Not Fair! Even Dogs Know the Importance of Gift-Equity

A repost of an original article from December 2012.

Don't leave out your best friend when
gift-giving this holiday season!
Photo by Ohsaywhat at Wikimedia.

When I was a child, I think one of the things that stressed my mom out most about the holidays was making sure that all of us kids got Christmas gifts worth the exact same amount. Why all the fuss? Because if the value of the gifts wasn’t equal, we were guaranteed to spend our holidays in a chorus of “Not fair!” cries rather than appreciating the holiday bounty and cheer around us.

As a species, we have a pretty developed sense of fairness. This sense of fairness is central to our ability to cooperate to achieve goals that are too difficult for one person to accomplish alone. But we’re not the only social species that cooperates… and it turns out, we’re not the only ones with a sense of fairness, either.

Domestic dogs and their wild relatives, like wolves and African wild dogs, are very social and have cooperative hunting, territory defense, and parental care. Friederike Range, Lisa Horn, Zsófia Viranyi, and Ludwig Huber from the University of Vienna, Konrad Lorenz Institute, and Wolf Science Center, all in Austria, sought out to test whether domesticated dogs have a sense of fairness.

The researchers tested pairs of dogs who had lived together in the same household for at least a year. All of these dogs had been previously trained to give their paw on command, as if giving a handshake. Each pair of dogs was asked to sit in front of an experimenter (one dog was designated the “subject” and the other was the “partner”). In this position, the willingness of the subject dog to shake paws with the experimenter was tested under six different situations.

An experimenter asks two dog-buddies to each give her a paw and they wait
to see who gets rewarded. Photo from Range et al., PNAS, 2009.

In the basic situation, both dogs were asked to give a paw, and both dogs were rewarded with a “low-value” reward (a piece of bread). This happened repeatedly and the researchers measured how many times the subject dogs would give their paw.

In another situation, both dogs were asked to give a paw, but the subject dog was rewarded with a “low-value” reward (a piece of bread) while its buddy was rewarded with a “high-value” reward (a piece of sausage).

In a third situation, both dogs were asked to give a paw, but only the partner dog was rewarded with a piece of bread (the subject dog got nothing).

In the fourth situation, only the subject dog was asked to give a paw, but both dogs were rewarded with a piece of bread.

In the fifth situation, the experimenter measured how many times the subject dog would give its paw for a piece of bread if his doggy-buddy wasn’t around.

In the last situation, the experimenter measured how many times the subject dog would give its paw for no reward if his doggy-buddy wasn’t around.

When both dogs received bread, they were happy to keep giving the experimenter their paw for as long as they were asked to. But when dogs saw their buddy get a piece of bread when they got nothing, they soon refused to give their paw to the experimenter (and started showing signs of stress). You may think this is just what happens when you stop rewarding a dog for doing what you ask, but something different was going on here. The dogs that never got a reward gave their paw to the experimenter for longer when their buddy wasn’t around than if their buddy was around and getting bread treats. Clearly, even dogs know that equal work for unequal pay is not fair.

But the doggy-sense-of-fairness is limited. As long as they got their bread when they gave their paw, they really didn’t seem to care (or notice) if their buddy got bread or sausage, or even whether their buddy had to perform the same trick or not.

So this holiday season, don’t forget to get a present for your four-legged friend so he doesn’t feel left out. But don’t worry about getting something expensive – He doesn’t care anyway. For him, it’s the gesture that counts.

Want to know more? Check these out:

1. Range F, Horn L, Viranyi Z, & Huber L (2009). The absence of reward induces inequity aversion in dogs. Proceedings of the National Academy of Sciences of the United States of America, 106 (1), 340-5 PMID: 19064923

2. Range, F., Leitner, K., & Virányi, Z. (2012). The Influence of the Relationship and Motivation on Inequity Aversion in Dogs Social Justice Research, 25 (2), 170-194 DOI: 10.1007/s11211-012-0155-x

Risky Business: Ape Style

A repost of an original article from April 3, 2013.

The decisions of this chimpanzee living in the
Tchimpounga Chimpanzee Sanctuary are affected
by his social situation. Photo by Alex Rosati.

If you have a choice between a prize that is awesome half the time and totally lame the other half of the time or a mediocre prize that is a sure-thing, which would you choose? Your choice probably depends on your personality somewhat. It may also depend on your needs and your mood. And it can depend on social contexts, like if you’re competing with someone or if you’re being watched by your boss or someone you have a crush on.

All animals have to make choices. Some choices are obvious: Choose the thing that is known to be of high quality over the thing that is known to be of low quality. But usually, the qualities of some options are uncertain and choosing them can be risky. As with us, the likelihood of some primates, birds, and insects to choose riskier options over safer ones can be affected by outside influences. And we aren’t the only species to have our risk-taking choices influenced by social context.

Anthropologists Alex Rosati and Brian Hare at Duke University tested two ape species, chimpanzees and bonobos, in their willingness to choose the riskier option in different social situations. They tested chimpanzees living in the Tchimpounga Chimpanzee Sanctuary and bonobos in the Lola ya Bonobo Sanctuary, both in the Democratic Republic of Congo. Most of the apes living in these sanctuaries are confiscated from poachers that captured them from the wild for the pet trade and for bushmeat. In these sanctuaries the animals live in social groups, generally spending their days roaming large tracts of tropical forest and their nights in indoor dormitories. This lifestyle rehabilitates their bodies and minds, resulting in psychologically healthy sanctuary inhabitants.

