Jun 21, 2018

Stone tools from ancient mummy reveal how Copper Age mountain people lived

This is a stone tool.
Stone tools found with a 5,300-year-old frozen mummy from Northern Italy reveal how alpine Copper Age communities lived, according to a study published June 20, 2018 in the open-access journal PLOS ONE by Ursula Wierer from the Soprintendenza Archeologia, Florence, Italy, and colleagues.

The Tyrolean Iceman is a mummified body of a 45-year-old man originally discovered with his clothes and personal belongings in a glacier of the Alps mountains, in the South Tyrol region, Italy. Previous research showed that the Iceman lived during the Copper Age, between 3370-3100 BC, and was probably killed by an arrow. In this study, the researchers analyzed the Iceman's chert tools to learn more about his life and the events that led to his tragic death.

The team used high-power microscopes and computed tomography to examine the chert tools in microscopic detail, including a dagger, borer, flake, antler retoucher, and arrowheads. The structure of the tools' chert reveals that the stone was collected from several different outcrops in what is now the Trentino region (Italy), about 70km away from where the Iceman was thought to live. Comparing this ancient toolkit with other Copper Age artefacts revealed stylistic influences from distant alpine cultures. By carefully analyzing the wear traces of the Iceman's chert tools, the authors concluded he was right-handed and probably had recently resharpened and reshaped some of his equipment.

These findings shed light into the Iceman's personal history and support previous evidence suggesting that alpine Copper Age communities maintained long-distance cultural contacts and were well provisioned with chert.

From Science Daily

Fossils show ancient primates had grooming claws as well as nails

Lemurs, lorises and galagoes have nails on most digits and grooming claws on their second toes, as seen on the feet of two greater slow lorises, Nycticebus coucang, in the Florida Museum mammals collection.
Humans and other primates are outliers among mammals for having nails instead of claws. But how, when and why we transitioned from claws to nails has been an evolutionary head-scratcher.

Now, new fossil evidence shows that ancient primates -- including one of the oldest known, Teilhardina brandti -- had specialized grooming claws as well as nails. The findings overturn the prevailing assumption that the earliest primates had nails on all their digits and suggest the transition from claws to nails was more complex than previously thought.

"We had just assumed nails all evolved once from a common ancestor, and in fact, it's much more complicated than that," said Jonathan Bloch, study co-author and Florida Museum of Natural History curator of vertebrate paleontology at the University of Florida.

The findings are scheduled to be published today in the Journal of Human Evolution.

Grooming in mammals is not just about looking good. Thick body hair is a haven for ticks, lice and other parasites -- possible health threats, as well as nuisances. Having a specialized claw for removing pests would be an evolutionary advantage, said Doug Boyer, an associate professor in the department of evolutionary anthropology at Duke University and the study's lead author.

It's one that has been retained in many primates. Lemurs, lorises, galagoes and tarsiers have nails on most of their digits and grooming claws on their second -- and in tarsiers, second and third -- toes.

So, why did the ancestors of monkeys, apes and humans lose their grooming claws? One possible answer: because we have each other.

"The loss of grooming claws is probably a reflection of more complex social networks and increased social grooming," Boyer said. "You're less reliant on yourself."

This could explain why more solitary monkey species, such as titi and owl monkeys, have re-evolved a grooming claw, he said.

Researchers had thought grooming claws likely developed independently several times along the lines that gave rise to living primates. But these fossils suggest grooming claws were hallmark features of the earliest primates, dating back at least 56 million years.

They also come from five different genera of ancient primates that belonged to the omomyoids, the ancestors of monkeys, apes, humans and tarsiers -- not the branch of primates that gave rise to lemurs, lorises and galagoes.

In 2013, Boyer was at the University of California Museum of Paleontology, sifting through sediment collected in Wyoming several decades earlier, when he found several curious primate fossils. They were distal phalanges, the bones at the tips of fingers and toes, from omomyoids. The shape of these bones reveals whether they support a claw or nail. Bones topped with a claw mimic its narrow, tapered structure while bones undergirding a nail are flat and wide. The distal phalanges that Boyer discovered looked like they belonged to animals with grooming claws.

