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Female Dolphins Sponge Their Way to Success

After 27 years, scientists finally appear to have unraveled most of the mystery surrounding a very enterprising group of (primarily) female bottlenose dolphins (tursiops aduncus) who live in Shark Bay, off the coast of Western Australia.

Why are those dolphins looking at me like that? (photo credit: Eric Patterson, Shark Bay Dolphin Project)

The story opens in 1984, when observers first noticed that some of the Shark Bay dolphins were breaking off conical marine basket sponges and wearing them over their beaks (rostra). Because only a small percentage of the dolphins in the area engaged in this behavior and it was very difficult to see what they were doing with the sponges, especially when they were underwater, the first research on this behavior wasn’t published until over a decade later.

Preliminary Findings: Tool Use by a Few Females

In a 1997 article in Ethology1, a team of researchers led by Janet Mann of Georgetown University described their initial findings: five female dolphins were regularly seen with sponges, and four additional dolphins (only one of which was a male) were each seen carrying sponges on a single occasion. The regular sponge users were relatively solitary, tended to use the sponges in a deep water channel area, and did not participate in the group feeding and social aggregations to which other dolphins in the group were attracted.

The researchers weren’t sure what the dolphins were doing with the sponges, but they assumed that there had to be some sort of functional advantage, since the sponges were often quite large, covering a large portion of the dolphin’s face, interfering with normal use of the mouth, contributing to hydrodynamic drag, and potentially impacting the ability to engage in echolocation. They considered three possibilities: that the dolphins were playing with the sponges, that the sponges contained some medicinal or other useful compound, or that the dolphins were using the sponges as a tool to aid in foraging.

They concluded that it wasn’t likely that the sponges were being used as toys, as the spongers were relatively solitary, used the sponges methodically for hours at a time, year after year, and didn’t engage in typical play postures, splashing or vocalizations as they carried the sponges. Similarly, they determined that medicinal or similar uses were unlikely, since, among other things, the regular sponge users all seemed healthy and there were no indications that they were ingesting the sponges (although the researchers conceded that this could be difficult to observe).

Hi ho, hi ho, it's off to sponge I go! (photo credit: Eric Patterson, Shark Bay Dolphin Project)

On the other hand, it did seem likely that the dolphins were using the sponges to help them forage for prey: they were seen eating fish when engaging in sponging behavior; they invested an amount of time in carrying sponges similar to that invested by other foraging dolphins; and they made sounds and generally behaved in ways consistent with foraging. The researchers speculated that sponges might be used to protect the dolphin’s face, either from spines or stingers of prey animals or from the abrasive sea floor as they flushed out burrowing prey. In either case, they believed that this would constitute “tool use,” something that had been reported in captive dolphins but never before in the wild.

Finally, the researchers drew no conclusions on why males didn’t engage in sponging, except to note that perhaps it required a degree of solitary living that was at odds with their need to form and maintain cohesive and cooperative alliances.

Additional Findings: A Cultural Tradition of Tool Use among a Related Group of Females

Next, in 2005, Mann’s researcher team expanded on its findings in a paper published in the Proceedings of the National Academy of Sciences2, with salient points of the research including the following:

  • Sponges Are Foraging Tools. By this time, the researchers had found 15 adults in the community who regularly used sponges, only one of whom was a male. Although not a focus of the paper, it appears that the researchers had concluded by this time that the dolphins were indeed using the sponges as tools to protect their rostra as they foraged for prey on the sea floor.
  • “Sponging Eve.” The researchers tested the mitochondrial DNA of the regular spongers and found that sponging had been passed on mainly along a single matriline (line of descent from mother to daughter) and that, due to the high degree of genetic relatedness, all spongers likely descended from one recent “Sponging Eve.”
  • Female Social Culture. After considering in detail whether the sponging behavior could have resulted from either a genetic propensity or some unique aspect of the deep-water channels where the most of the sponging occurred, the researchers found the evidence for these alternatives lacking and concluded that by far the best explanation was that the sponge use was being socially learned and transmitted from mother to daughter. The researchers weren’t overly surprised by this finding, given that studies had already shown that dolphins have uncommonly complex cognitive and imitative skills and the ability to excel at vocal and social learning.
  • Uncommon Cultural Diversity. It was particularly rare to see this sort of cultural phenomenon in a small subset of the overall population (a single maternal line comprising only about 10% of the females in the group). In other studies (for example, involving apes), this type of culturally learned behavior is seen across the entire population.
  • Can’t Explain Males. Once again, the researchers surmised that perhaps males didn’t engage in sponging because they had to associate at high levels with alliance partners, but they left this point open.

The Story Continues: Spongers Are Fit

The story continued to unfold in 2008, when Mann and her team published a paper in PLoS ONE3 that focused in more on whether sponging was an advantageous behavior, or whether the spongers were in some fashion subordinate or less competitive and were making the “best of a bad situation.”

