They’ll Take Two in the Bush – Crows and Ravens Show Patience

We live in an “act now!” world that frequently tests us, luring us with temptations and encouraging us to indulge. We may clearly see the importance of living within our budget yet still be dazzled by the shiny appeal of that new sports car; we may strongly believe in the benefits of a healthy diet yet still be weakened with lust for that large slab of double chocolate cake.

Nevertheless, we do sometimes succeed in delaying immediate gratification for the sake of something better in the future, in remembering those clichés about “good things come to those who wait” that our parents and grandparents inflicted on us. Undoubtedly, this is something we’re able to achieve because we’re humans, because we can be goal-directed and can prevail over our impulses, because we are more than unthinking animals who are captives to their immediate needs. Right?

Not so fast.

It is true that many animals seem unable to defer gratification, with prior experiments showing that animals such as rats, pigeons and chickens will rarely choose a delayed food reward over an immediate one, even if the delayed reward is much more attractive and the delay is only a few seconds. (From an evolutionary standpoint, this sort of impatience may make a lot of sense when an animal faces competition and future opportunities for food are unknown. “Life is uncertain, have dessert first!”)

To date, the major exception has appeared to be in primates: chimpanzees, bonobos, rhesus macaques and capuchin monkeys have demonstrated that they can wait for up to five minutes or so if that enables them to obtain a desirable food reward – a level of performance comparable to that of humans. (Interestingly, tests have shown that we humans seem to be much better at deferring money rewards than food rewards. Perhaps this, too, has a basis in natural selection, as food has been obviously always been an imperative, whereas money has existed for only an evolutionary blink of the eye.)

Also, while all of this might lead one to conclude that the ability to delay gratification lies solely within the province of humans and our closest relatives, it now turns out that corvids, the famously smart bird family (see prior AnimalWise posts here and here and here and here) that includes ravens and crows, may be every bit as patient.

When's dinner going to be ready? (from Wikipedia, photo credit: Cj005257)

As described in a paper published last week in Biology Letters, a team led by Valérie Dufour of the University of Strasbourg recently found that crows (Corvus corone) and ravens (Corvus corax) are able to tolerate delays of over five minutes in order to obtain a better reward, and that they may use the same sort of tactics to distract themselves while they wait as humans do.

In this study, six crows and six ravens were first trained to exchange tokens for food rewards, and then were given a series of “delayed exchange” tests. In each test, a bird would be handed an initial piece of food, which it could either eat immediately or, upon receipt of a signal after a designated waiting period, exchange for a more a desirable reward that it could see throughout the testing period. If the bird ate the initial reward or tried to exchange it too early, the test would end, but if it waited until the proper signal after the waiting period had elapsed – success, a better reward!

The researchers ran the tests with different types of reward (which they labeled as low-, medium- and high-quality) and with varying waiting periods (from 2 to 640 seconds).

Not surprisingly, the birds were generally more willing to exchange for the most highly preferred rewards and, as the following graphic illustrates, had a harder time as the delay period increased (with both crows and ravens maxing out at 320 seconds, or slightly over five minutes):

Interestingly, when the birds had to wait 20 seconds or longer before being able to exchange, they usually placed the “reward in the hand” on the ground and/or cached it in nearby crevices. The researchers believed this to be a distractive strategy, as “[t]hese behaviours probably alleviate the cost of waiting: not having to hold the food distracts the bird’s attention from it.”

As someone who routinely has to put snack food out of reach or even out of sight in order to prevent Homer Simpson-like devouring, this explanation makes a lot of sense to me. (For those of you who would prefer a more uplifting example of a strategy for avoiding temptation, I invite you to think about Ulysses having himself lashed to his ship’s mast so that he can safely listen to the songs of the Sirens.)

In any event, delaying gratification is significant because it involves, on some level, making a judgment about the future and the likelihood of achieving a prospective reward. While it’s not clear whether this entails a full “sense of self,” it is worth (re)noting that corvids are one of the few animals that have demonstrated the ability to recognize themselves in mirrors, a cognitive test that’s often used to measure whether an animal has at least rudimentary self-awareness.

Once again, corvids are no bird brains!

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ResearchBlogging.orgDufour V, Wascher CA, Braun A, Miller R, & Bugnyar T (2011). Corvids can decide if a future exchange is worth waiting for. Biology letters PMID: 21920957.

Rosati, A., Stevens, J., Hare, B., & Hauser, M. (2007). The Evolutionary Origins of Human Patience: Temporal Preferences in Chimpanzees, Bonobos, and Human Adults Current Biology, 17 (19), 1663-1668 DOI: 10.1016/j.cub.2007.08.033.

Heilbronner, S., & Platt, M. (2007). Animal Cognition: Time Flies When Chimps Are Having Fun Current Biology, 17 (23) DOI: 10.1016/j.cub.2007.10.012.

Grief in Animals

I’ve been thinking about grief lately. It can be so overpowering – the dull ache of emptiness, the stabbing pain of loss, and the prism of sadness that transforms the bright colors of everyday life into a harsh and alien landscape. Consumed by grief, we are alone; yet somehow our solitary suffering can end up strengthening the bonds we have with others we know and love.

I’ve also been thinking about grief in animals, and what we know about it. When our cat Puggsley died, our younger Siamese, Moose, felt the full impact of the loss. The two had always been close, perhaps tied together by their mutual skepticism over Wednesday, our third cat and official people-pleaser. Moose and Puggsley were constant companions, playmates, napping buddies, and a rather frightening pair of mischief makers. When Puggsley became old and frail, he would curl up stiffly by the fireplace, and Moose would bed down near him. At the very end, Moose was right there, tenderly licking Puggsley as he was overcome by a seizure. And after he was gone, she mourned – she was lost without her friend, and had little appetite or energy for weeks. She never bedded down by the fireplace again. How do I know this was grief? Well, it was obvious; I just know.