"Prior to this study, no one knew whether omomyoids had grooming claws," Boyer said. "Most recent papers came down on the side of nails."

Meanwhile, Bloch, picking through collections recently recovered from Bighorn Basin, Wyoming, came across what looked like a "strange, narrow nail" bone. But when he compared it to modern primates, "it looked just like a tarsier grooming claw." Smaller than a grain of rice, it matched the proportions of Teilhardina brandti, a mouse-sized, tree-dwelling primate.

Bloch and Boyer had co-authored a 2011 study describing the first fossil evidence of nails in Teilhardina. At the time, they believed the primate had nails on all its digits. Now, fossils were making them reevaluate their assumptions, not only about Teilhardina, but other omomyoids.

On the off-chance that they could add one more ancient primate to the growing list of claw-bearers, the pair drove out to Omomys Quarry, Wyoming, once inhabited by another genus of omomyoid, Omomys.

"We spent a day combing that site, never expecting to find something as tiny and delicate as a grooming claw," Boyer said.

The team picked one right off the surface. They had found grooming claws at three independent sites from omomyoids spanning about 10 million years in the fossil record.

"That was the last nail in the coffin," Boyer said.

Why did primates develop nails at all? The question is a contentious one, but Bloch and Boyer think the transition away from claws could have mirrored changes in primate movement. As we ramped up climbing, leaping and grasping, nails might have proven more practical than claws, which could snag or get in the way.

Grooming claws might seem insignificant, but they can provide crucial insights into ancient primates, many of which are known only from fossil teeth, Bloch said. These tiny claws offer clues about how our earliest ancestors moved through their environment, whether they were social or solitary and what their daily behavior was like.

Read more at Science Daily

How do horses read human emotional cues?

Several horses on a farm visited by Dr. Ayaka Takimoto.
Scientists demonstrated for the first time that horses integrate human facial expressions and voice tones to perceive human emotion, regardless of whether the person is familiar or not.

Recent studies showed the herd-forming animal possesses high communication capabilities, and can read the emotions of their peers through facial expressions and contact calls, or whinnies. Horses have long been used as a working animal and also as a companion animal in sports and leisure, establishing close relationships with humans just like dogs do with people.

Dogs are known to relate human facial expressions and voices to perceive human emotions, but little has been known as to whether horses can do the same.

In the present study to be published in Scientific Reports, Associate Professor Ayaka Takimoto of Hokkaido University, graduate student Kosuke Nakamura of The University of Tokyo, and former Professor Toshikazu Hasegawa of The University of Tokyo, used the expectancy violation method to investigate whether horses cross-modally perceive human emotion by integrating facial expression and voice tone. They also tested whether the familiarity between the horse and the person affected the horse's perception.

The expectancy violation method has been used to study infant cognitive development. Horses were shown a picture of a happy facial expression or an angry facial expression on a screen, and they then heard a pre-recorded human voice -- praising or scolding -- from a speaker behind the screen. Horses received both the congruent condition, in which the emotional values of facial expression and voice tone were matched, and the incongruent condition, in which they were not.

Results of the experiment showed that horses responded to voices 1.6 to 2.0 times faster in the incongruent condition than in the congruent condition regardless of familiarity of the person. In addition, the horses looked to the speaker 1.4 times longer in the incongruent condition than in the congruent condition when the person was familiar. These results suggest that horses integrate human facial expressions and voice tones to perceive human emotions, therefore an expectancy violation occurred when horses heard a human voice whose emotional value was not congruent with the human facial expression.

Read more at Science Daily

The seed that could bring clean water to millions

(left) Unshelled M. oleifera seeds, (middle) shelled seeds, (right) crushed seeds before protein extraction.
According to the United Nations, 2.1 billion people lack access to safely managed drinking water services, the majority of whom live in developing nations.

Carnegie Mellon University's Biomedical Engineering and Chemical Engineering Professors Bob Tilton and Todd Przybycien recently co-authored a paper with Ph.D. students Brittany Nordmark and Toni Bechtel, and alumnus John Riley, further refining a process that could soon help provide clean water to many in water-scarce regions. The process, created by Tilton's former student and co-author Stephanie Velegol, uses sand and plant materials readily available in many developing nations to create a cheap and effective water filtration medium, termed "f-sand."