I don't know what you mean, it's no more elaborate than the other hats at the Royal Wedding... (photo credit: Eric Patterson, Shark Bay Dolphin Project)

By this point, recurrent sponging had been seen in 41 of the dolphins and a few more of them were male (29 were females, 6 were males, and 6 were of unknown sex). This still represented a small percentage (about 11% of adult females were spongers) and, although it now appeared that more than one matriline was involved, the data continued to show that the behavior was consistently passed down from mother to daughter, and less frequently from mother to son: there were no instances observed where a calf adopted the behavior if its mother wasn’t a sponger, and of 19 offspring born to sponger females who could be observed and whose sex was known, 91% of the daughters (10 of 11) and 25% of the sons (2 of 8) adopted sponging.

Further, the researchers found that the spongers were highly specialized, not using other hunting techniques and spending approximately 96% of their foraging time using sponges. In fact, the researchers concluded that, due to their lifestyle and specialization, spongers actually used tools more than any non-human animal.

So, was the sponging advantageous or a way of coping for not particularly well-adapted dolphins? Well, the researchers did find that spongers were more solitary and spent more time foraging at deeper depths and on longer dives, but noted that they really didn’t seem to suffer from any kind of fitness cost, as their calving success was equivalent to that of other females in the population.

Since there was no evidence that any kind of competition for food was relegating the spongers to their strategy, the research concluded that sponging simply seemed to be an “all-or-none phenomenon,” that required a specialized approach and a commitment to a single foraging type, but that most likely opened up a particular hunting niche in a diverse environment. While other dolphins could theoretically adopt the strategy, the researchers noted that daughters in particular tend to adopt their mothers’ foraging strategy, and unless the mother was a sponger, a daughter might simply not have had sufficient exposure to develop this highly specialized technique while a calf.

Once again, the team hypothesized about the males, stating: “Male offspring are exposed to sponging as often as female offspring, but do not seem to adopt the behaviour early, if at all. … [M]ales likely range more widely post-weaning, focus on establishing long-term alliances, and cannot afford to adopt foraging tactics that both demand extensive effort and specialization and limit their range and access to females.”

The researchers offered no opinions about whether the male dolphins were simply slow on the uptake or whether they associated sponges with housework to be avoided.

The Latest Chapter: Explaining the Purpose of Sponging

While all of this research had answered many questions and shed light on a fascinating example of tool use in wild female dolphins, one fundamental question remained. Dolphins are great at using echolocation to detect prey (even prey that is buried), so why do the Shark Bay spongers probe the debris-covered sea floor with their noses, risking injury (even with the protection afforded by the sponges) instead of minimizing sea floor contact by simply echolocating for buried prey as they do in other locations (for example, the Bahamas)?

What a mess! This sea floor needs a good sponging! (photo credit: Eric Patterson, Shark Bay Dolphin Project)

This is the question is answered in the latest chapter, a research paper published last week in PLoS ONE4. Mann’s research team had fun with this one, grabbing poles and going sponging themselves. What they found, aside from the fact that dolphins are far more graceful than people, was that the nature of the prey turned up by sponging helps explain the dolphins’ behavior.

It turns out that most of the bottom-dwelling fish that hide in Shark Bay the sea bottom lack swim bladders, gas-filled chambers used by fish to control their buoyancy as they swim up and down. Because they lack the major characteristic that distinguishes their density from sea water, they generate relatively weak acoustic signals and are difficult to detect with echolocation. In addition, the debris (rock, shell and coral) on the sea floor in the area seemed likely to cause “interfering reverberation and echo clutter,” which would further reduce the effectiveness of echolocation.

Moreover, it’s worth it to go after these swim bladderless fish. They are attractive targets, as they are reliably present on the sea floor and exhibit consistent, predictable behavior when rousted out of their hiding places, allowing the dolphins to adopt a single efficient technique as they sponge. Further, bladderless fish tend to have a relatively high fat content, providing hungry dolphins with a particularly energy-rich meal.

So, the sponging female dolphins of Shark Bay really are quite remarkable. They have established a mother-daughter subculture of tool use in the wild, successfully devising a highly specialized way of exploiting an attractive niche in their diverse environment.

You go girl(s)!

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1Smolker, R., Richards, A., Connor, R., Mann, J., & Berggren, P. (2010). Sponge Carrying by Dolphins (Delphinidae, Tursiops sp.): A Foraging Specialization Involving Tool Use? Ethology, 103 (6), 454-465 DOI: 10.1111/j.1439-0310.1997.tb00160.x.

2Krutzen, M. (2005). Cultural transmission of tool use in bottlenose dolphins Proceedings of the National Academy of Sciences, 102 (25), 8939-8943 DOI: 10.1073/pnas.0500232102.

