Category Archives: Animals

Your cat is using your voice to constantly track your location inside the house

Previous studies suggested that cats aren’t really good at tracking objects they can’t see — but a new study shows they’re actually good at mapping your indoor position.

Image credits: Kristina Yadykina.

Cats have been with us for a very long time. However, there’s still much we don’t know about them, especially because cats are notoriously difficult to study. Compared to other pets like dogs, there have been fewer studies on cats. Saho Takagi, a researcher at Azabu University in Japan, wanted to shed new light on the minds of our adorable companions.

“My research motivation is simply to better understand cats’ mysterious minds. Cats are very familiar animals, but their minds are still shrouded in mystery compared to those of dogs because it is difficult to conduct experiments on cats.  Cats don’t adjust to humans, they sleep when they want to, and they don’t like strange places or people,” Takagi told ZME Science.

In a new study, Takagi and colleagues analyzed whether cats create mental maps of their owners inside the house. Cats have excellent hearing abilities, Takagi explains, and this ability was used to reveal tendencies inside cats’ minds.

Having a mental representation of non-visible things is linked to something called “object permanence” — the ability to know that objects or creatures continue to exist even when they are not seen. Humans develop this ability early on, and several animals have been shown to have it as well (including chimps, bonobos, bears, and jays).

In order to show if cats have the same ability, researchers devised an experimental setup in which they played recordings of their owners’ voices for cats from different parts of the house to simulate a “teleportation” scenario. This type of experiment has also been done with vervet monkeys.

Three experiments were carried out. In the first one, the owner’s voice was played back sequentially from two separate locations. In the second experiment, the voice of a familiar cat was played, and in the last one, a nonspecific sound was played as a control, to see if the cats were simply reacting to any sound, or just to that of their owner.

Image credits: Takagi et al (2021).

The team found that the cat vocalizations used in the second experiment weren’t suitable for evaluating cats’ abilities for several reasons, but results showed that cats were surprised when their owners appeared to “teleport” (ie when their voice was played from a different room than the one they were previously in). These suggest that cats keep a mental representation of their owner

“We revealed that cats have socio-spatial cognition. Specifically, when they heard their owners’ voices, they were found to be mentally tracking the location of their invisible owners. Thinking mentally about what we cannot see is a cognitive ability that forms the basis for more complex thinking skills. This study suggests that cats acquire a variety of information from sounds and “think” about them,” Takagi says.

We asked Takagi whether playing the owners’ voice through a speaker has disadvantages for recognition, but apparently, this has already been addressed in previous studies and should not pose a problem for this type of study.

“It is true that the audible range of humans is different from that of cats. In addition, since we used human speakers in this experiment, the sound may be different from what cats usually hear. However, previous studies have shown that cats can correctly identify people from their sounds even when using human speakers. This result cannot be explained without assuming that the cats are able to identify their owners’ voices.”

Ultimately, the results can only be explained if cats mentally map their owners. In other words, your cat is constantly tracking you in the house, showing an important cognitive ability.

The study has been published in PLoS.

Why did birds survive the asteroid impact that wiped out the dinosaurs?

The actual fossil (top) and the digital brain reconstruction of Ichthyornis, an ancient bird that lived during the Cretaceous. Credit: Torres et al, Science Advances.

You might have heard that birds are essentially living dinosaurs, just like humans are mammals. Dinosaurs actually represented a huge group spanning countless species of reptiles that held the top carnivore and top herbivore spots. But out of all these different dinosaur groups, it was only birds that survived the disastrous asteroid impact from 65 million years ago, which killed 80% of all life on Earth.

A new study tried to demystify what helped birds to survive when all other dinosaurs failed. According to the findings reported in the journal Science Advances, many ancient species of birds also perished in the wake of the damning asteroid impact off the coast of Mexico’s Yucatan Peninsula. However, the scientists found that the lineages of birds that did endure must have had larger forebrains. Turns out, you want to pick brains over brawn during an apocalypse.