It is in these familiar dormitories that Alex and Brian tested the apes’ propensity for making risky choices. For their experimental set-up, an experimenter sat across a table from an ape and offered them two options: an overturned bowl that always covered a treat that the apes kinda like (peanuts) versus an overturned bowl that covered either an awesome treat (banana or apple) or a lousy treat (cucumber or lettuce). In this paradigm, the peanut-bowl represents the safe choice because whenever the ape chooses it, they know they’re getting peanuts. But the other bowl is the risky choice, because half the time they get fruit (yum!), but the other half of the time they get greens (bummer).


This figure from Rosati and Hare's 2012 Animal Behavour paper shows Alex demonstrating the steps they would go through before the ape chose one of the two options.

After spending some time training the apes to be sure they understood the game, the researchers tested their choices in different social situations. In each test session, the ape was allowed to choose between the two bowls (and eat the reward) multiple times (each choice was called a trial). But before the test session began and in between choice trials, another experimenter sat with the ape for two minutes and did one of three things: In one group, the experimenter sat at the table and silently looked down (they called this the “neutral condition”). In another group, the experimenter repeatedly offered the ape a large piece of food, pulling it away and grunting whenever the ape reached for it (they called this the “competitive condition”). In a third group, the experimenter tickled and played with the ape (they called this the “play condition”).

Alex and Brian found out that whereas bonobos chose the safe option and the risky option about equally, the chimpanzees were significantly more likely to choose the risky option. But despite this species difference, both species chose the risky option more often in the “competitive condition”. Neither species increased their risk-taking in the “play condition”.

The graph on the left shows that wheras bonobos chose the safe option and the risky option each about 50% of the time (where the dashed line is), the chimpanzees chose the risky option much more often. The graph on the right shows that both species chose the risky option more often in the "competition condition" than they did in the "neutral condition". Figure from Rosati and Hare's 2012 Animal Behavour paper.

These are interesting findings, especially when you consider the natural behaviors and lifestyles of these closely related species. Bonobos can be thought of as the hippies of the ape world, happily sharing and using sex to settle disputes and strengthen relationships. In comparison, chimpanzees are more like gangsters, aggressively fighting over resources and dominance ranks. So in general, the more competitive species is more likely to take risks. But when the social environment becomes more competitive, both species up the ante. This effect doesn’t seem to be simply the result of being in a social situation, because the apes didn’t increase their risk-taking in the presence of a playful experimenter.

This still leaves us with some questions to ponder though. Are apes more likely to take risks when an experimenter is offering food and taking it away because of a heightened sense of competition, or is this the result of frustration? And would we see the same effect if the “competitor” were another ape of the same species, rather than a human experimenter? How would their behavior change if they were hungry? These questions are harder to get at, but this research does demonstrate that like in humans, the decision-making process in chimpanzees and bonobos is dependent on social context.


Want to know more? Check this out:

Rosati, A., & Hare, B. (2012). Decision making across social contexts: competition increases preferences for risk in chimpanzees and bonobos Animal Behaviour, 84 (4), 869-879 DOI: 10.1016/j.anbehav.2012.07.010

Why This Horde of Idiots is No Genius

A modified reposting of an article from May, 2012.

At first look (in Part 1 of this post), swarm theory seems to predict that the larger the social group, the better the resulting group decisions and behaviors. Then, with over 300 million of us in the U.S., shouldn’t we only be making brilliant decisions? And with over 7 billion worldwide, shouldn’t we have already prevented all international conflicts, cancer, and environmental destruction?

A riot in Vancouver, Canada after the Vancouver Canucks lost the Stanley Cup
in 2011 left the city with scars. Photo by Elopde at Wikimedia Commons.

Many large groups of people make incredibly stupid decisions. Like proverbial lemmings (a hoax perpetuated by Disney), large groups of people have caused incredible damage to their community after their hockey team lost the Stanley Cup, quit their jobs and given away all of their possessions believing the end of the world was coming on May 21, 2011 (ehem… we’re still here), and insisted that wearing baggy pants around the thighs is a reasonable thing to do even though it is not sexy and it trips you when you try to run. Where are we going wrong?

Tom Seeley at Cornell University has gained tremendous insight into effective group decision-making from his years observing honeybees, which he shares with us in his book, Honeybee Democracy. (By the way, this is also one of the best books out there for painting a picture of the life of a behavioral biologist).

Honeybees live in swarms of thousands. When the hive becomes overcrowded, about a third of the worker bees will stay home to rear a new queen while the old queen and the rest of the hive will leave to begin the process of finding a new home. During this time, the migrants will coalesce on a nearby branch while they search out and decide among new home options. This process can take anywhere from hours to days during which the colony is vulnerable and exposed. But they can’t be too hasty: choosing a new home that is too small or too exposed could be equally deadly.


This homeless honeybee swarm found an unconventional "branch". They'd better
decide on a new home before the cyclist gets back!  Photo by Nino Barbieri at Wikimedia.

Although each swarm has a queen, she plays no role in making this life-or-death decision. Rather, this decision is made by a consensus among 300-500 scout bees that results after an intense “dance-debate”. Then, as a single united swarm, they leave their branch and move into their new home. At this point, it’s critical that the swarm is unified in their choice of home site, because a split-decision runs the risk of creating a chaos in which the one and only queen can be lost and the entire hive will perish. This is a high-stakes decision that honeybees make democratically, efficiently, and amazingly, they almost always make the best possible choice! How do they do that? And how can we do that?



Each dot represents where on the body this dancer
was head-bumped by a dancer for a competing site.
Each time she's bumped, she's a little less
enthusiastic about her own dance. Figure from
Seeley, et al. 2012 paper in Science.