3Mann, J., Sargeant, B., Watson-Capps, J., Gibson, Q., Heithaus, M., Connor, R., & Patterson, E. (2008). Why Do Dolphins Carry Sponges? PLoS ONE, 3 (12) DOI: 10.1371/journal.pone.0003868.

4Patterson, E., & Mann, J. (2011). The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.) PLoS ONE, 6 (7) DOI: 10.1371/journal.pone.0022243.

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Chimps Don’t Ape Humans – Develop Tools Independently

The more we learn about the capabilities of animals, the less it seems we can claim as uniquely our own. Now it appears that we may even have to share our treasured Flintstones cartoons, as we have learned that we aren’t the only species to have enjoyed an ancient Stone Age history.

Chimp eating nuts and thinking about upcoming Chimpanzee Iron Age

A few years ago, archeologists led by Julio Mercader of the University of Calgary discovered that chimpanzees in West Africa were using stone tools to crack nuts thousands of years ago, before humans had begun engaging in agriculture in the area. The research team, exploring sites located in the Ivory Coast’s Taï National Park, found stone “hammers” that were 4,300 years old and that had all the hallmarks of chimpanzee tools, rather than human ones. Science 2.01 described the tool findings as follows:

The stone hammers that the team discovered, essentially irregularly shaped rocks about the size of cantaloupes – with distinctive patterns of wear – were used to crack the shells of nuts. The research demonstrates conclusively that the artifacts couldn’t have been the result of natural erosion or used by humans. The stones are too large for humans to use easily and they also have the starch residue from several nuts known to be staples in the chimpanzee diet, but not the human diet.

The research team elaborated further in the paper it published in the Proceedings of the National Academy of Sciences2:

This discovery speaks of true prehistoric great ape behavior that predates the onset of agriculture in this part of Africa. The chimpanzee assemblages are contemporaneous with the local Later Stone Age; thus, they represent a parallel “Chimpanzee Stone Age”….

The systematic archaeological study of prehistoric chimpanzee cultures suggests that the “Chimpanzee Stone Age” started at least 4,300 years ago, that nut-cracking behavior in the Taï forest has been transmitted over the course of >200 generations, and that chimpanzee material culture has a long prehistory whose deep roots are only beginning to be uncovered. These findings substantiate the contribution of rainforest archaeology to human evolutionary studies in areas other than the classical savanna-woodlands of East and Southern Africa and add support to fossil discoveries from these other regions indicative of an ancient chimpanzee past.

I love it: the Chimpanzee Stone Age! Also, it’s amazing that this tool use tradition has been passed down over 200 generations, and is still in use today.  Here’s a nice BBC video clip that shows today’s generation of chimps using the same sort of tools to expertly crack open nuts.

Archeology3, the official publication of the Archeological Institute of America, haled Mercader’s research as one of the “Top 10 Discoveries” of 2007, noting that:

The discovery shows that stone tool use is not a behavior that chimpanzees learned recently by watching the farmers who live in the area, as some skeptics believe. Mercader thinks that humans and chimpanzees may have inherited stone tool use from an ancestral species of ape that lived as long as 14 million years ago.

At this point, Mercader’s views on the origins of tool use are still open to debate and further research. The fact, though, that there can even be such a discussion about tool use, a capability once thought to so uniquely identify the human species, illuminates how much thinking we have had to do recently about the common characteristics we share with other animals. Interesting stuff.

We’ll keep you posted as the story unfolds, and let you know as soon as they discover the first prehistoric chimpanzee satellite TV dishes and computer operating systems.

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1Science 2.0, “Hammer Using Chimps Make Us Wonder Where They Learned It,” February 13, 2007.

2Mercader, J., Barton, H., Gillespie, J., Harris, J., Kuhn, S., Tyler, R., & Boesch, C. (2007). 4,300-Year-old chimpanzee sites and the origins of percussive stone technology Proceedings of the National Academy of Sciences, 104 (9), 3043-3048 DOI: 10.1073/pnas.0607909104.

3Archeology, “Ancient Chimpanzee Tool Use,” Volume 61, Number 1, January/February 2008.

Lizards Shed Reputation as Slow Learners

A new study has shown that anoles (Anolis evermanni), a tropical tree-dwelling lizard found in Puerto Rico, are surprisingly good problem-solvers who have cognitive abilities that rival those of birds known for their highly flexible behaviors.

Manual Leal, a professor at Duke University, led a study in which six anoles were given a series of challenges designed to test their behavior flexibility, cognitive abilities and memory.  In these experiments, the lizards were presented with a platform containing two wells, one containing a food reward and the other empty. The wells were covered with tight-fitting opaque discs of differing colors and patterns, and the lizards were given 15 minutes to obtain the reward.

