Category: Animal Science

By Michael H. Parsons, Hofstra University.

In an era when we can decode language among animals and design coatings that make military weapons virtually invisible, it may seem that there are few things science cannot accomplish. At the same time, we are surprisingly ignorant about some things that are much more ordinary. For me, perhaps the most intriguing example is city rats, which in many ways are the most important species of urban wildlife in our increasingly urbanized world.

Because rats are small, vigilant and live mainly underground, even behavioral ecologists like me know remarkably little about how they move through cities and interact with their environments. That’s a problem because rats foul our foods, spread disease and damage infrastructure. As more people around the world move to densely packed cities, they become increasingly vulnerable to rat behaviors and diseases. That makes it critically important to understand more about rats and the pathogens they carry.

I decided to study urban rats to help fill some gaps in our knowledge of how they use their sense of smell to seek favored resources (food and potential mates), and how this attraction influences their fine-scale movements across particular types of corridors.

Small animals with big impacts

Rats like to feed on small quantities of human rubbish while remaining just out of sight, so they have been associated with humans since the rise of agriculture. The ancestors of today’s urban rats followed humans across the great migratory routes, eventually making their way by foot or ship to every continent.

In cities, rats can enter buildings through openings as small as a quarter. They also may “vertically migrate” upward and enter residential dwellings through toilets. Because rats often make their way into homes from parks, subways and sewers, they can transport microorganisms they pick up from decomposition of wastes, thus earning the colloquial nickname of “disease sponges.”

Unlike humans, rats are not limited by the density of their population. In population biology, they are referred to as an “r-adapted species,” which means they mature rapidly, have short gestation periods and produce many offspring. Their typical life span is just six months to two years, but a female rat can produce up to 84 pups per year, and pups reach sexual maturity as soon as five weeks after birth.

Like other rodents (derived from the Latin word “rodere,” to gnaw), rats have large, durable front teeth. Their incisors rank at 5.5 on the Mohs scale, which geologists use to measure minerals’ hardness; for comparison, iron scores around 5.0. Rats use their constantly growing incisors to gain access to food. They can cause structural damage in buildings by chewing through wood and insulation, and trigger fires by gnawing on wiring. In garages, rats often nest inside cars, where they will also chew through insulation, wires and hoses.

In addition to causing physical damage, rats spread diseases directly by passing infectious agents through their blood, saliva or wastes, and indirectly by serving as hosts for disease-carrying arthropods such as fleas and ticks. They are known vectors for Lyme disease, Rocky Mountain spotted fever, Toxoplasma, Bartonella, Leptospira and other microorganisms, many as yet unnamed. A seminal 2014 study found 18 novel viruses in 133 rats collected in Manhattan.

Studying rats in the city

Although they are abundant, wild rats are exceptionally difficult to study. They are small, live mainly underground and are active at night, out of most humans’ sight. When people do see rats they are most likely to notice either the sickest or the boldest individuals – such as the “pizza rat” captured in a 2015 viral video – and make inaccurate generalizations about all rats.

Scientists study animal behavior by analyzing many individuals so that we can detect variations and patterns in behaviors within a population. It may be funny to see a rat drag a whole slice of pizza down subway stairs, but it is much more interesting and useful to know that 90 percent of a population is drawn to foods that are high in fat and protein. To draw conclusions like this, we need to observe how many individual animals behave over time.

Biologists typically track wild animals and observe their movements by capturing them and fitting them with radio or GPS transmitters. But these methods are nearly useless in urban areas: radio waves cannot pass through rebar-reinforced concrete, and skyscrapers block satellite link-ups.

In addition to physical barriers, working with wild rats also poses social challenges. Rats are the pariahs of the animal world: We associate them with filth, disease and poverty. Rather than striving to learn more about them, most people want only to avoid them. That instinct is so strong that last December an Air India pilot flying a Boeing 787 Dreamliner from Mumbai to London made an emergency landing after a single rat was spotted on the plane.

