First, in 2011, John Pilley and Alliston Reid published a paper in Behavioural Processes detailing a variety of word comprehension tests that they had given to Chaser, a rock star border collie famous for knowing the names of over 1,000 objects.

In one of these experiments, Pilley and Reid tested whether Chaser could independently understand the meanings of verbs and nouns. In this test, Chaser was asked to respond appropriately when three different commands (take, paw, and nose) were randomly associated with three different stuffed cloth toys (Lips, a toy resembling human lips; ABC, a cloth cube with those letters written on its side; and Lamb, a stuffed lamb) in 14 independent trials using a double-blind procedure. Chaser was familiar with the commands, but none of the three toys had ever been paired with any of the commands prior to the experiment.

The three toys were lined up on a soft pad in front of a one-meter high cloth barrier. During the trials, neither Chaser nor the experimenter could see each other, as the experimenter knelt on one side of the barrier, with Chaser hanging out with the toys on the other side. The experimenter, who had been given a toy and command combination generated with a random number table, gave Chaser his instructions, while a confederate sat to the side where she could see Chaser perform and signal to the experimenter with a hand wave when the trial was over. Here’s a picture of the setup, taken before the experimenter retreated to the other side of the barrier to commence the trial (note that the confederate’s legs are visible to the right of the picture):

The tests were videotaped with sound recording, with three independent raters (not the experimenter or the confederate) scoring whether Chaser chose the correct toy and performed the correct command. Each rater first watched the videotape with the sound turned off (so he/she wouldn’t know which instructions had been given to Chaser), and recorded which command was actually executed towards which toy. After rating all 14 trials, the rater then watched each trial again with the sound turned on in order to assess whether Chaser’s behavior accurately matched the instructions given by the experimenter.

How did Chaser do? Perfectly.

There was absolutely no disagreement among the raters – each judged Chaser to be 100% accurate across the 14 trials, performing the correct command to the correct toy as instructed. As Pilley and Reid put it:

These results clearly support the conclusion that Chaser understood reference – that the verbal noun of an object referred to a particular object with distinct physical features independent of actions directed toward that object.

Comprehending Sentences

Then, earlier this month, Daniel Ramos and Cesar Ades of the University of São Paulo published a study in PLoS One that extended the Chaser research.

In their study, Ramos and Ades tested Sofia, a female mongrel dog, on two-item requests over a two year period, starting when she was a two-month old puppy. The testing consisted of eight progressive phases, during which Sofia first learned some basic vocabulary and then gradually faced increasingly complex tests of her comprehension abilities. The specific phases were as follows:

  1. Learn the names for four objects (ball, key, bottle and stick) and two requests (point or fetch).
  2. When presented with two objects, approach the correct object on request, or perform the correct action upon request.
  3. Perform object and action requests in sequence – that is, first approach the proper object after being given an initial “object request” and then, after being given an “action request,” perform the correct action on the object.
  4. Perform single multi-part requests – that is, after being given a compound request (e.g., ball fetch, ball point, key fetch, key point, bottle fetch and stick point), approach the correct object and perform the correct action.
  5. To eliminate the possibility of inadvertent cues from the experimenter, perform the same tests as in phase 4 but with the following control variations: (1) experimenter wearing sun-glasses, (2) experimenter with mouth covered by a cloth band, (3) research assistant absent from the room, (4) unfamiliar person as experimenter, (5) testing in an unfamiliar room, (6) test objects scattered, distant from one another, and (7) new objects of the same category (new balls, keys, etc.) offered.
  6. Perform reversed multi-part requests – that is, in response to compound requests in which the word order has been switched from object-action to action-object (e.g., fetch ball, point ball, fetch key, point key, fetch bottle and point stick), approach the correct object and perform the correct action just as in phase 4.
  7. Perform multi-part requests with a new, previously-untested object, a teddy bear.
  8. Perform multi-part requests with new combination object-action pairs (stick fetch and bottle point) that had not been used at all during prior training or tests.

And how did Sofia do? Well, she wasn’t perfect like Chaser, but she was pretty impressive. Her success rate was significantly above chance in all phases except for the final one, in which she had only 3 out of 10 correct responses for both the stick fetch and the bottle point requests. Notwithstanding this one area of underperformance, Ramos and Ades concluded:

Our results suggest that dogs share with “linguistic” animals the capacity to encode in memory at least two heterogeneous items of information to be used in subsequent directed performance, a capacity which, although far from being “an infinite use of finite means” as human grammars are, may have comparative relevance as a forerunner to syntactical functioning.

Now, I know what you are saying. Yes, your dog can do that too. I’m aware that she consistently beats you and your friends at poker, and I’ve seen the video where she plays charades while riding around your house on a Roomba.

You see, that’s actually the issue. Dogs are incredibly good at picking up human signals, which is why carefully-designed experiments are important in ruling out the “Clever Hans” effect (named after a horse who, more than a century ago, amazed crowds with his apparent mathematic abilities, but who was ultimately found to be picking up on involuntary body language cues from his trainer).

By eliminating visual contact between Chaser, Sofia and the experimenters and by adding controls such as having unfamiliar persons issue requests and moving around the objects, the researchers ensured that the dogs had to rely exclusively on words rather than on inadvertent human signals or other contextual clues. By changing the size, shape and color of the requested objects and introducing a new object (the teddy bear), the researchers were able to test whether Sofia was able to generalize and apply concepts to new objects in the same category. By reversing word order and thereby changing the acoustics of compound requests, the researchers were able to rule out the possibility that Sofia was performing based on memorizing the sound properties of requests rather than actually understanding the individual words comprising the requests.

So, you were right all along – your dog really does understand you. The problem is everyone else.

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ResearchBlogging.orgPilley, J., & Reid, A. (2011). Border collie comprehends object names as verbal referents Behavioural Processes, 86 (2), 184-195 DOI: 10.1016/j.beproc.2010.11.007.

Ramos, D., & Ades, C. (2012). Two-Item Sentence Comprehension by a Dog (Canis familiaris) PLoS ONE, 7 (2) DOI: 10.1371/journal.pone.0029689.

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Social Learning in Tortoises

In a previous post, AnimalWise saluted the red-footed tortoise (Geochelone carbonaria) for its Ig Nobel Prize achievements but, in doing so, may have unfairly maligned the tortoise’s cognitive capabilities. To atone for any past disparagement, this post is dedicated to an impressive, and perhaps surprising, red-footed tortoise intellectual accomplishment.

Many social animals are able to solve problems and shortcut the costly process of trial and error learning by simply observing the behavior of their peers. While some have speculated that this type of observational learning is an adaptation for social living that may be unique to animals who live together in groups, a research team led by Anna Wilkinson of the University of Vienna wanted to see whether a decidedly non-social animal, the red-footed tortoise, could also learn by observing others. Wilkinson specifically hoped to test the hypothesis that social learning abilities may simply be a reflection of an animal’s general learning capacity, and that non-social animals may be able to learn by observing peer behavior in fundamentally the same way as they use other environmental stimuli to learn.

Finally – respect for my brains as well as my dashing good looks!

The red-footed tortoises were perfect subjects for this study. The natives of Central and South American forests are naturally solitary, receiving no parental care (once the eggs hatch, it’s every little tortoise for himself and herself!) and, unless presented with a mating opportunity, living apart from other tortoises.