Anole Lizard: will you quit messing with my dinner if I drop that whole GEICO thing? (photo credit: Manuel Leal, Duke University)

According to Leal’s research paper, which was published online on July 13, 2011, in the Journal of the Royal Society: Biology Letters1, two-thirds of the lizards were able to solve the puzzle and find the food reward, a “completely unexpected” result since:

The correct response required major changes to what has previously been considered highly stereotyped foraging behavior, which consists of scanning the environment for moving prey items and striking them from above. In our experiment, motion cues were absent and striking from above was ineffective at dislodging the disc. Lizards used multiple strategies to remove the disc. The first was a modified strike, laterally biting the disc and lifting it away from the reward. The second strategy required the lizard to advance on the disc with its head held against the substrate, using its snout as a lever to push the disc out of the way…. This strategy is not a natural foraging behaviour that has at least been witnessed, and may demonstrate an entirely novel solution, which is one of the main criteria used to recognize behavioural flexibility.

Here’s a video from the New Scientist2 that shows one of the lizards in action:

When the tests were repeated with the disc colors associated with the reward reversed, two of the lizards continued to flip the original disc in an unsuccessful search for the reward, but the remaining two, nicknamed Plato and Socrates by Leal’s team, figured out that the discs had been changed and solved the problem again, reversing their previously learned color associations. (This sort of test is known as a “reversal learning” test.) Although there haven’t been many studies of cognition in reptiles, Plato and Socrates’ success appears to be particularly notable since prior evidence had suggested that reptiles do better at solving puzzles involving location change than ones involving altered visual cues.

Finally, Leal and his team were surprised to discover that the anoles were able to solve the challenges presented in these experiments in only one-third the attempts needed by birds given similar tasks in comparable experiments. While the researchers did not draw any definitive conclusions about this, they did note that, due to the slower metabolisms of the cold-blooded anoles, they could be tested only one time a day, and that the tempo at which the tests were performed might have some bearing on the number of attempts required.

Perhaps because people don’t expect displays of cognitive flexibility in reptiles, Leal’s research has generated a fair bit of media attention, including articles in The Economist3, ScienceNOW4MSNBC5, BBC Nature News6 and LiveScience7. Enjoy!

Now, after a long week, I think I’m going to go out and lie on a warm rock and then get some dinner.

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1Leal M, & Powell BJ (2011). Behavioural flexibility and problem-solving in a tropical lizard. Biology letters PMID: 21752816.

2New Scientist, “Smart lizard solves a problem it’s never seen before,” July 13, 2011.

3The Economist, “Cold Blooded Cunning,” July 14, 2011.

4ScienceNOW, “Tropical Lizards Get Brainy,” July 12, 2011.

5MSNBC, “Don’t underestimate the brainpower of a lizard,” July 13, 2011.

6BBC Nature News, “Lizard has problem solving skills,” July 13, 2011.

7LiveScience, “Lizards Are Wizards At Solving Food Puzzle,” July 12, 2011.

Did You Hear the One About the Traveling Salesman and the Bumblebee?

Last fall, bumblebees enjoyed their moment in the sun, as a series of headlines proclaimed that they were mathematical geniuses:

“Tiny Bee Brains Beat Computers at Complex Math Problems”
Fox News1

“Bees Solve Complex Problems Faster Than Supercomputers”
The Daily Galaxy2

“Bees’ brains more powerful than computers”
Natural News3

Bumblebee solving quadratic equations (photo: U.S. Fish & Wildlife Service)

What was all the fanfare about? Are we about to enter a new era in which paparazzi stalk bees rather than reality TV stars? (We won’t complain if this is the case.) PhysOrg.com4 summarized the context as follows:

Scientists at Queen Mary, University of London and Royal Holloway, University of London have discovered that bees learn to fly the shortest possible route between flowers even if they discover the flowers in a different order. Bees are effectively solving the ‘Travelling Salesman Problem’, and these are the first animals found to do this.

The Travelling Salesman must find the shortest route that allows him to visit all locations on his route. Computers solve it by comparing the length of all possible routes and choosing the shortest. However, bees solve it without computer assistance using a brain the size of grass seed.

Professor Lars Chittka from Queen Mary’s School of Biological and Chemical Sciences said: “In nature, bees have to link hundreds of flowers in a way that minimises travel distance, and then reliably find their way home – not a trivial feat if you have a brain the size of a pinhead! Indeed such travelling salesmen problems keep supercomputers busy for days. Studying how bee brains solve such challenging tasks might allow us to identify the minimal neural circuitry required for complex problem solving.”

In actuality, the bumblebees’ achievements, while impressive, were a bit more modest than publicized.

Bumblebees (Bombus terrestris) do indeed visit flowers in predictable sequences called “traplines,” and the UK research team wanted to learn more about whether these sequences simply reflect the order in which flowers are discovered or whether they result from more complex navigational strategies enabling bees to optimize their foraging routes. Accordingly, the researchers set up an array consisting of four (not hundreds of) artificial flowers, which they introduced to bumblebees in sequence.