The honeybee house-hunting process has several features that allow them as a group to hone in on the best possible solution. The process begins when a scout discovers a site that has potential for a new home. She returns to her swarm and reports on this site, using a waggle dance that encodes the direction and distance to the site and her estimate of its quality. The longer she dances, the better she perceived the site to be. Other scouts do the same, perhaps visiting the same site or maybe a new one, and they report their findings in dance when they return. More scouts are recruited and the swarm breaks into a dancing frenzy, with many scouts dancing for multiple possible sites. Over time, scouts that are less enthusiastic about their discovered site stop dancing, in part discouraged by dancers for other sites that head-bump them while beeping. Eventually, the dancing scouts are unified in their dance for what is almost always the best site. The swarm warms up their flight muscles, and off they go, in unison to their new home.

What can we learn from this process? Tom has summarized his wisdom gained from observing honeybees in the following:

Tom Seeley’s Five Habits of Highly Effective Hives

1. “Group members share a goal”.
This is easy for honeybees, but not as much for us. All of the honeybees in a swarm share the same goal: Find the best possible home as quickly as possible. People are not always similar in our goals, needs and wants and one person’s goals are sometimes in direct conflict with another person’s goals. The trick here is finding common ground.

2. “Group members search broadly to find possible solutions to the problem”.
Seek out information from as many sources as you can. Be creative. Use your personal experience. And if the group is diverse, there will be a broader range of personal experience to harness. Diversity increases the ability of a group to make the best decisions.

3. “Group members contribute their information freely and honestly”.
This requires a welcoming and supportive environment that withholds judgment of the individuals for the ideas expressed. You don’t have to agree with an idea to respect and listen to the person expressing it.

4. “Group members evaluate the options independently and they vote independently”.
Just as scout bees don’t dance for a site they have not visited and assessed themselves, we should not advocate possible solutions or candidates that we have not ourselves looked into and thought critically about. A group can only be smarter than the individuals in it if the individuals think for themselves.

5. “Group members aggregate their votes fairly”.
Everyone gets a vote and each one counts equally. ‘Nuff said.

We can learn a lot from these honeybees. Even when the stakes are high, we can make good decisions for our group if we are open, honest, inclusive, fair and think independently.


Want to know more? Check these out:

1. Seeley, T., Visscher, P., Schlegel, T., Hogan, P., Franks, N., & Marshall, J. (2011). Stop Signals Provide Cross Inhibition in Collective Decision-Making by Honeybee Swarms Science, 335 (6064), 108-111 DOI: 10.1126/science.1210361

2. List, C., Elsholtz, C., & Seeley, T. (2009). Independence and interdependence in collective decision making: an agent-based model of nest-site choice by honeybee swarms Philosophical Transactions of the Royal Society B: Biological Sciences, 364 (1518), 755-762 DOI: 10.1098/rstb.2008.0277

3. Honeybee Democracy by Thomas Seeley

4. The Smart Swarm by Peter Miller

5. The Wisdom of Crowds by James Surowiecki

Can a Horde of Idiots be a Genius?

A modified reposting of an article from April, 2012.

Let’s face it: The typical individual is not that bright. Just check out these human specimens:

Yet somehow, if you get enough numbskulls together, the group can make some pretty intelligent decisions. We’ve seen this in a wide variety of organisms facing a number of different challenges.

In a brilliant series of studies, Jean-Louis Deneubourg, a professor at the Free University of Brussels, and his colleagues tested the abilities of Argentine ants (a common dark-brown ant species) to collectively solve foraging problems. In one of these studies, the ants were provided with a bridge that connected the nest to a food source. This bridge split and fused in two places (like eyeglass frames), but at each split one branch was shorter than the other, resulting in a single shortest-path and multiple longer paths. After a few minutes, explorers crossed the bridge (by a meandering path) and discovered the food. This recruited foragers, each of which chose randomly between the short and the long branch at each split. Then suddenly, the foragers all started to prefer the shortest route. How did they do that?

This figure from the Goss et al 1989 paper in Naturwissemschaften shows (a) the design of a single module, (b) ants scattered on the bridge after 4 minutes (I promise they’re there), and (c) ants mostly on the shortest path after 8 minutes

You can think of it this way: a single individual often tries to make decisions based on the uncertain information available to it. But if you have a group of individuals, they will likely each have information that differs somewhat from the information of others in the group. If they each make a decision based on their own information alone, they will likely result in a number of poor decisions and a few good ones. But if they can each base their decisions on the accumulation of all of the information of the group, they stand a much better chance of making a good decision. The more information accumulated, the more likely they are to make the best possible decision.

In the case of the Argentine ant, the accumulated information takes the form of pheromone trails. Argentine ants lay pheromone trails both when leaving the nest and when returning to the nest. Ants that are lucky enough to take a shorter foraging route return to the nest sooner, increasing the pheromone concentration of the route each way. In this way, shorter routes develop more concentrated pheromone trails faster, which attract more ants, which further increase pheromone concentration of the shortest routes. In this way, an ant colony can make an intelligent decision (take the shortest foraging route) without any individual doing anything more intelligent than following a simple rule (follow the strongest pheromone signal).

Home is where the heart is. Photo of a bee swarm by Tom Seeley

Honeybee colonies also solve complicated tasks with the use of communication. Tom Seeley at Cornell University and his colleagues have investigated the honeybee group decision-making process of finding a new home. When a colony outgrows their hive, hundreds of scouts will go in search of a suitable new home, preferably one that is high off the ground with a south-facing entrance and room to grow. If a scout finds such a place, she returns to the colony and performs a waggle dance, a dance in which her body position and movements encode the directions to her site and her dancing vigor relates to how awesome she thinks the site is. 