For Wilkinson’s study, eight young (juvenile or sub-adult) tortoises – four randomly assigned to the “non-observer” condition and the other four assigned to the “observer” condition – participated in a series of trials in which they needed to navigate around an obstacle to achieve a food reward. All trials took place in a square arena in which a 40 cm high V-shaped fence separated the tortoise from the desired food:

First, the tortoises in the non-observer groups were each given 12 trials (one per day) in which they were allowed two minutes to solve the task. Between trials, the bark flooring in the arena was redistributed to prevent the tortoises from being able to latch onto any scent trails from prior trials.

Next, the observer group tortoises had their turn. Their trials were identical except that, before each test, they were able to observe a specially-trained tortoise who invariably detoured around the right side of the obstacle and ate the food prize.

The results were unambiguous. While none of the non-observer tortoises ever solved the puzzle (they went up to the fence by the food, but never figured out how to go around the obstacle), all of the observer tortoises succeeded at least twice, with two of them correctly navigating around the barrier on the first attempt.

In other words, the red-footed tortoises have another addition for their trophy room. Not only are they the first red-footed and hard-shelled recipients of the Ig Nobel Prize, they are also the first non-social reptile to display social learning skills, revealing that group living is not necessarily a prerequisite for social learning.

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ResearchBlogging.orgWilkinson, A., Kuenstner, K., Mueller, J., & Huber, L. (2010). Social learning in a non-social reptile (Geochelone carbonaria) Biology Letters, 6 (5), 614-616 DOI: 10.1098/rsbl.2010.0092.

Show Me the Honey! Honeyguides and Humans Team Up at Dinnertime

Humans have a long history of spotting superior abilities in other animals, and then training those animals to use those abilities to advance our own interests. Everyone’s familiar with how we’ve trained pigs to sniff out truffles for us with their sensitive snouts and how we’ve domesticated dogs to herd our livestock, alert us to intruders, guide us when our vision fails, and perform other services. Similar but less well-known examples include our training bees to detect the odor of explosives, cormorants to catch fish for us, and llamas to guard our sheep from coyotes and other predators.

It’s far less common, though, to find relationships where non-humans participate on a more equal footing, where they appear to train us at least as much as we train them. (People who are owned by cats should feel free to rebut this statement in the comment section below.)

Today’s post features one such relationship, the partnership between humans and the greater honeyguide (Indicator indicator), a bird that lives in the trees of sub-Saharan Africa.

Honeyguides and humans have very complementary appetites. Honeyguides get most of their food from beehives, feasting on larvae and wax that they extract from honeycombs (yes, they actually eat and can digest the wax!). Of course humans, too, seek out beehives, although our interest lies more in the bees’ sweet honey, and we’re generally more than happy to leave the wax and grubs for others to enjoy.

The bee-related skills of humans and honeyguides are relatively complementary as well. Honeyguides can fly swiftly across large areas and are expert at locating bee colonies, but have difficulty in extricating the combs on their own. Humans move more slowly along the ground and aren’t so adept at finding colonies, but once we have one in our sights, we’re able to overcome bee defenses and dig the combs out, even when the bees have nested deep within rock crevices and other hard-to-reach locations.

Out of this opportunity for mutualistic benefit, honeyguides and humans have worked out an elaborate interspecies communication system that allows them to work in tandem with certain signals understood by both parties.  This partnership has been formally documented in a three year field study conducted in the dry bush country of northern Kenya, focusing on the interactions between honeyguides and the nomadic Boran people who populate the area.

I’m the *real* Greater Honeyguide – don’t let imposters lead you astray! Visit me at http://safari-ecology.blogspot.com/ and see first comment below.

Each partner knows how to get the other’s attention. To attract the birds, the Borans call them with a penetrating whistle (known in the Boran language as Fuulido) that can be heard over a distances of greater than a kilometer and that is made by blowing air into clasped fists, modified snail shells, or hollowed-out palm nuts. Comparably, hungry honeyguides flag down humans by flying up close, moving restlessly from perch to perch, and emitting a double-noted, persistent “tirr-tirr-tirr-tirr” call. (Side note: I’ve been practicing this at home, and it doesn’t seem to attract much other than odd stares and raised eyebrows.)

The joint food expedition commences when the honeyguide flies briefly out of sight and then returns to a nearby, conspicuously visible perch. When the human companion approaches this perch, the honeyguide takes off, displaying its white outer tail feathers, and flies to a new resting place a short distance away, calling loudly when it lands. The Boran partner then approaches the new perch and the bird flies off again, repeating the pattern. As the Borans work with the bird, they whistle and shout to keep the bird interested in guiding. (Again, this doesn’t seem to work too well at home.)

The researchers found that the honeyguides signal the path and distance to the bee colony in a variety of ways. First, they indicate the correct direction through their flight paths, traveling consistently in the direction of the nest and increasing their precision as they near the target. It appears that the know in advance where the nests are located, as the researchers observed the honeyguides briefly visiting nests before dawn, peering into the entrances while it was still dark and the bees were docile.

Also, the honeyguides vary their behavior depending on distance to the hive. For example, when the hive is relatively distant, the birds begin the process with a relatively long disappearance during their first flight; conversely, their first disappearance is briefer when the hive is relatively nearby. Further, the honeyguides stop more frequently and the legs between perches become shorter as they and their human followers approach the nest, especially during the last 200 meters. Finally, the honeyguides select increasingly lower perches as they close in on the colony.

Upon arrival at the destination, the honeyguides perch close to the nest and emits an “indication call.” The researchers describe the scene as follows:

This call differs from the previous guiding call in that it has a softer tone, with longer intervals between successive notes. There is also a diminished response, if any at all, to whistling and shouting by humans. After a few indication calls, the bird remains silent. When approached by the searching gatherer, it flies to another perch close by, sometimes after circling around the nest. The resulting flight path finally reveals the location of the colony to the gatherer. If the honey collector does not (or pretends not to) detect the nest, the bird gives up after a while. It may then leave the area either silently or start a guiding session to another colony. In the latter case, it switches from the indication call to the guiding call and resumes a fairly direct flight pattern. Once the human team members find the nest, it becomes their turn to go to work and hold up their part of the bargain. After using smoky fires to reduce the bees’ aggression, the Boran honey gatherers use tools or their hands to remove the honey comb, and then break off pieces to be shared with their honeyguide partners.

To sum things up, here’s a great BBC video (featuring David Attenborough!) that describes the bird-human partnership and shows the honeyguides in action:

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ResearchBlogging.org
Isack, H., & Reyer, H. (1989). Honeyguides and Honey Gatherers: Interspecific Communication in a Symbiotic Relationship Science, 243 (4896), 1343-1346 DOI: 10.1126/science.243.4896.1343.

Walk This Way! Experienced Female Elephants Show Their Naïve Younger Relatives How to Play the Mating Game

If you’re a female elephant, there’s a right way and a wrong way to play the mating game. To maximize your chances of reproductive success, it’s best to pair up with a dominant bull elephant in musth, a state of heightened arousal in which testosterone courses through the bull’s body, increasing both his sex drive and his aggression. A high-ranking musth elephant not only makes the fittest mate, but he can protect you by scaring off the less desirable younger males who would otherwise chase you around.

An experienced female knows this well, and plays the game accordingly. When she goes into heat – or oestrus – and attracts male suitors through chemicals in her urine, she gives impressive senior bulls the green light by holding her tail high, walking with an exaggerated gait, and exchanging affectionate trunk caresses. Lower-ranking young males don’t fare so well. She actively avoids them and, to the extent they aren’t chased off by her favored partner, she’ll often spurn their advances by running away. (Little known fact: female African elephants can typically outrun male ones.)