Working with Michael A. Deutsch, a medical entomologist at Arrow Pest Control, I have started designing studies to investigate urban rat behavior in situ so that we can, for the first time, learn the histories of individual animals in the wild. We capture rats by luring them with pheromones – natural scents that they find irresistible – and implant radio-frequency identification (RFID) microchips under their skin to identify each animal. This is the same technology that retail stores use to identify commercial products with bar codes and that pet owners can use to identify their dog or cat if it strays.

After we release the microchipped rats, we use scents to attract them back to specific areas and monitor when and how often they return. Using camera traps and a scale that the rats walk across, we can assess their health by tracking weight changes and looking for new wounds and bite marks. We also test their ability to penetrate barriers, such as wire mesh. And we repeatedly collect biological samples, including blood, stool and DNA, to document the rats’ potential to carry pathogens. We have become familiar enough with some rats to give them names that match their unique personalities.

In a pilot study published last year, we reported some initial findings. By monitoring individual rats, we learned that males foraged around the clock 24 hours per day, but females did so only during late mornings. Females and males were equally attracted to scents from lab rats, and females responded to pheromones at the same rate as males.

In 2016 we published our detailed methods
as a roadmap that other scientists can use to replicate this research. Using this approach, we believe scientists can learn when and where particular pathogens enter a given rat population. As far as we know, these are the first two studies to analyze wild city rats at the level of the individual in a major U.S. metropolitan area.

Overcoming taboos against studying city rats

In doing this research, I have encountered strong social taboos against working with rats. In 2013, while I was seeking opportunities to carry out field research on rats in New York City, I requested access to the CCTV surveillance cameras of “Theatre Alley,” a narrow lane in Manhattan’s Financial District where rats scurried at will. Just a few weeks later, I learned that Theatre Alley had been hastily cleaned, changing the setting forever and removing information that could have provided useful insights into rat movements and behavior.

We have also found that there is little money for this kind of research. Although New York City spends a lot of money training pest control workers and finding and exterminating rat colonies through public institutions such as the Metropolitan Transportation Authority and the Department of Health and Mental Hygiene, there are few opportunities for academic studies.

Officials at public agencies think pragmatically and respond to a specific threat after a problem has been reported. Thus, it is understandable that they may be unreceptive to requests for access to subways for theoretical purposes, or for disease-related surveillance in the absence of a demonstrated threat that may or may not come to fruition.

Instead, Michael Deutsch and I are looking for New York City residents who will allow us to do scientific research in their homes, businesses, apartment buildings and other establishments, without fear of publicity, fines or judgment. To do this work on a larger scale, we need to do more work to build bridges between academic research and front-line public health and sanitation agencies.

In New York alone, up to six million people use the subway system every day, coming into close proximity with rats, and nearly one-fourth of more than 7,000 restaurants inspected so far this year have shown signs of rat or mouse activity. We clearly need to know more about urban rats: how they behave, where they travel, when and where they pick up diseases and how long they spread them, how these diseases affect rats’ health and, eventually, how rats transmit infections to humans.

Michael H. Parsons, Scholar-in-Residence, Hofstra University

This article was originally published on The Conversation. Read the original article.

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By Nathan Jack Robinson, Indiana University–Purdue University Fort Wayne.

Many ancient cultures once believed that the world rested on the back of a giant sea turtle. This idea might seem far-fetched today, but for a diverse range of marine organisms, it’s reality. Collectively known as epibionts, these organisms make their homes on the backs of marine animals such as crabs, whales and sea turtles. These epibionts range in size, from microscopic plants called diatoms that are just a few hundredths of a millimeter across to fish called remoras than can grow to lengths of 75 centimeters. As scientists, we are finally starting to unlock the secrets of these mysterious hitchhikers.