Some scouts that see her dance may be persuaded to follow her directions and check out the site for themselves, and if impressed, may return to the hive and perform waggle dances too. Or they may follow another scout’s directions to a different site or even strike out on their own. Eventually, the majority of the scouts are all dancing the same vigorous dance. But interestingly, few scouts ever visit more than one site. Better sites simply receive more vigorous “dance-votes” and then attract more scouts to do the same. Like ants in search of a foraging path, the intensity of the collective signal drives the group towards the best decision. Once a quorum is reached, the honeybees fly off together to their new home.

But groups can develop better solutions than individuals even without communication. Gaia Dell’Ariccia at the University of Zurich in Switzerland and her colleagues explored homing pigeon navigation by placing GPS trackers on the backs of pigeons and releasing them from a familiar location either alone or in a group of six. Because they were all trained to fly home from this site, they all found their way home regardless of whether they were alone or in a group. But as a flock, the pigeons left sooner, rested less, flew faster, and took a more direct route than did the same birds when making the trip alone. By averaging the directional tendencies of everyone in the group, they were able to mutually correct the errors of each individual and follow the straightest path.

In each of these examples, each individual has limited and uncertain information, but each individual has information that may be slightly different than their neighbors’. By combining this diverse information and making a collective decision, hordes of idiots can make genius decisions.


Want to know more? Check these out:

1. Couzin, I. (2009). Collective cognition in animal groups Trends in Cognitive Sciences, 13 (1), 36-43 DOI: 10.1016/j.tics.2008.10.002

2. Goss, S., Aron, S., Deneubourg, J., & Pasteels, J. (1989). Self-organized shortcuts in the Argentine ant Naturwissenschaften, 76 (12), 579-581 DOI: 10.1007/BF00462870

3. Dussutour, A., Nicolis, S., Deneubourg, J., & Fourcassié, V. (2006). Collective decisions in ants when foraging under crowded conditions Behavioral Ecology and Sociobiology, 61 (1), 17-30 DOI: 10.1007/s00265-006-0233-x

4. List C, Elsholtz C, & Seeley TD (2009). Independence and interdependence in collective decision making: an agent-based model of nest-site choice by honeybee swarms. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 364 (1518), 755-62 PMID: 19073474

5. Dell'Ariccia, G., Dell'Omo, G., Wolfer, D., & Lipp, H. (2008). Flock flying improves pigeons' homing: GPS track analysis of individual flyers versus small groups Animal Behaviour, 76 (4), 1165-1172 DOI: 10.1016/j.anbehav.2008.05.022

6. Honeybee Democracy by Thomas Seeley

7. The Smart Swarm by Peter Miller

Risky Business: Ape Style

A reposting of an article from April, 2013

The decisions of this chimpanzee living in the
Tchimpounga Chimpanzee Sanctuary are affected
by his social situation. Photo by Alex Rosati.

If you have a choice between a prize that is awesome half the time and totally lame the other half of the time or a mediocre prize that is a sure-thing, which would you choose? Your choice probably depends on your personality somewhat. It may also depend on your needs and your mood. And it can depend on social contexts, like if you’re competing with someone or if you’re being watched by your boss or someone you have a crush on.

All animals have to make choices. Some choices are obvious: Choose the thing that is known to be of high quality over the thing that is known to be of low quality. But usually, the qualities of some options are uncertain and choosing them can be risky. As with us, the likelihood of some primates, birds, and insects to choose riskier options over safer ones can be affected by outside influences. And we aren’t the only species to have our risk-taking choices influenced by social context.

Anthropologists Alex Rosati and Brian Hare at Duke University tested two ape species, chimpanzees and bonobos, in their willingness to choose the riskier option in different social situations. They tested chimpanzees living in the Tchimpounga Chimpanzee Sanctuary and bonobos in the Lola ya Bonobo Sanctuary, both in the Democratic Republic of Congo. Most of the apes living in these sanctuaries are confiscated from poachers that captured them from the wild for the pet trade and for bushmeat. In these sanctuaries the animals live in social groups, generally spending their days roaming large tracts of tropical forest and their nights in indoor dormitories. This lifestyle rehabilitates their bodies and minds, resulting in psychologically healthy sanctuary inhabitants.

It is in these familiar dormitories that Alex and Brian tested the apes’ propensity for making risky choices. For their experimental set-up, an experimenter sat across a table from an ape and offered them two options: an overturned bowl that always covered a treat that the apes kinda like (peanuts) versus an overturned bowl that covered either an awesome treat (banana or apple) or a lousy treat (cucumber or lettuce). In this paradigm, the peanut-bowl represents the safe choice because whenever the ape chooses it, they know they’re getting peanuts. But the other bowl is the risky choice, because half the time they get fruit (yum!), but the other half of the time they get greens (bummer).


This figure from Rosati and Hare's 2012 Animal Behavour paper shows Alex
demonstrating the steps they would go through before the ape chose one of the two options.

After spending some time training the apes to be sure they understood the game, the researchers tested their choices in different social situations. In each test session, the ape was allowed to choose between the two bowls (and eat the reward) multiple times (each choice was called a trial). But before the test session began and in between choice trials, another experimenter sat with the ape for two minutes and did one of three things: In one group, the experimenter sat at the table and silently looked down (they called this the “neutral condition”). In another group, the experimenter repeatedly offered the ape a large piece of food, pulling it away and grunting whenever the ape reached for it (they called this the “competitive condition”). In a third group, the experimenter tickled and played with the ape (they called this the “play condition”).

Alex and Brian found out that whereas bonobos chose the safe option and the risky option about equally, the chimpanzees were significantly more likely to choose the risky option. But despite this species difference, both species chose the risky option more often in the “competitive condition”. Neither species increased their risk-taking in the “play condition”.