Who you calling bird brain

The fossil record hasn’t been kind to bird bones, which are more often than not too delicate and fragile to endure over millions of years. What few bird fossils paleontologists know about though are enough to firmly place birds in the same group as dinosaurs, having evolved from a group of meat-eating dinosaurs known as theropods. It’s the same group that the famous Tyrannosaurus rex belonged to, although birds evolved from much smaller theropods.

After a long reign spanning more than 140 million years, the age of the dinosaurs came to an abrupt end. Only puny birds remained, which rapidly expanded and filled vacant ecological roles. Some 150 million years ago, the oldest birds looked like feathered dinosaurs and had sharp teeth. Over time birds lost their teeth and evolved beaks.

Not very much is known though about the brains of early birds since their braincases (the interior of the skull) rarely fossilized. This is why scientists are very excited by a partial skull belonging to Ichthyornis, an ancient bird that lived about 85 million years ago in Kansas.

In a new study, researchers at the University of Texas at Austin have completed an X-ray CT scan of the fossil, digitally reconstructing the Cretaceous bird’s facial skeleton and braincase in 3D without having to invasively alter the fossils in any way.

The analysis showed that Ichthyornis‘ brain was surprisingly similar to that of other dinosaurs, in contrast to living birds that have disproportionately large forebrains relative to the rest of their brain regions. However, the ancient bird’s brain did have an ace up its sleeve: a wulst. This brain structure was previously observed only in bird species that appeared after the mass extinction event caused by the asteroid impact. The wulst is thought to have played a major role in visual and sensory processing that could have played a critical role in flight.

Ancient birds had brains more closely resembling those of dinosaurs rather than the birds of modern birds. The ancestors of modern birds likely later developed a larger cerebrum, helping them survive the mass extinction. Credit: Science Advances.

Finding a wulst in the brain of a Cretaceous dinosaur shows that ancient birds had brains that were more complex than previously thought. And since Ichthyornis is very closely related to modern birds but still lacked the massive forebrain we’re used to seeing in living birds, the researchers inferred that “those big brains evolved in the ancestor of living birds,” Chris Torres, a National Science Foundation postdoctoral research fellow in the Heritage College of Osteopathic Medicine at Ohio University, told Live Science. Torres was a graduate student at the University of Texas when he participated in the fossils’ CT scanning.

Ichthyornis exhibited a wulst and segmented palate, previously proposed to have arisen within extant birds. The origin of Aves (extant birds) is marked by larger, reshaped brains indicating selection for relatively large telencephala and eyes but not by uniquely small body size. Sensory system differences, potentially linked to these shifts, may help explain avian survivorship relative to other dinosaurs,” the authors wrote in their study.

The combination of bigger brains, small size, their ability to eat a wider palate of foods, and their ability to fly ultimately may have helped birds survive the last mass extinction. Today, there are at least 11,000 bird species. 

Fish like to rub on sharks, strangely enough, and use them as exfoliating soaps

In a somewhat surprising twist, new research finds that fish actually seek out sharks and… rub against them.

Shark. Original public domain image from Wikimedia Commons

What’s the most dangerous animal you’ve ever patted? For most of us, it’s probably a particularly feisty dog. Fish throughout the seven seas, however, put us to shame, it would seem. According to a collaborative research effort led by the University of Miami (UM) Shark Research and Conservation Program at the Rosenstiel School of Marine and Atmospheric Science, fish seek out sharks and chafe against them.

Such behavior is frequent and widespread, the team explains, which suggests that shark chafing could play an important ecological role for sea dwellers.

Dancing with the devil

“While chafing has been well documented between fish and inanimate objects, such as sand or rocky substrate, this shark-chafing phenomenon appears to be the only scenario in nature where prey actively seek out and rub up against a predator,” said UM Rosenstiel School graduate student Lacey Williams, who co-led the study with fellow graduate student Alexandra Anstett.

It’s not the first time we’ve seen fish engage in such behavior, but the study is our first reliable source of data on just how widespread and pervasive this behavior actually is.