The researchers observed that over time the bees tended to stop visiting the artificial flowers in their discovery order and, through a process of trial and error, began reorganizing their preferred routes to minimize total flight distance. In general, the bumblebees adopted a primary route and two or three less frequently used secondary routes, with the primary route typically being the shortest distance route. The bees also did a (reasonably) good job of remembering the most efficient route after an overnight break.

Even though the bees gravitated toward the shortest route, they did continue to experiment with novel routes, a behavior that – the researchers hypothesized – might allow them to fine tune their behavior as new sources of food were found over time.

Now, in their research paper5, the UK team did note that the bees’ search to find the shortest path among flowers is analogous to the traveling salesman problem, and did state that “Our findings suggest that traplining animals can find (or approach) optimal solutions to dynamic traveling salesman problems (variations of the classic problem where availability of sites changes over time) simply by adjusting their routes by trial and error in response to environmental changes.” These observations are, however, just a tad less dramatic than the “triumph over supercomputers” celebrated in the popular media reports on the research.

So what are the morals of this story?

  • While all too often animals are derided as “dumb beasts” and the like, sometimes we go in the opposite direction, overstating what animals are capable of accomplishing in order to create a sensation.
  • Even without the hyperbole, bumblebee route optimization behavior is noteworthy. There are often multiple ways to solve difficult problems, and sometimes the efficient approaches developed by animals who do not boast large brains can be surprisingly effective.
  • Insects, both in collective groups and as individuals, seem to be particularly adept at finding rational solutions that have an almost mathematical feel to them.
  • Bumblebees can sure generate a lot of buzz.

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1Fox News, “Tiny Bee Brains Beat Computers at Complex Math Problems,” October 25, 2010.

2The Daily Galaxy, “Bees Solve Complex Problems Faster Than Supercomputers,” October 26, 2010.

3Natural News, “Bees’ brains more powerful than computers,” October 27, 2010.

4PhysOrg.com, “Complex mathematical problem solved by bees,” October 25, 2010.

5Lihoreau M, Chittka L, & Raine NE (2010). Travel optimization by foraging bumblebees through readjustments of traplines after discovery of new feeding locations. The American naturalist, 176 (6), 744-57 PMID: 20973670.

Something to Crow About

Some of you may be aware that crows (who are corvids, like magpies and Clark’s Nutcrackers) are excellent problem solvers and that they are one of the few birds known to engage in tool use.

While there have been a variety of popular press articles describing tool use by New Caledonian crows, in this post I wanted to showcase a few videos that demonstrate visually just how impressive these crows are.

The first video features a New Caledonian crow creating a bent wire hook to fish out a food treat after realizing that a straight piece of wire won’t do the trick. Check it out; it’s pretty incredible:

In a second demonstration of cognitive abilities, the crow employs a sequence of three tools to obtain food reward – using a short stick to withdraw a medium-length stick, using the medium-length stick to obtain a long stick, and then using the long stick to reach the food. As the video notes, this is the first time a non-human animal with no explicit training has been observed using three different tools in the correct sequence to achieve a goal. Again, the video illustrates this feat quite nicely:

Finally, a recent Wired1 article, together with accompanying video, features a New Caledonian crow finding a novel use for a tool, poking a rubber spider. This sort of flexible tool use is quite rare, and crows are the first non-mammals who have demonstrated that they can use a single tool in multiple ways. Here’s the video:

I love how the crow gingerly pokes at the rubber spider and then jumps back – talk about a a familiar looking reaction!

For more information and videos relating to tool usage by New Caledonian crows, you can explore the tool use website2 of the Behavioural Ecology Research Group at the University of Oxford.

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1Wired, “Clever Crows Use Tools in New Way,” January 5, 2011.

2Visited on July 11, 2011.

Spotted Hyenas: Clever Carnivores, Not Simply Comedians

Underestimated by many, spotted hyenas (Crocuta crocuta) are providing insight into the roots of human intelligence.

Far from being clownish buffoons, spotted hyenas – also known as laughing hyenas – live in large, complex matriarchal communities, or clans, in which social intelligence is critical. They are fascinating animals – although they look something like dogs, they are more closely related to cats, and closer still to mongooses and civets. Female spotted hyenas are the true clan leaders: they are larger and more aggressive than males, socially dominant, and have even evolved to have male-like external features, including a pseudopenis that is extremely similar in appearance to the male’s sexual organ.

Spotted hyenas enjoying the water (photo credit: K. Holekamp)

Kay Holekamp, a professor of zoology at Michigan State University, has been studying these gregarious carnivores for many years, and is particularly focused on how they can help us gain a better understanding of why certain animals, including humans and other primates, have developed high intelligence and large brains (which, from a metabolic standpoint, are extremely expensive to maintain). More specifically, she has been looking at spotted hyena society as a means of probing the “social complexity” theory of intelligence, which posits that brainpower provides a significant edge to animals living in complex social groups, where individuals need to be able to anticipate, respond to and manipulate the social behavior of other group members.