Puggsley and Moose

But what do we really know about grief in animals – that is, in a scientific sense? Not particularly much, it turns out.

We are (mostly) beyond the era in which animals were considered thoughtless automatons, incapable of feeling pain and other emotions. Still, there have been relatively few formal studies of how animals experience grief.

In a way, this isn’t so surprising. For one, opportunities to systematically observe grieving behavior in the wild are rare and, if you think about it, it’s difficult to design ethical studies intended to cause social animals to grieve in captive settings. Also, what specifically do you test for and how do you quantify and evaluate an inherently subjective experience like grief? It’s tough enough to evaluate this sort of thing in humans, who can respond to questionnaires and use language to express their emotions….

As a result, most the scientific literature about grief in animals is anecdotal or observational in nature, and in many of these accounts it’s clear that otherwise objective researchers have struggled to come up with scientific ways of reporting what, in the end, are their own reactions, what they just know.

Although the record is sparse everywhere, there have been some recent papers on grief in primates. Brian Switek, who writes the Laelaps blog for Wired Magazine, has written a terrific piece on this research in his “What Death Means to Primates” posting (I strongly encourage you to check out Laelaps; it’s one of the best blogs out there on paleontology, evolution, and the history of science).

As Brian recounts in detail, studies have documented chimpanzee and other primate mothers who have continued to carry dead infants, sometimes for weeks and even to the point of mummification. In one of the studies1, researchers described two chimpanzee mothers (Jire and Vuavua) in Bossou, Guinea, who carried their dead babies (aged 1.2 years old and 2.6 years old, respectively) after they had died in a respiratory epidemic, grooming them regularly, chasing away flies, and carrying them during all travel. The researchers pondered:

An obvious and fascinating question concerns the extent to which Jire and Vuavua “understood” that their offspring were dead. In many ways they treated the corpses as live infants, particularly in the initial phase following death. Nevertheless they may well have been aware that the bodies were inanimate, consequently adopting carrying techniques never normally employed with healthy young (although mothers of handicapped young have also been known to respond appropriately).

In another study2, James Anderson, Alasdair Gillies and Louise Lock reported on the peaceful death of an older chimpanzee, Pansy, who lived in a safari park. They videotaped the reactions of Pansy’s companions and observed a number of behaviors that they found to be comparable to human bereavement. The degree to which the researchers sought out human counterparts to the chimps’ behavior is evident from the following description in their paper:

During Pansy’s final days the others were quiet and attentive to her, and they altered their nesting arrangements (respect, care, anticipatory grief). When Pansy died they appeared to test for signs of life by closely inspecting her mouth and manipulating her limbs (test for pulse or breath). Shortly afterwards, the adult male attacked the dead female, possibly attempting to rouse her (attempted resuscitation); attacks may also have expressed anger or frustration (denial, feelings of anger towards the deceased). The adult daughter remained near the mother’s corpse throughout the night (night-time vigil), while Blossom groomed Chippy for an extraordinary amount of time (consolation, social support). All three chimpanzees changed posture frequently during the night (disturbed sleep). They removed straw from Pansy’s body the next morning (cleaning the body). For weeks post-death, the survivors remained lethargic and quiet, and they ate less than normal (grief, mourning). They avoided sleeping on the deathbed platform for several days (leaving objects or places associated with the deceased untouched).

With this focus, it’s not surprising that they concluded by proposing that “chimpanzees’ awareness of death has been underestimated.”

Also, more anecdotally, many were moved by the apparent grief captured in this poignant National Geographic photo of chimpanzees at a rehabilitation center peering at the lifeless body of Dorothy, their long-time companion, being taken to her burial:

Chimpanzee burial (National Geographic, photo: Monica Szczupider)

There has also been some research into the behavior of elephants towards the dead and dying. In one study3, Iain Douglas-Hamilton, Shivani Bhalla, George Wittemyer and Fritz Vollrath reported on the death of Eleanor, a matriarch elephant in the Samburu National Reserve in Kenya. They were able to use GPS technology to track the movements of elephants in Eleanor’s family and in other families as they reacted to her collapse and subsequent death. The researchers found that Eleanor was visited frequently by both related and unrelated elephants, concluding:

Combined with earlier work and the data of other scientists it leads to the conclusion that elephants have a generalized response to suffering and death of conspecifics and that this is not restricted to kin. It is an example of how elephants and humans may share emotions, such as compassion, and have an awareness and interest about death.

Grace visiting Eleanor's body (photo: Douglas-Hamilton, et al)

In another paper4, Karen McComb, Lucy Baker and Cynthia Moss described experiments in which they assessed elephants’ strong interest in and sometimes dramatic reactions to elephant bones and tusks. After systematically presenting elephants in Amboseli National Park in Kenya with different combinations of elephant and other animal skulls, ivory and pieces of wood, the researchers found that the elephants were significantly more interested in elephant skulls and tusks than they were in the skulls of other animals or in the wood, but that they did not demonstrate a special affinity to the skulls or ivory of deceased relatives. The following video provides a nice glimpse into the way in which elephants seem to be fascinated by elephant bones and tusks:

Several reports have also documented cetaceans reacting with apparent grief. In one report5, for example, Mark Simmonds described an incident in which two male orcas appeared to grieve over the death of a female orca thought to be their mother. For years, the two males had spent all their time swimming with this female. After her death, the males were seen swimming together but apart from all other orcas for a day or two, repeatedly visiting the places that their mother had passed in her last few days. In another instance, Robin Baird of the Cascadia Research Collective reported seeing two orcas, a mother and adult son, swimming with a dead calf in the Puget Sound, with the mother balancing the calf on her rostrum or carrying it on top of her head and occasionally lifting it out of the water, and both adults diving deep to recover the baby when it began sinking.