"F-sand" uses proteins from the Moringa oleifera plant, a tree native to India that grows well in tropical and subtropical climates. The tree is cultivated for food and natural oils, and the seeds are already used for a type of rudimentary water purification. However, this traditional means of purification leaves behind high amounts of dissolved organic carbon (DOC) from the seeds, allowing bacteria to regrow after just 24 hours. This leaves only a short window in which the water is drinkable.

Velegol, who is now a professor of chemical engineering at Penn State University, had the idea to combine this method of water purification with sand filtration methods common in developing areas. By extracting the seed proteins and adsorbing (adhering) them to the surface of silica particles, the principal component of sand, she created f-sand. F-sand both kills microorganisms and reduces turbidity, adhering to particulate and organic matter. These undesirable contaminants and DOC can then be washed out, leaving the water clean for longer, and the f-sand ready for reuse.

While the basic process was proven and effective, there were still many questions surrounding f-sand's creation and use -- questions Tilton and Przybycien resolved to answer.

Would isolating certain proteins from the M. oleifera seeds increase f-sand's effectiveness? Are the fatty acids and oils found in the seeds important to the adsorption process? What effect would water conditions have? What concentration of proteins is necessary to create an effective product?

The answers to these questions could have big implications on the future of f-sand.

Fractionation

The seed of M. oleifera contains at least eight different proteins. Separating these proteins, a process known as fractionation, would introduce another step to the process. Prior to their research, the authors theorized that isolating certain proteins might provide a more efficient finished product.

However, through the course of testing, Tilton and Przybycien found that this was not the case. Fractionating the proteins had little discernible effect on the proteins' ability to adsorb to the silica particles, meaning this step was unnecessary to the f-sand creation process.

The finding that fractionation is unnecessary is particularly advantageous to the resource-scarce scenario in which f-sand is intended to be utilized. Leaving this step out of the process helps cut costs, lower processing requirements, and simplify the overall process.

Fatty Acids

One of the major reasons M. oleifera is cultivated currently is for the fatty acids and oils found in the seeds. These are extracted and sold commercially. Tilton and Przybycien were interested to know if these fatty acids had an effect on the protein adsorption process as well.

They found that much like fractionation, removing the fatty acids had little effect on the ability of the proteins to adsorb. This finding also has beneficial implications for those wishing to implement this process in developing regions. Since the presence or absence of fatty acids in the seeds has little effect on the creation or function of f-sand, people in the region can remove and sell the commercially valuable oil, and still be able to extract the proteins from the remaining seeds for water filtration.

Concentration

Another parameter of the f-sand manufacturing process that Tilton and Przybycien tested was the concentration of seed proteins needed to create an effective product. The necessary concentration has a major impact on the amount of seeds required, which in turn has a direct effect on overall efficiency and cost effectiveness.

The key to achieving the proper concentration is ensuring that there are enough positively charged proteins to overcome the negative charge of the silica particles to which they are attached, creating a net positive charge. This positive charge is crucial to attract the negatively charged organic matter, particulates, and microbes contaminating the water.

This relates to another potential improvement to drinking water treatment investigated by Tilton, Przybycien, and Nordmark in a separate publication. In this project, they used seed proteins to coagulate contaminants in the water prior to f-sand filtration. This also relies on controlling the charge of the contaminants, which coagulate when they are neutralized. Applying too much protein can over-charge the contaminants and inhibit coagulation.

"There's kind of a sweet spot in the middle," says Tilton, "and it lies in the details of how the different proteins in these seed protein mixtures compete with each other for adsorption to the surface, which tended to broaden that sweet spot."

This broad range of concentrations means that not only can water treatment processes be created at relatively low concentrations, thereby conserving materials, but that there is little risk of accidentally causing water contamination by overshooting the concentration. In areas where exact measurements may be difficult to make, this is crucial.

Water Hardness

Water hardness refers to the amount of dissolved minerals in the water. Although labs often use deionized water, in a process meant to be applied across a range of real world environments, researchers have to prepare for both soft and hard water conditions.

Tilton and Przybycien found that proteins were able to adsorb well to the silica particles, and to coagulate suspended contaminants, in both soft and hard water conditions. This means that the process could potentially be viable across a wide array of regions, regardless of water hardness.