The graph on the left shows that wheras bonobos chose the safe option and the risky option each about 50% of the time (where the dashed line is), the chimpanzees chose the risky option much more often. The graph on the right shows that both species chose the risky option more often in the "competition condition" than they did in the "neutral condition". Figure from Rosati and Hare's 2012 Animal Behavour paper.

These are interesting findings, especially when you consider the natural behaviors and lifestyles of these closely related species. Bonobos can be thought of as the hippies of the ape world, happily sharing and using sex to settle disputes and strengthen relationships. In comparison, chimpanzees are more like gangsters, aggressively fighting over resources and dominance ranks. So in general, the more competitive species is more likely to take risks. But when the social environment becomes more competitive, both species up the ante. This effect doesn’t seem to be simply the result of being in a social situation, because the apes didn’t increase their risk-taking in the presence of a playful experimenter.

This still leaves us with some questions to ponder though. Are apes more likely to take risks when an experimenter is offering food and taking it away because of a heightened sense of competition, or is this the result of frustration? And would we see the same effect if the “competitor” were another ape of the same species, rather than a human experimenter? How would their behavior change if they were hungry? These questions are harder to get at, but this research does demonstrate that like in humans, the decision-making process in chimpanzees and bonobos is dependent on social context.


Want to know more? Check this out:

Rosati, A., & Hare, B. (2012). Decision making across social contexts: competition increases preferences for risk in chimpanzees and bonobos Animal Behaviour, 84 (4), 869-879 DOI: 10.1016/j.anbehav.2012.07.010

Cow Pies Can Make You Smarter and Less Stressed

A reposting of an article from August, 2015

It seems like everyone is running around buying school supplies and books, registering for classes, and fretting about how hard it is going to be to learn another whole year’s worth of stuff. The secret to success, it turns out, may lie in cow dung.

A cow pie. Photo taken by Jeff Vanuga at
the USDA available at Wikimedia Commons.

Recent research has highlighted the important role that microbes living in animal digestive tracts have on host animals’ health and behavior. This influence of our gut microbes on our behavior is called the microbiota-gut-brain axis. Many of these microbes have long-standing populations that reproduce and spend their whole lives in our guts. Because our digestive tracts do not have much oxygen, these species are anaerobic (do not require oxygen to live). However, our gut communities also have more transient aerobic members (species that do require oxygen to live) that come in when they are ingested and die or leave with the droppings. One of these transient aerobic intestinal citizens is Mycobacterium vaccae (or M. vaccae for short), an aerobic bacterium that naturally lives in soil, water, and yes, cow dung.

When mice are injected with heat-killed M. vaccae, they develop an immune response that activates their brain serotonin system and reduces signs of stress. Serotonin is a neurotransmitter that is found in the brain and is involved in regulating alertness, mood, learning and memory. In fact, many antidepressant drugs work by increasing the amount of available serotonin in the brain. Interestingly, serotonin is also found in the digestive system, where it plays a role in digestive health. Since M. vaccae can increase serotonin function, and serotonin reduces anxiety and improves learning, researchers Dorothy Matthews and Susan Jenks at The Sage Colleges in New York set out to test whether eating live M. vaccae could reduce anxiety and improve learning in mice.

A drawing of the mouse maze used by Dorothy and Susan.
This image is from their 2013 Behavioural Processes paper.

The researchers developed a Plexiglas mouse-maze with three difficulty levels, where each increase in difficulty was marked by more turns and a longer path. They encouraged the mice to run the maze by placing a tasty treat (a square of peanut butter on Wonder Bread™) at the end of the maze. Half of the mice were given live M. vaccae on the peanut butter and bread treat three weeks and one week before running the maze, and then again on each treat at the end of each maze run. The other half were given peanut butter and bread without the bacterial additive. The mice then ran the maze roughly every other day: four times at level 1, four times at level 2 and four times at level 3. Each maze run was video recorded and the researchers later watched the videos to count stress-related behaviors.

The mice that ingested M. vaccae on their peanut butter sandwiches completed the maze twice as fast as those that ate plain peanut butter sandwiches. They also had fewer stress-related behaviors, particularly at the first difficulty level of the maze when everything was new and scary. In general, the fewer stress behaviors a mouse did, the faster its maze-running time was. The mice that ate the M. vaccae also tended to make fewer mistakes.

The researchers then wanted to know how long the effects of M. vaccae lasted. They continued to test the mice in the same maze, again with four runs at level 1, four runs at level 2 and four runs at level 3, but for these maze runs no one was given the M. vaccae. The mice that had previously eaten the M. vaccae continued to complete the maze faster and with fewer mistakes and to show fewer stress-related behaviors for about the first week before the M. vaccae effects wore off.

What does this all mean? It means eating dirt isn’t all bad (although I don't recommend eating cow poop). Letting yourself get a bit dirty and ingesting some of nature's microbes could even help you learn better, remember more, and stay calm - especially in new situations. Just something to think about as the school year gets started.


Want to know more? Check these out:

1. Matthews, D., & Jenks, S. (2013). Ingestion of Mycobacterium vaccae decreases anxiety-related behavior and improves learning in mice Behavioural Processes, 96, 27-35 DOI: 10.1016/j.beproc.2013.02.007

2. Lowry, C., Hollis, J., de Vries, A., Pan, B., Brunet, L., Hunt, J., Paton, J., van Kampen, E., Knight, D., Evans, A., Rook, G., & Lightman, S. (2007). Identification of an immune-responsive mesolimbocortical serotonergic system: Potential role in regulation of emotional behavior Neuroscience, 146 (2), 756-772 DOI: 10.1016/j.neuroscience.2007.01.067

Catch Him If You Can (A Guest Post)

By Caitlin Lockard

When playing Frisbee with your dog, do you ever wonder how they have the ability to catch it so effortlessly? The art of being able to figure out where something like a Frisbee is headed requires some crazy math skills. Ostracods are one kind of animal that puts their wicked math skills to the test while finding a mate.