The team pooled together underwater photos, videos, and drone footage for the research. In this body of data, they found 47 instances of fish engaging in chafing behavior with sharks. These chafing events took place in 13 different locations around the world and lasted anywhere from eight seconds to five minutes. Multiple species were involved, both in regards to fish and to the sharks being chafed-upon. Twelve different species of finfish were seen chafing against eight species of shark, including the infamous great white sharks. At least one interaction involved silky sharks (Carcharhinus falciformis) chafing on the head of another shark — a whale shark, in this particular case. The single largest group of fish that the team recorded during a single chafing event numbered in excess of 100 individuals.

Another dataset — aerial drone surveys of Plettenberg Bay, South Africa — revealed a further 25 cases of shark-chafing, involving leerfish (garrick, Lichia amia) and a passing white shark.

All of this is fine and well, but obviously leaves a big question unanswered: why would fish intentionally seek out and rub against their predators?

“While we don’t exactly know why it’s happening, we have a few theories. Shark skin is covered in small tooth-like scales called dermal denticles, which provide a rough sandpaper surface for the chafing fish,” said UM Rosenstiel School research associate professor and study co-author Neil Hammerschlag. “We suspect that chafing against shark skin might play a vital role in the removal of parasites or other skin irritants, thus improving fish health and fitness.”

In other words, fish might use sharks for the same purpose we use fancy soaps: exfoliation. Rubbing against sharks likely helps fish remove bacteria and parasites from their skins. Sharkskin is covered in tooth-like scales known as denticles, V-shaped structures that reduce turbulence and drag, allowing them to swim faster and with less effort. Presumably, these same denticles make them very good exfoliators, as well.

The paper “Sharks as exfoliators: widespread chafing between marine organisms suggests an unexplored ecological role” has been published in the journal Ecology.

Some worker ants can rewire their brains to become queens — and researchers are figuring out how

Animal brains are plastic, they can change their structure and function. But some ants take this to a pretty extreme level. Under some conditions, they can switch from a worker to a queen-like ant — and the key behind this change is governed by a single molecule.

Inside the underground nest of H. saltator. Photo by Bert Hölldobler.

In ant colonies, the queen’s main role is to lay eggs, while the workers, well, work. A colony of ants can contain more than one queen, depending on the species, but some species do something even more intriguing: they have ants that can lay eggs like queens. These “fake” queens are called gamergates.

In most ant species, workers are sterile, but in the others, gamergates reproduce in addition to queens. In some species, “normal” queens have been completely replaced by gamergates. But what makes a worker become an egg-laying gamergate, and how does this process take place exactly? To figure this out, a team of researchers studied ants from a species called Harpegnathos saltator (or the Indian jumping ant).

“Gamergates are workers that have taken over the social role of queens”, Robert Bonasio, of the University of Pennsylvania Perelman School of Medicine told ZME Science. It’s a “switch” between social roles, but also a physiological change. Although there are no physical changes observable from the outside, a lot of things do change on the inside. “For example, their ovaries become enlarged. Also, their brains are rewired to some extent,” explains Bonasio.

Bonasio and colleagues wanted to understand how turning certain genes “on” or “off” affect brain function and behavior. To do this, researchers had to devise a way to isolate ant neurons from ant brains and maintain them alive in plastic dishes and artificial culture medium. It’s a routine practice for mouse and rat research, but it’s much more difficult for insects. However, Dr. Janko Gospocic, the study’s first author came up with an important innovation.

“For a while, Janko was trying to make a culture medium by making extracts from ant pupae (i.e. freezing and homogenizing them) and then adding it to the cultured neurons,” Bonasio explains. “This proved to be impossible to sustain because of the sheer number of pupae required. Then he had a eureka moment. He thought that because ant and bees are relatively close cousins, it might work to substitute honeybee pupae in the recipe. Lo and behold, it worked. So the secret to healthy ant brains seems to be frozen honeybee smoothies!”.