Recently, my colleagues and I described the communities of epibionts living on three species of sea turtle in Las Baulas National Marine Park. Our work on the Pacific coast of Costa Rica is part of a broader effort from scientists worldwide to characterize the epibiont communities of all seven sea turtle species throughout the Pacific, Atlantic and Indian oceans.

As we fill in the knowledge gaps about how sea turtle epibionts vary globally, we hope to figure out if and why different sea turtles from different geographic areas host different epibiont communities. Furthermore, it’s becoming clear that the creatures found on each sea turtle can tell a story about where that turtle has been and what it was doing there . The information encoded in each sea turtle’s unique set of hitchhikers can, in turn, help guide management decisions to protect these animals during their lives at sea.

Who are these hitchhikers?

Sea turtles spend almost their entire lives in the water – this is where they feed, breed and sleep. But every few years, adult sea turtles migrate from their feeding areas to sandy tropical beaches where they lay their eggs. These migrations are among the longest in the animal kingdom, and sea turtles can cross entire ocean basins just to reach their preferred nesting beaches. Luckily for us, when sea turtles emerge onto land to nest we have a unique opportunity to work with these animals up close.

The three species that we examined for epibionts were the leatherback, olive ridley and green turtle. Many epibionts smaller than a millimeter in size and may be tucked away in difficult-to-reach places – under the shell at the base of the tail or in old scar tissue, for instance. But with persistence, we were able to uncover diverse ensembles of these tagalongs on the nesting sea turtles.

From a combined total of 43 different sea turtles, we encountered 20 different epibiont taxa. Many of these epibionts have only rarely been observed by scientists before – probably because they’ve only been found attached to sea turtles. In addition, many of these epibionts have bizarre adaptations that let them live life as hitchhikers.

We discovered hermaphroditic barnacles that use their heads to cement themselves to the sea turtle’s shell. Miniaturized males of the same barnacle species also live in the grooves of the shell of the larger hermaphroditic barnacle.

There were colonies of miniature shrimp-like amphipods with hooks at the end of their limbs for gripping onto the sea turtle. We currently think these animals graze on the algae that also grows on a sea turtle’s carapace.

In a subsequent study at the same location that is not yet published, we even discovered large isopods. These guys look like woodlice, with huge black eyes. They feed on the skin of living turtles.

Sea turtles have a complex relationship with their epibionts. Sea turtles might be directly harmed by some epibionts, while benefiting from others. In some instances, it might even be a bit of both. For example, barnacles can encrust over the turtle’s nostrils or eyes, yet they can also potentially provide camouflage. Indeed, a sea turtle resting on the sea floor with a shell covered in barnacles could very easily be mistaken for a rock.

Each epibiont has its own story to tell

In our study in Parque Nacional Marino Las Baulas, we statistically demonstrated for the first time that different sea turtle species do indeed have unique epibiont communities.

What is particularly interesting about this finding is that all three sea turtle species we sampled were from the same nesting area. Marine biologists believe epibionts attach to their sea turtle hosts in specific environments. If they were climbing aboard at the nesting site that these three turtle species share, then we’d expect the sea turtles to have similar epibiont communities.

Since they don’t, our data suggest the epibiont communities of these three sea turtle species are more reflective of where the turtles were feeding than where they nest. This discovery could help scientists worldwide uncover the secrets behind the epic migrations sea turtles make between their nesting beaches and the feeding habitats.

For example, say we know a particular epibiont species attaches to sea turtles only while they’re feeding in coastal lagoons. If we then spot a sea turtle anywhere in the world with this species of hitchhiker, we know it’s likely to have passed through a coastal lagoon sometime in the recent past.

In this way, we can start to think of epibionts as tiny data-loggers that can tell us about the movements and behavior of the sea turtle host. This kind of information can help guide management decisions that affect sea turtle conservation.

Implications for fisheries management

The largest threat sea turtles currently face worldwide is ending up as by-catch. Every year, hundreds of thousands of sea turtles are incidentally caught on hooks or entangled in nets intended to catch commercially harvested fish species.