Dolphin and calf (Tethys Research)

Scientists at the Tethys Research Institute related a similar occurrence off the coast of Greece, where a mother bottlenose dolphin was seen interacting with a dead newborn calf. Their description vividly underscores the difficulties in evaluating these sorts of situations from a scientific perspective:

Whilst researchers must avoid being driven by their own feelings and make arbitrary interpretations, in this case it was quite clear that the mother was mourning. She seemed to be unable to accept the death, and was behaving as if there was any hope of rescuing her calf. She lifted the little corpse above the surface, in an apparent late attempt to let the calf breath. She also pushed the calf underwater, perhaps hoping that the baby could dive again. These behaviours were repeated over and over again, and sometimes frantically, during two days of observation.

The mother did never separate from her calf. From the boat, researchers and volunteers could hear heartbreaking cries while she touched her offspring with the rostrum and pectoral fins. Witnessing such desperate behaviour was a shocking experience for those on board the research boat.

Finally, Marc Bekoff (he of the Yellow Snow fame) has written an eloquent article that includes many additional anecdotes regarding animal grief in his Psychology Today column.

Ultimately, there is much we will never be able to understand regarding how animals experience the world. We can trace commonalities between human and other animal brain structures and neural pathways associated with emotional experiences, and we can try to add more systematic observations to our collection of behavioral anecdotes, but in some fundamental ways the animal mind (and, for that matter, the mind of other humans) will always be cloaked in private experience, inaccessible to us. Moreover, as some of the accounts in this post have illustrated, our attempts at understanding animal emotions are inevitably colored by our own human experiences. We can know human grief, but how can we understand what it means to experience chimp grief, or elephant grief, or orca grief?

Nevertheless, just because we cannot fully comprehend what we see in other animals, that does not mean that grief in animals does not exist or that animals cannot lead rich emotional lives. Indeed, what we do see is a pattern that makes it increasing clear that death can impact other animals profoundly.

How do I know this? Just ask Moose, Puggsley or Wednesday – I just know.

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ResearchBlogging.org1Biro, D., Humle, T., Koops, K., Sousa, C., Hayashi, M., & Matsuzawa, T. (2010). Chimpanzee mothers at Bossou, Guinea carry the mummified remains of their dead infants Current Biology, 20 (8) DOI: 10.1016/j.cub.2010.02.031.

2Anderson, J., Gillies, A., & Lock, L. (2010). Pan thanatology Current Biology, 20 (8) DOI: 10.1016/j.cub.2010.02.010.

3Douglas-Hamilton, I., Bhalla, S., Wittemyer, G., & Vollrath, F. (2006). Behavioural reactions of elephants towards a dying and deceased matriarch Applied Animal Behaviour Science, 100 (1-2), 87-102 DOI: 10.1016/j.applanim.2006.04.014.

4McComb, K., Baker, L., & Moss, C. (2006). African elephants show high levels of interest in the skulls and ivory of their own species Biology Letters, 2 (1), 26-28 DOI: 10.1098/rsbl.2005.0400.

5Simmonds, M. (2006). Into the brains of whales Applied Animal Behaviour Science, 100 (1-2), 103-116 DOI: 10.1016/j.applanim.2006.04.015.

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.

Multi-Modal Monkey Memory

Recognizing someone you know is actually not a simple cognitive task – it requires you interpret the information you’re currently receiving through your senses, and then link back to a previously-formed conceptual representation you have of the individual in question. It’s especially difficult if you are acting cross-modally, for example matching someone’s voice to a photograph or vice versa.

Oh yeah, I remember him. He's the one with the high squeaky voice, isn't he? (photo credit: Joe Kegley)

Recently, two separate studies have shown that rhesus macaque monkeys (Macaca mulatta) are quite up to this challenge, reflecting that they possess a considerable degree of social memory and engage in complex conceptual thinking about other individuals.

French Pictures

In the first study1, published earlier this year in Proceedings of the National Academy of Sciences, a French research team headed by Julian Sliwa of the University of Lyon confirmed that rhesus macaques are able to spontaneously match the faces of known macaques and humans to their voices.

In their experiments, the research team gave six macaques a large number of tests in which they played short voice samples of known individuals (coos and grunts for other macaques, short French sentences and phrases for humans) and then measured how long the macaques spontaneously looked at cropped photographs of two known faces, only one of which matched the voice they had heard. The researchers statistically analyzed whether the macaques spent more time looking at specific photos after hearing the matching voice than they did after hearing a different voice, and found that the macaques did indeed stare significantly longer at a photo – whether of another macaque or a human – if the matching voice had been played first.

In reviewing individual performance, the researchers observed that five of six of the macaques displayed this effect overall, and that a greater number were better at recognizing photos that matched human voices than ones matching the voices of fellow macaques (the researchers noted that they were surprised at this finding, but pointed out that perhaps the explanation was that there were more useful auditory cues in the human speech samples than there were in the monkey coo vocalizations). Finally, the researchers found that five of the six monkeys showed preferences for specific faces, spending an especially long time looking at matching” photos of certain individuals – often a “neighbor” monkey or the researcher who was their main caregiver.

The researchers concluded that rhesus macaques can recognize individuals, linking together abbreviated visual and auditory perceptual cues (small, two-dimensional photos and short sound samples) to spontaneously identify other macaques and socially-relevant humans, and even to reflect the preference biases they have towards specific individuals.

At the Movies

The second study2, published last week in PLOS ONE, extended the findings to show that rhesus macaques can also recognize photos of other macaques whom they had seen during video clips, an additional challenge because specific features can be harder to identify in dynamic movies than in still images.

In this study, researchers led by Ikuma Adachi of the Yerkes National Primate Research Center began by training five macaques to watch brief silent video clips of familiar individuals before identifying which of five randomly placed photos represented the individual in the video. At first the macaques were allowed to continue to look at the last frame of the video before having to choose the correct photo, but in a second phase of the experiment the screen went black after the video was played, and the monkeys had to choose the correct photo after a time lag.