It’s not so easy for a young female entering oestrus for the first time. She sometimes runs from the larger musth males, who can weigh more than twice as much as her, and not infrequently ends up consorting with a series of younger, lesser males. This can lead to unfortunate results, especially when you consider that an elephant pregnancy lasts 22 months.

Now, though, there’s evidence that experienced females may help their younger relatives in sorting through the confusing tangle of elephant sexual dynamics. These helpful older elephants – sisters, aunts, mothers, and matriarchs – appear to simulate oestrus in order to show their innocent family members how to act, enabling them to avoid the pitfalls of poor mating choices.

If I said you had a beautiful trunk, would you hold it against me? (photo: WildlifeDirect, Dzanga Forest Elephants)

After hearing anecdotal accounts of this behavior, a team led by Lucy Bates of the University of St. Andrews decided to dig deeper by taking advantage of an invaluable resource – a comprehensive multi-decade database cataloging the daily life activities of 2,200 Amboseli elephants compiled by Cynthia Moss, Joyce Poole, and other researchers as part of the Amboseli Elephant Research Project (AERP).

Bates and her colleagues systematically combed through 28 years of detailed AERP records and located all occasions on which an observer had concluded that an identifiable elephant was in oestrus (based on postural and behavioral changes in females, interactions with males, etc.). In total, they found descriptions of 999 oestrus events, slightly less than 10% of which (98 events) recorded two or more members of the same elephant family displaying simultaneous oestrus behavior.

Next, the researchers cross-referenced these accounts with AERP demographic records to find any that must have been “false” oestrus events, which they defined as oestrus-like behavior by a female who was either already pregnant, in a state of lactation-induced infertility, or senescent (which they deemed to be the case if she was over 50 years old, had not given birth to any calves during the prior five years, and had no subsequent calves).

They discovered that, while false oestrus behavior was relatively rare (occurring only 19 times and representing only about 2% of all recorded oestrus events), its timing was fascinating. Very often, it occurred just when a young relative was coming into oestrus for the first time.

Even though simultaneous oestrus behavior had been recorded less than 10% of the time, over half of the false oestrus events (10/19) clearly occurred at the same time as the true oestrus of a young female family member who had never given birth. Further, subsequent birth records confirmed that on four additional occasions a false oestrus event occurred during the month that a young relative conceived her first calf (that is, the young female must have been in oestrus at the time, even though it wasn’t specifically called out in the AERP database). Finally, one of the false oestrus events occurred simultaneously with the genuine oestrus of a female relative who had given birth before. Thus, the large majority of the false oestrus events – 15 of 19 – coincided with true oestrus events, in most cases, the first oestrus of a young relative. (Moreover, note that the balance of the false oestrus events could also have coincided with true ones if, as in the four cases described above, the true oestrus event simply had not been observed or recorded in the AERP database.)

The researchers then examined various hypotheses that might explain the false oestrus behavior:

  • That false oestrus merely results from hormonal changes and has no functional purpose;
  • That it somehow induces sexual receptivity in the simulating female, thereby increasing her own chances of successfully reproducing;
  • That it indirectly benefits the simulating female by providing a young family member with increased access to suitable males (this type of indirect benefit is known as an inclusive fitness benefit); or
  • That it indirectly benefits the simulating female by encouraging a confused younger relative to engage in more suitable oestrus behavior (another potential example of inclusive fitness).

They quickly rejected the all but the final hypothesis. For one, hormonal changes couldn’t adequately explain either the observed patterns (false oestrus occurred in both pregnant and non-pregnant females, as well as during all stages of pregnancy) or the higher-than-expected coincidence of false oestrus with the genuine oestrus events of inexperienced relatives. Second, it was clear that the simulating elephants weren’t improving their own reproductive success: in 14 of 19 cases the simulating the female was already pregnant, and in four others she was senescent. Third, AERP records revealed that false oestrus behavior had no impact on the number of available males, the relative percentage of males who were in musth, or the amount of sexual activity engaged in by inexperienced female.

Ultimately, the researchers concluded that:

Further data is required to confirm or reject the hypothesis that this behaviour functions to teach the young, naïve females, but we suggest that it remains the only viable possibility based on the current analyses.

In particular, they noted that additional research and data collection was necessary to explain the instances in which false oestrus didn’t appear to coincide with an inexperienced relative’s oestrus as well as to support the notion that inexperienced females were able to correct substandard mating behavior after they were shown what to do by their older relatives.

In the meantime, though, you’d be well advised to stay away from those frivolous young guys and find yourself a dashing older bull who knows his way around the herd.

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ResearchBlogging.orgBates, L., Handford, R., Lee, P., Njiraini, N., Poole, J., Sayialel, K., Sayialel, S., Moss, C., & Byrne, R. (2010). Why Do African Elephants (Loxodonta africana) Simulate Oestrus? An Analysis of Longitudinal Data PLoS ONE, 5 (4) DOI: 10.1371/journal.pone.0010052.

The Wisdom of the Aged: Matriarch Elephants Lead with Experience

As many people know, African elephants (Loxodonta africana) live in complex matrilineal societies, with closely-knit family groups led by a matriarch who is typically the oldest and largest female in the family. In order to appreciate the importance of these matriarchs, it may help to first consider a traditional Japanese folktale:

Once there was an arrogant young village lord who, deciding that old people were useless, banished them to the mountains to die. Although the villagers were distressed, they obeyed rather than face severe punishment. One young farmer couldn’t bear to follow this cruel decree, though, and hid his aged mother away in a safe and secret room.

Several years later, an invader arrived, announcing that he’d spare the village only if three tasks could be performed. First, he must be presented with a box containing one thousand ropes of ash. Next, a silk thread must be drawn through a small hole that bent seven times along the length of a log. Finally, he must be given a drum that sounded without being beaten.

In each case, the village lord offered rewards, cajoled and threatened the townspeople, but nobody knew what to do; all were in despair. The tasks all seemed impossible. Each time, though, the farmer asked his mother and she knew the answer: soak ordinary rope in salt water before burning it; tie the silk thread to an ant at one end of the hole and place sugar at the other; put a bumblebee in a drum and it will buzz as it tries to escape. The village was spared.

Ultimately, the lord finds out that they have all been saved by the wise old mother, and from that time on elders in the village are revered.

Shifting scenes now from the mountains of long-ago Japan to the plains of today’s Africa, it turns out that older matriarch elephants are much like the heroic old Japanese mother – they are the ones with the answers, the ones that can save their fellow elephants from outside threats with the wisdom they have accumulated through experience.

Listen to your Grandmother! (image copyright ElephantVoices)

As we know from the decades of observation and research performed by Cynthia Moss and her colleagues in Kenya and Tanzania, matriarch elephants act as group leaders, holding together their families and providing behavioral guidance during times of crisis. Many observers believe that the oldest matriarchs – those with the most experience and greatest ecological knowledge – make the best decisions, but until recently it has proved to be difficult to quantify the relevant skills in a manner conducive to experimental testing.

In a March 2011 paper published online in the Proceedings of the Royal Society B, however, a team of scientists led by Karen McComb of the University of Sussex reported on a clever set of experiments that tested whether older Amboseli National Park matriarchs were better than their younger counterparts at assessing the perceived threat posed by various lion roar recordings.