The image above of a female ostracod was provided by Trevor Rivers.

You’ve never heard of an ostracod you say? Ostracods are small crustaceans, which basically means they have lots of legs and are covered by a hard shell. Male ostracods can be seen roaming throughout the ocean trying to enchant females with light displays. Typically, just after sunset, males begin their light displays, which consist of two phases. The first phase is the bright phase, which is short. The goal here is to signal to the female that “I’m here, single (except all my buddies that I brought with me of course) and ready to mingle”. The second phase is where males spiral up in a helix while pulsing repeatedly. This phase is much dimmer and is used by females to choose a mate. But exactly how do female ostracods go about catching the moving and light-pulsing man of her dreams?

Scientists, Trevor Rivers of the University of Kansas and Jim Morin of Cornell University, set off to explore if female ostracods try to intercept the moving and pulsing males or if they just chase them. In order to conduct this experiment, immature female ostracods were collected off the shore of Southwater Caye in Belize. After catching the ostracods, females were put into tanks and raised to maturity, ensuring that all the females were sexually mature virgins. Rivers and Morin put an LED light behind the different tanks in order to mimic an actual mating display. The LED light looked like a string of Christmas lights pulsing from bottom to top, mimicking the males’ helical light display. In the control group, there was an LED light placed behind the tank, however it was turned off. The duo questioned whether or not the LED light show was able to mimic the display put on by male ostracods. Also, they questioned how females respond to the males’ display by measuring the height at which females intercepted the LED light, how straight of a line the female swam in, if the female swam at an angle, and what direction the female swam in. Check out a video here.

The scientists found that the LED light was able to mimic the helical phase that male ostracods put on well enough for the females to respond. Females in the control group merely swam at the same height, as there was no reason for her to waste her energy with no “male” around. However, females in the experimental group had to think on their feet to figure out where their male crush was heading. They swam directly toward but slightly above the “male” than when there was no “mate” around. If the female merely headed to the same spot where her “male” previously was, she would miss him. Instead, she had to anticipate where he was going next and head that direction.

What’s the moral of the story here? If you’re a female ostracod, your man will always be on the move, so you better have some gnarly geometry skills in order to track him down.


Work Cited:

Rivers, T., & Morin, J. (2013). Female ostracods respond to and intercept artificial conspecific male luminescent courtship displays Behavioral Ecology, 24 (4), 877-887 DOI: 10.1093/beheco/art022

Caught in My Web: The Intelligence and Creativity of Crows, Octopuses, Monkeys, Fish and Dogs

Image by Luc Viatour at Wikimedia.

For this edition of Caught in My Web, we marvel at animal intelligence.

1. Joshua Klein talks about crow intelligence and their potential for training in this fun TED talk.

2. Jason Goldman at io9 explains an amazing discovery that Atlantic cod can also innovate to solve problems.

3. Sarah Williams at Science explains research out of Harvard that shows that untrained rhesus monkeys can do math and we can use this to learn about how we think.

4. A veined octopus shows off his imagination as he creates a “hiding” place:

5. And last, but not least, three shelter dogs were taught to drive! Here are the results:

Cow Pies Can Make You Smarter and Less Stressed

It seems like everyone is running around buying school supplies and books, registering for classes, and fretting about how hard it is going to be to learn another whole year’s worth of stuff. The secret to success, it turns out, may lie in cow dung.

A cow pie. Photo taken by Jeff Vanuga at
the USDA available at Wikimedia Commons.

Recent research has highlighted the important role that microbes living in animal digestive tracts have on host animals’ health and behavior. This influence of our gut microbes on our behavior is called the microbiota-gut-brain axis. Many of these microbes have long-standing populations that reproduce and spend their whole lives in our guts. Because our digestive tracts do not have much oxygen, these species are anaerobic (do not require oxygen to live). However, our gut communities also have more transient aerobic members (species that do require oxygen to live) that come in when they are ingested and die or leave with the droppings. One of these transient aerobic intestinal citizens is Mycobacterium vaccae (or M. vaccae for short), an aerobic bacterium that naturally lives in soil, water, and yes, cow dung.

When mice are injected with heat-killed M. vaccae, they develop an immune response that activates their brain serotonin system and reduces signs of stress. Serotonin is a neurotransmitter that is found in the brain and is involved in regulating alertness, mood, learning and memory. In fact, many antidepressant drugs work by increasing the amount of available serotonin in the brain. Interestingly, serotonin is also found in the digestive system, where it plays a role in digestive health. Since M. vaccae can increase serotonin function, and serotonin reduces anxiety and improves learning, researchers Dorothy Matthews and Susan Jenks at The Sage Colleges in New York set out to test whether eating live M. vaccae could reduce anxiety and improve learning in mice.

A drawing of the mouse maze used by Dorothy and Susan.
This image is from their 2013 Behavioural Processes paper.

The researchers developed a Plexiglas mouse-maze with three difficulty levels, where each increase in difficulty was marked by more turns and a longer path. They encouraged the mice to run the maze by placing a tasty treat (a square of peanut butter on Wonder Bread™) at the end of the maze. Half of the mice were given live M. vaccae on the peanut butter and bread treat three weeks and one week before running the maze, and then again on each treat at the end of each maze run. The other half were given peanut butter and bread without the bacterial additive. The mice then ran the maze roughly every other day: four times at level 1, four times at level 2 and four times at level 3. Each maze run was video recorded and the researchers later watched the videos to count stress-related behaviors.