In each case the macaques became proficient at the task, even performing well after seeing videos taken from a novel perspective that was substantially different than the view in the training videos. Thus, their performance suggested that they were able to recognize specific features of known individuals as they appeared in dynamically-changing scenes in a range of videos, and then extract that information to identify those individuals later on in still images.

Next, the researchers repeated the testing, but this time they tweaked the conditions by playing a brief vocalization right after showing the last frame of the some of the videos – either a vocalization of the macaque in the video (the “congruent condition”) or of a different macaque (the “incongruent condition”). Only two of the macaques participated in this testing, as apparently the other three weren’t comfortable with working in the sound isolation booth necessary for this phase.

The researchers found that the macaques, who had never been trained to use vocalizations to guide their test responses, continued to be good at choosing the “correct” photo, but that when they made errors, they were statistically more likely than chance to pick the image of the vocalizing monkey, rather than the one in the video.

In other words, hearing the vocalizations systematically biased the macaques’ choice behavior, indicating that the voices may have activated visual representations of the vocalizing monkeys that occasionally superseded the impact of what had been seen in the video. Again, the macaques were demonstrating how they processed the information they used to recognize information cross-modally.

So, clearly “see no evil” is linked to “hear no evil” – perhaps we’ll see how “speak no evil” fits into the picture in a later post.

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ResearchBlogging.org

1Sliwa J, Duhamel JR, Pascalis O, & Wirth S (2011). Spontaneous voice-face identity matching by rhesus monkeys for familiar conspecifics and humans. Proceedings of the National Academy of Sciences of the United States of America, 108 (4), 1735-40 PMID: 21220340.

2Adachi, I., & Hampton, R. (2011). Rhesus Monkeys See Who They Hear: Spontaneous Cross-Modal Memory for Familiar Conspecifics PLoS ONE, 6 (8) DOI: 10.1371/journal.pone.0023345.

Grandmothers and Menopause in Cetaceans and Humans

As single income families become rarer and aging baby boomers begin to play a greater role in caring for their grandchildren, people have increasingly come to appreciate how much help a doting grandmother can provide. In fact, interest in the helpful role played by the elderly has given rise to the so-called grandmother hypothesis, which posits that women have evolved to live well past their reproductive years because, free from the costs of childbearing, they are able to invest more time into benefiting their grandchildren and other younger family members, raising the odds that their genes will be carried on to future generations.1 While the strength of the evidence for the grandmother hypothesis is still being debated2, it’s certainly got some intuitive appeal (especially, perhaps, to harried young parents).

What’s also quite fascinating is that the long post-reproductive life of human females – up to a third of a woman’s lifespan or more – is extremely rare: menopause appears to be unique to humans and (somewhat controversially) certain other great apes, as well as to certain toothed whales, including short-finned pilot whales and killer whales. (It’s possible that other species of cetacean may undergo menopause, but this hasn’t been established yet; also, more to come about elderly elephant matriarchs in a later post…)

To grandmother's house I go! (Photo: © Alice MacKay, Cascadia Research)

So, why is post-reproductive life is so rare? If the grandmother hypothesis applies to great apes and toothed whales, why isn’t it at work with other long-lived animals who live in socially-cooperative societies? Also, if evolution favors post-reproductive life because it provides distinct social advantages, why did menopause evolve in humans and toothed whales, given the very different social structures of humans and whales?

A fascinating study published last year in Proceedings of the Royal Society B3 by Rufus Johnstone of the University of Cambridge and Michael Cant of the University of Exeter may offer plausible answers to these questions.

In a nutshell, they found that, although humans, pilot whales and killer whales have quite different social systems, in each case older females become, on average, more genetically related to those with whom they associate. By contrast, in most other long-lived complex mammal societies, older females become increasingly less related to those in their local groups as they age.

Did grandma pinch you on the cheek too? (photo credit: NOAA)

The researchers began by developing a mathematical model that would allow them to draw general conclusions about age-related changes in the genetic relatedness of long-lived social animals as individual group members disperse, die and are replaced over time. (For those interested in such things, they based their approach on the “infinite island” model that is commonly used in considering the process of gene flow among a set of subpopulations.)

With their model in hand, the researchers analyzed three relevant social scenarios:

  1. Males Move On. In the large majority of social animal societies, males tend to move on as they mature, ultimately mating with unrelated females they find within new social groups. In this type of society, the researchers’ model determined that, over time, an older female will become less related to her group mates as she ages. She starts out in a highly related group that includes her father, but over time her older male relatives die, and her sons, and the sons of her relatives, leave the group and are replaced by unrelated males from other groups. Her average genetic relationship to the females in the group doesn’t change much, but since her relatedness to local males declines, overall her genetic connection to the group lessens as she gets older.
  2. Females Move On. Conversely, evidence suggests that during the course of human evolution, women were the ones that were more likely to move on to start families in new environments. (In support of this proposition, Johnstone and Cant cite the behavior of other great apes, human DNA variation patterns, and social patterns among human forager societies, evidence they concede is “far from conclusive.”) In this type of society, where males stay at home and females disperse, an older female tends to become more related to her fellow group members over time. She begins her reproductive life in new surroundings where she has few genetic ties to those around her, but as she produces sons who are likely to remain in the group, her relatedness to local males builds up over time. Again, because the degree of her relatedness to other females stays fairly constant – she starts out with little relation to the females in her new group and this doesn’t change much as her daughters leave and are replaced by new unrelated females – her overall genetic connection to the group increases as she ages.
  3. Males and Females Stay Put, But Mating Occurs Between Different Groups. In the resident killer whale and pilot whale societies studied, males and females stay with their natal groups for life, but mating occurs non-locally, that is, between females and males from other groups. In this final scenario, even though the social structure is quite different from “female moves on” societies, the results are the same: an older female tends to become more related to her fellow group members over time. A female begins her reproductive life separate from her father and her paternal relatives (who belong to a different group), but as she has male offspring her relatedness to males within her group grows over time. Once again, her relatedness to other females stays more or less constant, meaning that her overall genetic affinity with her group increases as she grows old.