While African elephants are able to fend off most natural predators, they have to watch out for lions, who occasionally prey upon younger calves. Also, even though lionesses perform the, ahem, lion’s share of the hunting for the pride, male lions actually pose a greater threat to elephants. Male lions, despite their generally well-deserved reputation for laziness, are, on average, half again as large as females and much stronger, giving them a better chance of overpowering a vulnerable young elephant.

Accordingly, the researchers assembled lion “playbacks” in four separate categories – single female roars, single male roars, three female group roars and three male group roars – which they then played to 39 elephant family groups over a period of slightly more than two years. Because of the extensive demographic information compiled by the Amboseli Elephant Research Project, they knew the age of the matriarch in each of the 39 families.

After playing the different roars, the researchers analyzed video of the elephants’ responses, focusing particularly on the behavior of the matriarchs. They documented specific defensive reactions, including prolonged listening to the roars, whether the family bunched around the matriarch after hearing the roars, the speed and intensity of any bunching behavior, and whether the matriarch changed her direction and moved toward the source of the playback.

Here are two brief videos, one showing an elephant family reacting to lion roars and the other narratively describing the reactions as reflected in still images:

After recording all of the responses, the research team performed statistical analyses and sorted their results by matriarch age. They found that, while matriarch age did not have an impact on how the elephants reacted to varying number of lions (all elephant families consistently ratcheted up the intensity of their response when the number of lions roaring went from one to three), it did have a strong impact on the elephants’ response to the more serious threat presented by male lion roars, with male roars leading to more prolonged listening and intensive defensive bunching in families led by older matriarchs.

As the researchers put it:

Our work provides the first direct experimental evidence that older matriarchs are in fact able to make better decisions when faced with ecological challenges — in this case, the presence of dangerous predators. It thus bridges an important gap between theoretical predictions about how knowledge might be expected to affect leadership and empirical studies, which to date have been largely confined to observational accounts.

Based on these findings, I’m quite confident that the older matriarchs will do quite well on their next set of tasks involving burning ropes, crooked logs and drums. Now, if only that was enough to keep humans from invading their villages….

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ResearchBlogging.org

The Japanese folktale can be found, among other places, in The Wise Old Woman/retold by Yoshiko Uchida; illustrated by Martin Springett. ISBN: 0689505825.

McComb, K., Shannon, G., Durant, S., Sayialel, K., Slotow, R., Poole, J., & Moss, C. (2011). Leadership in elephants: the adaptive value of age Proceedings of the Royal Society B: Biological Sciences, 278 (1722), 3270-3276 DOI: 10.1098/rspb.2011.0168.

Analogical Reasoning in Animals

In today’s post, I’d like to explore some surprising recent findings about the abilities of animals in the area of analogical reasoning.

Reasoning by analogy is central to the way we think, enabling us to use familiar concepts to solve new problems. When a catastrophic event strikes Wall Street, economists inevitably point to analogous historical disruptions in their attempts to predict whether we’re facing long-term troubles or a quick recovery. When lawyers advocate on behalf of clients in new realms such as digital media, they often ground their arguments in principles that evolved centuries ago to protect real property interests. When scientists explain the motion of molecules and other phenomena that we cannot directly perceive, they frequently turn to concrete examples such as colliding billiard balls or streams of water.

On a more mundane level, analogical thinking underlies many of our idioms and permeates our everyday language. Think how lost you’d be if you were suddenly unable to understand phrases that explicitly or implicitly apply concepts from one context to events or actions in another. Conversations at work would confuse you (more than usual). Your boss’ suggestion that you take some time off to recharge your batteries would leave you scratching your head rather than looking for deals on tropical island vacations. You wouldn’t be able to follow political discussions (oh no!). You’d be the only one asking “oh my god, was it with guns or knives?” after hearing that one candidate outdueled another in a debate. You’d be the only one worrying about cannibalism after learning that the people were hungry for new leadership. You’d find sports to be newly upsetting, as you’d literally go into mourning after learning of your favorite team’s fatal missteps. (Ok, I take that back – nothing has changed here, especially for Boston Red Sox fans.)

Relational Matching Tests

One of the most common tests used to assess an individual’s ability to solve analogy problems is known as relational matching-to-sample or RMTS. In its classic form, RMTS involves first showing the subject a sample set consisting of two or more objects that are either identical (for example, two circles) or nonidentical (for example, a square and a circle). Sets containing identical objects are sometimes referred to as reflecting the “identity relation” and those containing nonidentical objects are said to reflect the “nonidentity relation.” Next the subject is shown two comparison sets containing novel objects, one embodying the identity relation (e.g., two triangles) and the other the nonidentity relation (e.g., a rectangle and a triangle). To succeed, the subject must choose the comparison set that matches the relationship demonstrated by sample set. For instance, the correct choice for a subject shown two circles in the sample would be the comparison set containing the two triangles, whereas the correct choice for the subject initially shown the square and the circle would be the comparison set containing the rectangle and the triangle.

RMTS is particularly well suited for testing the abilities of non-human animals, as it poses an analogy problem in a strictly visual manner, not relying in any way on linguistic skills. In essence, success requires the subject to not only make a “first order comparison” between same and different, but also to make a “second order comparison” by applying this underlying distinction to a novel environment. Many researchers consider this ability to lie at heart of analogical reasoning.

A “Profound Disparity”?

Until recently, studies have suggested that humans and a select few great apes stand far apart from all other animals in terms of analogical reasoning abilities. While many animals can successfully distinguish between same and different shapes or colors, they tend to struggle when it comes to making second order comparisons of the sort required by RMTS tasks. Since only humans and some chimpanzees, gorillas and orangutans have performed well at RMTS testing, researchers have proposed that a “profound disparity” exists between the analogical reasoning capacity of hominids and other animals.

For example, several studies have shown that some baboons and pigeons can learn to pass RMTS tests if they involve large-sample and comparison sets (e.g., comparisons involving 4 x 4 grids of 16 all identical and 16 all different objects), but that their performance rapidly deteriorates as the size of the grid decreases as well as when the distance between the objects in the grid increases. According to researchers, one reason why animals do better with larger sample sets may be that there’s a greater amount of variation or “entropy” between non-analogous grids in larger sample and comparison sets, which makes the task of distinguishing between potential answers easier.

Notwithstanding these prior findings, however, two studies published in the last few months now pose a challenge to the “profound disparity” concept, suggesting that a suitable testing environment can showcase robust analogical reasoning skills in non-apes.

Clever Capuchins

In the first study, which was published in PLoS ONE in August 2011, researchers led by Valentina Truppa and Elisabetta Visalberghi of the National Research Council in Rome, Italy, found that New World tufted capuchin monkeys (Cebus apella) were capable of solving RMTS tasks involving sample and comparison sets involving sets of as few as two objects.

What are all of those freaking squiggles in that diagram above my head? (image credit: Charlesjsharp)

The research team studied five capuchin monkeys, testing them over and over again on RMTS tasks involving varying numbers of icons. While the specific tests varied, the general approach was to start by giving the monkeys trials involving a relatively small pool of different icons and, only if and when a monkey achieved proficiency (as measured by percentages of correct answers) over the course of thousands of trials, to introduce novel icons for comparison. Also, in one of the experiments, if the monkey did not ultimately reach the proficiency threshold on a two-icon comparison test, “entropy” was increased and the monkey was given an easier four-icon test.

