Linking Isolated Languages: Linguistic Relationships of the Carabayo

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Like PLOS ONE, the English language is rapidly taking over the world (we kid). In 2010, English clocked in at over 360 million native speakers, and it is the third-most-commonly used native language, right behind Mandarin Chinese and Spanish. While these languages spread, however, other indigenous languages decline at an accelerated pace. A fraction of these enigmatic languages belong to uncontacted indigenous groups of the Amazonian rainforest, groups of people in South America who have little to no interaction with societies beyond their own. Many of these groups choose to remain uncontacted by the rest of the world. Because of their isolation, not much is known about these languages beyond their existence.

The researchers of a recent PLOS ONE paper investigated one such language, that of the Carabayo people who live in the Colombian Amazon rainforest. Working with the relatively scarce historical data that exists for the Carabayo language—only 50 words have been recorded over time—the authors identified similarities between Carabayo and Yurí and Tikuna, two known languages of South America that constitute the current language family, Ticuna-Yurí. Based on the correspondences, the authors posit a possible genealogical connection between these languages.

Few resources were available to the authors in this endeavor. They analyzed historical wordlists collected during the last encounter with the Carabayo people in 1969—the only linguistic data available from this group— against wordlists for the Yurí language. In addition, they sought the expertise of a native speaker of Tikuna, a linguist trained in Tikuna’s many dialects. Using these resources, the authors broke down the Carabayo words into their foundational forms, starting with consonants and vowels. They then compared them to similarly deconstructed words in Yurí and Tikuna.

The examination involved the evaluation of similarities in the basic building blocks of these words: the number of times a specific sound (or phoneme) appeared; the composition and patterns of the smallest grammatical units of a word (a morpheme); and the meanings attached to these words. When patterns appeared between Carabayo and either Yurí or Tikuna, the authors considered whether or not the languages’ similarities constituted stronger correspondences. They also paid attention to the ways in which these words would have been used by the Carabayo when the lists were originally made many years ago.

The Yurí language was first recorded in the 19th century, but it is thought to have become extinct since then. From these lists, five words stood out: in Carabayo, ao ‘father’, hono ‘boy’, hako ‘well!’, and a complex form containing both the Yurí word from warm, noré, and the Yurí word, t?au, which corresponds in English to ‘I’ or ‘my’. Given the evidence, the authors contend that the strongest link between Carabayo and Yurí is found in the correspondence of t?au. The study of other languages has indicated that first person pronouns are particularly resistant to “borrowing”, or the absorption of one language’s vocabulary into another. Therefore, the authors surmise it is unlikely in this instance that either of the languages absorbed t?au from the other, but that they share a genealogical link.

Similarly, the comparison of Carabayo words to words of the living language of Tikuna provided a high number of matches, including in Carabayo gudda ‘wait’ and gu ‘yes’. The matches especially exhibit sound correspondences of Carabayo g (or k) and the loss of the letter n in certain circumstances. Table 7 from the article shows the full results (click to enlarge):

Carabayo-Tikuna correspondences

Carabayo-Tikuna correspondences

 

Although it is possible that the Carabayo language represents a language that had not yet been documented until the time of 1969, the results of the researchers’ evaluation have led them to conclude that Carabayo more likely belongs to the language family of Ticuna-Yurí. The relationship of Carabayo to Yurí and Tikuna changes the structure of the Ticuna-Yurí family by placing Carabayo on the map as a member of that family. The Tikuna language, once considered to be the sole surviving member of the Ticuna-Yurí family, might now have a sibling, and the identity of a barely known language has become that much more defined.

For the authors, this research is a complicated endeavor. The desire to advance our knowledge and understanding of these precious languages must be balanced with the desires of the uncontacted indigenous groups, some of whom voluntarily choose to remain in isolation. As the authors themselves express, the continued study of these uncontacted languages seeks to engender an awareness in the larger community of the people who speak these languages, and to reiterate their right to be left to live their lives as they wish—in isolation.

Citation: Seifart F, Echeverri JA (2014) Evidence for the Identification of Carabayo, the Language of an Uncontacted People of the Colombian Amazon, as Belonging to the Tikuna-Yurí Linguistic Family. PLoS ONE 9(4): e94814. doi:10.1371/journal.pone.0094814

Image 1: Sunset on the Amazon by Pedro Szekely

Image 2: pone.0094814

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A Disease of Considerable Antiquity: Cancer Detected in a Nubian Skeleton

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Cancer, the transformation of normal cells into malignant tumor cells, reigns among diseases as one of the leading causes of death around the world. In 2012, cancer claimed 8.2 million lives, and numbers continue to increase each year. While our understanding of cancer is far from complete, we’ve been able to attribute some of the killer’s virulence to increased environmental risk: Increased pollutants and other environmental carcinogens, coupled with an average increase in tobacco and alcohol use and added to a concurrent decrease in daily exercise, cumulatively represent significant risk factors directly related to an increasingly modern world. Ironically, we humans also live a lot longer than we used to, which increases the disease’s chances of occurring.

However, we have identified far fewer examples of the disease in the archaeological record compared to its current frequency in the current population, which has led to the idea that cancer was much less widespread in antiquity. As a result, very little is known about its evolutionary history.

As part of a larger research project undertaken by the British Museum in the city of Amara West, Sudan, the authors of a PLOS ONE paper dug a little deeper into the dark, early history of cancer. Their subject of interest was an over 3,000 year-old skeleton of a young man from ancient Nubia, then part of Egypt, whose remains were excavated at this site, designated on the map below.

Figure 1

When the researchers uncovered skeleton 244-8, as he has been cataloged, they were presented with the difficulties of examining a less-than-complete body. Parts of the skeleton had been broken, highlighted as fragmentary in the image below. In addition, salt in the surrounding soil had slowly damaged the skull over time. The soft tissue of the over 3,000-year-old skeleton, was also long gone.

Figure 3

On top of these difficulties, damages to the body incurred over time, both before and after death, can look very similar to the eye. Cancer, in particular, is notoriously hard to diagnose in human remains; its similarities to other pathologies combined with natural damages sustained after burial made the researchers’ task of properly diagnosing skeleton 244-8 a complicated one. The earliest signs of cancer in bone are also only visible via methods like X-ray that allow us to visualize the inner parts of bone where the disease begins, which the naked eye cannot see.

The researchers assessed the condition of skeleton 244-8, using digital microscopes, scanning electron microscopes (SEM), and radiography (X-rays), and by examining the visual markers on the bone. They looked for evidence of sustained lesions, or damage on the bone, which they found on his vertebrae, ribs, sternum, pelvis, and other parts of the skeleton.

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In the X-ray and photo image above of a rib, we can see the damage as noted by the arrows. The parts of the skeleton most affected by lesions were sections of the spine. The image below depicts an especially damaged thoracic vertebra.