The majority of intelligence research in this area has been performed on primates, but Holekamp notes in recent research1 that social complexity theory predicts that “if indeed the large brains and great intelligence found in primates evolved in response to selection pressures associated with life in complex societies, then cognitive abilities and nervous systems with primate-like attributes should have evolved convergently in non-primate mammals living in large, elaborate societies in which individual fitness is strongly influenced by social dexterity.”

In this research, Holekamp acknowledges that much remains to be learned about social cognition in spotted hyenas, but concludes:

Work to date on spotted hyenas has shown that they live in social groups just as large and complex as those of cercopithecine primates [AW: a subfamily of Old World monkeys], that they experience an extended early period of intensive learning about their social worlds like primates, that the demand for social dexterity during competitive and cooperative interactions is no less intense than it is in primates, and that hyenas appear to be capable of many of the same feats of social recognition and cognition as are primates.

While the paper includes much more detail, the following are among Holekamp’s observations regarding spotted hyena social knowledge and skills:

  • Individual recognition. Spotted hyenas possess a rich repertoire of visual, acoustic and olfactory signals, which other hyenas can use to discriminate clan members from alien hyenas, to recognize the other members of their social units as individuals and to obtain information about signalers’ affect and current circumstances.
  • Kin recognition.Hyenas can distinguish vocalizations of kin from those of non-kin, with intensity of responses increasing with degree of relatedness between vocalizing and listening animals, and kin recognition potentially occurring among hyenas as distantly related as great-aunts and cousins.

    Basking spotted hyena cub (photo credit: K. Holekamp)

  • Imitation and behavior coordination. Although hyenas have not been observed to engage in true imitation (that is, replicating a novel act performed by a species member) the way some primates do, they do appear to modify their behavior after observing goal-directed behavior of other hyenas. In addition, they engage in cooperative hunting involving complex coordination and division of labor among hunters. This cooperation, which enables them to capture prey many times their size, involves – at a minimum – communicating by simple rules of thumb (e.g., “move as necessary to keep the prey between you and another hunter”), if not the operation of higher mental processes.
  • Social rank and social memory. Spotted hyenas are intensely aware of social rank, and they learn quickly where they and their relatives fit into their clan’s dominance hierarchy. They are able to remember previous interactions they have had with other individuals, and appear to remember the identities and ranks of their clan mates throughout their lives. They apply their knowledge of social ranks in many ways, including to avoid conflict, figure out feeding priority, help them choose appropriate mates, determine which social relationships are desirable to establish and maintain, and when to reconcile after conflicts have occurred.
  • Flexible problem-solving. Similar to certain primates, it appears that spotted hyenas are able to achieve short-term goals through a variety of different tactics. As stated in the Holekamp’s research article, “For example, a hyena can avoid aggression by leaving the aggressor’s subgroup, exhibiting appeasement behavior or distracting the aggressor. A hyena can potentially use greeting ceremonies to reconcile fights, reintroduce itself to conspecifics [AW: members of their own species] from which it has been separated, or increase conspecifics’ arousal levels in preparation for a border patrol or group hunt.”
  • Tactical deception. One sign of social cleverness, which should be familiar to all humans, is tactical deception. It appears that hyenas may share this sophisticated behavior as well, as anecdotal accounts of hyena deception include a low-ranking hyena noticing an unprotected meal but ignoring it until higher-ranking group mates were out of range, and other low-ranking individuals similarly emit alarm vocalizations in what appear to be deceptive attempts to gain access to food.

Finally, here’s a brief video in which Holekamp shows one of the ways she and her colleagues have been assessing the puzzle-solving skills and memories of spotted hyenas:

So, hats off to laughing hyenas: they may sound comical, but they are seriously smart!

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1Holekamp, K., Sakai, S., & Lundrigan, B. (2007). Social intelligence in the spotted hyena (Crocuta crocuta) Philosophical Transactions of the Royal Society B: Biological Sciences, 362 (1480), 523-538 DOI: 10.1098/rstb.2006.1993.

My Border Collie Is Smarter Than Your Honor Student

Or so the bumper sticker says.

On this Fourth of July, it seems appropriate to salute man’s best friend in a brief holiday post. Meet Chaser, a true canine linguistic champion.

Chaser understands more than 1,000 words, along with simple sentences. Her vocabulary includes the names of 1,022 objects, including 800 stuffed animals, 116 balls and 26 “Frisbees,” any of which she can fetch on command.

Chaser, resting after studying for the bar exam (photo credit: ABCNEWS.com)

In addition, if a new toy is placed among her playthings, she is able to retrieve it when given its unfamiliar name, inferring its identity by a process of exclusion. She also has been studying her verbs, demonstrating that she knows how to “find,” “nose” and “paw” each of her toys. I assume that next she will be working on her gerunds and finishing her mastery of the subjunctive mood.