Ultimately, after a total of 21,888 trials (yes, that’s correct!) one of the five capuchins, Roberta, proved to be a real overachiever. As the researchers put it:

The current study demonstrates the acquisition of abstract concepts based on second-order relations by one capuchin monkey, Roberta. She was first successful with four-item stimuli and then with two-item stimuli, the latter being the most difficult condition previously thought to be mastered only by apes. Since her performance was robust across different types of stimuli and well above that of the other subjects, we can argue that relational analogies are very difficult for capuchins, but under specific circumstances not impossible.

Way to go, Roberta!

Bright Baboons

In a second study, published on September 20, 2011, in Psychological Science, a research team headed by Joël Fagot of the Centre National de la Recherche Scientifique at the Université de Provence reported that guinea baboons (Papio papio) can learn to perform surprisingly well at RMTS tasks … and then retain this ability over a 12-month period. In this study, 29 baboons with no language training and little or no experience with relational matching tests participated in various RMTS experiments involving geometric shape comparisons.

All this RMTS stuff gives me a headache (image: Animal Globe)

The first experiment consisted of classic RMTS trials, each involving a sample set made up of pairs of identical or nonidentical geometric shapes, and two comparison sets with new geometric shapes, with only one of the comparison sets matching the relationship demonstrated by the sample set. At first, the testing pairs were selected randomly from among 10 geometric shapes, but once a baboon had achieved an accuracy level of 80% or better in three consecutive sessions of 100 trials, new geometric shapes were introduced up to a maximum of 90 shapes by the end of the experiment. Six of the 29 baboons were able to make it to the 80% threshold level, and five were ultimately able to proceed through testing until they reached all 90 shapes.

The second experiment included changes designed to make the challenge more difficult: the geometric shapes were moved further apart and, perhaps more significantly, in half of the tests the “incorrect” comparison pair, rather than containing all new geometric shapes, actually contained one of the shapes from the sample pair. In other words, even though this comparison pair was incorrect from the standpoint of analogy testing, it contained a shape that was directly linked to the sample set, potentially confusing the baboon if it was focused on the similarity of the shapes rather than the conceptual relationship between the shapes.

In spite of the enhanced degree of difficulty, all five of the baboons who participated – the same baboons who had been successful in the first experiment – performed at above chance levels throughout the second experiment (although, not surprisingly, their performance tailed off somewhat in the trials where the incorrect response shared a shape with the sample set).

Finally, the research team retested the five successful baboons in accordance with the first experiment methodology after a one-year lapse during which the baboons had no practice at RMTS tasks. All five baboons reached the 80% success level far more quickly than they had the first time around, providing strong evidence that they had been able to retain their relational matching skills over this one-year period.

As with the capuchin monkeys, the baboons were not naturals at these tests – they went through thousands upon thousands of trials and only gradually acquired their relational-matching skills. Once again, though, the research strongly suggests that there is not a bright line “profound disparity” between the capabilities of hominids and those of other animals, and that other animals can demonstrate the cognitive foundation necessary for abstract analogical reasoning.

So, as in other areas, the more we explore the abilities of animals, the more we find that we have been wrong about what we thought were cognitive barriers. As we become more adept at designing experiments that are patiently conducted and thoughtfully tailored to the skills and natural adaptations of the specific animals we are studying (rather than the skills and adaptations of college undergraduates), we should continue to see the breakdown of additional barriers.

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ResearchBlogging.orgTruppa, V., Piano Mortari, E., Garofoli, D., Privitera, S., & Visalberghi, E. (2011). Same/Different Concept Learning by Capuchin Monkeys in Matching-to-Sample Tasks PLoS ONE, 6 (8) DOI: 10.1371/journal.pone.0023809

Fagot, J., & Thompson, R. (2011). Generalized Relational Matching by Guinea Baboons (Papio papio) in Two-by-Two-Item Analogy Problems Psychological Science, 22 (10), 1304-1309 DOI: 10.1177/0956797611422916

Converging with Canines: Are Humans and Dogs Evolving Together?

In our man-made world, it can feel like everything is converging all at once. Indistinguishable glass skyscrapers sprout up in cities all over the globe, near identical car models vent carbon dioxide into the air on different continents, and people around the world see their waistbands expand as they gulp down the same McFood. Global economies are more connected than ever, with natural disasters in Japan, sovereign debt issues in Europe, and rumors of Wall Street misdeeds shaking worldwide markets within minutes. Even the social media that deluge us with information seem like they’re growing more and more alike, as we now drown in unending streams of look-alike feeds, postings, messages and links from Twitter, Facebook, Google+ and others.

You may wonder whether the forces of convergence are a recent phenomenon, a product of human technology, or whether they may have deeper roots in the natural world. In fact, convergence can and does occur in the realm of biological evolution, albeit at a more comfortable pace. For example, “convergent evolution” occurs when different species independently evolve similar solutions to comparable evolutionary pressures. A classic example of this is the development of wings and the ability to fly by birds, bats and pterosaurs:

Diagram of wing morphology and/or and comparative network hub structure of Twitter, Facebook and Google+ (image credit: National Center for Science Education)

Consider also the independent evolution of sleek, torpedo-shaped bodies by fish, cetaceans and ichthyosaurs:

Sleek ocean swimmers (image credit: All About Reptiles)

Closer to home, scientists at the Max Planck Institute for Evolutionary Anthropology have concluded that we may be undergoing a process of cognitive convergent evolution with dogs based on our social relationships over thousands of years with these “best friends” of ours. In a paper published in Trends in Cognitive Sciences, Brian Hare and Michael Tomasello reviewed a large number of studies focused on canine, human, and non-human primate social and communicative skills and reached some interesting conclusions.

Proof of convergent canine-human evolution (source unknown)

They began their analysis by focusing on research showing how well domestic dogs do at interpreting human social and communicative behavior. For example, dogs excel at tests in which experimenters hide food in one of several opaque containers and then signal where it has been hidden by pointing, gazing, bowing or nodding, or placing markers in front of the target location. The dogs easily interpret this type of cue, passing tests such as these on the first attempt and performing correctly even when humans try to trick them by walking towards the wrong container while pointing in the opposite direction to the correct container.

Also, studies have shown that dogs are aware of what humans can see. For instance, if a human turns around during a game of fetch, the dog will almost invariably bring the ball back around the human and drop the ball in front of his face. Similarly, dogs have shown that they prefer to beg for food from humans whose eyes are visible than from ones whose eyes are covered with a blindfold or bucket, but are more likely to approach forbidden food when a human’s eyes are closed.

Indeed, dogs actually consistently outperform chimpanzees and other primates at these types of skills, even though, in areas of non-social cognitive performance, dogs do not do so well. For example, non-human great apes are much better at making inferences about the location of hidden food based on non-social cues (such as a tilted board that might be tipped up by hidden treats) and at tests that require them to achieve food rewards by, for example, reeling in food attached to strings.

With this in mind, Hare and Tomasello turned to whether domestic dogs’ specialized social skills are likely to be due to convergent cognitive evolution with humans or whether another explanation is more plausible.

First, they considered the possibility that dogs learn to recognize human social cues based on their experiences growing up in human households. They found, however, that studies show that even puppies as young as nine weeks old are adept at solving problems using human pointing and gaze cues, and that puppies raised without much exposure to humans are equally skilled at interpreting these cues.