Tilton and Przybycien recently published a paper on this research, "Moringa oleifera Seed Protein Adsorption to Silica: Effects of Water Hardness, Fractionation, and Fatty Acid Extraction," in ACS Langmuir.

Overall, the conclusions that Tilton, Przybycien, and their fellow authors were able to reach have major benefits for those in developing countries looking for a cheap and easily accessible form of water purification. Their work puts this novel innovation one step closer to the field, helping to forge the path that may one day see f-sand deployed in communities across the developing world. They've shown that the f-sand manufacturing process displays a high degree of flexibility, as it is able to work at a range of water conditions and protein concentrations without requiring the presence of fatty acids or a need for fractionation.

Read more at Science Daily

Nearly 80 exoplanet candidates identified in record time

NASA’s Kepler Space Telescope orbits the Sun in concert with the Earth, slowly drifting away from Earth.
Scientists at MIT and elsewhere have analyzed data from K2, the follow-up mission to NASA's Kepler Space Telescope, and have discovered a trove of possible exoplanets amid some 50,000 stars.

In a paper that appears online today in The Astronomical Journal, the scientists report the discovery of nearly 80 new planetary candidates, including a particular standout: a likely planet that orbits the star HD 73344, which would be the brightest planet host ever discovered by the K2 mission.

The planet appears to orbit HD 73344 every 15 days, and based on the amount of light that it blocks each time it passes in front of its star, scientists estimate that the planet is about 2.5 times the size of the Earth and 10 times as massive. It is also likely incredibly hot, with a temperature somewhere in the range of 1,200 to 1,300 degrees Celsius, or around 2,000 degrees Fahrenheit -- about the temperature of lava from an erupting volcano.

The planet lies at a relatively close distance of 35 parsecs, or about 114 light years from Earth. Given its proximity and the fact that it orbits a very bright star, scientists believe the planet is an ideal candidate for follow-up studies to determine its atmospheric composition and other characteristics.

"We think it would probably be more like a smaller, hotter version of Uranus or Neptune," says Ian Crossfield, an assistant professor of physics at MIT who co-led the study with graduate student Liang Yu.

The new analysis is also noteworthy for the speed with which it was performed. The researchers were able to use existing tools developed at MIT to rapidly search through graphs of light intensity called "lightcurves" from each of the 50,000 stars that K2 monitored in its two recent observing campaigns. They quickly identified the planetary candidates and released the information to the astronomy community just weeks after the K2 mission made the spacecraft's raw data available. A typical analysis of this kind takes between several months and a year.

Crossfield says such a fast planet-search enables astronomers to follow up with ground-based telescopes much sooner than they otherwise would, giving them a chance to catch a glimpse of planetary candidates before the Earth passes by that particular patch of sky on its way around the sun.

Such speed will also be a necessity when scientists start receiving data from NASA's Transiting Exoplanet Survey Satellite, TESS, which is designed to monitor nearby stars in 30-day swaths and will ultimately cover nearly the entire sky.

"When the TESS data come down, there'll be a few months before all of the stars that TESS looked at for that month 'set' for the year," Crossfield says. "If we get candidates out quickly to the community, everyone can start immediately observing systems discovered by TESS, and doing a lot of great planetary science. So this [analysis] was really a dress rehearsal for TESS."

Speed dips

The team analyzed data from K2's 16th and 17th observing campaigns, known as C16 and C17. During each campaign, K2 observes one patch of the sky for 80 days. The telescope is on an orbit that trails the Earth as it travels around the sun. For most other campaigns, K2 has been in a "rear-facing" orientation, in which the telescope observes those stars that are essentially in its rear-view mirror.

Since the telescope travels behind the Earth, those stars that it observes are typically not observable by scientists until the planet circles back around the sun to that particular patch of sky, nearly a year later. Thus, for rear-facing campaigns, Crossfield says there has been little motivation to analyze K2 data quickly.

The C16 and C17 campaigns, on the other hand, were forward-facing; K2 observed those stars that were in front of the telescope and within Earth's field of view, at least for the next several months. Crossfield, Yu, and their colleagues took this as an opportunity to speed up the usual analysis of K2 data, to give astronomers a chance to quickly observe planetary candidates before the Earth passed them by.