The mice that ingested M. vaccae on their peanut butter sandwiches completed the maze twice as fast as those that ate plain peanut butter sandwiches. They also had fewer stress-related behaviors, particularly at the first difficulty level of the maze when everything was new and scary. In general, the fewer stress behaviors a mouse did, the faster its maze-running time was. The mice that ate the M. vaccae also tended to make fewer mistakes.

The researchers then wanted to know how long the effects of M. vaccae lasted. They continued to test the mice in the same maze, again with four runs at level 1, four runs at level 2 and four runs at level 3, but for these maze runs no one was given the M. vaccae. The mice that had previously eaten the M. vaccae continued to complete the maze faster and with fewer mistakes and to show fewer stress-related behaviors for about the first week before the M. vaccae effects wore off.

What does this all mean? It means eating dirt isn’t all bad (although I don't recommend eating cow poop). Letting yourself get a bit dirty and ingesting some of nature's microbes could even help you learn better, remember more, and stay calm - especially in new situations. Just something to think about as the school year gets started.

Want to know more? Check these out:

1. Matthews, D., & Jenks, S. (2013). Ingestion of Mycobacterium vaccae decreases anxiety-related behavior and improves learning in mice Behavioural Processes, 96, 27-35 DOI: 10.1016/j.beproc.2013.02.007

2. Lowry, C., Hollis, J., de Vries, A., Pan, B., Brunet, L., Hunt, J., Paton, J., van Kampen, E., Knight, D., Evans, A., Rook, G., & Lightman, S. (2007). Identification of an immune-responsive mesolimbocortical serotonergic system: Potential role in regulation of emotional behavior Neuroscience, 146 (2), 756-772 DOI: 10.1016/j.neuroscience.2007.01.067

The Weirdest Animals on Earth: 12 Amazing Facts About Octopuses



Photo of a day octopus by
Ahmed Abdul Rahman available
at Wikimedia Commons.

1. The plural of octopus is octopuses. How an English word is pluralized depends, in part, on its origins. Latin words that end in –us are generally pluralized by replacing the –us with an –i (the plural of alumnus, for example, is alumni). But octopus is not Latin – It comes from the ancient Greek word októpous, whose plural is októpodes. Although octopodes is technically correct, since it has been adopted into the English language, the word is now pluralized in the English way, making it octopuses. So octopi is commonly used but not technically correct, octopodes is technically correct but not commonly used and octopussies is just plain wrong.

2. Octopuses are mollusks. This means that they are not only closely related to squid and cuttlefish, but also to clams, oysters, snails and slugs.

3. Octopuses are crazy-smart. They can solve problems, learn from watching others, use tools, and remember experiences. They even have personalities and play with toys. Check this out:

4. Octopuses have nine brains! Rather than a large centralized brain like ours, octopus brains are more like the internet. Their main CPU is a fairly small brain in their head, but each of their eight arms has an additional brain of its own. In fact, two-thirds of an octopus’ neurons are in the arms, which can independently attach to things, push things, and even smell things. They can even react after they have been severed! Not only that, but their severed arms recognize their previous owner:

5. If an octopus loses an arm, it can grow back. Those crazy arms are like the brooms in Disney's Sorcerer's Apprentice in Fantasia!

6. Octopuses are amazing camouflage artists. Their soft bodies can squeeze into ridiculously small cracks and crevices and take on any number of shapes. A 50-pound octopus, for example, can squeeze through a 2-inch hole! They can also change the color and texture of their skin to match their background.

The mimic octopus, the ultimate master of disguise, doesn’t just imitate their background, but also flounders, starfish, poisonous lionfish, and sea snakes.



A vertebrate eye (left) versus an octopus eye (right).
1: Retina, 2: Nerve fibers, 3: Optic nerve, 4: Blind spot.
Image by Jerry Crimson Mann at Wikimedia.

7. Octopuses don’t have visual blind-spots. Most animal eyes detect light patterns when light travels to the retina (the layer in the back of the eye) and falls on photoreceptor cells, causing the cells to send electrical signals through the optic nerve to the brain. Vertebrate photoreceptor cells face backwards, so their nerve fibers come in front of the retina and then exit the eye together through the optic nerve, creating a small region in the back of the eye with no photoreceptor cells. If light falls on this spot, we literally will not see it, although our brain will compensate for this missing light by imagining what should be there based on the rest of what we see. We call this our blind spot. You can test your blind spot by closing your left eye and focusing your right eye on the “R” below. Move your face towards or away from the screen until the “L” disappears. You can test your left eye by staring at the “L” in the same way.

In octopus eyes, the photoreceptor cells face forwards and the nerve fibers go behind the retina. This means that they have a continuous layer of photoreceptor cells and no blind spot.

8. Octopuses are more blue blooded than police officers. Their blood is truly blue, due to the fact that they don’t have hemoglobin, our respiratory pigment that contains iron and turns red when it binds to oxygen. Rather, they have hemocyanin, which contains copper and turns blue when oxygen binds to it.

9. Octopuses have three hearts! They have two small hearts that each pump blood through the gills and a main systemic heart that collects the blood and pumps it through the circulatory system.

10. Octopus ink is a defensive chemical concoction. It not only obscures the view of an attacker, but it also contains a chemical that irritates the predator’s eyes and temporarily paralyzes its sense of smell.

11. Octopuses bite with a bird-like beak and venomous saliva, which is mostly used to subdue prey. Of the approximately 300 octopus species, only the small blue-ringed octopus is known to be deadly to humans.

