4 Real-Life Monsters

A repost of an original article published October 26, 2015.

During the Halloween season, we find ourselves surrounded by monsters in movies, stores and decorations. We laugh at the ridiculousness of it all, oblivious to the fact that there are true monsters on our planet today! Mind you, these are not monsters in that they are evil, but they do have many of the same abilities and inclinations of our own mythical werewolves, vampires, zombies and shape-shifters.

Werewolf birds:

A Barau's petrel. Photo by SEOR
available at Wikimedia Commons.

Barau’s petrel is a migrating sea bird that is most active during nights with a full moon. Researchers tied bio-loggers on the birds’ feet to track their activity levels and found that under the full moon, the birds spent nearly 80% of these moonlit nights in flight! It is thought that since these birds migrate longitudinally (parallel with the equator), they can’t use changes in day length as a cue to synchronize their breeding, so they use the phases of the moon instead.

Vampire bats:

Three different bat species feed solely on blood: the common vampire bat, the hairy-legged vampire bat and the white-winged vampire bat. Feeding on blood is not uncommon – The actual term for it is hematophagy, and it is common in insects (think of those pesky mosquitos) and leeches. Although we don’t commonly think of it this way, blood is a body tissue and, like meat, it is rich in protein and calories. The reason it has not become a more popular food source among mammals is probably because it is so watered down (literally) compared to meat, that it can’t provide enough nutrition to sustain a large warm-bodied mammal. This is where our little vampire bat friends come in… small, stealthy, and with specialized saliva that prevents their victims’ blood from clotting, these guys are able to take advantage of this abundant resource, drinking up to half of their body weight in blood every night.

Zombees:

Scientists have recently discovered some strange honey bees: They mindlessly leave their hives in the middle of the night and fly in circles, often towards lights. It turns out that these honey bees are being parasitized by a species of phorid fly called the zombie fly. Female phorid flies lay their eggs inside the abdomens of honey bees, where the eggs hatch into larvae. The larvae feed on the insides of their bee hosts until they are mature enough to leave through the poor bee’s neck (the honey bee is generally dead by this time). Once out, the zombie flies develop into adults so they can breed and start the cycle anew with a new bee host. This phenomenon is still in the early stages of discovery, so if you would like to get involved in this project by watching honey bees in your area, check out ZomBee Watch, a citizen science project to track this zombie infestation.

Shape shifters:

The mimic octopus is a small harmless octopus that lives on the exposed shallow sandy bottoms of river mouths. To avoid its many predators it has developed an amazing strategy: it pretends to be something else, morphing its body into new shapes, like the shape of a deadly lion-fish, a poisonous flatfish, a venomous banded sea-snake, or any number of other animals that live in the area. Not only does the mimic octopus change its shape, it also changes its behavior to match its “costume” to convincingly fool predators. Most cephalopods, which include octopuses, are well-known for their ability to change the color, pattern and texture of their skin to blend in with rocks, coral and plants. Furthermore, octopuses do not have rigid skeletal elements, which allows their bodies great flexibility in the forms they imitate. But this ability to change both physical appearance and behavior to switch back and forth among imitations of multiple species is unique to this astounding shape shifter.

It Feels Good When You Sing a Song (In Fall)

A repost of an original article published October 3, 2012.

Most male songbirds will sing when they see a pretty female during the breeding season. But some male songbirds sing even when it’s not the breeding season. Why do so many birds sing in fall at all?

Maybe singing feels good… But how do you ask a bird if it feels good to sing? European starlings are one of those bird species that sing both in spring (the breeding season) and in fall (not the breeding season). Lauren Riters, Cindi Kelm-Nelson, and Sharon Stevenson at the University of Wisconsin at Madison did a series of ingenious experiments to ask starlings if and when it feels good to sing.

A European starling sings his fall-blues away. Photo by Linda Tanner at Wikimedia.

Psychologists have long used a paradigm called conditioned place preference (CPP) to evaluate whether an animal finds something rewarding or pleasurable. CPP is based on the idea that if an animal experiences something meaningless while at the same time experiencing something else that is rewarding, the animal will learn to associate these two things with each other in a phenomenon called conditioning. For example, a puppy that has learned that every time it sits it gets a treat, will find itself sitting more often.

A researcher can also compare how rewarding different types of treats are. If we want to know if puppies like carrots or steak better, we can give one group of puppies a carrot every time they sit and another group of puppies a piece of steak every time they sit. If the group of puppies that are conditioned with steak spend more time sitting, we can conclude that steak is more rewarding to puppies than carrots are.

Lauren and Sharon used this principle to ask starlings if singing is rewarding. They put spring starlings in a cage with a nestbox and a female and let them sing away, while counting how many songs they sang in 30 minutes. Then they immediately put them in another cage that was decorated with yellow materials on one side and green materials on the other, but they restricted each bird to only one of the two colored sides. This is the conditioning phase in which the bird learns to associate the colored cage with the feeling they get from singing.

The next day, they put the starlings in the yellow and green cage without restrictions so they could choose what side they wanted to hang out in. If singing is rewarding, we would expect starlings that sang a lot to spend more time on the side with the color they were placed in the day before.



Do people that sing in the car spend more time in the car?
Photo by freedigitalphotos.net.

That didn’t happen. The spring starlings spent the same amount of time in the yellow or green side of the cage regardless of how much they sang the day before.

But when Lauren and Sharon did the same test with fall starlings singing without a female, there has a huge effect: Males that sang more spent much more time on the colored side of the cage they were placed in the day before. Singing, for a male starling, is apparently rewarding in fall, but not in spring.