Thus for human and certain whale societies, in contrast to most other social animal groupings, a female’s relatedness to her group increases as she becomes older.

Johnstone and Natal next considered the fitness costs of reproduction. They noted that having children imposes costs on other breeders within one’s group due to increased competition for food, resources and mating opportunities, whereas cessation of reproduction confers a benefit, due to a corresponding reduction in competition. Then, using a using a statistical model involving an “inclusive fitness” approach to generate quantitative results for the three scenarios described above, they reached a not-surprising conclusion: in scenario 1 (males move on), it is less advantageous for older females to “help” younger generations by stopping their own breeding, whereas in scenarios 2 and 3 (the human and toothed whale scenarios), non-breeding “help” is favored by evolution, as it confers advantages on a younger generation that is progressively more related to the older helper.

So there you have it. Does Johnstone and Natal’s analysis sound plausible? It certainly offers a neat way of finding an underlying similarity in great ape and whale societies that may explain menopause and support the grandmother hypothesis in these very distinct groups.

No wonder cetaceans often look like they’re grinning – they’ve been spoiled by their grandmothers!

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ResearchBlogging.org1See, e.g., Lahdenperä, M., Lummaa, V., Helle, S., Tremblay, M., & Russell, A. (2004). Fitness benefits of prolonged post-reproductive lifespan in women Nature, 428 (6979), 178-181 DOI: 10.1038/nature02367; Shanley, D., Sear, R., Mace, R., & Kirkwood, T. (2007). Testing evolutionary theories of menopause Proceedings of the Royal Society B: Biological Sciences, 274 (1628), 2943-2949 DOI: 10.1098/rspb.2007.1028.

2See, e.g., Kachel, A., Premo, L., & Hublin, J. (2010). Grandmothering and natural selection Proceedings of the Royal Society B: Biological Sciences, 278 (1704), 384-391 DOI: 10.1098/rspb.2010.1247.

3Johnstone, R., & Cant, M. (2010). The evolution of menopause in cetaceans and humans: the role of demography Proceedings of the Royal Society B: Biological Sciences, 277 (1701), 3765-3771 DOI: 10.1098/rspb.2010.0988.

The Honeybee Waggle Dance – Is it a Language?

The Dance

More than half a century ago, Karl von Frisch rocked the world of behavioral biology with his conclusion that the honeybees (Apis mellifera) can actually communicate the distance to and direction of valuable food sources through an elaborate “waggle dance.” In what later led to his receipt of the Nobel Prize in Physiology or Medicine, von Frisch determined that bees recruited by this dance used the information encoded in it to guide them directly to the remote location of the resource.

In the typical waggle dance, a foraging worker bee who has found by a rich food source returns to the hive, is greeted by other bees, and commences dancing on the vertical comb surface within the dark nest (in other species of bee, like Apis florea, the dance is performed on a horizontal surface in direct view of the sun and/or other landmarks). She dances in a figure-eight pattern, alternating “waggle runs,” during which she vigorously waggles her body from side to side in a pendulum motion at about 13 times per second as she moves forward in a straight line, with return phases in which she circles back to the approximate starting point of the previous waggle run, alternatingly between clockwise and counter-clockwise returns. Here’s a video of a bee doing the waggle dance:

As the video indicates, the honeybee’s dance encodes key information about the resource. For instance, as she performs waggle runs on the vertical comb surface, her average body angle with respect to gravity corresponds to the direction of the food source relative to the current position of the sun (the sun’s azimuth). Accordingly, if the food source lies in the exact direction of the sun, she will waggle straight upwards; if the food lies, say, 30 degrees to the right of the imaginary line to the sun, she will angle upwards 30 degrees to the right of vertical. Also, the duration of her waggling runs is directly linked to the flight distance from the hive to the food source, with (for many bee subspecies) every extra 75 milliseconds of waggling adding roughly another 100 meters to the distance. Further, the more attractive the destination, the longer and more vigorously she dances, and the more quickly she returns for the start of each waggle run. Depending on the richness of the food source, she may perform up to 100 waggle runs in a single dance.

Next week ... the Tango!

Cognitive Complexity

It seems, then, that honeybees have evolved an extraordinary complex form of symbolic communication about distant resources, one that is beyond the capabilities of virtually every other species except for humans. Not bad for an insect.

The cognitive tasks implicated by the waggle dance are not insignificant: the dancer must remember the location and characteristics of a specific site she has seen on her foraging trips, and translate this information into the appropriate dance characteristics. She must also remember and take into account the position of the sun, and update that position as the sun moves (the ability to compensate for the sun’s movement by memory has been documented by researchers observing dances over several hours of overcast weather, when there are no celestial cues to be seen). The observing bees must “read” the dance, translate their sensory input into a resource location, and then find the resource, navigating as necessary around hills, houses and other obstacles.

In fact, the feat is so stunning that von Frisch’s findings were initially met with significant skepticism and controversy.1 At this point, the controversy has essentially been settled, with scientists recognizing that there is compelling evidence that honeybees really do communicate and act on the information encoded in the waggle dance, even though uncertainty remains regarding exactly which signals (tactile, odor, vibrations, air flows, etc.) the observing bees use to translate the dance into actionable information regarding the resource location.2

Is the Waggle Dance a “Language”?

So, the waggle dance is an extremely complex communication system, but is it a language?