Then, they considered whether domestic dogs may have simply inherited their social skills based on their common ancestry with wolves, since wolves are, after all, pack hunters who need to be able to follow complex social interactions with other wolves and with prey. However, although wolves are generally equal to or better than domestic dogs at memory tests and tasks involving general problem-solving abilities, wolves (even those raised by humans) are simply unable to match the performance of dogs at spontaneously using human social cues to solve problems.

Next, the researchers sought evidence for the evolution of social skills in dogs through their long-term relationship with humans. They looked at a population of domesticated foxes, where the selection for breeding had been based solely on the tendency of individual foxes to be non-aggressive and fearless around humans. Interestingly, these foxes were just as adept as dogs in using and interpreting human social cues, and far better than a population of control foxes that had been bread randomly with respect to their attitude towards humans.

Based on all of these comparative findings, Hare and Tomasello concluded that the best explanation for dogs’ specialized social skills is that they evolved as a consequence of dogs having been domesticating by humans, representing a case of convergent cognitive evolution. Interestingly, Hare and Tomasello went further and, based on their review of the research on domesticated foxes, concluded that the evolution of specialized social skills in domesticated dogs may actually have been an incidental byproduct of an initial decision to select based solely on nonaggression (as opposed to social intelligence).

Finally, turning to primate evolution, Hare and Tomasello speculated that a similar process may have contributed to differences between human and chimpanzee social skills. Under what they refer to as the “emotional reactivity” hypothesis, they predicted that differences in temperament between humans and other primates may help explain some of humans’ extraordinary social cognitive abilities. They point to studies showing that chimpanzees’ willingness to cooperate with each other can often be limited by lack of social tolerance for one another resulting from fear and/or aggression, and contrast this to a more socially tolerant temperament that may ultimately have enabled our hominid ancestors to develop flexible forms of cooperation and communication. In other words, humans underwent a form of self-domestication leading to greater social abilities, thereby convergently evolving with our canine companions who were undergoing the same process.

I’m not sure I entirely buy the notion that we humans are so exceptionally tolerant, but I have noticed that you’ve started to look a bit like your dog. In a future post, we may look at whether we may also be evolving to be more like members of the cat family:

Which one is the lion? (source unknown)

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ResearchBlogging.orgHare, B., & Tomasello, M. (2005). Human-like social skills in dogs? Trends in Cognitive Sciences, 9 (9), 439-444 DOI: 10.1016/j.tics.2005.07.003

Rise of the Planet of the Ants

These days, we’ve been hearing quite a bit about a future in which humans find their dominion over the planet suddenly challenged by a group of super intelligent apes. This may make for an exciting Hollywood movie plot and some stunning visual effects, but I wonder whether we really need to look to humanoid science fiction in order to feel a shiver of doubt regarding our supremacy as a species.

Maybe all we need to do is to look at the world the way it is, a world that could well be called … The Planet of the Ants!

So, why is it that we should feel just a wee bit threatened by these small six-legged colonizers? Here are just a few reasons.

Quadrillions of Ants

Burning Man seems more crowded every year, doesn't it? (photo credit: Mehmet Karatay)

Like us, ants thrive just about anywhere, with the exception of Antarctica and a few isolated islands. Moreover, while there are approximately seven billion of us on the planet, conservative estimates put the number of ants at between one and ten quadrillion.1 That’s between 150,000 and 1,500,000 ants for each and every one of us. At the higher figure, this means that, if you were to put all the world’s ants onto a giant scale, they would weigh about as much as all of the humans on the planet put together.2 In fact, on average, it has been estimated that ants make up 15–20% of the terrestrial animal biomass on Earth (and more than 25% of the animal biomass in tropical regions).3

Our tendency as humans is to unquestioningly assume that we are far and away the most successful species that has ever been. If we take a step back, though, and simply consider the above numbers and the possibility that an animal’s success is most properly measured by the degree to which it has been able to thrive in various environments, perhaps we should already be feeling a pang of doubt about how incontestable our supremacy really is.

Ants Teach

While many animals are able to learn through imitation, ants are the only non-mammal known to engage in interactive teaching.4 In at least one species of ant, knowledgeable workers actively teach inexperienced nest mates where to find food through a process known as “tandem running,” in which the lead worker ant recruits an inexpert follower, and then makes sure that the follower stays on track, slowing down when it lags and speeding up when it gets too close.

Ants Learn

Ants are also able to engage in so-called latent learning, whereby they memorize information that they cannot use at once, but that may be useful later on – a behavior that’s been labeled as “planning.”5 Specifically, ants have been shown to be able to reconnoiter potential new living spaces, retaining information about relative desirability and tailoring their choices based on how urgently the need to move is.

Ants Can Learn to Navigate Mazes

Ants can be trained to remember multiple visual patterns presented in a fixed sequence, enabling them to navigate mazes.6 Ok, I’m not sure how exactly this leads to world domination, but it is definitely pretty cool.

Ants Practice Agriculture

Approximately 50 million years ago (and, accordingly, approximately 49+ million years before Homo Sapiens first arose as a species), ants began engaging in agriculture.7 Today, different species of leafcutter ants have adopted a purely agrarian lifestyle, feeding exclusively on gardens of fungus that they actively weed and cultivate, feed with fresh-cut leaves, and keep free from parasites and other pests.8 Here’s a video of some fungus farming ants:

Ants Engage in Animal Husbandry

Some ants raise aphids and feed on the sugary honeydew the aphids secrete when “milked” by the ants’ antennae. The ants are careful with their herds, keeping predators and parasites away, moving the aphids from one feeding location to another, and often bringing the aphids with them when they migrate.9 Here’s a video of ants tending to their aphids:

Ants Sometimes Enslave Other Ants

Certain types of ants are incorrigible slave-makers, raiding other colonies of ants and making captured slaves perform all routine tasks for their masters, including brood care, foraging, and even feeding slave-maker workers who are unable to feed themselves.10 Obviously, this isn’t a particularly attractive ant characteristic, but unfortunately it is one that may seem all too familiar to us humans.

Ants Use Tools

That’s right, tools. For example, some ants transport liquid and other non-solid food by dropping bits of leaves, sand or mud pellets or pieces of wood into a pool of food and, after the food has soaked in, using these objects to carry the meal back to their nests.11 Other ants use pebbles and soil pellets as weapons, dropping them on other ants or ground-dwelling bees, and then attacking and killing their competitors.12

Ants Build Cooperative Solutions

Hey, watch your foot! You're stepping on my head! (photo: Mlot, Tovey & Hu)

Ants, including army ants, are known to self-assemble into living bridges or ladders that allow them to cross gaps while on the move. When a single ant cannot make it across alone, other ants will successively grab on, steadily lengthening the bridge until it’s long enough to reach the destination. These structures, which can span significant distances and can even cross water, are then used by the rest of the colony and may stay in place for hours, until traffic dies down.13 Comparably, fire ants self-assemble into waterproof rafts to survive floods. These rafts can be made up from anywhere from a few hundred to many thousand ants and are incredibly durable, allowing ants to sail for months at a time as they migrate.

Ants Have “Collective Intelligence”

The concept of collective intelligence has been hot lately, with a number of books and articles describing how groups can make collectively make sophisticated decisions and solve complex problems, even where each individual in the group knows very little, collectively a g (think of the analogy of each individual acting as a neuron, and the group as a whole acting as a collective brain). Collective intelligence is a topic unto itself, one we may address in future posts, but for now suffice it to say that if ants truly can make wise decisions as a group, we humans may really have something to envy!