This result actually makes a lot of sense. In spring, males sing to attract and court females, so they are rewarded by the feeling they get from the female’s response, not from the act of singing itself. But in fall, males are not attracting females. So why do they sing in fall? Because it feels good.

It looks like Sesame Street got it right with their 1970s song “It Feels Good When You Sing a Song”:

You can't go wrong
when you're singing a song
Sing it loud, sing it strong
It feels good when you sing a song

But why does singing feel good? At least some of the reason, it seems, is opioids. Not quite what Sesame Street had in mind, but hey.

Despite their reputation for being one of the world’s oldest drugs, many opioids are naturally occurring neuropeptides (brain chemicals). They are involved in pain relief and euphoria, commonly combined in the phenomenon of runner’s high. Could opioids be involved in the feel-good sensation created by singing? Maybe.

Cindi, Sharon and Lauren suspect that singing in fall causes male starlings to release opioids in their little brains, which makes singing more rewarding and makes them want to sing more. But how do we know how much opioid an animal has in its brain? Hmmm… Opioids cause analgesia (pain relief). Therefore, if singing a lot in fall releases more opioids, then birds that sing a lot in fall should be more pain-tolerant, right? The researchers let male starlings sing and counted how many songs they produced for 20 minutes. Then they dipped their foot in uncomfortably warm water and timed how long it took for the bird to pull its toes out. Fall males that sang more took longer to pull their feet out of the birdy foot-spa than did the males that sang less.

Interestingly, if you give starlings a drug to enhance opioids, they leave their feet in the foot-spa longer than if you give them a drug to block opioids. So it seems that singing in fall increases pain tolerance in the same way that opioids do, likely because the act of singing in fall causes the brain to release its own opioids. (Although it is also possible that birds that produce more opioids feel like singing more).

And what about singing in spring? When Cindi, Sharon and Lauren repeated the study with spring starlings, these birds did not get pain relief from singing. Again, they are probably rewarded by their interactions with females and not the act of singing.

So if you ever find yourself in pain, just

Sing
Sing a song
Make it simple
To last your whole life long
Don't worry that it's not good enough
For anyone else to hear
Sing
Sing a song
La la la la la la la la la la la
La la la la la la la

Want to know more? Check these out:

1. Riters LV, & Stevenson SA (2012). Reward and vocal production: song-associated place preference in songbirds. Physiology & Behavior, 106 (2), 87-94 PMID: 22285212

2. Kelm-Nelson, C.A., Stevenson, S.A., & Riters, L.V. (2012). Context-dependent links between song production 1 and opioid-mediated analgesia in male European starlings (Sturnus vulgaris) PLOS One, 7 (10)

3. Riters LV, Schroeder MB, Auger CJ, Eens M, Pinxten R, & Ball GF (2005). Evidence for opioid involvement in the regulation of song production in male European starlings (Sturnus vulgaris). Behavioral neuroscience, 119 (1), 245-55 PMID: 15727529

4. Kelm CA, Forbes-Lorman RM, Auger CJ, & Riters LV (2011). Mu-opioid receptor densities are depleted in regions implicated in agonistic and sexual behavior in male European starlings (Sturnus vulgaris) defending nest sites and courting females. Behavioural brain research, 219 (1), 15-22 PMID: 21147175

A Yawn & Man’s Best Friend

By Erin Gellings

There’s nothing quite like the feeling of coming home after a long hard day and being welcomed by your dog. Many things dogs do are in response to their owners’ actions, including comforting and mimicking actions like yawning. There are many theories about why humans and other animals yawn, but no one theory has been proven 100% correct. What causes dogs to yawn in response to seeing a human yawn though?

Yawning Dog. Image by Scientre from Wikimedia Commons

This was the question Silvia Karine and Bessa Joana from the Universidade do Porto in Portugal set out to examine. The researchers found preliminary evidence that simply the sound of a human yawn and their relationship with their owner is enough to make a dog yawn.

Sometimes, when dogs are under stress, they can do something called a ‘tension yawn.’ There is still little evidence that explains why dogs yawn when experiencing stress. The best way to know if a dog is yawning due to feeling stressed, or in response to a human is to look at the environment. If the dog is in a new setting with new people, it is likely yawning due to stress. Researchers were very careful to make sure all the yawns dogs produced were genuine and not stress related. This was partly achieved by allowing dogs to become used to researchers before being introduced to audio of yawns. They made this determination by carefully reviewing what events led up to the dog’s yawn.

Karine and Joana used 29 dogs of various breeds and let each one become acclimated to them by just sitting in the dog’s home for about 10 minutes before they started the experiment. The researchers then exposed them to four conditions: a prerecorded sound of their owner’s yawn, familiar control sounds from their home, a stranger’s yawn, or control sounds not from their home. Each dog experienced the prerecorded sounds in a random order during two different sessions. A researcher played the sounds through a large set of speakers from audio files from a laptop in the dog’s home. The researcher wrote down every time the dog yawned, and also made a video recording of the dogs listening to the sounds so other researchers could go back and double check that their count was correct.

Twelve of the twenty-nine dogs yawned during the experiment. Out of the dogs who yawned, more dogs yawned at the yawning audio than at the background audio. This leads us to believe that the sounds of yawning are contagious and the dogs “caught” the yawn. The researchers also found that dogs yawned more when listening to the yawn of their owners than of strangers.

Aside from showing that dogs tend to yawn after hearing a human yawn, this research also hints that there may be some sort of social variable in why dogs yawn more at their owner’s yawn. The researchers suggest this may be related to a sense of empathy dogs feel towards humans, but this claim needs more research in order to be demonstrated. This research also showed that dogs do not necessarily need a visual cue of seeing a person yawn in order to yawn on their own. This is a claim that is unique to this particular project. While this research is still in its early stages, it does give us a new perspective on why dogs may yawn when around humans, and what leads to this unique behavior.