Eileen Crist, Associate Professor in Science and Technology in Society at Virginia Tech, makes a rather compelling case that the waggle dance embodies many of the attributes of a true language.3 After noting that the waggle dance is always performed in front of an audience and is clearly communicative in nature, she describes some of the principal features that support its being characterized as a language:

  1. Rule-Governed. If a communication system is to be considered linguistic in nature, it generally must be based on a set of rules that are structured and used with regularity. This is the case with the waggle dance: the dance is always performed in a designated place within the hive, it is never done unless an audience is present, and it always follows a standard template for conveying direction, distance, and desirability. While the general rule is that the waggle dance is to be used to inform other bees about sources of nectar, when the colony has a special requirement (e.g., locating water when the hive is overheating or finding a new home when part of the colony must relocate) then the rules dictate that the dance purpose switches to this pressing need. Also, the general rule is that foragers dance about rich, reliable and near resources, but in times of need the “dance threshold” for less desirable resources is lowered.
  2. Complexity. A key dimension of a true language is its complexity, as it is unlikely that a communication system based on just a few rules will qualify as a language. The bee dance rules are not only extremely intricate, but they are applied in a versatile and complex fashion to respond to differing environmental factors and hive requirements.
  3. Stability and Dynamism. A core feature of human language is that a relatively fixed and stable syntax enables the dynamic generation of an indefinite number of new sentences. Similarly, while the waggle dance always takes the same recognizable forms, it “accommodates different purposes, shifting circumstances, urgent needs, and unprecedented events; while structurally identical every time, it is also contextually flexible.”
  4. Symbolic. By itself, the symbolic nature of the waggle dance has led to its being called a language. The dance symbolically represents conditions existing in the real world, actually enabling human researchers to “read” the information encoded in the dance to find specific honeybee food sources and even to design experiments about honeybee foraging behavior.
  5. Performative. According to linguistic theory and as first articulated by John Austin, languages not only describe the world, they also include what he called “performative” utterances, which are used to carry out actions.4 Not only is the waggle dance symbolically descriptive, but it has performative force in the sense that it elicits action from the bees who watch it (as Crist notes, the performative nature of the waggle dance is implicit in the way in which scientists “routinely deploy a vocabulary of announcing, reporting, summoning, recruiting, soliciting, inviting, commanding, and guiding” in describing it).

James Gould, Professor of Ecology and Evolutionary Biology at Princeton University, summarized both the controversy over the issue and the nature of honeybee dance communication as follows:

Some of the resistance to the idea that honey bees possess a symbolic language seems to have arisen from a conviction that “lower” animals, and insects in particular, are too small and phylogenetically remote to be capable of “complex” behavior. There is perhaps a feeling of incongruity in that the honey bee language is symbolic and abstract, and, in terms of information capacity at least, second only to human language.5

Gould estimates that the waggle dance is capable of communicating at least 40 million unique messages (“sentences”), more than 10 times as many as any other animal except for man.6

Not surprisingly, not everyone agrees that the waggle dance constitutes a true language. For example, Stephen Anderson, Professor of Linguistics at Yale University, acknowledges that honeybee dance communication is elaborate and cognitively rich, but concludes that it is unlike human natural language in that, for example, it is genetically fixed rather than learned through environmental interactions, it lacks a syntax in which the order of the communicative elements (words or actions) impacts meaning, and there is a close correspondence between the structure of the dance signals and the nature information to be conveyed (e.g., orientation of the waggle run and the direction to the resource).7

Some bees are better at the dance than others...

To Bee or Not to Bee

In the end, there will probably always be debate and disagreement over whether the waggle dance is a true language. Clearly, the waggle dance and human language are vastly different communication systems, and how we label the waggle dance in human terms may be missing the point. From the honeybee standpoint, the dance serves its purposes and contains all of the communicative nuances that the bees need within their environment. Maybe, the real point is that we should sit back and appreciate the fact that the honeybee, a small insect with tiny brain, has been able to evolve a system of communications that is so sophisticated that it has challenged human linguists to wrestle with the question of what distinguishes a true language and whether human language is really so unique.

Anyhow, time to stop droning on and sign off!

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1See, e.g., Gould, J. (1975). Honey bee recruitment: the dance-language controversy Science, 189 (4204), 685-693 DOI: 10.1126/science.1154023.

2See, e.g., Landgraf, T., Rojas, R., Nguyen, H., Kriegel, F., & Stettin, K. (2011). Analysis of the Waggle Dance Motion of Honeybees for the Design of a Biomimetic Honeybee Robot PLoS ONE, 6 (8) DOI: 10.1371/journal.pone.0021354; Gil, M., & De Marco, R. (2010). Decoding information in the honeybee dance: revisiting the tactile hypothesis Animal Behaviour, 80 (5), 887-894 DOI: 10.1016/j.anbehav.2010.08.012.

3Crist, E. (2004). Can an Insect Speak?: The Case of the Honeybee Dance Language Social Studies of Science, 34 (1), 7-43 DOI: 10.1177/0306312704040611.

4Hymes, D. (1965). : How to Do Things with Words . John L. Austin. American Anthropologist, 67 (2), 587-588 DOI: 10.1525/aa.1965.67.2.02a00970.

5Gould, J. L. Ibid. at 692.

6Gould, J. L. Ibid. at note 37.

7Anderson, S. R. 2004. Doctor Dolittle’s delusion: Animals and the uniqueness of human language. New Haven, Conn.: Yale University Press. ISBN-13: 978-0300115253.

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.

The “Yellow Snow” Test for Self-Recognition

The Mirror Self-Recognition Test

The mirror self-recognition (MSR) test has long been used to assess whether an animal is self-aware, whether it has a sense of self. In the classic version of the test, a colored mark is placed on an animal’s body in such a way that it can only be seen in a mirror. To pass the test, the animal must spontaneously use the mirror to detect the mark and then scratch or otherwise direct activity toward it, thereby indicating recognition of the image in the mirror as itself and not some other animal.

Not only is self-recognition considered to be an indication of higher cognitive functioning, but it has also been seen as a potential springboard to even more sophisticated abilities, such as being able to attribute mental states to other individuals (sometimes referred to as “theory of mind”).