Armed with this method, the team could study the underlying molecular mechanisms that cause this switch. They identified two hormones (juvenile hormone and ecdysone) that are present at different levels in the bodies of workers and gamergates. These hormones seem to produce distinct patterns of gene activation in the brains of the two castes. This was surprising, Bonasio says, because researchers were expecting to find one or more dedicated transcription factors (a protein that turns genes on or off) in workers and then a different set of transcription factors only active in gamergates. “It was interesting to find one that could play both roles,” Bonasio told ZME Science.

However, the surprise came when researchers found that both hormones influenced the cells by activating a single protein called Kr-h1. However, researchers caution that this isn’t the only switch responsible for turning a worker into a queen or vice versa.

“This is not to say that Kr-h1 is the only protein that regulates caste identity. These things typically are complex and Kr-h1 is likely one of many switches that control the social transition,” Bonasio says.

It’s hard to draw direct lines from invertebrates to humans, Bonasio says, but researchers can build on this study to understand brain plasticity and the mechanisms that govern it in different types of animals.

“Plasticity is of course very important for any brain, including ours, and loss of plasticity has negative consequences. It would be very exciting if we could find that proteins and hormones with similarities to those we found in ants are also at work in the mammalian brain, and we will certainly pursue this line of investigation in the future,” Bonasio concludes.

Journal Reference: Janko Gospocic, Karl M. Glastad, Lihong Sheng, Emily J. Shields, Shelley L. Berger, Roberto Bonasio. Kr-h1 maintains distinct caste-specific neurotranscriptomes in response to socially regulated hormones. Cell, 2021; DOI: 10.1016/j.cell.2021.10.006

Dogs that tilt their heads aren’t just adorable: they’re super smart

Credit: Cooper Photo.

If your pet canine tilts its head when hearing its name, congratulations: that dog may be a genius. I’m not making this up. A new study found that the seemingly perplexing head tilt isn’t a sign of confusion as we may be led to believe. Instead, it’s actually a sign that the dog is processing the meaning of words like oral commands and making connections. Dogs that tilted their heads most often were also the best performing at successfully responding to commands, some of them quite complex.

Dr. Andrea Sommese, the lead author of the study and a researcher at the Eötvös Loránd University in Budapest, was inspired to conduct this research after being involved in the Genius Dog Challenge, a live broadcasted series that features very talented dogs. During the broadcasts, some of the gifted dogs were very good at learning the names of a wide variety of toys. When the name of the toys was uttered by their owners, the dogs often tilted their heads.

Head tilting, as well as tail wagging, nostril sniffing, and pointing one of the ears, is a type of asymmetrical movement typical for canines that shows the animal prefers to use one of its body parts over others when interacting with the environment.

“Tilting the head is yet another asymmetrical movement in dogs, but it had never been studied. We investigated the frequency and direction of this behavior in response to a specific human verbal vocalization: when the owner asks the dog to bring a toy by saying its name. We did so after realizing that it often happened when the dogs were listening to their owners,” Sommese said in a statement.

Sommese and colleagues carefully analyzed all the broadcasts from the Genius Dog Challenge, which involved 40 dogs of various breeds. The owners were asked to teach their pets the names of two toys and test how well they were at the task once a month for three months. The test was simple: the dog had to fetch the correct toy when its name was uttered from an adjacent room.

Most of the dogs, however, failed at this task. Even two toy names proved too much. However, all seven border collies aced the test flawlessly. Collies are regarded as one of the most intelligent dog breeds in the world, and this experiment validated their cognitive prowess with the Hungarian researchers calling them “gifted word learners”.

Throughout the experiment, the scientists recorded the presence or absence of head-tilts when the owners would say the name of the toy. The typical dogs rarely tilted their heads while the gifted dogs more often than not tilted their heads upon hearing the fetch command.

In fact, the difference was striking. The gifted learners tilted their heads 43% of the time while the other 33 dogs did so just 2% of the time. That doesn’t sound like a coincidence, and the researchers seem to concur.