Although this study does not help us understand the function of yawning in dogs, it does bring us closer to understanding why dogs yawn in response to humans and sets the stage for future research in the field. So, after your next long day when you sit down and yawn and notice your dog yawn too, take a moment to appreciate the connection they have with you.


References

Finlay, K. (2017, June 15). Why do dogs yawn? American Kennel Club.

Silva, K., Bessa, J., & De Sousa, L. (2012). Auditory contagious yawning in domestic dogs (Canis familiaris): First evidence for social modulation. Animal Cognition, 15(4), 721-724.

Why do I yawn? (2019).

A Tiny Surprise in Regards to Regeneration (A Guest Post)

A reposting of an original article by Jessica Klein in The Scorpion and the Frog.

The ability to regenerate limbs and tails is nothing new to reptiles and amphibians. Many lizards are able to drop their tails to escape an enemy, whereas salamanders have been known to grow back entire legs with muscle after being attacked by a predator. These regenerative characteristics have been seen to some extent in rabbits and pika before 2012, but were later discovered to occur extensively in, surprisingly enough, small African spiny mice.

One of the African spiny mouse species. Photo by Ashley Seifert and Tom Gawriluk.

In a study done by Ashley W. Seifert and Megan G. Seifert at the University of Kentucky, Todd M. Palmer and Malcolm Maden at the University of Florida, Stephen G. Kiama at the University of Nairobi, and Jacob R. Goheen at the University of Wyoming, African spiny mice were studied in order to view the extent of their regenerative properties, why they might occur, and the physiological processes that make it happen.

The rodents were captured in Kenya, where researchers learned that vigorous movement during handling caused the skin of African spiny mice to come apart. One mouse was reported to have an open wound that took up 60% of its back, just from being handled! Therefore, Dr. Seifert measured the amount of strength it took to tear the skin of spiny mice using something called a Hounsfield tensometer. He took the measurements from that tool and graphed them on a plot, creating something called a stress-strain curve which showed how much strength it took to tear the skin of the mouse.

The strength measurements revealed that the skin of these species was 77 times weaker than average mice, explaining why their skin tore so easily during the handling process. In order for the African spiny mice to survive such large injuries due to their extremely fragile skin, it would be beneficial to heal quickly or regenerate the skin. This is exactly what Dr. Seifert discovered.

An African spiny mouse shows
the regenerative process with
(1) being before the wound
(2) being after the wound and
(3) showing how the wound was
completely healed after 30 days.
Figure from Seifert, et al., 2012.

After the strength measurements were completed, the rodents were anaesthetized and had 4mm and 1.5cm wounds made on their skin, as well as 4mm holes punched in their ears in order to view the regeneration process. In an average rodent, the repair of a 4mm skin wound takes around 5 to 7 days and is accompanied by a significant amount of scarring. However, in the African spiny mouse it only took 1 to 2 days for scabbing of the skin wound to occur with new cells forming on the outside of the wound to repair it. After just 10 days, the ear of the mouse was fully healed. In the ear punches, there were no signs of scarring that would have been expected in a rodent, and healthy cartilage had formed. By the 21st day of the experiment, African spiny mice had developed new hair follicles and healthy new hair covering the once wounded area. In total, Dr. Seifert discovered that African spiny mice were capable of regenerating their skin, hair follicles, and sweat glands.

Dr. Seifert suggested the skin of African spiny mice is fragile because it allows them to escape predators. This would require a quick healing time to reduce the chance of infection and ultimately death in the mouse after escaping. This is why they may have gained the ability to regenerate their skin, but how exactly does this happen? Dr. Seifert and his research team recently showed that, in these species, it occurs through a process known as epimorphic regeneration. This is when a blastema (a mass of immature, unspecialized cells) forms where the wound once was. These cells are capable of turning into whatever type of tissue was present in that area. This particular method of regeneration is how salamanders are capable of regenerating their limbs. Again, more research would need to be done in order to confirm or deny this. However, one thing is true, and that is that more research into this could prove to be useful in the future of medicine when it comes to healing critical and invasive injuries. By discovering the physiological process behind this, and then being able to replicate it in a lab, researchers may discover ways to heal injuries faster.

Works Cited

Seifert, Ashley W., Stephen G. Kiama, Megan G. Seifert, Jacob R. Goheen, Todd M. Palmer, and Malcolm Maden. "Skin Shedding and Tissue Regeneration in African Spiny Mice (Acomys)." Nature 489 (2012): 561-65. doi:10.1038/nature11499

Gawriluk, Thomas R., Jennifer Simkin, Katherine L. Thompson, Shishir K. Biswas, Zak Clare-Salzler, John M. Kimani, Stephen G. Kiama, Jeramiah J. Smith, Vanessa O. Ezenwa & Ashley W. Seifert. "Comparative analysis of ear-hole closure identifies epimorphic regeneration as a discrete trait in mammals" Nature Communications 7.11164 (2016). doi:10.1038/ncomms11164

Does Social Status Change Brains?

A reposting of an original article in The Scorpion and the Frog.

Photo by The Grappling Source Inc.
at Wikimedia Commons

Being subordinated is stressful. The process of one individual lowering the social rank of another often involves physical aggression, aggressive displays, and exclusion. In addition to the obvious possible costs of being subordinated (like getting beat up), subordinated individuals often undergo physiological changes to their hormonal systems and brains. Sounds pretty scary, doesn’t it? But what if some of those changes are beneficial in some ways?