12. Octopuses die after they mate for the first time. And they mate in an odd way too: males use the tip of their third arm on the right to either insert their spermatophores (sperm packets) directly into the female’s tubular breathing funnel or he just hands it to her (The tip of the third right arm can be used to tell if an octopus is male or female). If he hands it to her, she accepts it with one of her right arms (we don’t know why they’re right-handed this way). Then the males go off to die. The females eventually lay up to 400,000 fertilized eggs, although they can wait months before they do this. She tends them and guards them at the exclusion of all else until they hatch, at which point her body rapidly deteriorates as her cells die off.

Crocodilians Hunt With Tools!

A crocodile lures in birds with sticks that would make a nice nest.
Photo by Dinets published in Ethology, Ecology & Evoluton 2013.

What would happen to mankind if crocodiles and alligators were to develop enough intelligence that they could hunt with tools? Would we see the rise of new dominant species as in Rise of the Planet of the Apes?

Well, shudder in your boots, people, because we are already there!

This week at Accumulating Glitches I talk about the discovery of how at least two species of crocodilians use tools to lure in prey. Check it out here.

And to learn more, check this out:

Dinets, V., Brueggen, J.C.. and Brueggen, J.D. Crocodilians use tools for hunting, Ethology Ecology & Evolution, (2013). DOI: 10.1080/03949370.2013.858276.

Risky Business: Ape Style

The decisions of this chimpanzee living in the
Tchimpounga Chimpanzee Sanctuary are affected
by his social situation. Photo by Alex Rosati.

If you have a choice between a prize that is awesome half the time and totally lame the other half of the time or a mediocre prize that is a sure-thing, which would you choose? Your choice probably depends on your personality somewhat. It may also depend on your needs and your mood. And it can depend on social contexts, like if you’re competing with someone or if you’re being watched by your boss or someone you have a crush on.

All animals have to make choices. Some choices are obvious: Choose the thing that is known to be of high quality over the thing that is known to be of low quality. But usually, the qualities of some options are uncertain and choosing them can be risky. As with us, the likelihood of some primates, birds, and insects to choose riskier options over safer ones can be affected by outside influences. And we aren’t the only species to have our risk-taking choices influenced by social context.

Anthropologists Alex Rosati and Brian Hare at Duke University tested two ape species, chimpanzees and bonobos, in their willingness to choose the riskier option in different social situations. They tested chimpanzees living in the Tchimpounga Chimpanzee Sanctuary and bonobos in the Lola ya Bonobo Sanctuary, both in the Democratic Republic of Congo. Most of the apes living in these sanctuaries are confiscated from poachers that captured them from the wild for the pet trade and for bushmeat. In these sanctuaries the animals live in social groups, generally spending their days roaming large tracts of tropical forest and their nights in indoor dormitories. This lifestyle rehabilitates their bodies and minds, resulting in psychologically healthy sanctuary inhabitants.

It is in these familiar dormitories that Alex and Brian tested the apes’ propensity for making risky choices. For their experimental set-up, an experimenter sat across a table from an ape and offered them two options: an overturned bowl that always covered a treat that the apes kinda like (peanuts) versus an overturned bowl that covered either an awesome treat (banana or apple) or a lousy treat (cucumber or lettuce). In this paradigm, the peanut-bowl represents the safe choice because whenever the ape chooses it, they know they’re getting peanuts. But the other bowl is the risky choice, because half the time they get fruit (yum!), but the other half of the time they get greens (bummer).


This figure from Rosati and Hare's 2012 Animal Behavour paper shows Alex demonstrating the steps they would go through before the ape chose one of the two options.

After spending some time training the apes to be sure they understood the game, the researchers tested their choices in different social situations. In each test session, the ape was allowed to choose between the two bowls (and eat the reward) multiple times (each choice was called a trial). But before the test session began and in between choice trials, another experimenter sat with the ape for two minutes and did one of three things: In one group, the experimenter sat at the table and silently looked down (they called this the “neutral condition”). In another group, the experimenter repeatedly offered the ape a large piece of food, pulling it away and grunting whenever the ape reached for it (they called this the “competitive condition”). In a third group, the experimenter tickled and played with the ape (they called this the “play condition”).

Alex and Brian found out that whereas bonobos chose the safe option and the risky option about equally, the chimpanzees were significantly more likely to choose the risky option. But despite this species difference, both species chose the risky option more often in the “competitive condition”. Neither species increased their risk-taking in the “play condition”.

The graph on the left shows that wheras bonobos chose the safe option and the risky option each about 50% of the time (where the dashed line is), the chimpanzees chose the risky option much more often. The graph on the right shows that both species chose the risky option more often in the "competition condition" than they did in the "neutral condition". Figure from Rosati and Hare's 2012 Animal Behavour paper.

These are interesting findings, especially when you consider the natural behaviors and lifestyles of these closely related species. Bonobos can be thought of as the hippies of the ape world, happily sharing and using sex to settle disputes and strengthen relationships. In comparison, chimpanzees are more like gangsters, aggressively fighting over resources and dominance ranks. So in general, the more competitive species is more likely to take risks. But when the social environment becomes more competitive, both species up the ante. This effect doesn’t seem to be simply the result of being in a social situation, because the apes didn’t increase their risk-taking in the presence of a playful experimenter.

This still leaves us with some questions to ponder though. Are apes more likely to take risks when an experimenter is offering food and taking it away because of a heightened sense of competition, or is this the result of frustration? And would we see the same effect if the “competitor” were another ape of the same species, rather than a human experimenter? How would their behavior change if they were hungry? These questions are harder to get at, but this research does demonstrate that like in humans, the decision-making process in chimpanzees and bonobos is dependent on social context.


Want to know more? Check this out:

Rosati, A., & Hare, B. (2012). Decision making across social contexts: competition increases preferences for risk in chimpanzees and bonobos Animal Behaviour, 84 (4), 869-879 DOI: 10.1016/j.anbehav.2012.07.010