Tuesday, April 16, 2019

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

Tuesday, April 9, 2019

What To Do If You Find Orphaned Wildlife

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

A nest of baby cottontails waiting for sunset when their
mom will return. Image by Jhansonxi at Wikimedia.
Spring is finally in the air, and with Spring come babies! Finding baby animals in the wild is thrilling, but also concerning. Does this animal need your help? Where is its mom? What do you do?

Whenever possible, baby animals will do best when we leave them in the care of their mom. Even a well-meaning human is seen by a wild animal as a threat. Our interactions with them cause them extreme stress that can cause serious health problems and even death. Furthermore, if we take a baby animal home, it will not be able to learn its species-specific behaviors and skills and it can lose its natural and healthy fear of humans. It is also very hard to meet the specialized dietary needs of a wild animal in a captive setting. Taking a wild animal home can cause problems for us as well: many carry diseases that can be transmitted to our pets or even ourselves. And most wild animals are protected by state and federal laws that prohibit unlicensed citizens from possessing or raising them.

Luckily, most baby animals that seem alone actually have a mom that is not far away, either looking for food to feed herself and her babies or simply hiding from you. For example, rabbit mothers actively avoid their nests most of the time so as to not attract predators to the nest. Cottontail moms visit their babies only briefly at dawn and dusk for quick feedings. If you find a bunny nest, you can test to see if the mom is visiting by placing a few blades of grass or thin twigs in an X-shape over the babies. If you come back the next day and the pattern has been disturbed, then their mom is still caring for them and you should leave them be.

Many animal moms are prevented from taking care of their young when concerned people are hovering. Deer moms, for example, also actively avoid their babies (called fawns) so as to not attract predators to it. They generally return to nurse the fawns every few hours, but they won’t return to nurse if people or pets are around. If you find a fawn and it is not wandering and crying non-stop all day, then leave it alone so its mom will come back.

A red fox mom and baby. Photo by Nicke at Wikimedia.

Even if you find a baby all by itself in the open, the best course of action is often still to leave it alone. Many mammal moms, like squirrels, raccoons, mice, rats, foxes, and coyotes, will retrieve their young if they fall out of their nest or wander away from their den. Although it is a myth that most animal moms will abandon their babies if you get your smell on them, your odor can attract predators. It is best not to touch wildlife babies if you can avoid it.

Awww... as tempting as it is to pick up an adorable baby skunk, don't do it
unless you are a trained and licensed wildlife rehabilitator (like this woman is).
Image by AnimalPhotos at Wikimedia.

So when should you get involved? If an animal is in a dangerous location (like a busy street), then it may need to be moved. You can slowly, quietly and gently try to guide a mobile baby animal away from hazards and to a safer location. If the animal is not yet mobile, in most cases, you can use clean gloves to pick up the animal and move it to a safer location, placing it as close as possible to where you found it.

If you know that the mom is dead or has been relocated, then you are dealing with a truly orphaned baby animal. Likewise, if an animal has been attacked (or brought to you by your “helpful” cat), or is bleeding, injured, wet and emaciated, weak, infested with parasites, or has diarrhea, then it may need medical attention. In these cases, contact a licensed wildlife rehabilitator. Wildlife rehabilitators have been trained and have the necessary equipment to temporarily care for and treat injured, sick and orphaned wild animals so they can be released back into the wild. If you can’t find a wildlife rehabilitator, contact the Department of Natural Resources, a state wildlife agency, animal shelter, humane society, animal control agency, nature center, or veterinarian. Ideally, they will come to pick up the animal themselves. If they can’t, then they should give you detailed instructions for your situation on how to catch and transport the animal.

For more information, check here:

The Humane Society of the United States

The Wisconsin Department of Natural Resources

The Virginia Department of Game and Inland Fisheries

Tuesday, April 2, 2019

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.