During C16, K2 observed 20,647 stars over 80 days, between Dec. 7, 2017, and Feb. 25, 2018. On Feb. 28, the mission released the data, in the form of pixel-level images, to the astronomy community. Yu and Crossfield immediately began to sift through the data, using algorithms developed at MIT to winnow down the field from 20,000-some stars to 1,000 stars of interest.

The team then worked around the clock, looking through these 1,000 stars by eye for signs of transits, or periodic dips in starlight that could signal a passing planet. In the end, they discovered 30 "highest-quality" planet candidates, whose periodic signatures are especially likely to be caused by transiting planets.

"Our experience with four years of K2 data leads us to believe that most of these are indeed real planets, ready to be confirmed or statistically validated," the researchers write in their paper.

They also identified a similar number of planet candidates in the recent C17 analysis. In addition to these planetary candidates, the group also picked out hundreds of periodic signals that could be signatures of astrophysical phenomena, such as pulsating or rotating stars, and at least one supernova in another galaxy.

Stars in spades

While the nature of a star doesn't typically change over the course of a year, Crossfield says the sooner researchers can follow up on a possible planetary transit, the better chance there is of confirming that a planet actually exists.

"You want to observe [candidates] again relatively soon so you don't lose the transit altogether," Crossfield says. "You might be able to say, 'I know there's a planet around that star, but I'm no longer at all certain when the transits will happen.' That's another motivation for following these things up more quickly."

Since the team released its results, astronomers have validated four of the candidates as definite exoplanets. They have been observing other candidates that the study identified, including the possible planet orbiting HD 73344. Crossfield says the brightness of this star, combined with the speed with which its planetary candidate was identified, can help astronomers quickly zero in on even more specific features of this system.

Read more at Science Daily

Jun 20, 2018

Swedes have been brewing beer since the Iron Age, new evidence confirms

Carbonized germinated grains found at Uppåkra, Sweden.
Archaeologists at Lund University in Sweden have found carbonised germinated grains showing that malt was produced for beer brewing as early as the Iron Age in the Nordic region. The findings made in Uppåkra in southern Sweden indicate a large-scale production of beer, possibly for feasting and trade.

"We found carbonised malt in an area with low-temperature ovens located in a separate part of the settlement. The findings are from the 400-600s, making them one of the earliest evidence of beer brewing in Sweden," says Mikael Larsson, who specialises in archaeobotany, the archaeology of human-plant interactions.

Archaeologists have long known that beer was an important product in ancient societies in many parts of the world. Through legal documents and images, it has been found, for example, that beer was produced in Mesopotamia as early as 4 000 BCE. However, as written sources in the Nordic region are absent prior to the Middle Ages (before ca 1200 CE), knowledge of earlier beer production is dependent on botanical evidence.

"We often find cereal grains on archaeological sites, but very rarely from contexts that testify as to how they were processed. These germinated grains found around a low-temperature oven indicate that they were used to become malt for brewing beer," says Mikael Larsson.

Beer is made in two stages. The first is the malting process, followed by the actual brewing. The process of malting starts by wetting the grain with water, allowing the grain to germinate. During germination, enzymatic activities starts to convert both proteins and starches of the grain into fermentable sugars. Once enough sugar has been formed, the germinated grain is dried in an oven with hot air, arresting the germination process. This is what happened in the oven in Uppåkra.

"Because the investigated oven and carbonised grain was situated in an area on the site with several similar ovens, but absent of remains to indicate a living quarter, it is likely that large-scale production of malt was allocated to a specific area on the settlement, intended for feasting and/or trading," explains Mikael Larsson.

Early traces of malt in connection with beer brewing have only been discovered in two other places in the Nordic region. One is in Denmark from 100 CE and one is in Eketorp on Öland from around 500 CE.

Read more at Science Daily

Beluga whales have sensitive hearing, little age-related loss

Beluga whales have small external ear openings, located a few inches behind each eye. All work conducted under NMFS permit no. 14245.
Scientists published the first hearing tests on a wild population of healthy marine mammals. The tests on beluga whales in Bristol Bay, Alaska, revealed that the whales have sensitive hearing abilities and the number of animals that experienced extensive hearing losses was far less than what scientists had anticipated.