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The authors discussed four possible causes for the skeleton’s bone damage:

  • Metastatic organ cancer, or the rapid creation of abnormal cells that spread from the original site in the organs to other parts of the body
  • Multiple myeloma, a cancer of the plasma cells in bone marrow
  • Fungal infection
  • Taphonomic damage, or natural decay after death

Although very similar, the visual markers on bone differ slightly depending on the malady causing the damage. We can see in the image below of the tibia that taphonomic damage caused by insects is slightly more uniform in shape than lesions caused by cancer, and the holes continue straight through to the other side of the affected bone.

Figure 13

Based on the shape, size, and appearance of the lesions under X-ray, the authors surmised that the man suffered from metastatic cancer, originating in the man’s organs. However, since no soft tissue was preserved over time, it is nearly impossible to ascertain the exact location of skeleton 244-8’s primary tumor, which would have affected soft tissue like his organs.

Considering the decay caused by time, salt, and insects, the researchers were able to ascertain quite a lot about skeleton 244-8 based on their examinations of the skeleton. In addition to diagnosing him with metastatic cancer, researchers suggest that skeleton 244-8 was a young man between the ages of 25 to 35 who belonged to a middle-class Nubian family at the time of his death, based on the context of his burial.

With increasing advances in the technology used to examine subjects like skeleton 244-8, the inner secrets and pathologies held in places like the inside of bone become less of a mystery. With further study, we’ll be able to understand a little more about the environmental risk factors of skeleton 244-8’s own world: for instance, the possible use of fires in poorly ventilated mudbrick houses, or possible infectious diseases spread by parasites. By taking a closer look at human remains like skeleton 244-8, it may eventually be possible to see the effects of a disease not only of our time, but of considerable antiquity.

Citation: Binder M, Roberts C, Spencer N, Antoine D, Cartwright C (2014) On the Antiquity of Cancer: Evidence for Metastatic Carcinoma in a Young Man from Ancient Nubia (c. 1200BC). PLoS ONE 9(3): e90924. doi:10.1371/journal.pone.0090924

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3000 Years Ago, We Were What We Ate

Efate, VanuatuFor many of us, moving to a new house means recruiting a couple good friends to help pack and haul boxes. After a day or two of work, everyone shares a pizza while resting tired muscles at the new home. But 3000 years ago, enjoying a post-move meal may have required a little more planning. Early settlers of remote tropical islands in the Pacific had to bring along all resources needed for survival, including food, from their original homes overseas.

The Lapita people were early settlers of islands in the Pacific, called Remote Oceania (pictured below). When these people, whose culture and biology links to Southeast Asian islands, first decided to sail to the island Vanuatu, they brought domestic plants and animals—or what you might call a ‘transported landscape’—that allowed them to settle this previously uninhabited, less biodiverse (and less resource-available) area. However, the extent to which these settlers and their domestic animals relied on the transported Remote Oceanialandscape at Vanuatu during the initial settlement period, as opposed to relying on the native flora and fauna, remains uncertain.

To better understand the diet and lives of the Lapita people on Vanuatu, archaeologist authors of a study in PLOS ONE analyzed the stable carbon, nitrogen, and sulfur isotopes from the bones of ~ 50 adults excavated from the Lapita cemetery on Efate Island, Vanuatu.

Why look at isotopes in human remains? Depending on what we eat, we consume varying amounts of different elements, and these are ultimately deposited in our bones in ratios that can provide a sort of “dietary signature”; in this way, the authors can investigate the types of plants, animals, and fish that these early people ate.

For instance, plants incorporate nitrogen into their tissue as part of their life cycle, and as animals eat plants and other animals, nitrogen isotopes accumulate. The presence of these different ratios of elements may indicate whether a human or animal ate plants, animals, or both. Carbon ratios for instance differ between land and water organisms, and sulfur ratios also vary depending on whether they derive from water or land, where water organisms generally have higher sulfur values in comparison to land organisms.

Scientists used the information gained about the isotopes and compared it to a comprehensive analysis of stable isotopes from the settlers’ potential food sources, including modern and ancient plants and animals. They found that early Lapita inhabitants of Vanuatu may have foraged for food rather than relying on horticulture during the early stages of colonization. They likely grew and consumed food from the ‘transported landscape’ in the new soil, but appear to have relied more heavily on a mixture of reef fish, marine turtles, fruit bats, and domestic land animals.

The authors indicate that the dietary analysis may also provide insight into the culture of these settlers. For one, males displayed significantly higher nitrogen levels compared to females, which indicates greater access to meat. This difference in food distribution may support the premise that Lapita societies were ranked in some way, or may suggest dietary differences associated with labor specialization.  Additionally, the scientists analyzed the isotopes in ancient pig and chicken bones and found that carbon levels in the settlers’ domestic animals imply a diet of primarily plants; however, their nitrogen levels indicate that they may have roamed outside of kept pastures, eating foods such as insects or human fecal matter. This may have allowed the Lapita to allocate limited food resources to humans, rather than domestic animals.

Thousands of years later, the adage, “you are what you eat” or rather, “you were what you ate” still applies. As the Lapita people have shown us, whether we forage for food, grow all our vegetables, or order takeout more than we would like to admit, our bones may reveal clues about our individual lives and collective societies long after we are gone.

Citation: Kinaston R, Buckley H, Valentin F, Bedford S, Spriggs M, et al. (2014) Lapita Diet in Remote Oceania: New Stable Isotope Evidence from the 3000-Year-Old Teouma Site, Efate Island, Vanuatu. PLoS ONE 9(3): e90376. doi:10.1371/journal.pone.0090376

Image 1: Efate, Vanuatu by Phillip Capper

Image 2: Figure 1

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The Science of Snakeskin: Black Velvety Viper Scales May be Self-Cleaning

West African Gaboon Viper

West African Gaboon viper

Whether you love them or hate them, snakes have long captivated our interest and imagination. They’ve spurred countless stories and fears, some of which may have even affected the course of human evolutionary history. We must admit, there is something a little other-worldly about their legless bodies, willingness to swallow and digest animals much bigger than them, and fangs and potentially fatal (or therapeutic?) venomous bites.

Not least of all, their scaly skin is quite mesmerizing and often laden with intricate and beautifully geometric patterns just perfect for camouflaging, regardless of whether they live high up in a tree, deep in murky waters, or on the forest floor. Snakeskin was the focus of recent research by the authors of this PLOS ONE study who sought to determine whether it has any special properties less obvious to the naked eye.

Please meet the West African Gaboon viper, Bitis gabonica rhinoceros (pictured above). Native to the rainforests and woodlands of West Africa, these large, white-brown-and-black snakes can be identified by large nasal horns and a single black triangle beneath each eye—nevermind that, because they also lay claim to titles for the longest fangs and most venom volume produced per bite. The pattern of their skin is intricate and excellent for camouflage, and the black sections have a particularly velvety appearance. These eye-catching characteristics intrigued zoology and biomechanics researchers from Germany, who decided to take a closer look.