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ResearchBlogging.org1Holldobler, B & E. O. Wilson (2009). The Superorganism: The Beauty, Elegance, and Strangeness of Insect Societies. New York: W. W. Norton. p. 5. ISBN 0-393-06704-1.

2Ibid.

3Schultz, T. (2000). In search of ant ancestors Proceedings of the National Academy of Sciences, 97 (26), 14028-14029 DOI: 10.1073/pnas.011513798.

4Franks, N., & Richardson, T. (2006). Teaching in tandem-running ants Nature, 439 (7073), 153-153 DOI: 10.1038/439153a; Richardson, T., Sleeman, P., McNamara, J., Houston, A., & Franks, N. (2007). Teaching with Evaluation in Ants Current Biology, 17 (17), 1520-1526 DOI: 10.1016/j.cub.2007.08.032.

5Franks, N., Hooper, J., Dornhaus, A., Aukett, P., Hayward, A., & Berghoff, S. (2007). Reconnaissance and latent learning in ants Proceedings of the Royal Society B: Biological Sciences, 274 (1617), 1505-1509 DOI: 10.1098/rspb.2007.0138.

6Chameron, S., Schatz, B., Pastergue-Ruiz, I., Beugnon, G., & Collett, T. (1998). The learning of a sequence of visual patterns by the ant Cataglyphis cursor Proceedings of the Royal Society B: Biological Sciences, 265 (1412), 2309-2313 DOI: 10.1098/rspb.1998.0576; Reznikova, Z. 2008: Experimental paradigms for studying cognition and communication in ants (Hymenoptera: Formicidae). Myrmecological News 11: 201-214.

7Schultz, T., & Brady, S. (2008). From the Cover: Major evolutionary transitions in ant agriculture Proceedings of the National Academy of Sciences, 105 (14), 5435-5440 DOI: 10.1073/pnas.0711024105.

8Ibid.; Schultz, T. (1999). Ants, plants and antibiotics. Nature, 398 (6730), 747-748 DOI: 10.1038/19619.

9Nielsen, C., Agrawal, A., & Hajek, A. (2009). Ants defend aphids against lethal disease Biology Letters, 6 (2), 205-208 DOI: 10.1098/rsbl.2009.0743; Styrsky, J., & Eubanks, M. (2007). Ecological consequences of interactions between ants and honeydew-producing insects Proceedings of the Royal Society B: Biological Sciences, 274 (1607), 151-164 DOI: 10.1098/rspb.2006.3701.

10Pohl, S., & Foitzik, S. (2011). Slave-making ants prefer larger, better defended host colonies Animal Behaviour, 81 (1), 61-68 DOI: 10.1016/j.anbehav.2010.09.006; Brandt M, Foitzik S, Fischer-Blass B, & Heinze J (2005). The coevolutionary dynamics of obligate ant social parasite systems–between prudence and antagonism. Biological reviews of the Cambridge Philosophical Society, 80 (2), 251-267 PMID: 15921051; Hölldobler, B. & Wilson, E.O., 1990. The Ants, Harvard University Press.

11FELLERS, J., & FELLERS, G. (1976). Tool Use in a Social Insect and Its Implications for Competitive Interactions Science, 192 (4234), 70-72 DOI: 10.1126/science.192.4234.70.

12See, e.g., Pierce, J. (1986). A Review of Tool Use in Insects The Florida Entomologist, 69 (1) DOI: 10.2307/3494748.

13Mlot NJ, Tovey CA, & Hu DL (2011). Fire ants self-assemble into waterproof rafts to survive floods. Proceedings of the National Academy of Sciences of the United States of America, 108 (19), 7669-73 PMID: 21518911.

Elephant Insight

With each passing week, it seems like we’re finding out more and more about how smart elephants are. Now, in addition to their other cognitive abilities, it turns out that elephants can have “aha!” moments of insight as they face puzzling dilemmas. [No, not a-ha as in 1980s synth-pop from Norway; if you’re looking for an early MTV a-ha moment, you should probably go here!]

Elephants have the largest brains and the greatest volume of cerebral cortex of all terrestrial mammals. They live in elaborate matriarchal societies that include long-lasting relationships, close family bonds, and complex social groupings that change over time. They squabble and negotiate with each other over travel directions; they flirt, show empathy towards one another and solve problems cooperatively. They are one of the very few animals that can recognize themselves in mirrors (more about self-recognition testing here and here). True to their reputations, they have terrific memories, are adept at making and using tools, are logical thinkers, and even appear to mourn their dead in a “ceremonial” manner suggesting they may have a real awareness of the separate lives and experiences of other elephants.

Until now, however, on the few occasions when elephants have been tested for insightful problem solving abilities, they have been performed poorly. In these previous tests, the elephants failed to use their trunks in order to gain access to food treats that had been placed just beyond reach (for example, by using a stick grasped in the trunk to reach out for the food, or by pulling on a retractable cord with their trunks in order to reel in the food reward).

In a paper just published online on August 18th in PLoS ONE, a research team led by Preston Foerder and Diana Reiss of the City University of New York reported on its own revelation that led to a breakthrough in tests for elephant problem-solving insight. The researchers surmised that the problem with prior testing was not that elephants were incapable of insight, but rather that the tests had called for the elephants to act in ways that undermined their ability to use their trunks as effective sense organs during the task:

We believe that the problem in previous studies has been in treating the elephant trunk as a grasping appendage analogous to a primate hand. Although the trunk is a highly manipulable appendage, in food foraging its function as a sensory organ may take precedence. The elephant has an extraordinary sense of smell, and the tip of the trunk is as highly enervated as a human fingertip…. When a stick is held in the trunk, the tip is curled backwards and may be closed, prohibiting olfactory and tactile feedback…. We posit that previous failures to observe insightful problem solving in elephants is not indicative of a lack of cognitive ability but rather is due to the reliance on problem solving tasks that precluded the use of the trunk as a sense organ.

To address this issue, the researchers set up a series of experiments designed to allow elephants to keep their trunks free while facing problem-solving challenges. They tested three Asian elephants (Elephas maximus), two adult females and a 7-year-old juvenile male, at the Smithsonian National Zoo in Washington, DC, with the juvenile male, Kandula, soon emerging as the rock star problem-solver.

In the first experiment, the researchers dangled enticing fruit rewards from a cable they had placed across the elephant yard, including from positions that were just beyond trunk-reach. After leaving a large plastic cube and some other objects in the yard, they let Kandula into the yard for sessions to see whether he would figure out how to obtain the dangling food reward. While Kandula had previously played with the cube as an enrichment toy, he had no prior training in pushing large objects or in standing on them to reach for things.

During an initial six sessions, each lasting 20 some minutes, Kandula showed interest in the food dangling above his reach, played with the cube, moved it on several occasions, and once even stood on it briefly, but never tried to reach out for anything while standing on the cube.

Then, during the seventh session, Kandula suddenly had his moment of epiphany: he rolled the cube into position beneath the hanging food, stood on the cube with his front two feet, stretched out his trunk, and grabbed his prize.

Kandula - Insightful and Now Less Hungry Elephant

From then on, Kandula was off to the races. In the next session, he not only rolled the cube over and stood on it to reach the fruit again, he also started using the cube as a tool to reach other objects: e.g., standing on it to explore the inside of an enrichment object and, after rolling it to the edge of the yard, using it as a platform to reach for blossoms on an overhanging tree branch.