Happy Fourth, Chaser!

You can read more about Chaser and see her in action in this ABC News1 story.

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1ABC News, “World’s Smartest Dog? Meet a Border Collie Whose Memory Astounds,” February 9, 2011.

The Awesome Octopus

I wanted to devote today’s post to a wonderful presentation on cephalopods that Maggie Koerth-Baker, the Science Editor at BoingBoing.net, gave last January at the University of New Mexico’s annual conference on Integrating Nanotechnology with Cell Biology and Neuroscience.

There is also a 10-minute edited version of the presentation, which you can find here, but I highly recommend spending half an hour to take in the full video (below), since many of the really fascinating stories have been edited out of the shorter version.

There are parts of Koerth-Baker’s presentation that I just love, particularly how she addresses the question of how we define intelligence.  As she puts it (and this part isn’t contained in the edited version):

Intelligence is a loaded word.  What does intelligence mean to you? IQ tests, grade point average, the ability to communicate via spoken language?

One thing is certain: “intelligence” makes us think of human stuff, people things. And that’s not fair.

An octopus doesn’t need to be able to pass a written exam. It never has. To judge animals against human ideas of what intelligence means in humans is to miss the point of evolution. Our brains are not this private club that the rest of animal-kind is trying to be cool enough to get into. Every species has adapted over millions of years to have a brain that allows it to be smart for its particular niche.

Octopus brains can get octopus jobs done, and they don’t have to worry about whether they can tackle human issues. Your octopus will not do your homework, but that doesn’t mean it’s stupid.

Later, she adds:

It is absolutely true that there is something very different, and very exciting, going on in the cephalopod brain, especially when you consider its nearest relatives. Cephalopods are closely related to mollusks, and their family reunion would feature such dignitaries as snails and oysters.

A layman might go ahead and call it “intelligence.” I’m just going to call it “being awesome.”

These are not big brained creatures. They can’t navigate a maze like a cephalopod can. They can’t react quickly and change their behavior to reflect minute by minute changes in their environment. And, with a couple of notable exceptions, they don’t seem to be able to remember information and use it in the future.

In the nature and in the lab, invertebrate cephalopods act more like vertebrates. Researchers describe this special class of conduct as “behavior plasticity” or “behavioral flexibility.” A layman might go ahead and call it “intelligence.” I’m just going to call it “being awesome.”

The full presentation goes on to illustrate various “awesome” abilities of the cephalopods, including decision-making, arguable tool use, and communication with other cephalopods. Koerth-Baker also provides a vivid example of how an octopus will engage in highly sophisticated mental processes in executing tactics to escape predators. When faced by a researcher perceived to be attacking:

an octopus would swim backwards away from [the researcher] toward handy places where it could hide. When it got to one of these spots, the octopus would squirt out a jet of ink in one direction, and dive away in the opposite direction, immediately changing its camouflage to match its new hidey-hole. Basically, it was giving him the old dodge and feint routine.

Now, think about everything an octopus had to do to process that. While swimming for its life, it had to know where [the researcher] was and where the next hidey holes were. It had to think about the timing to trick [the researcher] with the ink squirt. And it had to know what color and texture to turn its skin as it dove away. All of that pretty much at the same time. That’s broad awareness and complex decision-making, done at high speeds by a creature with a mollusk brain.

Verdict: awesome.

Indeed.

It really is thought provoking to consider the concept of intelligence, particularly in animals that are so different than we are. The latter part of the video provides an overview of the octopus brain and neural anatomy – if you think you know how a brain generally looks and functions (or should look and function), you will find this segment to be eye opening.

So, how intelligent are the cephalopods? They can’t read or write, they can’t speak, they aren’t particularly social. Their brains, while larger than any other invertebrate’s (and comparable in size to the brains of dogs and cats), are nowhere near the size of human brains, and cephalopods don’t exhibit many of the higher cognitive functions that we test when we measure human intelligence. Their SAT scores would undoubtedly be unimpressive.

On the other hand, how would we humans do on an octopus intelligence test, one that required us to consciously change our shapes, colors, textures and brightness in order to adapt to threats and changing environmental conditions? Cephalopods have incredible mental abilities that we are totally lacking – what does this say about whether those mental abilities are, or are not, evidence of intelligence?

These are hard questions, but one point should be pretty clear. Octopuses are awesome.

Thank you, Maggie.

A Smart Fish in a Dangerous Pond

Mistakes are the portals of discovery.
James Joyce

Do not fear mistakes. You will know failure. Continue to reach out.
Benjamin Franklin

Nice quotes, but I think I’ll just avoid making mistakes, thank you very much.
Stickleback Fish

When you or I make a mistake, we can seek comfort in witty sayings, self-help programs and expensive therapy sessions. When a nine-spined stickleback fish makes a mistake, it often ends up in the belly of another marine animal.