“It seems that there is a relationship between success in retrieving a named toy and frequent head tilts upon hearing its name. That is why we suggest an association between head-tilting and processing relevant and meaningful stimuli” clarifies Shany Dror, co-author of the study. 

However, these findings don’t necessarily mean your pooch is intellectually challenged just because they’re missing the head tilt.

“It is important to notice that this study only investigated head tilts during a very specific dog-owner communicative interaction: when the owner asks the dog to fetch a named toy. Hence, it is important to refrain from thinking that only Gifted Word Learner dogs tilt their heads in other situations not tested in this study” adds Andrea Temesi, another researcher working on the project. 

The researchers continued to work just with the collies in a series of other, more challenging experiments. Due to COVID-19 restrictions, they collected the data remotely with the help of the owners, who cooperated and installed two cameras connected to a livestream software that monitored both the dogs’ and their owners’ behaviors.

In the new experiment, the collies were challenged with learning the names of 12 new toys and had only a week to do so. They were then tested by fetching the correct toy out of the bunch one month and then two months later.

The collies performed wonderfully, retrieving the correct toy 86% of the time. One of the collies, named Whisky, was particularly gifted bringing back the correct toy 54 out of 59 times. One month later, the retrieval rate dropped to 61%. Two months later it dropped to 57%, which isn’t bad at all considering the dogs lost their training.

Credit: Helge O. Svela.

Once again, the dogs tilted their heads when they heard the name of the toys called out by the owners. Every dog tended to tilt their heads to just one side or the other fairly consistently. For the researchers, this is seen as yet another piece of evidence that dogs engage in this behavior when they’re concentrating on a cognitive task.

Learning and remembering object names is not exclusive to collies, though. After the study ended, the researchers discovered that canines of other breeds are also adept at learning new words. These include a German shepherd, a Pekingese, a mini Australian shepherd, and a few dogs of mixed breeds.

“What we tested is a very specific skill: the capacity to learn object names,” Dror told NBC News.

“All dogs, however, are good at understanding their humans,” she said. “They do so by being able to read even the very subtle movements we make and learning in what context we do what. They are fine tuned to all our activities and can learn a lot by observing us.”

The findings appeared in the journal Animal Cognition.

Whales eat much more than we assumed, and it has huge ecological implications

Baleen whales eat a lot more food than previously assumed: three times as much, to be exact, according to new research. The findings are not meant to shame these animals into going on a diet. Rather, they shed light on the key ecological role whales play in the ocean.

Image via Pixabay.

The sheer size and appetite of whales make them important players in the ocean. In particular, they serve as key drivers of nutrient recycling in the ocean. They consume vast amounts of food, releasing important nutrients back into the water following digestion. A new paper refines our understanding of just how much food whales as a group can consume, and take a look at the ecological implications of the decline in whale numbers since the onset of the 20th century.

Big eaters

“While it may just seem like a fun trivia fact, knowing how much whales eat is an important aspect of ecosystem function and management,” Matthew Scott Savoca, a Postdoctoral Research Fellow at Stanford University and corresponding author of the paper, told ZME Science. “If we want to protect whales and make sure they are thriving in modern oceans, then knowing how much food they need to survive and reproduce is critical.”

“There are implicit benefits of having whales on the planet — isn’t it cool to think that we live at a time when we’re alongside the largest animal in the history of life on Earth? Beyond that, whales have direct value as carbon sinks (e.g., sequestering carbon in their bodies and exporting it to the deep sea when they die and sink – which we did not discuss in this study). In addition, whale watching is a multi-billion dollar per year global business that is expanding as whales are recovering.”

Previous estimates of just how much whales eat were built upon data obtained from metabolic models or direct analysis of the stomach contents of whale carcasses. Such data can give us a ballpark figure but, according to the new paper, they are quite inaccurate.