Tuesday, March 26, 2019

Interrupting Insects

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

What do you think of when I say “communicate”? Most likely, you are imagining people communicating by an auditory mode (talking and listening, making expressive sounds) or by a visual mode (observing body language, reading and writing). As a species, humans inherently rely heavily on our hearing and vision to perceive the world around us and so it makes sense that we communicate with one another using these modalities. But animal species are incredibly diverse in their means of perceiving their worlds and their modes of communication. Because we have been so focused on studying animal signals that we can perceive, we have only recently begun to more actively explore animal communication in these other modes. One of these modes is soundless surface vibrations.

The photo is of an adult Tylopelta gibbera on a host plant stem
(photo (c) Rex Cocroft).
Despite the fact that we do not perceive most animal surface vibration signals around us, vibrational communication is very common, especially among insects and spiders. Rex Cocroft at the University of Missouri at Columbia and Rafa Rodríguez at the University of Wisconsin at Milwaukee point out in a review of vibrational communication that over 195,000 species of insects communicate using soundless surface vibrations. We can experience many of these substrate vibration signals by broadcasting them through a speaker as an airborne vibration (which we perceive as sound).

Vibrational signals serve a number of functions in the insect worlds. Social insects, like ants, termites, and bees, often use vibrational signals to coordinate foraging. Groups of juvenile thornbug treehoppers vibrate when a predator approaches, calling in the mother to defend them. Males of many species have been found to use vibrational signals to attract females and the females often use these signals to choose a mate.

Vibrational signals are carried through a solid substrate, so they can only travel as far as the substrate is continuous and they are affected by attributes of the substrate (like changes in density). Because of these constraints, most vibrational signals can only travel about the length of a human arm. Many insects that use vibrational communication live on host plants, and it is these host plants that transmit the vibration signals. These animals face many challenges in transmitting their signals to the intended recipient. For example, wind, rain, and environmental sounds can create competing vibrations (background noise). In addition to environmental background noise, the vibrational soundscape of a given plant stem will likely include many signaling individuals, often of many species. Not only are there difficulties in getting your signal to your intended audience, but there are also risks of eavesdropping predators and competitors.

Frédéric Legendre, Peter Marting and Rex Cocroft at the University of Missouri at Columbia, demonstrate the social complexities of vibrational communication in a new study of competitive signaling in a treehopper species, Tylopelta gibbera. Tylopelta gibbera is a small treehopper in the southern United States, Mexico and Guatemala, that only lives on plants from the Desmodium genus. Males will attract and court females with vibrational signals and interested females will respond to the male with vibrational signals of their own. However, many individuals can often be found on a single plant and if two signaling males are present, the receptive female will typically respond to both of them and only mate with one (generally the first one she encounters). What is a competing male to do?

Listen to a male Tylopelta gibbera advertisement signal here.

The researchers performed a series of experiments, in which they observed treehoppers on potted host plants in the lab. With this set-up, they could control the environmental conditions, decide the number of males and females on the plant, record vibrational signals and play them back. They found that once a male signals and detects a female response, he will actively search for her along the plant, alternating signals and steps in a “Marco Polo” mating game until he finds her. Males found the females almost twice as fast if they were the only male on the plant, indicating that the presence of a second male on the plant somehow interferes with their ability to locate the female. Also, when two males were on the plant, they produced a new signal type that was never produced by a lone male on a plant. Males that had no male competition only produced signals that had a whine sound, followed by a series of pulses (and the female would then immediately respond with a harmonic sound of her own). This male signal is called the advertisement signal. Males that had a competing male on the plant would produce an additional signal that was a short tonal note. Interestingly, these males often produced this second signal at the same time that their competitor was advertising himself. Hmmm… could this be a masking signal used to interrupt the competitor? How could you figure that out?