The latter findings contrasted with expectations from previous studies of humans and bottlenose dolphins, which showed more hearing loss as they aged, says Aran Mooney, a biologist at Woods Hole Oceanographic Institution (WHOI) and lead author of two new studies on beluga whales. "But unlike the wild beluga population, the dolphins that were studied lived in a very noisy environment, as most humans do."

At a time when noise in the ocean is increasing from human activities, such as oil and gas exploration and ship traffic, understanding the natural hearing abilities of whales and other endangered marine mammals is crucial to assessing potential noise impacts on animals and to management efforts to mitigate sound-induced hearing loss.

In the two related studies, WHOI researchers and their colleagues measured the hearing sensitivity of 26 wild belugas and then compared the audiograms to acoustic measurements made within their summer habitat in Bristol Bay to study how natural soundscapes-all sounds within their environment-may influence hearing sensitivity. The soundscape also reveals sound clues that the belugas may use to navigate. The first study was published May 8, 2018, in the Journal of Experimental Biology. Results from the soundscape study were published June 20, 2018, in the Journal of Ecoacoustics. "In the first paper, we characterized the beluga population's hearing ability, which had not been done before in a healthy, wild population," says Mooney. "And in the second paper, we put that into context to see how they might use acoustic differences in their habitat and how their hearing is influenced by the natural ambient noise in their environment."

How do you test a beluga whale's hearing? Researchers applied the same screening method that doctors use to test the hearing of newborn babies who can't yet vocally respond to whether or not they hear sounds: automated auditory brainstem response.

A suction cup sensor is gently placed on the whales' head, just behind the blowhole, and another is placed on the back for reference. A series of quiet tones are played, and the sensors help measure the brain's response to the sounds from the surface of the skin.

"It's fairly straightforward," Mooney says. "We just had to make a portable system that we could bring out into an extreme environment in order to perform the hearing tests."

The test itself goes quickly, taking only about five minutes to measure each frequency. The most challenging part, says Mooney, is catching the participants.

For that, the researchers relied on the expertise of Alaskan Natives who hunt belugas. From small aluminum boats, the team would approach an individual adult whale-no calves were included in the study-in shallow waters of the bay. Taking care not to stress or injure the whale, they would catch it in a soft net. Marine mammal handlers, including teams from Georgia Aquarium, Shedd Aquarium, and Mystic Aquarium, would then get in the water to help secure the animal's tail with a rope before moving it to a belly band (like a small stretcher) in the water next to a soft inflatable boat where the hearing tests took place.

"The belugas stayed relatively relaxed during the tests, seemingly employing a resting behavior that they may use to avoid killer whales," Mooney explains. "When a killer whale is hunting them, belugas will often move to very shallow water and quietly stay there until they can safely return to deeper waters."

In addition to the auditory testing, the researchers also performed a physical exam to assess the overall health, sex, and estimated age of each animal and obtained skin, breath, and blood samples to collect information on the whales' hormone levels, microbiome bacteria, and other health-related data. The assessments were part of a beluga population health assessment program coordinated by the NOAA Fisheries Alaska Fisheries Science Center, the Alaska Department of Fish and Game, and Alaska SeaLife Center. Satellite transmitters were attached to some of the whales before release to study the whales' movements.

The hearing tests revealed little hearing loss in the seemingly older members of the population, which could be because the estuary where the belugas reside is fairly quiet compared to more urban areas.

"Because there haven't been any other studies of the hearing of wild marine mammals, we compared the results to previous studies of captive dolphins in San Diego and in Russia," Mooney says. "The dolphins showed clear hearing loss as they aged, but the San Diego group lives in a very noisy environment, as most humans do."

Mooney and colleagues also compared the wild belugas tests to those of belugas living in human care facilities. Both groups heard similarly well, and the authors suggest that it is likely due to the quiet environments in which they live.

"Sensitive hearing within a quiet soundscape could allow belugas to detect predators, navigate, and communicate with their young via low-amplitude signals," Mooney explains. "This hearing sensitivity could be compromised in a noisier environment. It also suggests management concerns for animals that inhabit noisy areas, where they may already be showing greater proportions of hearing loss."