Dominance hierarchies are a fact of life across the animal kingdom. In a social group, everyone can’t be dominant (otherwise, life would always be like an episode of Celebrity Apprentice, and what could possibly be more stressful than that?). Living in a social group is more peaceful and nutritive when a clear dominance hierarchy is established.

Establishing that hierarchy often involves a relatively short aggressive phase of jostling for position, followed by a longer more stable phase once everyone knows where they fall in the social group. Established dominance hierarchies are not always stable (they can change over time or from moment to moment) and they are not always linear (for example, Ben can be dominant over Chris, who is dominant over David, who is dominant over Ben). But they do generally help reduce conflict and the risk of physical injury overall.

Nonetheless, it can be stressful to be on the subordinate end of a dominance hierarchy and these social interactions are known to cause physiological changes. Researchers Christina Sørensen and Göran Nilsson from the University of Oslo, Cliff Summers from the University of South Dakota and Øyvind Øverli from the Norwegian University of Life Sciences investigated some of these physiological differences among isolated, dominant, and subordinate rainbow trout.

A photo of a rainbow trout by Ken Hammond at the USDA.
Photo at Wikimedia Commons.

Like other salmonid fish, rainbow trout are aggressive, territorial and develop social hierarchies as juveniles. Dominant trout tend to initiate most of the aggressive acts, hog food resources, grow larger, and reproduce the most, whereas subordinate trout display less aggression, feeding, growth, and reproduction. The researchers recorded the behavior, feeding and growth rates in three groups of fish: trout housed alone, trout housed with a more subordinate trout, and trout housed with a more dominant trout. The researchers also measured cortisol (a hormone involved in stress responses), serotonin (a neurotransmitter involved in mood, the perception of food availability, and the perception of social rank, among other things) and the development of new neurons (called neurogenesis) in these same fish.

This video of two juvenile rainbow trout was taken by Dr. Erik Höglund. Here is Christina Sørensen’s description of the video: “What you see in the film is two juvenile rainbow trout who have been housed on each side of a dividing wall in a small aquarium. The dividing wall has been removed (for the first time) immediately before filming. You will see that the fish initially show interest for each other, followed by a typical display behaviour, where they circle each other. Finally one of the fish will initiate aggression by biting the other. First the aggression is bidirectional, as they fight for dominance, but after a while, one of the fish withdraws from further aggression and shows only submissive behaviour (escaping from the dominant and in the long run trying to hide... and as is described in the paper, depressed feed intake). The video has been cut to show in quick succession these four stages of development of the dominance hierarchy”.

The researchers found that as expected, the dominant trout were aggressive when a pair was first placed together, but the aggression subsided after about 3 days. Also as expected, the dominant and isolated trout were bold feeders with low cortisol levels and high growth rates, whereas the subordinate trout did not feed as well, had high cortisol levels and low growth rates. Additionally, the subordinate trout had higher serotonin activity levels and less neurogenesis than the dominant or isolated trout. These results suggest that the subordination experience causes significant changes to trout brain development (Although we can’t rule out the possibility that fish with more serotonin and less neurogenesis are predisposed to be subordinate). In either case, this sounds like bad news for subordinate brains, right? Maybe it is. Or maybe the decrease in neurogenesis just reflects the decrease in overall growth rates (smaller bodies need smaller brains). Or maybe something about the development of these subordinate brains improves the chances that these individuals will survive and reproduce in their subordination.

A crayfish raising its claws. Image by Duloup at Wikimedia.

Research on dominance in crayfish by Fadi Issa, Joanne Drummond, and Don Edwards at Georgia State University and Daniel Cattaert at the University of Bordeaux helps shed light on this third possibility. Crayfish (which are actually not fish at all, but are freshwater crustaceans that look like small lobsters) form long-lasting and stable social hierarchies. If you poke a crayfish in the side, an isolated or dominant crayfish will turn towards whatever poked it and raise its posture and claws to confront it; A subordinate crayfish will do one of two maneuvers that involves lowering the posture and backing away from whatever poked it. Furthermore, dominant and subordinate crayfish have different neuronal activity patterns in response to being poked, and part of this difference involves differences in the activity of serotonergic neurons.

It appears that the brains of dominant and subordinate individuals function differently and part of this difference involves serotonin. This may help dominant animals to continue to behave in a dominant fashion and subordinate individuals to continue to behave in a subordinate fashion, thereby preserving the peace for the whole social group.

Want to know more? Check these out:

1. Sørensen, C., Nilsson, G., Summers, C., & Øverli, �. (2012). Social stress reduces forebrain cell proliferation in rainbow trout (Oncorhynchus mykiss) Behavioural Brain Research, 227 (2), 311-318 DOI: 10.1016/j.bbr.2011.01.041

2. Issa, F., Drummond, J., Cattaert, D., & Edwards, D. (2012). Neural Circuit Reconfiguration by Social Status Journal of Neuroscience, 32 (16), 5638-5645 DOI: 10.1523/JNEUROSCI.5668-11.2012

3. Yeh, S., Fricke, R., & Edwards, D. (1996). The Effect of Social Experience on Serotonergic Modulation of the Escape Circuit of Crayfish Science, 271 (5247), 366-369 DOI: 10.1126/science.271.5247.366

4. Issa, F., & Edwards, D. (2006). Ritualized Submission and the Reduction of Aggression in an Invertebrate Current Biology, 16 (22), 2217-2221 DOI: 10.1016/j.cub.2006.08.065

5 Animal Species With Surprising Memories

A repost of an original article from The Scorpion and the Frog.

We often think of animals as having hilariously short memories – the “memory of a goldfish”, if you will. But many animals have memories that can put yours to shame.