In a previously published paper, the authors analyzed the Gaboon viper’s skin surface texture by using scanning electron microscopy (SEM), as well as its optical abilities by shining light on the snakeskin in different ways to see how it’s reflected, scattered, or transmitted. They found that only the black sections contained leaf-like microstructures streaked with what they call “nanoridges” on the snake scales, a pattern that has not been observed before on snakeskin. What’s more, the black skin reflects less than 11% of light shone on it—a lot less than other snakes—regardless of the angle of light applied. The authors concluded from the previous study that both of these factors may contribute to the viper’s velvet-like, ultra-black skin appearance.

Scanning electron microscopy (SEM) of viper scales

Scanning electron microscopy (SEM) of viper scales

In their most recent PLOS ONE paper titled “Non-Contaminating Camouflage: Multifunctional Skin Microornamentation in the West African Gaboon Viper (Bitis rhinoceros),” the authors conducted wettability and contamination tests in hopes of further characterizing the viper skin’s properties, particularly when comparing the pale and black regions.

To test the wettability of the viper scales, the authors sprayed droplets of water, an iodide-containing compound (diiodomethane), and ethylene glycol on the different scale types shown above, on both a live and dead snake, and then measured the contact angle—the angle at which a liquid droplet meets a solid surface. This angle lets us know how water-friendly a surface is; in other words, the higher the contact angle, the less water-friendly the surface.

Contact angle (A) and snake skin with water droplet on light and dark areas (B)

Contact angle (A) and snake skin with water droplet on light and dark areas (B)

As you can see in the graph above, the contact angle was different depending on the liquid applied and the type of scale; in particular, the contact angle on the black scales was significantly higher than the others, in a category that the authors refer to as “outstanding superhydrophobicity,” or really, really, really water-repelling. This type of water-repelling has been seen in geckos, but not snakes.

Water droplet appearance on live snake skin

Water droplet appearance on live snake skin

The authors then took some of the snake carcass and dusted it with a sticky powder in a contamination chamber, after which they generated a fog for 30 minutes and took pictures.

Skin before dusting (A), skin under black light after dusting (B), skin under black light after fogging (C), section of SEM, showing light and dark skin (D)

Skin before dusting (A), skin under black light after dusting (B), skin under black light after fogging (C), section of SEM, showing light and dark skin (D)

After 30 minutes of fogging, the black areas were mostly free of the dusting powder, while the pale areas were still completely covered with dust. The powder itself was also water-repelling, and so the authors showed that despite this, the powder rolled off with the water rather than sticking to the black areas of snake skin. Therefore, as suggested by the authors, this could be a rather remarkable self-cleaning ability. The authors suspect that the “nanoridges,” or ridges arranged in parallel in the black regions, may allow liquid runoff better than on the paler areas of the snake.

How does this texture variation help the snake, you ask? The authors posit that all these properties basically contribute to a better form of camouflage. If the snake were completely covered in one color, it may stand out against a background of mixed colors (or “disruptive coloration”), like that of a forest floor. If the black regions have fairly different properties from the paler regions, mud, water, or other substances would rub off in these areas and continue to provide the light-dark color contrast and variation in light reflectivity that helps the snake do what it does best: slither around and blend in unnoticed.

Citations

Spinner M, Kovalev A, Gorb SN, Westhoff G (2013) Snake velvet black: Hierarchical micro- and nanostructure enhances dark colouration in Bitis rhinoceros. Scientific Reports 3: 1846. doi:10.1038/srep01846

Spinner M, Gorb SN, Balmert A, Bleckmann H, Westhoff G (2014) Non-Contaminating Camouflage: Multifunctional Skin Microornamentation in the West African Gaboon Viper (Bitis rhinoceros). PLoS ONE 9(3): e91087. doi:10.1371/journal.pone.0091087

Images

First image, public domain with credit to TimVickers

Remaining images from the PLOS ONE paper

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Infectious Earworms: Dealing with Musical Maladies

earworm - record playing This menace may leap out at you in the subway or find you when you’re tucked away, safe in your bed; it might follow you when you’re driving down the street or running at the gym. Hand sanitizer can’t protect you, and once you’re afflicted, the road to recovery can be a long one. However, this isn’t the Bubonic plague or the common cold—instead, the dreaded earworms!

Derived from the German word ohrwurm, which translates literally to “ear-worm,” an earworm commonly refers to a song, or a snippet of a song, that gets stuck in your head. Earworms can occur spontaneously and play in our heads in a seemingly infinite loop. Think of relentlessly catchy tunes, such as “Who Let the Dogs Out?,” “It’s a Small World,” or any Top 40 staple. An estimated 90% of people fall prey to an earworm at least once a week and most are not bothersome, but some can cause distress or anxiety. And yet, despite the earworm’s ubiquity, very little is known about how we react to this phenomenon. With the assistance of BBC 6 Music, the authors of a recent PLOS ONE study set out to connect the dots between how we feel about and deal with these musical maladies.

Researchers drew upon the results of two existing surveys, each focusing on different aspects of our feelings about earworms. In the first, participants were asked to reflect on whether they felt positively or negatively toward earworms, and whether these feelings affected how they responded to them. The second survey focused on how effective participants felt they were in dealing with songs stuck in their heads. Responses to both surveys were given free form.

To make sense of the variety of data each survey provided, the authors coded participant responses and identified key patterns, or themes. Two researchers developed their own codes and themes, compared notes and developed a list, as represented below.

earworm - Finnish study

Survey responses. Participants either chose to “cope” with their earworms or “let it be.”

The figure above represents responses from the first survey, in which participants assigned a negative or positive value to their earworm experiences and described how they engaged with the tune. The majority didn’t enjoy earworms and assigned a negative value to the experience. These responses were clustered by a common theme, which the researchers labelled “Cope,” and were associated with various attempts to get rid of the internal music. A significant number of participants reported using other music to combat their earworms.

Participants in the second survey, which focused on the efficacy of treating earworms, responded in a number of different ways. Those whose way of dealing was effective often fell into one of two themes: “Engage” or “Distract.” Those that engaged with their earworms did so by, for example, replaying the song; those that wanted distraction often utilized other songs. Most opted to engage.

Ultimately, the researchers concluded that our relationships with these musical maladies can be rather complex. Yet, whether you embrace these catchy tunes or try to tune them out, the way we feel about earworms is often connected to how we deal with them.

Want to put in your two cents? You can tell the authors how you deal with earworms at their website, Earwormery. For more on this musical phenomenon, listen to personal anecdotes on Radiolab, read about earworm anatomy at The New Yorker, or dig deeper in the study.

 

Citation: Williamson VJ, Liikkanen LA, Jakubowski K, Stewart L (2014) Sticky Tunes: How Do People React to Involuntary Musical Imagery? PLoS ONE 9(1): e86170. doi:10.1371/journal.pone.0086170

 

Images: Record playing by Kenny Louie

Figure 1 from the paper.