This figure from Legendre, Marting and Cocroft's 2012 Animal Behaviour paper shows
the whine and pulses of a male advertisement signal (top) and a histogram of when the
masking signal occurs in relation to the timing of the advertisement signal (bottom).
First, the researchers asked, “When do males produce this second signal?” The researchers put two males on a plant with one female and recorded their vibrations. They found that in this situation, males typically produced this second signal while his competitor was just beginning the pulse section of his advertisement signal. Next, the researchers played back recordings of male advertisement signals followed by female responses to a lone male on a plant. All of the males tested produced the masking signal during the pulse section of the male advertisement signal on the recording.

Don't you hate it when someone does this?

Next, the researchers asked, “How do females respond to this second signal?” On plants with one female and two males, females didn’t respond as much to advertisement signals overlapped by a second signal as they did to advertisement signals alone. The researchers then played recordings of male advertisement signals to lone females on the plants. Females responded significantly more often if the advertisement signal was not overlapped by a masking signal.

So, male treehoppers get an edge up on getting the girl by interrupting the other competing males. Sneaky buggers!

Want to know more? Check these out:

1. COCROFT, R., & RODRÍGUEZ, R. (2005). The Behavioral Ecology of Insect Vibrational Communication BioScience, 55 (4) DOI: 10.1641/0006-3568(2005)055[0323:TBEOIV]2.0.CO;2

2. Legendre, F., Marting, P., & Cocroft, R. (2012). Competitive masking of vibrational signals during mate searching in a treehopper Animal Behaviour, 83 (2), 361-368 DOI: 10.1016/j.anbehav.2011.11.003

3. A Japanese research team has harnessed this phenomenon to create a remote-control that makes annoying people stop talking. Find out more at the blog Gaines on Brains!

Tuesday, March 12, 2019

Reduce Stress with this Animal Behavior Meditation

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

In a search for the promised inner peace and tranquility of meditation, I attended a meditation class at a local yoga studio. In a room with dim fluorescent lights and an artificial wood floor I laid on my back on my yoga mat, sandwiched between a fidgety woman who kept her smartphone on the edge of her mat and a man whose stress had apparently resulted in a flatulence problem. I was told to close my eyes, breathe deeply, and think about nothing. I closed my eyes, took a deep breath, and thought: “How do I think about nothing?” I thought about black. “Does black count as nothing? Wondering if I’m thinking about nothing is definitely not nothing. Am I doing this wrong? Is this going to work? If this isn’t going to work, I’m just wasting my time. I could be working through my to-do list right now. Oh! I forgot to put laundry on my to-do list. Oh, right… think about nothing. Black?

This ring-tailed lemur has found her inner peace - Can you find yours?
Photo by Margaret at Wikimedia Commons

It was years later that I realized that meditation doesn’t have to be so painfully contrived. I do it all the time naturally. Maybe you do too. We just have to nurture those moments. Here’s one way to do it:

1) Go to a place where you have seen at least one animal in the recent past. Maybe you saw a squirrel or a songbird in that tree in your yard. Maybe you saw fish in the creek you pass over on your way to school. Maybe there’s an occupied spider web in the corner. Maybe you have a favorite spot at the local zoo or aquarium. Go there. Don’t worry if there is an animal there now or not.

2) Sit down in a comfortable position and take a deep breath. Look around and take in your surroundings. Feel the environmental conditions. Listen to the sounds around you. Wait and observe. If you’re quiet, they will come.

3) When an animal shows up, focus on it. If multiple animals show up, pick one to be your focal animal. Observe every possible detail of your focal animal: What does it look like? Does it have any markings? What is it doing? How does it position itself with respect to its surroundings? What is its posture? How does it respond to changes in its surroundings?

4) Allow your mind to wander into your focal animal’s world (or umwelt). How do you think your focal animal perceives its surroundings?

5) Allow your mind to ponder explanations and consequences of your focal animal’s behavior.

6) Continue for as long as you can keep your mind focused on your animal, or until you have somewhere else you are supposed to be.

Try this out for yourself, and then let us know what you experienced!