There are many different kinds of memory and each of them is controlled differently by different parts of the brain. Short-term memory can be thought of as the brain’s scratch pad: It holds a small amount of information for a short period of time while your brain decides whether it is worth retaining in long-term memory or if it can just fade away. When a short-term memory becomes a long-term memory, this process is called consolidation and involves physiological changes in the brain.

Long-term memory can be further divided into two main types: procedural memory and declarative memory. Procedural memory is used to remember how to do things and what objects are needed to do those things. Declarative memory is used for recall and can be further divided into memory used to recall facts (semantic memory) and events (episodic memory).Each of these different types of memories are stored in different parts of the brain. Furthermore, different types of facts (remembering faces versus numbers, for example) and different types of events (depending on if they have an emotional component or not, for example) are also stored in the brain differently. Because species differ in how we rely on our brains, it makes sense that this might be reflected in our abilities to remember in different ways.

So let’s check out some of the most amazing memories in the animal kingdom:

Do you know what all your kids and nieces and nephews are
doing right now? These elephants do. Photo by PJ KAPDostie
at Wikimedia.

1) They say an elephant never forgets. Elephants are very social animals that live in large stable herds. This has led to some incredible feats of social memory. They can keep track of the whereabouts of 30 group members at once and they can remember an animal they briefly met over 20 years ago. For an animal that lives about 50 or 60 years, this is very impressive. Elephants also have outstanding episodic memory: In 1993, Tarangire National Park in Tanzania suffered the worst drought that it had seen in 35 years. It was so severe that it killed 20% of elephant calves, compared to the average loss of about 2%. Of three herds that lived in the park in 1993, two of them were led by females that had lived during the severe droughts of 1958-61 and those herds left the park and were more successful at finding food and water. The herd that stayed was led by a younger female that had never experienced such a severe drought and that herd suffered 63% of the total mortality.

Dolphins never forget a name. Photo from the
NOAA Photo Library available at Wikimedia.

2) Bottlenose dolphins have even more incredible social memories. They, like elephants, live in complex social groups. Each dolphin has a unique whistle that it uses like a name. When they are played recordings of whistles of companions they lived with years or even decades earlier, they approach the speakers for longer than when they are played the whistles of dolphins they never met. The fact that they, like elephants, remember companions for over 20 years is much more impressive because their lifespan is only 40-50 years!

Sea lions can remember
meaningless tricks for years.
Photo by LSA2886 at Wikimedia.

3) Sea lions have amazing procedural memory. In 1991, marine biologists at the University of California, Santa Cruz, taught a California sea lion named Rio a card trick. They held up one card with a letter or number on it and another set of two cards: one that matched the first card and one that did not. Rio learned to pick the matching card to be rewarded with a fish. Everyone was impressed and she didn't do the trick again... until 10 years later, when researchers pulled out the cards and asked her to do it again. Rio had the same score in 2001 with no practice that she did in 1991 when she originally learned the trick!

Clark's nutcrackers can remember where they stashed
30,000 pine nuts.I can't even keep track of my keys.
Photo by Gunnsteinn Jonsson at Wikimedia.

4) Clark’s nutcrackers can remember the exact location of 30,000 pine nuts. This kind of superhero ability is born out of necessity: nutcrackers completely rely on their caches of food to get them through the winter. However, despite their amazing long-term spatial memory, their short-term memory is below average: they can’t even remember the color of a light for 30 seconds.

5) Chimpanzees can put your working memory to shame. Working memory is a form of short-term memory that is applied to a task. A group of researchers taught chimpanzees to do a task in which they were shown the numbers from 1-9 in random locations on a computer screen. When the numbers are covered, chimps can remember where each number was. Furthermore, they only need to see these randomly placed number for a few seconds to get this task correct. In comparison, only people that are considered savants have comparable abilities.

Hey Hey! We’re The Monkeys!

 Updated and reposted from March 6, 2013.

A tamarin rock star
(photographed by Ltshears at Wikimedia)

Our moods change when we hear music, but not all music affects us the same way. Slow, soft, higher-pitched, melodic songs soothe us; upbeat classical music makes us more alert and active; and fast, harsh, lower-pitched, dissonant music can rev us up and stress us out. Why would certain sounds affect us in specific emotional ways? One possibility is because of an overlap between how we perceive music and how we perceive human voice. Across human languages, people talk to their babies in slower, softer, higher-pitched voices than they speak to adults. And when we’re angry, we belt out low-pitched growly tones. The specific vocal attributes that we use in different emotional contexts are specific to our species… So what makes us so egocentric to think that other species might respond to our music in the same ways that we do?

A serene tamarin ponders where he placed
his smoking jacket (photographed by
Michael Gäbler at Wikimedia)

Chuck Snowdon, a psychologist and animal behaviorist at the University of Wisconsin in Madison, and David Teie, a musician at the University of Maryland in College Park, teamed up to ask whether animals might respond more strongly to music if it were made specifically for them.

Cotton-top tamarins are squirrel-sized monkeys from northern Colombia that are highly social and vocal. As in humans (and pretty much every other vocalizing species studied), they tend to make higher-pitched tonal sounds when in friendly states and lower-pitched growly sounds when in aggressive states. But tamarin vocalizations have different tempos and pitch ranges than our tempos and pitch ranges.

Chuck and David musically analyzed recorded tamarin calls to determine the common attributes of the sounds they make when they are feeling friendly or when they are aggressive or fearful. Then they composed music based on these attributes, essentially creating tamarin happy-music and tamarin death metal. They also composed original music based on human vocal attributes. They played 30-second clips of these different music types to pairs of tamarins and measured their behavior while the song was being played and for the first 5 minutes after it had finished. They compared these behavioral measures to the tamarins’ behavior during baseline periods (time periods not associated with the music sessions).