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It’s a Mad, Mad, Mad, Mad, but Predictable World: Scaling the Patterns of Ancient Urban Growth

cities from sapce

With more than 7.1 billion people living across the globe, cities house more than 50% of the world’s population. The United Nations Population Fund projects that by 2030 more than 5 billion people will live in cities across the world. The Global Heath Observatory, a program run by the World Health Organization, predicts that by 2050, 7 out of 10 people will live in cities, compared to 2 of 10 just 100 years ago.

Recently, researchers developed what is called “urban scaling theory” to mathematically explain how modern cities behave in predictable ways, despite their unprecedented growth. Recent work in urban scaling research considers cities “social reactors”. In other words, the bigger the city, the more people and more opportunity for social interaction.  Think for a moment about the social interactions that occur just on the block outside of your local coffee shop; now multiply those interactions by millions. Cities magnify the number of interactions, increasing both social and economic productivity and, ultimately, encouraging their own growth.

The authors of a recent PLOS ONE paper sought to determine whether ancient cities “behaved” in predictable patterns similar to their modern counterparts. To do so, they developed mathematical models and tested them on archaeological settlements across the Pre-Hispanic Basin of Mexico (BOM, approximated by the red square in the figure below). Based on their findings, they suggest that the principles of settlement organization, which dictate city growth, were very much the same then as they are now, and may be consistent over time.

To test their predictions, the researchers analyzed archaeological data from over 1,500 sites in the BOM, previously surveyed in the 60s and 70s by researchers from the University of Michigan and Penn State.

BOM Location

Using low-altitude aerial photographs and primary survey reports from the original surveyors, the researchers organized the following data from approximately 4,000 sites: the settled area, the average density of potsherds—broken pieces of ceramic material—within it, the count and total surface area of domestic architectural mounds, the settlement type, the estimated population, and the time period.

The researchers were interested in examining areas of the BOM that enabled social interaction between residents, so they excluded site types that did not allow social interaction, for example, isolated ceremonial centers, quarries, and salt mounds. They then grouped the remaining 1,500 sites into both chronological groups and size groups. For chronological grouping, each site was assigned to one of four time periods: the Formative period (1150 B.C.E.–150 B.C.E.), the Classic period (150 B.C.E.–650 C.E.), the Toltec period (650–1200 C.E.), and the Aztec period (1200-1519 C.E.). By the Aztec period, the area had developed from amorphous rural settlements to booming metropolises comprising over 200,000 people.

BOM Population

For site grouping, settlements greater than 5,000 people were categorized differently than smaller settlements. In the figure above, panel B denotes settlements dating to the Formative period (1150 B.C.E.–150 B.C.E.), and panel C, settlements dating to the Aztec period (1200-1519 C.E.).

After separating the data into both chronological groups and size groups, the researchers applied their mathematical models and tested their predictions about urban growth in the settlements of the BOM. One aspect of city development assessed by the researchers was the evolution of defined networks of roads and canals in growing cities. Because roads act as conduits, directly influencing social interaction—much like the roads leading to the aforementioned coffee shop—growing cities develop increasingly defined networks to connect social hubs to one another.

Take, for example, the figure below, which displays both a city in an early stage (panel A) and later (panel B) of growth:

Settlements

Panel A shows the early, or Amorphous Settlement Model, displaying a small settlement easily accessible to the individual via walking, and thus negating the necessity for clearly defined networks of roads. Panel B, on the other hand, shows the Networked Settlement Model, an infrastructure-dense area where networks are clearly defined to accommodate the increased size of the city and density of the residents. Larger cities analyzed by the authors, like Teotihuacan of the Classic period and Tenochtitlán of the Aztec period, epitomize the Networked Settlement Model with its organized network of roads and canals. The findings from the BOM echo the earlier-stated notion that, like their modern counterparts, ancient cities may have acted as “social reactors”, in part by facilitating an increasingly defined network of roads, themselves directly influencing the ability of residents to socially interact.

Scientists use urban scaling theory to show that population and social phenomena follow distinct, mathematical patterns over time. By developing mathematical models to predict measurable changes in city growth, these researchers applied the same patterns to ancient cities and concluded that the development of settlements over time in the BOM seem analogous to those observed in modern cities. Researchers predict that the same mathematical models could be reformatted to estimate population size of ancient cities, as well as to develop measures for calculating socio-economic output like the production of art and public monuments based on the relationship size between settlement size and division of labor. Although there is still much to be solved through the equations of urban scaling theory, the consistency of city growth over time has implications for both the past and the present.

Citation: Ortman SG, Cabaniss AHF, Sturm JO, Bettencourt LMA (2014) The Pre-History of Urban Scaling. PLoS ONE 9(2): e87902. doi:10.1371/journal.pone.0087902

Image 1: Auroras Over North American as Seen From Space by the NASA Goddard Space Flight Center

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Two Shark Studies Reveal the Old and Slow

Sharks live in the vast, deep, and dark ocean, and studying these large fish in this environment can be difficult. We may have sharks ‘tweeting’ their location, but we still know relatively little about them. Sharks have been on the planet for over 400 million years and today, there are over 400 species of sharks, but how long do they live, and how do they move? Two recent studies published in in PLOS ONE have addressed some of these basic questions for two very different species of sharks:  great whites and megamouths.

The authors of the first study looked at the lifespan of the great white shark. Normally, a shark’s age is estimated by counting growth bands in their vertebrae (image 1), not unlike counting rings inside a tree trunk. But unfortunately, these bands can be difficult to Great white vertdifferentiate in great whites, so the researchers dated the radiocarbon that they found in them. You might wonder where this carbon-14 (14C) came from, but believe it or not, radiocarbon was deposited in their vertebrae when thermonuclear bombs were detonated in the northwestern Atlantic Ocean during the ‘50s and ’60s. These bands therefore provide age information. Based on the ages of the sharks in the study, the researchers suggest that great whites may live much longer than previously thought. Some male great whites may even live to be over 70 years old, and this may qualify them as one of the longest-living shark species. While these new estimates are impressive, they may also help scientists understand how threats to these long-living sharks may impact the shark population.

A second shark study analyzed the structure of a megamouth shark’s pectoral fin (image 2) to understand and predict their motion through the water. Discovered megamouth finin 1976, the megamouth is one of the rarest sharks in the world, and little is known about how they move through the water. We do know that the megamouth lives deep in the ocean and is a filter feeder, moving at very slow speeds to filter out a meal with its large mouth. But swimming slowly in the water is difficult in a similar way flying slowly in an airplane is difficult. Sharks need speed to control lift and movement.