The information we get from sea turtles’ epibionts could help alleviate this problem. With better knowledge of sea turtle movements based on their epibionts, we can start to fish in a more informed way. We can design strategies to avoid sea turtle hot spots, while ensuring that fisheries are still able to catch their desired commercially harvested species.

And of course, any efforts to protect sea turtles will also directly benefit their epibiont hitchhikers. Indeed, an epibiont’s fate is inescapably tied to that of its sea turtle host. This is of particular concern in certain sea turtle populations, such as the East Pacific leatherback turtle, which has declined by 98 percent in less than three decades. As this population teeters on the brink of extinction, so do many of its epibionts.

Epibionts and sea turtles have coexisted for millennia. While it could be said that these epibionts have just been along for the ride, it now seems they could play a crucial role in designing conservation management plans for sea turtles. Far from being passive bystanders in their own decline, these epibionts could be the sea turtle’s saviors if we use just a little human ingenuity.

Nathan Jack Robinson, Post-Doctoral Fellow in Biology, Indiana University–Purdue University Fort Wayne

This article was originally published on The Conversation. Read the original article.

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The way animals move their tails reveals a lot about their emotional state, particularly the frustration they feel when they can’t solve a problem.

“Our results demonstrate the universality of emotional responses across species,” says study lead author Mikel Delgado, a doctoral student in psychology at the University of California, Berkeley. “After all, what do you do when you put a dollar in a soda machine and don’t get your soda? Curse and try different tactics.”

For the study, published in the Journal of Comparative Psychology, researchers tracked 22 fox squirrels in their leafy habitats, putting them through a series of foraging tasks that had them puzzle their way into various open and locked containers to get to nuts or grains.

The more frustrated the squirrels became—especially if the container was locked—the more they flicked their bushy tails.

On a positive note, these stages of tail-flagging irritation, and even aggression, led fox squirrels to try new strategies, such as biting, flipping, and dragging the box in an attempt to land a reward. The results imply that acts of frustration may be necessary and beneficial to problem-solving, Delgado says.

“Animals in nature likely face situations that are frustrating in that they cannot always predict what will happen. Their persistence and aggression could lead them to try new behaviors while keeping competitors away. While not a direct intelligence test, we think these findings demonstrate some of the key building blocks to problem-solving in animals—persistence and trying multiple strategies.”

Frustration has been observed in chimpanzees, pigeons, and even fish, “but we don’t know much about what function they serve,” Delgado says.

NUTS! THE BOX IS LOCKED

To find out, she and psychology professor Lucia Jacobs, trained campus fox squirrels to open containers to get walnuts.

After nine trials of being rewarded with easy-to-obtain walnuts, the squirrels were faced with the unexpected: Some found an empty box, others a locked box, and still others a piece of corn instead of a walnut. As predicted, their tails flicks increased with each disappointment. The locked box was the most irritating.

Researchers videotaped the squirrels’ foraging trials and found that once the critters got over their frustration, they tried new tactics, such as biting the box, flipping it, dragging, and spending time puzzling over how to get it open.

“This study shows that squirrels are persistent when facing a challenge,” Delgado says. “When the box was locked, rather than giving up, they kept trying to open it, and tried multiple methods to do so.” Their results were published in the Journal of Comparative Psychology.

Source: Republished from Futurity.org as a derivative work under the Attribution 4.0 International license. Original article posted to Futurity by Yasmin Anwar-UC Berkeley.

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By Chris Cornelison, Georgia State University.

The U.S. Fish and Wildlife Service and the U.S. Geological Survey last month delivered a sobering update on the white-nose syndrome (WNS) epidemic in North America. WNS has been confirmed in a little brown bat (Myotis lucifugus) near North Bend, Washington, over 1,300 miles west of the previously identified western edge of the disease front, Nebraska.