As the researchers had predicted, tamarins were much more affected by tamarin music than by human music. Happy tamarin music seemed to calm them, causing the tamarins to move less and eat and drink more in the 5 minutes after the music stopped. Compared to the happy tamarin music, the aggressive tamarin music seemed to stress them out, causing the tamarins to move more and show more anxious behaviors (like bristling their fur and peeing) after the music stopped.

The tamarins also showed lesser reactions to the human music. They showed less anxious behavior after the happy human music played and moved less after the aggressive human music played. So, human voice-based music also affected the tamarins to some degree, but not as strongly. This may be because there are some aspects of how we communicate emotions with our voice that are the same in tamarins.

Can you imagine what we could do with this idea of species-specific music? Well, David and Chuck did! They have since developed music for cats using similar techniques.

We often think of vocal signals conveying messages in particular sounds, like words and sentences. But calls seem to do much more than that, making the emotions and behaviors of those listening resemble the emotions of those calling.

Want to know more? Check these out:

Snowdon, C., & Teie, D. (2009). Affective responses in tamarins elicited by species-specific music Biology Letters, 6 (1), 30-32 DOI: 10.1098/rsbl.2009.0593

Snowdon, C., Teie, D. and Savage, M. (2015). Cats prefer species-appropriate music. Applied Animal Behaviour Science, 166, 106-111.

The Contagious Cancer (A Guest Post)

By Stephanie Stanton

The Tasmanian devil, perhaps more popularly known by its animated counterpart Taz in Warner Bros.’ “Looney Toons,” is a carnivorous marsupial native to Tasmania, an island off the southern coast of Australia. Similar to Taz, the Tasmanian devil lives a violent lifestyle. While a good portion of fights don’t go beyond screaming matches, sometimes (especially during the mating season) fights escalate to full-on biting matches. Unfortunately, it is this aggressive nature that has been linked to the alarming drop in Tasmanian devils’ numbers over the last decade. However, it is not violent wounds acquired during fights that are causing this rapid decline, but rather the Devil Facial Tumor Disease (DFTD), a contagious cancer.

DFTD is a transmissible cancer that operates as its own living entity- it is genetically distinct from its host and lives on its host’s face. Most of these tumors appear on their faces. Coincidentally, this also happens to be where a majority of open wounds are acquired in this species. Because of this, it is believed that DFTD is transferred through open wounds on the skin.

A healthy Tasmanian devil in all his glory. Photo by Chen Wu at Wikimedia Commons.

This cancer has been so successful in spreading throughout the population because of the devils’ small population size and low genetic diversity. Among the genes with low genetic diversity in the population is the Major Histocompatibility Complex (MHC), a collection of genes responsible for a strong immune response in vertebrates. Without a strong immune response, it is difficult to fight off serious threats such as DFTD. Unfortunately for the devils, the tumors growing on their faces do not even register on their limited immune system’s radar- so their bodies don’t even fight back! Because of this, DFTD is in most cases fatal within six to nine months of showing clinical symptoms.

A Tasmanian devil afflicted with DFTD. Photo courtesy of Menna Jones, available at Wikimedia Commons

Three Australian scientists by the names of Rodrigo Hamede, Hamish McCullum, and Menna Jones from the University of Tasmania and Griffith University recognized the alarming decline in the Tasmanian devil population and sought to find a way to better understand and control the spread of the disease. They looked at two separate populations over four seasons, collecting data once every three months by taking counts of bites on individual devils and tracking who got DFTD, when, and on what part of their bodies. They hypothesized that because the tumor was transmissible through open wounds, then the number of open wounds could be used as an early predictor for the onset of DFTD.

And they were right…although perhaps not in the ways they thought they would be. Contrary to what common sense would have everyone believe, devils with the least amount of facial wounds were the most likely to develop the fatal cancer. How could this be?

Simply put, it appears that the disease is getting transferred from devil to devil not because their bodies are exposed to a bite from an infected individual, but because devils are biting the tumors of infected individuals, thereby creating a direct path for the tumor to enter the new host.

The scientists argued that the devils that have the fewest open wounds were better at fighting and also the most aggressive (A side effect of the cancer? Perhaps.) Tasmanian devils are likely to have cuts or scrapes in their mouths because of their aggressive eating style, providing a port for the cancer cells to invade. It was because they were biting the tumors of the infected devils that they were contracting the disease, which also explains the higher occurrence of tumors in the mouth. Less aggressive devils accumulated more injuries to the face, but as long as the cancer cells did not come into contact with open wounds, their likelihood of contracting the disease was slim.

Rodrigo, Hamish and Menna hope that their results along with further research can help reduce the effects of the disease on the shrinking Tasmanian devil population by offering potential solutions to better control its spread. Exciting research published in 2016 is also already offering hope in keeping Taz and his furry counterparts alive for future generations to enjoy.


Want to know more? Check out the original article below:

Hamede, Rodrigo K., McCullum, H., Jones, M. (2013). “Biting injuries and transmission of Tasmanian Devil facial tumour disease. Journal of Animal Ecology. DOI: 10.1111/j.1365-2656.2012.02025.x.

One of These Sharks is Not Like the Others (A Guest Post)

By Emily Masterton

When you think of a shark, what usually comes to your mind? Big teeth and the beach, right? Well, that’s not how the Greenland shark likes to live at all. Like the name denotes, this shark prefers cold waters and depths that would kill most sharks and people. The Greenland shark is mostly restricted to the waters of the far North Atlantic Ocean and the Arctic Ocean, which range from 34 – 68 degrees Fahrenheit. The Greenland shark has also been recorded diving down to depths ranging from 0 – 4000 feet. To put that in perspective, that’s equal to 3.2 Empire State Buildings stacked on top of each other!