To date, only a relatively few animals have passed the MSR test, including certain primates, dolphins, elephants, and, as we saw in a prior post, magpies.

But is the test itself biased? We humans rely heavily on our eyesight and may naturally – anthropocentrically – have settled on a test that is based on visual interpretation.

What about animals who rely more on their sense of smell – dogs, for instance? Well, Marc Bekoff, Professor Emeritus of Ecology and Evolutionary Biology at the University of Colorado, Boulder, wondered about this too.

The Yellow Snow Test

Over a five year period, Bekoff performed a study1 in which he diligently tracked the behavior of his own dog, Jethro, when Jethro encountered clumps of snow saturated with his own and other dogs’ urine (“yellow snow”) while walking freely along a bicycle path in Colorado on winter mornings.

Snow pile, snow pile, on the ground, who’s the finest smelling hound? (photo: Walter Jeffries)

Bekoff would wait until Jethro (a neutered male German Shepherd and Rottweiler mix) or other known female and male dogs urinated on snow, and then scoop up the clump of yellow snow as soon as Jethro was elsewhere and did not see him pick it up or move it (Bekoff used clean gloves each time and took other precautions to minimize odor and visual cues). Bekoff then moved the yellow snow varying distances down the path so that Jethro would run across the displaced urine: (i) within about 10 seconds, (ii) between 10-120 seconds later, or (iii) between 120-300 seconds later. After Jethro arrived, Bekoff recorded how long he sniffed at the yellow snow, whether he urinated over it using the typical male raised-leg posture, and whether urination immediately followed the sniffing (“scent marking”).

After compiling and statistically analyzing the data, Bekoff found that Jethro paid significantly less attention to his own displaced urine than he did to the displaced urine of other dogs. For example, when Jethro encountered the yellow snow within 10 seconds, he sniffed for longer than 3 seconds only about 10% of the time when it was his own urine, compared to over 80% of the time when it was other dogs’ urine. (Jethro did tend to have longer sniffs at his own urine when he arrived after more than 10 seconds, but in all scenarios he still sniffed significantly longer at the other dogs’ urine.) Likewise, he very rarely urinated over or scent-marked his own yellow snow, but frequently did so with the yellow snow of other dogs, particularly other males.

The following table summarizes the data collected (note that the reference to “120-150s” in the Arrives column appears to be erroneous, and should instead read “120-300s”):

In sum, Jethro’s behavior clearly demonstrates that he was able to discriminate the scent of his own urine from that of other dogs. Of course this is just one set of tests on one dog, but would it surprise anyone if other dogs showed similar abilities?

Is there a fundamental difference between an animal recognizing its own image in a mirror and one recognizing its own scent in yellow snow? There certainly are different cognitive process involved (Bekoff himself has suggested that the yellow snow test may be more indicative of a sense of “mine-ness” in dogs than of a sense of “I-ness”2).

At a minimum, though, the yellow snow test stands as a useful warning that we humans need to be careful not to make quick judgments about animal intelligence or cognitive capacity (or lack thereof) based on tests that are well-suited to humans, but that fail to match the skills and abilities of the particular animal.

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1Bekoff, M. (2001). Observations of scent-marking and discriminating self from others by a domestic dog (Canis familiaris): tales of displaced yellow snow Behavioural Processes, 55 (2), 75-79 DOI: 10.1016/S0376-6357(01)00142-5.

2Bekoff, M. Considering Animals—Not “Higher” Primates. Zygon 38, 229-245 (2003).

Be Kind to Cattle

The AnimalWise Soapbox

In a more ideal world, cattle would be free to lead lives consistent with their ancestry as nomadic grazers covering wide ranges. Of course, this isn’t a perfect world, particularly for the cows and other farmyard animals whose entire existence we have repurposed into the provision of meat and dairy products.

Without wading too deeply into the morass of moral issues raised by how we humans have transformed the environment and put other animals to work to serve our needs, it’s pretty clear that we have assumed a responsibility for the well-being of these animals who depend on us for everything.

Now, jumping down from the soapbox, what’s interesting is that, even if we were to disavow any ethical obligation to our bovine helpers, research continues to underscore how much it is in our own selfish interest to treat them with kindness and care.

A Cow by Any Other Name…

For example, one recent study1 that enjoyed some popular press attention found that named cows were better milk providers. That’s right, cows with names.

Uh oh, here comes what's-his-name...

In this study, researchers led by Catherine Bertenshaw and Peter Rowlinson of Newcastle University sent a detailed survey to every fourth dairy farm in England and Wales (1,000 in total), asking, farmers a number of questions regarding their attitudes toward cattle, how they managed dairy herds, and their perceptions of cows’ emotional and cognitive capacities. The response rate was 56% (52% after weeding out respondents who had recently ceased farming), with 90% coming from experienced stock managers who had worked with cattle for more than 15 years.

As noted above, cows don’t appear to enjoy toiling away in obscurity. On 46% of the surveyed farms, cows are called by name, and these cows produced an average of 258 liters more of milk per 10 month lactation period than did their anonymous peers (7938 liters versus 7680 liters). Moreover, on farms where the stock manager thought it important to know every individual animal, heifers had a 197 liter higher average milk yield over their first lactation than on farms where the manager thought it wasn’t important (6931 liters versus 6734 liters).

Does this mean that cows recognize their own names and appreciate it when they hear themselves being singled out?

While this is possible, the more likely explanation is that farmers who name and individually recognize dairy cows are more likely to treat them well. Bertenshaw and Rowlinson cite previous research finding attitude to be a reliable predictor of a person’s behavior around animals and that those having a positive attitude towards cows are “likely to handle animals patiently, to believe that regular positive contact is important, and to show positive behaviors towards the cows.”