Read more at Science Daily

Birds have time-honored traditions, too

By faithfully copying the most popular songs, swamp sparrows create time-honored song traditions that can be just as long-lasting as human traditions, researchers report.
What makes human cultural traditions unique? One common answer is that we are better copycats than other species, which allows us to pass our habits and ways of life down through the generations without losing or forgetting them.

But a new study of birdsong finds that swamp sparrows are good impersonators too. And by faithfully copying the most popular songs, these birds create time-honored song traditions that can be just as long-lasting as human traditions, researchers say.

In fact, swamp sparrow song traditions often last hundreds of years, with some songs going back further than that.

"According to the models, some of the songs could go back as far as the Vikings," said first author Robert Lachlan, a lecturer in psychology at Queen Mary University of London.

The results appear June 20 in the journal Nature Communications.

The slow trill of the swamp sparrow can be heard in marshes and wetlands across eastern and central North America.

A grey-breasted bird with brownish wings, the swamp sparrow attracts mates and defends his territory with songs built from two- to five-note snippets, repeated over and over.

Researchers observed decades ago that swamp sparrows living in different places sing slightly different songs. Birds in New York might tend to sing in three-note repeats while their counterparts in Minnesota favor four, or combine the same basic notes in a different order.

Young birds learn the local customs in the first weeks of life by imitating their elders.

But while similar cultural traditions -- shared behaviors that are learned from others and passed from one generation to the next -- have been observed in all sorts of animals, the thinking has been that human traditions are more likely to last.

To test the idea, the researchers recorded the songs of 615 male swamp sparrows in six populations across New York, Pennsylvania, Michigan and Wisconsin.

Using computer software to measure and analyze each song, the team identified 160 song types across the species' range.

Each male has only a handful of songs in his repertoire. To figure out how young birds choose which songs to learn, the researchers developed a mathematical model that simulates how each new song type spreads within groups over time.

Each run of the model represented 5,000 years, at the end of which the researchers measured the song types in each group of birds.

With their model they also compared various song-learning strategies. For example, young birds might prefer to imitate one particular adult, such as their dad or a male with a good territory. Alternately, they might pick certain songs because they find them inherently more attractive, regardless of who sings them.

When they looked at how well their simulations fit the real data, the researchers found that young birds don't just randomly pick any song they hear and imitate that.

Instead, they copy the crowd, mimicking the most popular songs more often than one would expect by chance. Unique or rare songs that go against the mainstream rarely get a peep.

"It's called a 'conformist bias'," Lachlan said.

What's more, swamp sparrows learn their songs with amazing fidelity, correctly matching the songs they attempt to imitate more than 98 percent of the time.

There's an evolutionary benefit to fitting in, the researchers say. Previous studies show that females prefer typical tunes over outliers.

The end result, their models show, is that local song customs in swamp sparrows are far from fleeting trends, quickly going out of fashion and never to be uttered again.

Instead, they are handed down from one swamp sparrow generation to the next, with song types often persisting for 500 years or more, the researchers estimate.

The study also shows that creating traditions that pass the test of time doesn't necessarily require exceptional smarts.

The birds need not keep track of how many birds are singing each song to figure out how to fit in, the analyses show. They memorize a variety of songs early in life, from multiple older birds, but once they reach adulthood they only keep the songs they repeatedly hear others singing.

"The longstanding stable traditions so characteristic of human behavior have often been ascribed to the high cognitive abilities of humans and our ancestors," said study co-author Stephen Nowicki, professor of biology at Duke. "But what we're showing is that a relatively simple set of rules that these songbirds are capable of following can achieve equally lasting traditions."

"We're not saying that birds have anything akin to human culture," Lachlan said. "It shows that just those two ingredients -- a preference for popular songs, and the ability to copy them -- can get you quite a long way to having stable complex culture."