Nine-Spined Stickleback (BBC News)

Perhaps motivated by this rather unpleasant truth, sticklebacks – a small fish commonly found in North America, Europe and Asia – have developed some unusually sophisticated social learning capabilities. In particular, sticklebacks are able to compare the feeding behavior of other sticklebacks with their own experience and choose which fish to copy in order to find more food. This capability, sometimes referred to as a “hill climbing” strategy, has not been observed in any animals other than sticklebacks and humans … at least those humans who aren’t too busy making mistakes in order to enjoy character-building learning opportunities. More importantly (to the sticklebacks), this voyeuristic approach to feeding enables them to learn where to feed while relaxing in safe places rather than running a gauntlet of predators to search for feeding sites in the open.

In a study published in Behavioral Ecology1, English researchers placed 270 sticklebacks in a tank with two feeders, one of which – the “rich feeder” – supplied a lot more food than the other. The fish that learned to prefer the rich feeder were then allowed to watch other sticklebacks feeding in the same  tank but, this time, the rich feeder no longer provided more food (in some cases, it provided less food, in others it provided about the same amount of food). When the observing group was given another opportunity to feed, about 75% were “clever” enough to know from watching the other fish that they should avoid the formerly rich feeder if it was now giving out less food, choosing the new improved feeder instead. However, in situations where the change in feeders resulted in each providing roughly the same amount of food, the observers did not copy the other fish and stuck with their initial choice.

As reported in ScienceDaily2, the BBC News3, and the Guardian4, one of the authors, professor Kevin Laland from the School of Biology at St Andrews University, saluted the sticklebacks for their learning prowess: “Nine-spined sticklebacks may be the geniuses of the fish world. It’s remarkable that a form of learning found to be optimal in humans is exactly what these fish do.” Another researcher, Jeremy Kendal from Durham University’s anthropology department added: “Hill-climbing strategies are widely seen in human society whereby advances in technology are down to people choosing the best technique through social learning and improving on it, resulting in cumulative culture. But our results suggest brain size isn’t everything when it comes to the capacity for social learning.”

So, in a fish eat fish world where mistakes can be costly, we would be well advised to balance our trial by error tendencies against the wisdom of a species that has learned how to succeed without putting itself into jeopardy.

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1Jeremy R. Kendal, Luke Rendell, Thomas W. Pike, and Kevin N. Laland. Nine-spined sticklebacks deploy a hill-climbing social learning strategy. Behavioral Ecology, 2009; 20 (2): 238.

2ScienceDaily, “Common Fish Species Has ‘Human’ Ability To Learn,” June 17, 2009.

3BBC News, “‘Genius’ claim for sticklebacks,” June 17, 2009.

4The Guardian, “Sticklebacks show human-like intelligence when searching for food,” June 16, 2009.

Memory: Chimp is Champ!

It didn’t sound like a fair contest: the memory champion of the UK against a lowly chimpanzee. In one corner, Ben Pridmore, a man capable of memorizing all of the cards in a shuffled deck in less than half a minute; in the other corner, Ayumu, a seven year old hairy primate wearing no clothes.

No, it wasn’t fair at all.

As reported in the UK Daily Mail1, both chimp and man watched a computer screen on which five numbers flashed up at various positions before being obscured by white squares, and then had to touch the squares in order of the numbers they concealed, from lowest to highest.

Ayumu hard at work (photo credit: Primate Research Institute Kyoto University)

By the time the competition heated up and the numbers were shown for a mere fifth of a second, the results weren’t even close: while the winner was able to order the numbers correctly almost 90% of the time, the loser couldn’t even manage 33%.

Fortunately, NaturalNews.com2 notes that the loser was gracious in defeat: “It is extremely impressive for anybody,” Pridmore said when asked about Ayumu’s performance. “He is doing something which I think is a really great performance even by human standards, so I’m sort of forgetting he is not a human being. When I bring that into the equation, it makes it overwhelmingly impressive.”

(If you wish to try to avenge Mr. Pridmore’s loss, the good news is that there’s a website3 where you can watch a video of Ayumu in action and then take the memory test yourself. Good luck, our species is counting on you.)

You may be thinking that this is a meaningless fluke, a highly specific area where a chimpanzee just happens to excel, a parlor trick that is not at all indicative of true intelligence. Well, maybe so, but don’t we as humans like to point to these sorts of unique abilities as precisely what set us apart from the rest of the animal kingdom? Are we tilting the playing field by giving inordinate weight to the mental gifts that we enjoy, downplaying others and defining intelligence to suit ourselves and our abilities? Perhaps we should ask Ayumu what he thinks…

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1The Mail Online, “I’m the chimpion! Ape trounces the best of the human world in memory competition,” January 26, 2008.

2NaturalNews.com, “Chimpanzee Beats Human Memory Genius in Memorization Competition,” August 3, 2008.

3lumosity games website, visited June 28, 2011.

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