To better understand the megamouth’s slow movement, the researchers measured the cartilage, skin histology, and skeletal structure of the pectoral fins of one female and one male megamouth shark, caught accidentally and preserved for research. The researchers found that the megamouth’s skin was highly elastic, and its cartilage was made of more ‘segments’ than any other known shark, which may provide added flexibility compared to other species. megamouth jointThe authors also suggest that the joint structure (image 3) of the pectoral fin may allow forward and backward rotation, motions that are largely restricted in most sharks.  The authors suggest that this flexibility and mobility of the pectoral fin may be specialized for controlling body posture and depth at slow swimming speeds. This is in contrast to the fins of fast-swimming sharks that are generally stiff and immobile.

In addition to the difficulties in exploring deep, dark seas, small sample sizes present challenges for many shark studies, including those described here. But whether studying the infamous great white shark or one of the rare megamouths, both contribute to a growing body of knowledge of these elusive fish.

Citations: Hamady LL, Natanson LJ, Skomal GB, Thorrold SR (2014) Vertebral Bomb Radiocarbon Suggests Extreme Longevity in White Sharks. PLoS ONE 9(1): e84006. doi:10.1371/journal.pone.0084006

Tomita T, Tanaka S, Sato K, Nakaya K (2014) Pectoral Fin of the Megamouth Shark: Skeletal and Muscular Systems, Skin Histology, and Functional Morphology. PLoS ONE 9(1): e86205. doi:10.1371/journal.pone.0086205

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Resolution Inspiration: What Will You Work on in 2014?

Resolutions 2012 - Flickr - Lori Ann

Though we are well into January, there is still time to set resolutions for 2014. What would you like to accomplish in the next twelve months? For some resolution inspiration, here’s a selection of PLOS ONE research articles to get you started:

Restaurant Bwyty sign by Dave GoodmanLearn a Language

Whether for work or pleasure, learning a new language can be a rewarding experience. It can also take a lot of time. Fear not—according to research published last year, you may be able to learn new words in a foreign language while performing other tasks. The key to this method of vocabulary building is exposure. In the study, participants were given a letter and tasked with finding the letter in a written Welsh word. As they looked for the letter, one group informally heard the word and saw an image of what it represented. Afterward, when participants were asked to determine whether a Welsh word matched an image, those who were exposed to corresponding images and audio scored higher than their counterparts in the control group.

 

Sing Along with Me (10 365) by John Liu

Get Vocal

For those of you with musical aspirations, take a nod from this study on vocal synchronization and rhythm. In it the researchers found that when participants read aloud together in real time, their speech patterns synchronized more readily than participants who read aloud with the recording of their partner’s voice. Though the study was primarily concerned with spoken rhythms, the researchers propose that the social component of rhythm, and the shared goal of synchronization, may be pertinent to music too. Musical rhythm, they suggest, may stem from social interaction rather than sexual selection.

 

smile by jessicahtamDe-stress

Under pressure? According to the authors of this next PLOS ONE paper, those who experience chronic stress may suffer from impaired problem-solving skills. To combat the deleterious effects of stress, they suggest performing a “self-affirmation” exercise before tackling a problem. In the study, the researchers asked underperforming and self-reportedly stressed college students to rank a series of values, such as creativity and friends/family, according to order of personal importance. They were then asked to write about why the top value was most important to them, or why one of the bottom values might be important to others. After completing the exercise, the students were given a word association test. Stressed-out students that wrote about their top value and its personal importance outperformed their peers. Talk about the power of positive thinking!

Whether you want to pick up a new language, reduce your stress, or get out and sing more karaoke this year, we hope you are inspired to try out a few resolutions. For even more inspiration, check out other posts in the PLOS Blogs network: Alessandro Demaio’s Translational Global Health and Peter Janiszewski’s post on Obesity Panacea.

 

Citations:

Bisson M-J, van Heuven WJB, Conklin K, Tunney RJ (2013) Incidental Acquisition of Foreign Language Vocabulary through Brief Multi-Modal Exposure. PLoS ONE 8(4): e60912. doi:10.1371/journal.pone.0060912

Bowling DL, Herbst CT, Fitch WT (2013) Social Origins of Rhythm? Synchrony and Temporal Regularity in Human Vocalization. PLoS ONE 8(11): e80402. doi:10.1371/journal.pone.0080402

Creswell JD, Dutcher JM, Klein WMP, Harris PR, Levine JM (2013) Self-Affirmation Improves Problem-Solving under Stress. PLoS ONE 8(5): e62593. doi:10.1371/journal.pone.0062593

 

Image: Resolutions 2012 by Lori Ann

Restaurant Bwyty sign by Dave Goodman

Sing Along with Me (10/365) by John Liu

Smile by jessicatam

The post Resolution Inspiration: What Will You Work on in 2014? appeared first on EveryONE.

A Year in Review: 2013 PLOS ONE Papers in the Media

 

6647478555_f408a731f9_oImage Credit: Yutaka Tsutano

 

Tired of year-end lists? We know you’ve got room for at least one more. 2013 was a great year for PLOS ONE media coverage: We had over 5,000 news stories on over 1450 published articles.

The PLOS ONE press team poured tirelessly over the list to whittle down the papers that stood out the most. In celebration of the New Year, we’d like to share some of these titles with you.

Zipping back to January 2013 and moving forward from there, here they are:

 

1. Flowers Flowering Faster

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In “Record-Breaking Early Flowering in the Eastern United States,” US researchers used 161 years of historical reports—initiated by Henry David Thoreau and Aldo Leopold in 1935—to track spring flowering times. They discovered that exceptionally warm spring temperatures in Massachusetts and Wisconsin in 2010 and 2012 may have resulted in the earliest recorded spring in the eastern United States. Furthermore, scientists indicate that these advanced flowering times could be predicted based on the historical data. This research received media attention from the The New York Times, National Geographic, and NPR.

 

2. Lend an Ear?

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US scientists 3D-printed a human ear using collagen hydrogels (a network of polymers that form a gel with water) derived from cow cartilage in the lab. They shared their results in “High-Fidelity Tissue Engineering of Patient-Specific Auricles for Reconstruction of Pediatric Microtia and Other Auricular Deformities.” The authors suggest that this advancement may be a significant first step toward creating patient-specific tissue implants for those who require ear prosthesis. Popular Science, Discovery News, and NPR covered this research.

 

3. Central African Elephants in Big Trouble

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African forest elephant populations may have declined by an alarming 62% in the last decade, according to the study “Devastating Decline of Forest Elephants in Central Africa.” The authors suggest that this dramatic drop is largely due to continuing illegal ivory trade and inadequate efforts to put a stop to it. ScienceNow, TIME, Slate, Smithsonian, and many others covered this story.

 

4. Wrapped up in a Book

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For everyone who enjoys a good page-turner, researchers in the study “The Expression of Emotions in 20th Century Books” indicate that recent British and American books have fewer emotional “mood” words than they did in the earlier half of the 20th century. What’s more, the study’s authors provide evidence that American authors express more emotion than British authors, and that newer American books use more words conveying fear than older ones. This research was covered by the The New York Times Arts Beat, Jezebel, our EveryONE blog, and Nature.