The news hit the WNS and bat conservation community hard. For the previous 10 years, WNS has spread in a stepwise manner from state to state in a radial pattern from Albany, New York, which is thought to be where the infections started. The consistency of this spread allowed researchers to model the movement of the pathogen, Pseudogymnoascus destructans, with an anticipated arrival on the Pacific Coast in 2026.

Researchers have been developing strategies to control WNS and prevent the massive bat mortalities that have been the hallmark of WNS since 2007. And yet, the disease has spread faster than predicted. Where does this new point of infection leave researchers developing techniques to stall this devastating disease?

Gateway to the west

In order to understand why this is such bad news for bats, one needs to understand how wildlife biologists seek to control the spread of devastating pathogens.

Many of the strategies currently being investigated to minimize the impact of WNS on susceptible bat populations are predicated on the idea that “stop-gap” methods could be employed at geographical choke points to delay the spread of the disease to new populations. That would buy time for scientists to develop permanent solutions, such as vaccinations or “gene silencing” techniques to control the disease.

The arrival of WNS on the West Coast takes this approach off the table in many respects, as it’s already past the geographical bottleneck spots where scientists had hoped to slow it down. But the WNS community has other reasons for concern with this new case.

“Come here often?”

Studies of the fungus from the eastern U.S. have shown the pathogen to be mono-clonal. That is, P. destructans in Georgia is the same genetically as P. destructans in Missouri or New York. This is a good thing for bats because it gives them a better chance to develop resistance.

Subsequent evaluation indicates that P. destructans, like most fungi, is likely capable of participating in sexual reproduction in areas where complementary mating types (think male and female, but with numerous potentially compatible “genders”) exist together. When this is considered along with the recent finding that P. destructans and WNS are widespread in eastern Asia, it presents the possibility that this West Coast case may have been introduced a new way or it represents a different strain of the fungus. Significantly, it could be a complementary mating type to P. destructans in the eastern U.S.

This could be a very bad thing for bats for several reasons. To understand how bad this infection could be to the future of WNS in North America, researchers will need to determine its source and any sexual compatibility with existing isolates.

Tougher than your average spore

The spores (reproductive cells produced by fungi) that are produced in asexual reproduction are known as conidia. All the current work being conducted to make spores inactive to control the spread of WNS are predicated on the sensitivity of these conidia to a given control agent.

Yet the phylum of this fungus, known as Ascomycota, can reproduce in another way – sexually, through a type of spore known as ascospores. In numerous examples in other Ascomycota, it has been shown that ascospores are more resistant to control methods than conidia.

If researchers find that the particular P. destructans fungus is capable of producing ascospores – that is reproducing sexually, rather than asexually as with conidia – then current decontamination protocols will need to be revised to address the increased resilience of these sexual spores.

A Red Queen and brown bats

The ultimate significance of whether the fungus reproduces sexually involves a long-debated theory of evolutionary biology that many have been hopeful will ultimately save susceptible North American bat species: the Red Queen hypothesis.

The idea is that in a system with a host (bat) and parasite (P. destructans), coevolution occurs as the disease recurs through numerous generations. If only the host is reproducing sexually (i.e., WNS in North America) and generating greater variation with each generation, the host will be able to evolve a tolerance to the parasite.

However, in a system where both the host and parasite reproduce sexually, coevolution supports the status quo. So as bats evolve tolerance to one strain of P. destructans another strain resulting from sexual recombination that is capable of causing disease in the new tolerant host will become the dominant strain.

Thus, the analogy of the Red Queen running in place in “Through the Looking-Glass, and What Alice Found There” by Lewis Carroll. Although evolution is occurring (running), everyone is evolving together so the disease paradigm never changes.

This is the possibility the introduction of a complementary mating type presents to WNS in North America. Bats won’t be able to evolve a significant tolerance as the fungus reproduces sexually and rapidly adapts to any resistance the bats develop.