Overall, the survey results indicate that – at least from the farmers’ perspective – there is a relatively positive relationship between dairy cows and stock persons on UK farms. Ninety percent of the respondents thought that cows had “feelings,” only 21% believed that dairy cattle were fearful of humans, and 78% thought cows were intelligent. (It would be interesting to see what percent think that their human coworkers were intelligent.) Also, on a somewhat reassuring note, 44% gave “love of cows” as a reason why they chose to work with cows.

Obviously, this is a subjective survey from one viewpoint (no word on when the cows will be receiving their questionnaires), but it provides important insight into the importance of our nurturing our relationships with other animals … and lessons that will serve us well when the Revolution comes (hilarious Dana Lyons video below):

♫  ♫  We will fight for bovine freedom, and hold our large heads high!   ♪  ♫  ♪

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1Bertenshaw, C., & Rowlinson, P. (2009). Exploring Stock Managers’ Perceptions of the Human–Animal Relationship on Dairy Farms and an Association with Milk Production Anthrozoos: A Multidisciplinary Journal of The Interactions of People & Animals, 22 (1), 59-69 DOI: 10.2752/175303708X390473.

Pantomiming Primates

When considering language abilities in non-human animals, it pays to keep in mind that spoken words are not the only path to sophisticated communication. For example, while great apes like chimpanzees and orangutans may be limited in their ability to adapt their vocalizations to human speech, they are able to control their hand movements very well, and can engage in extremely expressive and effective gesturing behavior.

In a thought-provoking study first published online last year and now appearing in the August 23, 2011 issue of Biology Letters1, two Canadian researchers, Anne Russon of Glendon College and Kristin Andrews of York University, reported on their extensive review of data regarding instances in which orangutans in Borneo have used “pantomime” to communicate with their target audiences.

What part of "give me more food" don't you understand? (photo credit: Tom Low)

Russon and Andrews mined 20 years’ data that had been collected during systematic observational studies on the behavior of ex-captive orangutans as they underwent rehabilitation and were living free or semi-free lives in the forest. After reviewing original field notes and videos covering over 7,000 hours of observation, they identified 18 salient pantomime cases (14 addressed to humans and four to other orangutans) in which orangutans physically acted out messages in order to communicate specific goals.

In most of the cases, the orangutans used pantomime to provide additional or better information after an initial attempt at communication had failed – for example, by being more specific about an action, item or tool requested; by offering better tools for a requested task after a previous tool had been ignored; by pretending to be unable to perform a task after a request for help had been ignored; or by clarifying friendly intent after non-aggressive approaches had been refused.

A few specific examples will help to illustrate how the orangutans used pantomime to achieve specific communication goals:

  • An adolescent female named Siti, who had partially opened and eaten a coconut, handed it to a technician who in turn handed it back to her, gesturing to her that she should finish the job. She proceeded to briefly, weakly and ineffectively poke at the coconut (very much in contrast to her prior behavior), before handing it back to the technician. When he again refused to help her, she used a palm petiole (stalk) to chop at the coconut repeatedly, as one would with a machete. Russon and Andrews described their interpretation of the incident in the data supplement to their paper:

After [the technician’s] first refusal she faked inability to do the job herself; after the second refusal she elaborated her request by acting out what she wanted done, specifying what tool and target to use and how to use the tool.  She acted out the actions she wanted of her partner, which included a skill that was not in her own repertoire (machete use).  Given the complex conjunction of conditions and the specificity of her request, Siti’s pantomime must have been invented on the spot even if she was familiar with all constituent elements.

Fortunately, you can see this incident for yourself, as there’s a video of Siti and the coconut – enjoy!

  • After a three year old female named Kikan had hurt her foot on a sharp stone, a research assistant removed the stone and dripped latex from the stem of a fig leaf on the wound to help make it heal faster. After that, Kikan (who had previously not been particularly friendly with the assistant, hitting or trying to bite her when she passed by) approached the assistant in a friendly manner on a number of occasions, holding up her wounded foot for the assistant to see. On one specific occasion, Kikan picked up a leaf, pulled the assistant’s hand until she paid attention, and then acted out the leaf treatment the assistant had given to the foot. (This is not only interesting for its communication content, but it could be an indication of episodic-like memory (mental time travel), a topic that Felicity Muth recently discussed in some detail in two Scientific American blog posts, here and here).
  • An adult female named Unyuk played with forest assistant who pretended to give her a haircut with a Swiss Army Knife. While they played she noticed a backpack, an item regularly stolen by orangutans in hopes of finding food. Unyuk made no immediate move for the pack – instead she continued to act out her role in the haircutting game, grabbing the hair on top of her head and inviting the assistant to continue playing as she gradually moved sidewise and closer to the pack. Once she had a free path, she lunged and made a grab for the unattended pack. (This was one of seven pantomimes that the researchers labeled as deceptive, where the actor feigned an inability, an interest or an intent in order to obtain help, distract, or express friendly intent and facilitate reconciliation.)

Russon and Andrews believe that some of the pantomime cases contain attributes of natural language:

including compositionality (large meaningful units are composed of smaller meaningful units…), systematicity (the actions and entities pantomimed are meaningfully rearranged following predictable patterns…) and productivity (…unique creations of the moment). Thus, orangutans can communicate content with propositional structure and have the kind of cognitive capacities with constituent structure typically associated with linguistic capacities.

Although spontaneous pantomiming appears to be fairly rare among orangutans (again, a total of 18 examples were unearthed from 20 years’ of data), the underlying data came from studies that were not focused on communication, and the researchers believe that other studies may have missed similar pantomiming to the extent that they focused on the functional aspects of gestures rather than the significance of pantomime as a medium for communication.

In any event, the study offers an eye-opening lesson in how sophisticated – to the point of being linguistic – non-verbal communication can be. If nothing else, we should not be too overconfident if we ever have a chance to play charades against a team of orangutans.

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1Russon, A., & Andrews, K. (2010). Orangutan pantomime: elaborating the message Biology Letters, 7 (4), 627-630 DOI: 10.1098/rsbl.2010.0564.

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