 

5. Gaming for All Ages

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In the article “A Randomized Controlled Trial of Cognitive Training Using a Visual Speed of Processing Intervention in Middle Aged and Older Adults,” researchers from multiple institutions in Iowa discovered that when middle-aged and older adults played video games, they scored better on cognitive function tests. The authors hope that these results might help us slow cognitive decline in older individuals. This paper was covered by the The Wall Street Journal, Nature, and The Telegraph.

 

6. Seafood Watch for Arctic Foxes?

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In another saddening story of declining wild animal populations, researchers studying the “Correlates between Feeding Ecology and Mercury Levels in Historical and Modern Arctic Foxes (Vulpes lagopus)” found that mercury levels in seafood may be the culprit. They emphasize that overall direct exposure to toxic materials may not be as important as the feeding ecology and opportunities of predators, like the arctic fox, that have a very marine-based diet, which may contain these toxic substances. This research received media attention from Wired UK, Scientific American, and The Guardian.

 

7. Cancer in Neandertals

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At least one Neandertal 120,000 years ago had a benign bone tumor in a rib, according to researchers in the study “Fibrous Dysplasia in a 120,000+ Year Old Neandertal from Krapina, Croatia.” The authors note, however, that they cannot comment on any health effects or the overall health condition of the individual without further evidence. This article received media attention from sources including the BBC, The New York Times, ScienceNOW, and Gizmodo.

 

8. Who Needs Rows of Teeth When You’ve Got a Tail to Slap Sardines?

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Image credit: PLOS ONE article

Thresher Sharks Use Tail-Slaps as a Hunting Strategy” contains the first video evidence of long-tailed sharks tail-slapping to stun their sardine prey. The authors suggest that this method may be effective when hunting prey that swim in schools. A Scientific American podcast, National Geographic’s Phenomena blogs, and NBC News were some of the media outlets that covered this research.

 

9. Contagious Yawning in Dogs and Chimps

Video credit: PLOS ONE article

Yawning animals were the focus of more than one PLOS ONE article in 2013. In one study, “Familiarity Bias and Physiological Responses in Contagious Yawning by Dogs Support Link to Empathy,” Japanese researchers found that dogs yawn more often in response to their owners’ yawns rather than a stranger’s, and received media coverage from The Guardian, CBS News, and The Telegraph. The authors of another research article “Chimpanzees Show a Developmental Increase in Susceptibility to Contagious Yawning: A Test of the Effect of Ontogeny and Emotional Closeness on Yawn Contagion” showed that chimpanzees appear to develop a contagion for yawning as they get older, just as humans do, and this article received media attention from The New York Times Science Takes, Los Angeles Times, and Scientific American Blogs.

 

10. What, the Cat? Oh, He’s Harml…

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Our favorite parasite Toxoplasma gondii strikes again. Mice are normally terrified of cats, and rightly so, but Berkeley researchers (including a PLOS founder Mike Eisen) in “Mice Infected with Low-Virulence Strains of Toxoplasma gondii Lose Their Innate Aversion to Cat Urine, Even after Extensive Parasite Clearance” show that mouse exposure to the parasite, carried in cat feces, may alter the mouse’s brain, causing the mouse to permanently lose their fear of cats. The story received coverage from several news outlets, including a CNN segment by Charlie Rose, BBC, National Geographic Phenomena, and Nature.

 

11. Just in Time for the Movie: Jurassic Park is Fake

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Sorry in advance for the disheartening news: Jurassic Park will likely remain a work of fiction. In “Absence of Ancient DNA in Sub-Fossil Insect Inclusions Preserved in ‘Anthropocene’ Colombian Copal,” UK researchers were unable to find any evidence of ancient DNA in specimens of prehistoric insects fossilized in hardened tree sap. Conveniently, the article published right when the newest Jurassic Park film series was announced, and was covered by San Francisco Chronicle, The Telegraph, The Conversation, and others.

 

12. Not Now, Honey – The Pressure Just Dropped

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Insects avoid sex when a drop in atmospheric pressure occurs, which usually precedes rain, according to researchers in the study “Weather Forecasting by Insects: Modified Sexual Behaviour in Response to Atmospheric Pressure Changes.” Injury from rain can be deadly for some insect species, so the authors suggest that the insects modified their behavior to enhance survival (good choice!). The article has received attention from nearly 20 news outlets, including Nature, Los Angeles Times, Scientific American, and ScienceNOW.

 

13. Dinos with Squishy Joints and Tiny Arms

 

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Image credit: PLOS ONE article

Dinosaurs were a popular item in PLOS ONE in 2013, especially with the launch of PLOS ONE’s New Sauropod Gigantism Collection. The most popular article was a simulation of how the largest dinosaur, the Argentinosaurus, might have walked in “March of the Titans: The Locomotor Capabilities of Sauropod Dinosaurs,” which was covered in Washington Post and The Guardian. Another group of researchers showed that squishy joints were a major factor in the massiveness of saurischian dinosaurs in “What Lies Beneath: Sub-Articular Long Bone Shape Scaling in Eutherian Mammals and Saurischian Dinosaurs Suggests Different Locomotor Adaptations for Gigantism.” The article was covered by Gizmodo, Inside Science, and Discovery. Finally, a new super-predator larger than T. rex lived 80 million years ago and was described in “Tyrant Dinosaur Evolution Tracks the Rise and Fall of Late Cretaceous Oceans” and covered by BBC, Nature, and Discovery.

 

14. Huh?

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The title of this next study says it all: “Is “Huh?” a Universal Word? Conversational Infrastructure and the Convergent Evolution of Linguistic Items.” The authors of this article suggest that it is, and that at least ten countries use a variation of this word to verbally express confusion. The article was featured in NPR, The New York Times, and LA Times.

 

15. Little Red Riding Hood: The Evolution of a Folk Tale

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Little Red Riding Hood has very deep roots, as the authors of “The Phylogeny of Little Red Riding Hood” show in their article. It has made its way across China to Europe and back again, but where did it begin? The authors indicate that phylogenetic methods (like the branched chart above) may be a new way to analyze cultural relationships among folk tales and oral narratives. This article received coverage in ScienceNOW, National Geographic, and Nature.

Thank you to all of our Academic Editors, reviewers, and authors for making these articles a reality. Needless to say, PLOS ONE staff cannot wait to see what lies ahead in 2014!

The post A Year in Review: 2013 PLOS ONE Papers in the Media appeared first on EveryONE.

Fish Beware – A New Species of Parasite is Discovered

Drawing of  Lethacotyle vera.

Drawing of Lethacotyle vera.

The world is full of creepy crawlers; some are harmless bugs while others are blood sucking parasites. Adding to the list of parasites this month is one identified in a recent PLOS ONE article, Lethacotyle vera n. sp, a new species of fish parasite, found in the South Pacific. Lethacotyle vera is part of the class Polyopisthocotylean monogenean, which are tiny (less than 1-cm long), parasitic flatworms that live on fish gills.