Picture of a Greenland shark in the Admiralty Inlet, Nunavut.
Image by Hemming 1952 at Wikimedia Commons.

The Greenland shark is able to survive in this harsh environment because of the shark's high levels of nitrogenous waste products (any metabolic waste product that contains nitrogen) in their tissues. The nitrogenous waste products that are found in the Greenland shark are urea and trimethylamine N-oxide (TMAO). These chemicals help the shark maintain their osmotic balance (the movement of water across cells) in this very salty environment. This osmotic balance is important for the body to function and keep water and salt in balance in the cells.

TMAO and urea act as a type of anti-freeze that keeps the cells from freezing and developing ice crystals. The TMAO and urea work by preventing ice crystals from forming in the shark’s cells. They work by lowering the freezing point of water in the cells and by binding to ice crystals and preventing them from forming or growing. This protects the cells from denaturing due to the extreme pressure from the depths the shark dives at. If there were no TMAO and urea in the shark, then ice crystals could form and break cell walls, which could result in tissue and organ damage, then death.

This figure shows how TMAO and urea bind to the shark's protein and keep ice crystals from growing and forming. This prevents the protein from denaturing and ultimately killing the shark. Image by Emily Masterton.

While these chemicals are great for the Greenland shark, they are bad news for anyone or thing who decides to eat them. TMAO and urea are very toxic. The Greenland shark has the most toxic skin among all sharks and even made it to the Guinness World Records in 2013 for this level of toxicity. If you were to eat the skin of a Greenland shark without preparing it right, you will have symptoms similar to being extremely drunk.

Greenland shark meat is eaten in Iceland in a dish called Hákarl. The shark’s meat must be prepared a certain way so that the TMAO and urea are no longer present in the meat. This is done by fermenting the meat and then drying it for 4-5 months. Once it has been dried and is ready to eat, it is often served in cubes on toothpicks in small servings.

Although these extreme conditions would kill any human being or another shark, the Greenland shark is able to survive and thrive in these conditions, thanks to the chemicals TMAO and urea. These chemicals keep ice crystals from forming in the cells of the shark and ultimately keep the shark alive. There are 465 species of sharks in the ocean, but only one can call the harsh North Atlantic Ocean and Arctic Ocean its home.


References
• Farrell, Anthony Peter, et al. Physiology of elasmobranch fishes: internal processes. Academic Press/Elsevier, 2016
• Strøksnes, Morten. “My Hunt for the 400-Year-Old Shark Whose Flesh Gets You High.” Vice, 30 June 2017
• O’Connor, M. R. “The Strange and Gruesome Story of the Greenland Shark, the Longest-Living Vertebrate on Earth.” The New Yorker, The New Yorker, 15 Feb. 2018
• “The Greenland Shark: An Icy Mystery.” Greenland Shark | Sharkopedia Sharkopedia
• Polar Seas: Greenland Shark

Why You Can’t Hibernate the Winter Away

A reposting of an original article from January, 2015.

You open your eyes, slap the alarm, and pull the covers a little tighter around your shoulders. It’s still dark outside and you dread the moment that you step out from under the warm comforter and the cold sucks your breath out. Can’t you just hibernate and sleep the winter away?

A dormouse in his snuggly hibernation state.
Image by Krysztof Dreszer at Wikimedia.

Actually, no. Hibernation and sleep are two completely different physiological processes (shown by studies of brain function). And chances are, you don’t have the physiological bits needed to hibernate safely.

Hibernation has more to do with energy and body temperature than it does with sleep. Hibernation is defined as a process in which an animal allows its body temperature to approximate the environmental temperature for several days or longer. It is a strategy that some animals use during periods of food shortage to conserve the energy that would normally be used to generate body heat. When food is scarce in the winter, the animal will lower its metabolism (the burning of food molecules to create energy and heat), which will result in the animal having less energy (and entering a sleep-like state) and less heat (until the body approaches the environmental temperature). So really, hibernation is the reduction of metabolism when food is scarce. Lack of activity and cold body temperatures are just the by-products.

Almost all species that hibernate are small mammals, including some hamsters, dormice, jumping mice, ground squirrels, marmots, woodchucks, bats, marsupials and monotremes. Bears, common examples of hibernating species, are actually debated by scientists as to whether they should even be considered hibernators due to the fact that their metabolisms and body temperatures do not decline as much as those of other hibernating species. The only bird species known to hibernate is the poorwill.

Each hibernating species has a specific range of body temperatures that their body can endure. Their first line of defense is to find a hibernaculum (a chamber or cavity in which to hibernate that is more insulated than the exposed environment). If the hibernaculum becomes so cold that the animal’s body temperature drops below its minimum endured range, it will either increase its metabolism slightly to raise its body temperature or it will arouse (wake up). Arousal is the process of increasing metabolic heat production to near-normal levels. All hibernating species seem to undergo multiple periods of temporary arousals during hibernation and scientists are still unsure why. Increasing the metabolism and body temperature from lower levels is an energetically costly process (similar to how your car uses more gas to accelerate than to maintain a higher speed). In most hibernating species, the process of increasing the metabolism uses a specialized tissue called brown fat.

Fat cells come in two main types: white fat and brown fat. White fat, the squishy stuff that we constantly try to diet and exercise away, is filled with lipids (fats) that we store to generate energy in the future. Brown fat cells also contains lipids, but they are specialized to break them down faster. Brown fat is found in newborn mammals and adult hibernators and is commonly located on the upper back, neck, chest and belly (like a vest) and around major arteries. Brown fat cells have lots of mitochondria (the metabolic parts of the cell that break down food molecules like lipids to generate energy). Brown fat mitochondria is specialized in that they have a protein called uncoupling protein 1 that causes them to generate heat rather than energy when they break down lipids. When the body becomes stressed, it releases norepinephrine, a stress hormone, which causes brown fat cells to increase the rate at which they break down lipids to generate heat. This heat warms the major arteries and increases blood flow, which then distributes the heat throughout the body.