Bats everywhere but not a hibernacula to treat

In addition to the strategic and biological challenges that a Pacific Coast WNS case may introduce, there is also a major logistical challenge that has been looming over the WNS community: where are hibernacula – the shelters where bats hibernate – in the west?

Currently there are no known little brown bat hibernacula in Washington. This doesn’t mean that bat ecologists think little brown bats don’t hibernate in Washington, but rather they have never been able to find large hibernacula as is common in the eastern U.S.

Treating bats during the spring, summer and fall when they are widely dispersed on the landscape is impractical. The effort it takes to capture a few individuals is not scalable to an extent that could have a significant impact on WNS-related population declines. That is why most efforts to develop management strategies have been focused on intervention during the winter at known hibernacula where large groups of bats could be treated together with reasonable effort.

If any of the treatments currently under investigation were available today, how could they be used in Washington? Without understanding how these western bat species use the landscape and where they hibernate, there is no way to deliver any future management tool.

Bad, badder, baddest

In many ways this new western case changes the paradigm of WNS.

In the worst-case scenario, a complementary strain has been introduced into North America and will eventually find its way to locations where the East Coast strain exists, facilitating a more recalcitrant and adaptable pathogen.

In the best-case scenario, this case represents a loss of containment within North America, reducing the value of efforts to slow the westward spread of WNS while treatments can be developed and western bat hibernacula can be identified. Either way, the news of a WNS-positive bat in Washington state represents another disaster for bats that are already experiencing unprecedented declines.

Chris Cornelison, Postdoctoral Research Associate, Georgia State University

This article was originally published on The Conversation. Read the original article.

Featured Photo Credit:  Progressive Animal Welfare

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Unlike most octopuses, which tackle their prey with all eight arms, a rediscovered tropical octopus subtly taps its prey on the shoulder and startles it into its arms.

“I’ve never seen anything like it,” says Roy Caldwell, professor of integrative biology at the University of California, Berkeley. “Octopuses typically pounce on their prey or poke around in holes until they find something.

“When this octopus sees a shrimp at a distance, it compresses itself and creeps up, extends an arm up and over the shrimp, touches it on the far side, and either catches it or scares it into its other arms.”

BEAK-TO-BEAK MATING

The creature, known as the larger Pacific striped octopus, also turns out to be among the most gregarious of known octopuses. While most species are solitary, these have been seen in groups of up to 40 off the Pacific coasts of Nicaragua and Panama.

And while male octopuses typically share sperm with females at arm’s length, ready to flee should the female get aggressive or hungry, mating pairs of this octopus when observed in captivity sometimes cohabit in the same cavity for at least a few days while mating, with little indication of escalated aggression.

Mating pairs have even been observed to share meals in an unusual beak-to-beak position. They do engage in rough sex, however. The pair grasp each other’s arms sucker-to-sucker and mate beak-to-beak, as if kissing. The females mate frequently and lay eggs over several months, whereas the females of most known octopuses die after a single brood.

“HARLEQUIN” OCTOPUSES

The peculiar behaviors seen in the larger Pacific striped octopus are actually a testament to how little is known about most octopuses. While their behavior and neurobiology have been extensively studied, most research is based on observations of just a handful of the more than 300 species of octopus worldwide, Caldwell says.

“There are a lot of species of octopus, and most have never even been seen alive in the wild and certainly haven’t been studied.”

Panamanian biologist Arcadio Rodaniche first observed much of this strange behavior in the 1970s while studying captured specimens in a saltwater swimming pool in Panama. The behavior was so at odds with accepted octopus behavior, however, that he was unable to publish more than an abstract. The species has still not been officially described and has no scientific name.