For any type of ectoparasite (parasites that live outside their host’s body) staying attached to their host is an important ability. One of the most notable features of Polyopisthocotylea is their multiple sucking clamps that allow them to keep their position on the fish. These clamps are found on the haptor, a body part developed specifically for attaching. Some parasites in this group can have hundreds of clamps as part of their haptor. In fact, Polyopisthocotylea literally translates to ‘many sucker-cups at the rear’. Thank goodness they only like fish!

However, there is one rare species discovered 60 years ago, Lethacotyle fijiensis, that appears to be clamp-less. The only available specimen for study is the one shown in the picture below.

The only available specimen of L. fijiensis

The only available specimen of L. fijiensis.

 

This close up below shows you what L. fijiensis actually looks like. The clamp-less haptor is the oblong protrusion on the very left end.

 

Close up of L. fijiensis

Because only four specimens of L. fijiensis have ever been found, and because having clamps is a major distinguishing feature of monogeneans, many researchers have assumed that L. fijiensis was incorrectly identified as clamp-less, and that these specimens probably lost their clamps through mishandling of the specimens by people.

In an attempt to verify the true nature of L. fijiensis, the authors went in search of additional specimens in the Pacific, where it was originally discovered. While they were unable to find any, they instead unearthed a hereto-undiscovered close relative, which they named Lethacotyle vera (vera is Latin for true, meaning that the genus Lethacotyle, is indeed real).

Haptor and Hooks

As it turns out L. vera is also a monogenean without clamps. The main physical difference between L. vera and L. fjiensis is the length in the male reproductive organ. The authors noted that L. vera has flaps on its haptor that are covered in many ridges, as well as hooks. A drawing of the haptor with its ridges and hooks can be seen in part F in the image to the right.

 

The authors sequenced the DNA from two of the eighteen specimens. The extracted DNA showed that the genetic information in L. vera is unique from all other known monogeneans. Then, in an effort to determine why L. fijiensis and L. vera don’t have the typical clamps of their family, they compared the ratio of clamp-to-body surface area in 120 different monogenean species. They found that members of the monogenean family to which L. vera and L. fijiensis belong, protomicrocotylids, had consistently the smallest clamp-to-body ratio. Additionally, many other species of polyopisthocotylean monogeneans had lateral flaps with ridges on their haptors.

From this observation, the authors concluded that in the family protomicrocotylids, their clamps are in fact slowly disappearing, and that in the specific case of L. fijiensis, the clamps have completely disappeared. The authors suggest that flaps can also hold onto the host, and that this process is assisted by the ridges and hooks along the flaps.

The discovery of a new species is always exciting, and as the case of L. vera shows us, can lead to insights about the larger family of related organisms. Read more about new species at PLOS ONE, such as this orchid or this Indonesian owl.

Citation: Justine J-L, Rahmouni C, Gey D, Schoelinck C, Hoberg EP (2013) The Monogenean Which Lost Its Clamps. PLoS ONE 8(11): e79155. doi:10.1371/journal.pone.0079155

Image 1 Credit: doi:10.1371/journal.pone.0079155.g001

Image 2 Credit: doi:10.1371/journal.pone.0079155.g002

Image 3 Credit: doi:10.1371/journal.pone.0079155.g007

Awkward Silences: Technical Delays Can Diminish Feelings of Unity and Belonging

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Smooth social interaction is fundamental to a sense of togetherness. We’ve all experienced disrupted conversations—some caused by human awkwardness and others by breakdowns in technology. The content of our interactions does influence our connection to each other, but the form and process of communication also play a role.  Technical delays that occur below our conscious detection can still make us feel like we don’t quite click with the person we are trying to communicate with. The authors of a recently published PLOS ONE article, funded by a Google Research Award, investigated how delays introduced into technologically mediated conversations affected participants’ sense of solidarity with each other, defined as unity, belongingness, and shared reality.

For this research, conducted at University of Groningen, The Netherlands, participants in three sets of experiments sat in cubicles with headsets connected to computers (conditions that many of us with desk jobs can relate to) and were asked to talk about holidays for five minutes with an assigned partner. Some conversations were uninterrupted. Others were manipulated by introducing a one-second auditory delay. Some pairs knew about the delay and others did not. Afterward, the conversationalists completed a questionnaire about their sense of unity, belonging, understanding, and agreement with their partners.

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Researchers found that those participants whose conversations were interrupted expressed significantly diminished feelings of unity and belonging. Awareness of technical problems had no apparent effect on perceived solidarity.  Even acquaintances stated that they felt a disconnect, though to a lesser degree, than participants who did not know each other. Despite participants expressing that they felt less unity and belongingness with their partner even when they had the opportunity to attribute it to technical problems, technology did not get a free pass on the delayed signal. Those with an interrupted connection also expressed less satisfaction with the technology. Points may have been lost for both relationships and telecommunications.

In a world where our interactions are increasingly mediated by computers and mobile phones with less than perfect signals, the authors suggest that this research provides insight into how our daily interactions may be affected. The method of communication we choose may influence our personal and business relationships, especially among strangers. The authors also posit that technology meant to improve long distance communication by imitating face-to-face interaction may not measure up to expectations if it is not executed without interruptions or delays. Perhaps this is something to consider during your next awkward phone call or video conference— though your awareness of technology as a possible barrier ultimately may not make a difference in how you perceive the person on the other end of the line.

Citation: Koudenburg N, Postmes T, Gordijn EH (2013) Conversational Flow Promotes Solidarity. PLoS ONE 8(11): e78363. doi:10.1371/journal.pone.0078363

Images: First image by Villemard is in the public domain. Second image is Supplemetary Figure 1 from the article.

PLOS ONE at AGU 2013

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PLOS ONE is excited to participate in the American Geophysical Union’s (AGU) Fall Meeting 2013, held this week in San Francisco’s Moscone Center. Conveniently, Moscone is just down the street from our San Francisco office, so several members of PLOS staff will be in attendance and available to chat with you about the journal. We’re looking forward to meeting both current and potential Academic Editors, reviewers, and of course authors! Please stop by Booth #301 to say hello.

Last week was a very geophysics-oriented one for us, with both the publication of Hansen et al.’s work “Assessing “Dangerous Climate Change”: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature” and with the announcement of our call for papers in a new collection entitled “Responding to Climate Change.” What’s more exciting is that James Hansen will be in attendance at AGU and will be giving a talk today (December 10th) on this topic, in support of taking significant, active measures to reduce fossil fuel emissions.

Last year, at AGU 2012, we were a little bit of an unfamiliar face to many. This year, we hope to continue our conversation with the physical sciences community about our commitment to open access and the publication of sound scientific research in all areas of science and medicine, including geoscience, space science, chemistry, and physics.