A PET scan shows brown fat in a human.
Image by Hellerhoff at Wikimedia.

Although humans are born with a fair amount of brown fat, we lose it as we age. More specifically, it converts to white fat. We used to think that we lost it completely, but in recent years we have learned that some lean adults maintain a few pockets of brown fat in their necks and chests that obese people are more likely to lose. Researchers are currently exploring if and how we can convert some of our adult white fat to brown fat in order to increase our metabolisms and potentially combat obesity and diabetes.

So for now, we can’t hibernate the winter away. But continuing research into hibernating animals may hold an important secret to our own health.

Nature Shapes Faithful and Unfaithful Brains

A reposting of an original article from January 22, 2017.

Among monogamous animals, some individuals are more faithful than others. Could these differences in fidelity be, in part, because of differences in our brains? And if so, why does this diversity in brain and behavior exist?

A snuggly prairie vole family. Photo from theNerdPatrol at Wikimedia Commons.

Prairie voles are small North American rodents that form monogamous pair bonds, share parental duties, and defend their homes. Although prairie voles form monogamous pairs, that does not mean they are sexually exclusive. About a quarter of prairie vole pups are conceived outside of their parents’ union.

Not all male prairie voles cheat on their partners at the same rates. In fact, some males are very sexually faithful. It turns out, there are both costs and benefits to being faithful and to cheating. Mariam Okhovat, Alejandro Berrio, Gerard Wallace, and Steve Phelps from the University of Texas at Austin, and Alex Ophir from Cornell University used radio-telemetry to track male prairie voles for several weeks to explore what some of these costs and benefits might be. Compared to males that only sired offspring with their own partner, unfaithful males had larger home ranges, intruded on more territories of other individuals, and encountered females more often. However, these unfaithful males were also more likely to be cheated on when they were away (probably because they were away more). I guess even rodents live by The Golden Rule.

Maps of how paired male voles in this study used space. The solid red/orange/yellow peaks show where a faithful male (in the left map) and unfaithful male (in the right map) spent their time in relation to where other paired males spent their time (showed by open blue peaks). Image from the Okhovat et al. Science paper (2015).

Vasopressin is a hormone that has been found to affect social behaviors such as aggression and pair bonding when it acts in the brain. Mariam, Alejandro, Gerard, Alex, and Steve all set out to determine how vasopressin in the brain may relate to sexual fidelity in prairie voles. They found that faithful males had lots of a particular type of vasopressin receptor (called V1aR) in certain brain areas involved in spatial memory. Surprisingly, faithful males did not have more V1aR in brain regions typically associated with pair bonding and aggression. A male that has more V1aR in spatial memory regions might better remember where his own mate is and where other males have been aggressive, which would decrease the chances that he would intrude on other territories in search of other females and increase the time that he spends home with his own mate. A male that has less V1aR in spatial memory regions might be less likely to learn from his negative experiences and more likely to sleep around.

Photos of a brain section from a faithful male (left) and unfaithful male (right). The dark shading shows the density of V1aR vasopressin receptors. The arrows show the location of the retrosplenial cortex (RSC), a brain area involved in spatial memory. Faithful males had significantly more V1aR receptors in the RSC compared to unfaithful males. Image from the Okhovat et al. Science paper (2015).

The research team then found genotype variations that related to having lots or not much V1aR in one of these spatial memory regions (called retrosplenial cortex … but we’ll just call it RSC). They confirmed these findings with a breeding study, in which they reared siblings that were genetically similar, but some had the genotype they predicted would result in lots of V1aR in RSC and some had the genotype they predicted would result in very little V1aR in RSC. They confirmed that these genetic variations correspond with the amount of vasopressin receptor in this specific spatial memory area.

The researchers then looked closer at the different versions of this vasopressin receptor gene in the RSC brain region to see if differences in the amount of vasopressin receptors in RSC may be caused by the epigenetic state of the gene (i.e. how active the gene is). They found that the genotype that results in very little V1aR in RSC had many more potential methylation sites, which can repress gene activity.

All of this data together tells a very interesting story. Male prairie voles that have the genotype for more V1aR vasopressin receptors in their RSC part of their brain are more likely to remember where their home and mate are and to remember where other aggressive prairie voles are, which will make them more likely to spend more time with their partner, to be sexually faithful and to have sexually faithful partners. Male prairie voles that have the genotype for less V1aR in their RSC are more likely to forget where their home and mate are and where other aggressive prairie voles are, which will make them more likely to cheat and to be cheated on. Overall, faithful and unfaithful male prairie voles have roughly the same number of offspring, but advantages may emerge with changes in population density. Prairie vole populations vary anywhere from 25 to 600 voles per hectare from year to year. When population densities are high, you (and your partner) are more likely to encounter more potential mates and it may benefit you to cheat (and have a “cheater’s brain”). When population densities are low, you (and your partner) are less likely to encounter more potential mates and it may benefit you to be faithful (and have a “faithful brain”). But when populations fluctuate between high and low densities, both faithful and unfaithful genotypes will get passed along from generation to generation.


Want to know more? Check this out:

Okhovat, M., Berrio, A., Wallace, G., Ophir, A., & Phelps, S. (2015). Sexual fidelity trade-offs promote regulatory variation in the prairie vole brain Science, 350 (6266), 1371-1374 DOI: 10.1126/science.aac5791