Moreover, Kandula showed he was able to apply his insight to new situations. For example, in a second experiment, the researchers used the same general setup, but began moving the cube around from place to place, including behind fences and in locations that Kandula couldn’t see as he entered the yard. In each case, Kandula found the cube and rolled it over to capture his food reward. Here’s a video of Kandula retrieving the cube from behind a fence:

Next, the researchers replaced the cube with a large tractor tire – in three of four sessions Kandula used the tire as a tool, rolling it to the proper place, and then standing on it to obtain the food reward.

In a final experiment, the researchers replaced the cube and the tire with a variety of other objects, including large plastic balls, discs, cones, a barrel lid and three cutting boards that would have to be stacked to form a platform for Kandula to reach the food. While Kandula didn’t stack all three boards (he did stack two, though), he experimented with various approaches such as standing with one foot on separate objects. Ultimately, he reached the food by standing on a plastic ball, a solution that surprised the researchers since he had never placed his weight on a similarly unstable platform before.

So, to summarize, Kandula demonstrated sudden insight – using a tool to solve a problem in a novel and spontaneous fashion, without evidence of prior trial and error learning. Further, he showed that he could repeat, transfer and extend his technique in subsequent sessions.

If you’re an elephant, please feel free to give yourself a pat on the back. Job well done!

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1Foerder, P., Galloway, M., Barthel, T., Moore, D., & Reiss, D. (2011). Insightful Problem Solving in an Asian Elephant PLoS ONE, 6 (8) DOI: 10.1371/journal.pone.0023251.

Sheep: Barnyard Brainiacs

It turns out that sheep are far more intelligent than their reputation for barnyard slowness would lead one to believe. In recent research published in PLoS ONE1, Professor Jenny Morton of the Department of Pharmacology at the University of Cambridge and her colleague Laura Avanzo reported that domestic sheep can perform extremely well on tests of designed to measure cognitive abilities, possibly as well as any animal other than primates.

Professor Morton, who had been studying Huntington’s disease, wanted to find out whether transgenic sheep with a specific genetic defect might be useful in preclinical research regarding potential treatments for this neurodegenerative disease. Because Huntington’s is characterized by cognitive deterioration, Morton was particularly interested in seeing how well sheep would perform cognitively, since suitable research subjects for neurologic disorders like Huntington’s inevitably must undergo systematic cognitive testing relevant to the disease.

Accordingly, Morton and Avanzo devised a series of tests that they gave to seven female Welsh Mountain sheep, six of whom completed the whole study. No word on why all of the ungulate volunteers were female, although my guess is that the males were off rollicking around with male bottlenose dolphins who were avoiding sponge fishing duty.

Welsh Mountain ewe: wool-giver and five-time Jeopardy champion (photo credit: Vertigogen)

The Tests

The tests were designed to measure the ability of the sheep to perform in three areas (discrimination learning, reversal learning and “attentional set-shifting”), which are relevant to what the researchers refer to as executive function – that is, the “ability to learn associations between stimuli, actions and outcomes, and to then adapt ongoing behavior to changes in the environment.” While the sheep took a large number of very specific tests, the tests fell into the following general categories:

  1. Simple discrimination tests. Sheep must choose between two feed buckets that are identical except one is blue the other is yellow. One color contains a food reward; the other is empty. Later “retention tests” repeat the original tests after time has passed to see how well the sheep remember.
  2. Simple discrimination reversal tests. Sheep must relearn the correct answer after sneaky researchers reverse the color of the bucket containing the food reward. (Note: we encountered this type of testing in the earlier AnimalWise post about the clever Anole lizards). Again, later “retention tests are given.
  3. Compound discrimination tests. The rewarded color is the same as in 1 above, but the relevantly-colored objects are now “perforated sports cones” rather than buckets. Additional buckets of irrelevant colors (one black, one green) are placed next to the sports cones, with the food reward in whichever bucket happens to be next to the correctly-colored sports cone.
  4. Intradimensional shift tests. Now, the sheep are presented with new shapes (rhomboids and cones) and new colors (purple and green). The sheep must still make a correct choice based on color, but need to learn the new color to apply.
  5. Intradimensional shift reversal tests. Same as 4, but sheep must relearn correct answer after the researchers change the rewarded color.
  6. Extradimensional shift tests. Again, the sheep are presented purple or green cones or rhomboids, but this time they must figure out now that the reward is based on choosing the correct shape, rather than a particular color.
  7. Extradimensional shift reversal test. Same as 6, but sheep must relearn after researchers swap which shape is rewarded.

Of the above tests, 1 & 3 measure “discrimination learning”; 2, 5 & 7 measure “reversal learning”; and 4 & 6 measure “attentional set-shifting.”

The Results

In a nutshell, the sheep did amazingly well.

They very quickly learned to pass the initial simple discrimination test (within seven sets of eight discriminations). When presented with the first reversal test, their performance initially dropped off, but they learned the new correct answer within three days of testing (11 sets of discriminations). For the compound discrimination testing, their performance again dropped slightly at the outset, but within two days they had this new puzzle figured out as well. Moreover, the retention tests showed that the sheep were able to remember the correct answer after time had passed (six weeks in the case of the simple discrimination test; two weeks for the simple reversal test).

At first, the sheep performed no better than chance on the more difficult intradimensional shift test, but they soon were performing at over 90% correct. They also experienced a large drop off in performance on the extradimensional shift test, but improved gradually until they reached 80% correct on the fourth day of testing. The sheep learned also were able to learn the reversals (within eight sets of discriminations for the intradimensional reversal and within 10 sets for the extradimensional reversal).

Morton and Avanzo summarized the results as follows:

We show that not only can normal can sheep perform discrimination reversal learning tasks, but they can also perform attentional set shifting tasks that test executive function. To our knowledge, this is the first time that these executive functions have been demonstrated in any large animal, apart from primates.

They were surprised by this success, conceding that they hadn’t been expecting the sheep to do well on the more difficult tests and indicating that they were “driven more by curiosity than expectation” in even giving the tests to them.

So, given these results, sheep seem to have gotten a bum rap for intelligence. There are relatively few studies on ovine intelligence, although research has shown that they can learn and remember how to navigate complex maze2 and that they are very good at remembering faces3.  And then there’s my favorite, that they’ve learned to roll their way across hoof-proof metal cattle grids in order to raid villagers’ valley gardens4!

One reason for the mistaken impression about sheep cognition may be that we have a bit of a blind spot when it comes to intelligence. We expect it in ourselves and a few other select animals, but even scientists can be quite surprised when it pops up elsewhere. Perhaps the main lesson here is that we should do our best to remain open to finding intelligence in unexpected places – if nothing else, this sort of a mental stretch will be a good test of our own cognitive abilities.

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1Morton, A., & Avanzo, L. (2011). Executive Decision-Making in the Domestic Sheep PLoS ONE, 6 (1) DOI: 10.1371/journal.pone.0015752.

2LEE, C., COLEGATE, S., & FISHER, A. (2006). Development of a maze test and its application to assess spatial learning and memory in Merino sheep Applied Animal Behaviour Science, 96 (1-2), 43-51 DOI: 10.1016/j.applanim.2005.06.001.

3Kendrick, K., da Costa, A., Leigh, A., Hinton, M., & Peirce, J. (2007). Sheep don’t forget a face Nature, 447 (7142), 346-346 DOI: 10.1038/nature05882.

4See, e.g., BBC News, “Crafty sheep conquer cattle grids,” July 30, 2004.

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