After AGU, look out for the PLOS booth again in just a few days at the American Society for Cell Biology!

Image Credit: Detailed view of Arctic Sea Ice in 2007, from NASA Visible Earth.

Winter Service Update

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As we head into winter and as the holiday festivities begin, we wanted to let our authors know in advance that they may experience a slight delay in the peer review process of their manuscript if they submit anytime between now and the end of the year. This is because many of our academic editors and external referees will be out of the office at some point during the holiday season.

Despite many people being on vacation, the work of the journal continues and so we will endeavor to ensure that all manuscripts submitted to PLOS ONE are evaluated as quickly as possible, but please accept our advance apologies for any delays you experience.

In the meantime, we encourage you to visit the following links for information and answers to some of our common questions. For anything not covered here, please contact us at plosone@plos.org and we will respond as quickly as possible.

Image: Emily’s Snowman Cookies by Ralph Daily

I’ll Have What He’s Having: Dogs Eavesdrop on Human Interactions

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In the spirit of Thanksgiving and sharing a warm meal with loved ones, we’d like to take a moment to give some social credit to our loving, faithful, and clever furry friends. Researchers have been investigating the question of whether animals can eavesdrop—or listen in on third-party interactions—for some time, and evidence of potential eavesdropping has been identified in dogs and other mammals, fish, and birds.

Dogs are especially good candidates for studying eavesdropping because they are social animals and have been domesticated, so they are accustomed to interacting with humans day-in and day-out. Most dog owners know how well their dogs can “read” them, and some might argue that their dogs can do this better than other people they know. Researchers have also confirmed that dogs can recognize human emotions, facial expressions, and friendliness versus hostility, the latter even in strangers.

In a more nuanced form of social interaction, dogs have been shown to prefer certain people over others depending on the outcome of third-party interactions. To further investigate how dogs respond to interactions among people, the authors of this recently published PLOS ONE article asked whether dogs can develop a preference for or against givers, or “donors,” in a “begging” interaction between people.

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The study recruited 72 dogs of various breeds and sizes and put them in a testing environment that either resembled a home or a dog care facility. While the dog watched from across the room, two human assistants acted as “donors” (females, pictured above) who offered food to a “beggar” (male, above), and the beggar either reacted positively or negatively to the offered food. The extent of the reaction was controlled to try to determine which social cues the dog was picking up on: gesture + verbal (GV), gesture only (G), or verbal (V) only.

In the GV group positive scenario, the beggar received a yummy corn flake, ate it, and said “So tasty!”; in the negative scenario, the beggar said “So ugly!” gave the corn flake back, and then turned his back. The G and V groups differed in that they isolated the gesture and verbal components, respectively. After the beggar left, the dog was released and had 10 seconds to decide between the donors, who did not signal the dog in any way. Dogs that did not make a choice were removed from the analysis.

As the results below show, dogs were more likely to choose the donor who received a positive reaction; the authors also noted that the dogs tended to watch or gaze at the donor who received a positive reaction longer than the donor who received a negative reaction. However, the authors state that both gesture and verbal cues (the GV group) were required to show a reliable difference among the groups.

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Although these results alone are not conclusive, as it is difficult to control for all the variables affecting these scenarios (e.g., the authors note that dogs chose randomly if the donors switched places), the authors suggest that the dogs may have attributed a “reputation” to the donor based on the beggar’s reaction, where both gesture and verbal cues were required for the dog to make this association.

While not the same as a scientific experiment, it might be fun to “test” your dog in various eavesdropping scenarios, especially in relation to available food* on the Thanksgiving table.

Happy Thanksgiving from PLOS ONE!

Citation: Freidin E, Putrino N, D’Orazio M, Bentosela M (2013) Dogs’ Eavesdropping from People’s Reactions in Third Party Interactions. PLoS ONE 8(11): e79198. doi:10.1371/journal.pone.0079198

Image Credits: Figure 1 by carterse, Figures 2 and 3 from the article

*food safe for pets to eat, of course!

Burning the Candle at Both Ends: Intertidal Ant Species Can Work Night and Day

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If you’ve ever experienced rush hour traffic, you know firsthand that most humans base our schedules roughly around the rise and setting of the Sun, during daylight hours. However, the Australian intertidal ant, Polyrhachis sokolova, must instead schedule its busy day of foraging in the mangrove forest according to the rise and fall of the tide. Low tide can occur day or night, and to function effectively in both the brightest and darkest conditions, these ants possess several useful eye structures—not unlike the pupils in our eyes, or night vision goggles—that help them adjust to different light levels so that they can find food.

AntFaceThere are thousands of ant species that can have a variety of habitats, morphologies (shapes), and navigation methods. Australian intertidal ants use vision to identify landmarks like trees, and celestial cues like the angle of starlight to find their way. Low tide, whenever that may be, is the best time for foraging, so these ants need to see in all light levels without the assistance of flashlights or sunhats. Exactly how they manage to adapt to such a wide range of light conditions was investigated and described in a recent PLOS ONE study.

To learn more, researchers made tiny casts of intertidal ants’ eyes using fingernail polish. They flattened the casts and examined them under a microscope. Ants have compound eyes, meaning that their eyes are made of many tiny facets, or eye units, compared to simple eyes like ours that only have one eye unit each. Researchers counted the number of facets in each compound eye and measured each one’s diameter. The eyes were cast at different times—10am and 10pm—to inspect how the eye structures changed in dark versus light conditions. The light sensitivity of the eyes was calculated based on this morphological data.

journal.pone.0076015.g003Intertidal ants’ compound eyes each have around 596 facets and are similar to the eyes of other ant species specifically adapted to darker conditions. Eyes that “see” in the dark tend to have larger lenses and be extremely sensitive to light to get the most out of the little available light. This night vision adaptation would typically limit an ant’s ability to function in daylight because bright light would overload the photoreceptors in these highly sensitive structures, but the researchers found  other mechanisms that protect these ants’ eyes, restricting the amount of light that can enter—like a pupil—by making the openings that allow light to pass smaller. This mechanism helps the ants adapt their night-vision eyes to bright daylight.  This type of pupil is seen in other nocturnal ants but had not been found previously in ants that forage during the day.

Finally, to assist in navigation, the researchers found yet another structure in the ants’ eyes: special light detectors that act like skylights and help determine direction by sensing the angles of light sources in the sky. Therefore, Australian intertidal ants do not have the very best day or night vision, but they instead sacrifice some of their ability to see well in each condition in order to see “adequately” in both.

Citation: Narendra A, Alkaladi A, Raderschall CA, Robson SKA, Ribi WA (2013) Compound Eye Adaptations for Diurnal and Nocturnal Lifestyle in the Intertidal Ant, Polyrhachis sokolova. PLoS ONE 8(10): e76015. doi:10.1371/journal.pone.0076015

Image Credits: Images are from Figures 1, 2, and 3 from the manuscript.