Caldwell, too, once doubted the brief description of the octopus’s behavior, and only stumbled across the species while pursuing a smaller relative, Octopus chierchiae, on the Pacific coast of Central America. Both are “harlequin” octopuses, so called because of their semi-permanent stripes and spots. The animal lives in water between 40 and 50 meters (150 feet) deep, typically on muddy, sandy plains at the mouths of rivers, probably living in cast-off shells or rock cavities. Females grow to less than 7 centimeters across (3 inches), while males max out at less than 4.5 centimeters (2 inches).

‘DENIZENS OF THE DEEP’

For a new study, published in the journal PLOS ONE, Caldwell and coauthor Richard Ross of the California Academy of Sciences obtained 24 live specimens from a pet supplier between 2012 and 2014 and observed them in their laboratories. Ross even put some on display at the academy’s Steinhart Aquarium, where guests could have observed several pairs mating daily and producing multiple clutches of eggs.

“Personally observing and recording the incredibly unique cohabitation, hunting, and mating behaviors of this fascinating octopus was beyond exciting—almost like watching cryptozoology turn into real-life zoology,” Ross says. “It reminds us how much we still have to learn about the mysterious world of cephalopods.”

“Each time a different type of octopus is studied, we need to redefine our theories about their behavior. It turns out most don’t live up to their ‘denizen of the deep’ reputation,” says former UC Berkeley doctoral student Christine Huffard of the Monterey Bay Aquarium Research Institute.

In these captive environments, the biologists observed females laying eggs for up to six months and brooding for up to eight months. Even after their eggs began hatching, females continued to feed, mate, and lay hundreds more eggs—another unusual behavior.

The larger Pacific striped octopus exhibits a striking high-contrast display of colors and patterns, which can vary from a pale to dark reddish-brown hue to black with white stripes, and spots with both smooth and uneven skin textures.

“They certainly respond to one another when they display their highly contrasting stripes and spots, so their coloration appears to be useful for group living,” Caldwell says. “Nevertheless, while they tolerate one another and sometimes pair up, I don’t think they are highly social.

“Only by observing the context in which these behaviors occur in the wild can we begin to piece together how this octopus has evolved behaviors so radically different from what occurs in most other species of octopus,” he says.

Source: Republished from Futurity.org as a derivative work under the Attribution 4.0 International license. Original article posted to Futurity by Robert Sanders-UC Berkeley.

Featured Photo Credit: Roy Caldwell

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The long, complex vocal sequences of monkeys living in Ethiopia follow a pattern seen in many human languages: the longer the overall sequence, the shorter the sounds within it.

The linguistic pattern in humans is known as Menzerath’s law. According to the law, longer words tend to be made up of shorter syllables and longer phrases are usually made up of shorter words. The law had never been tested in the vocal communication of any other species.

Researchers led by Morgan Gustison, a University of Michigan doctoral student in psychology, and Stuart Semple, a professor of evolutionary anthropology at the University of Roehampton, tested this law in geladas, a species in which males produce long sequences of different calls—up to 25 calls in all—made up of six different call types.

They analyzed 1,065 of these vocal sequences (composed of 4,747 individual calls) recorded from 57 males living in the Sankaber area of the Simien Mountains National Park, Ethiopia.

The researchers found a negative relationship between the sequence length in terms of the number of calls, and the mean duration of the constituent calls. Calls did not vary in length according to their position in the vocal sequence.

The length of the first calls in sequences was closely related to how long the total sequence was. In other words, sequences started off with calls of the “appropriate” length for that sequence: short sequences started with long calls and long sequences started with short calls.

“The findings of this work not only reveal a basic pattern of sequence structure shared by human and nonhuman animal communication, but may also have profound implications for our understanding of biological systems more broadly,” Gustison says.

Other researchers include Ramon Ferrer-i-Cancho at Universitat Politècnica de Catalunya in Spain and Thore Bergmann at the University of Michigan.

The findings appear in the Proceedings of the National Academy of Sciences.

Source: Republished from Futurity.org as a derivative work under the Attribution 4.0 International license. Original article posted to Futurity by Jared Wadley-Michigan.

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