Read more at Science Daily

Dogs understand what's written all over your face

Dogs can understand emotional expressions of humans.
Dogs are capable of understanding the emotions behind an expression on a human face. For example, if a dog turns its head to the left, it could be picking up that someone is angry, fearful or happy. If there is a look of surprise on a person's face, dogs tend to turn their head to the right. The heart rates of dogs also go up when they see someone who is having a bad day, say Marcello Siniscalchi, Serenella d'Ingeo and Angelo Quaranta of the University of Bari Aldo Moro in Italy. The study in Springer's journal Learning & Behavior is the latest to reveal just how connected dogs are with people. The research also provides evidence that dogs use different parts of their brains to process human emotions.

By living in close contact with humans, dogs have developed specific skills that enable them to interact and communicate efficiently with people. Recent studies have shown that the canine brain can pick up on emotional cues contained in a person's voice, body odour and posture, and read their faces.

In this study, the authors watched what happened when they presented photographs of the same two adults' faces (a man and a woman) to 26 feeding dogs. The images were placed strategically to the sides of the animals' line of sight and the photos showed a human face expressing one of the six basic human emotions: anger, fear, happiness, sadness, surprise, disgust or being neutral.

The dogs showed greater response and cardiac activity when shown photographs that expressed arousing emotional states such as anger, fear and happiness. They also took longer to resume feeding after seeing these images. The dogs' increased heart rate indicated that in these cases they experienced higher levels of stress.

In addition, dogs tended to turn their heads to the left when they saw human faces expressing anger, fear or happiness. The reverse happened when the faces looked surprised, possibly because dogs view it as a non-threatening, relaxed expression. These findings therefore support the existence of an asymmetrical emotional modulation of dogs' brains to process basic human emotions.

"Clearly arousing, negative emotions seem to be processed by the right hemisphere of a dog's brain, and more positive emotions by the left side," says Siniscalchi.

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Jun 19, 2018

Clovis site: Montana burial site answers questions about early humans

The burial mound at the Anzick site.
Scientists have shown that at the Anzick site in Montana -- the only known Clovis burial site -- the skeletal remains of a young child and the antler and stone artifacts found there were buried at the same time, raising new questions about the early inhabitants of North America, says a Texas A&M University professor involved in the research.

Michael Waters, director of the Center for the Study of the First Americans and colleagues from the University of Oxford and Stafford Research of Colorado have had their work published in the current issue of PNAS (Proceedings of the National Academy of Sciences).

The main focus of the team's research centered on properly dating the Anzick site which is named after the family who own the land. The site was discovered in 1968 by construction workers, who found the human remains and stone tools which include Clovis spear points and antler tools. It is the only known Clovis burial site and is associated with Clovis stone and antler artifacts.

"One thing that has always been a problem has been the accurate dating of the human remains from the site," explains Waters.

"The human remains yielded a younger age that was not in agreement with the ages from the antler artifacts which dated older than the human remains. If the human remains and Clovis artifacts were contemporaneous, they should be the same age." To resolve the issue, the team used a process called Specific Amino Acid Radiocarbon Dating, which allows a specific amino acid, in this case hydroxyproline, to be isolated from the human bones.

"This amino acid could only have come from the human skeleton and could not be contaminated," Waters adds.

"The other previous ages suffered from some sort of contamination. With the new method, we got very accurate and secure ages for the human remains based on dating hydroxyproline. As a test, we also redated the antler artifacts using this technique."

The results prove that both the human remains and antler Clovis artifacts are of the same date.

"The human remains and Clovis artifacts can now be confidently shown to be the same age and date between 12,725 to 12,900 years ago," Waters notes. "This is right in the middle to the end of the Clovis time period which ranges from 13,000 to 12,700 years ago.

"This is important because we have resolved the dating issues at the site. Some researchers had argued that the human remains were not Clovis and were younger than the Clovis artifacts, based on the earlier radiocarbon dates. We have shown that they are the same age and confirmed that the Anzick site represents a Clovis burial."

While not the earliest inhabitants of the Americas, Clovis is the first widespread prehistoric culture that first appeared 13,000 years ago. Clovis originated south of the large Ice Sheets that covered Canada at that time and are the direct descendants of the earliest people who arrived in the New World around 15,000 years ago. Clovis people fashioned their stone spear tips with grooved, or fluted, bases. They invented the "Clovis point,' a spear-shaped weapon made of stone that is found in Texas and other portions of the United States and northern Mexico, and these weapons were used to hunt animals.

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