Savoca and his colleagues directly measured the feeding rates of 321 baleen whales across seven species in the Atlantic, Pacific, and Southern oceans. They tracked foraging behavior and estimated prey consumption by tracking the whales using GPS tags. Location data was then combined with sonar measurements of prey density, of the quantity of prey consumed per feeding, and current estimates of how much each species typically eats per feeding event.

Overall, the results suggest that we’ve underestimated how much food baleen whales ingest by a factor of three. On average, these animals consume between 5% and 30% of their body weight per day, depending on species, across all the investigated regions. In total, blue, fin, and humpback whales in the California Current Ecosystem consume over two million tonnes of krill every year per species.

The study also puts into perspective just how massive an impact whaling and other stressors have placed on whales and, by extension, on the ecosystems they inhabit. Prior to the 20th century, the team estimates, whales in the Southern Ocean were consuming around 430 million tonnes of Antarctic krill per year. This figure is twice the total estimated biomass of Antarctic krill today.

Whales, the paper explains, serve an important ecological role as nutrient recyclers, tying into that last tidbit of information. Prior to the 20th century, before whales were hunted in meaningful numbers, these animals consumed a massive amount of biomass, releasing much of the nutrients in their food back into the ocean as waste. This, in turn, allowed for much greater productivity in the ocean (as they made large quantities of nutrients freely-available for krill and other phytoplankton to consume).

“In brief, if whales eat more than we thought, then they also recycle more nutrients (i.e., poop) than we thought. If that is the case then limiting nutrients may have been used more effectively and efficiently in a system that had many more whales,” Savoca said for ZME Science. “It’s not that these whales add more iron (or other nutrients) to the system, they just [move] it from within the bodies of their prey, to in the seawater itself where it could, in theory, fertilize phytoplankton — the base of all open ocean food webs.”

To put things into perspective, the authors estimate that today, baleen whales in the Southern Ocean recycle around 1,200 tons of iron per year; prior to the 20th century, this figure was likely around 12,000 tons of iron per year. In essence, whaling has led to a 90% decrease in the amount of essential nutrients whales can recycle in their ecosystems.

I asked Savoca whether there is any overlap between the decline in baleen whale populations and the detrimental effects of industrial fishing on today’s ocean ecosystems. Should we expect trouble ahead as we’re removing key nutrient recyclers from one side of the equation, and taking more fish out of the sea on the other?

“You are hitting on a major issue,” he admitted. “We have noticed that oceans have become less productive after removing millions of large whales in the 19th and 20th centuries. The same is true of ongoing industrial fishing. The collapse of predatory fish communities have the same detrimental impacts on marine communities as the wholesale decimation of the whales did.”

“I am not against fishing, but we have to do so as sustainably as possible if we want to maintain essential ocean productivity into the future.”

Whales and their extended family — cetaceans — have been experiencing immense pressures ever since the onset of industrial-scale whaling in the early 20th century. Commercial whaling only slowed down in the 1970s, which is a very, very short time ago from an ecological perspective. This has allowed whales and other cetaceans some much-needed respite, but they are still struggling. Over half of all known cetacean species today are inching towards extinction, 13 of which are listed as “Near Threatened”, “Vulnerable”, “Endangered”, or “Critically Endangered” on the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species. Besides the lingering effects of whaling, this family is still struggling under the combined effects of (chemical and noise) pollution, loss of habitat, loss of prey, climate change, and direct collisions with ships.

Research such as this study and many others before it can raise an alarm that not all is well with the whales. But actually doing something about it hinges on us and governments the world over taking the initiative to protect them. Understanding just how important whales are for the health of our oceans and, through that, for our own well-being and prosperity definitely goes a long way towards spurring us into action.

But Savoca’s conclusion to our email discussion left an impression on me. There is great beauty in natural ecosystems that we’re destroying, oftentimes unaware. Beyond the practical implications of conserving whale species, we have a chance to conserve these for our children and all future generations.

“I remember one day in Monterey Bay when we were surrounded by blue whales (likely over a dozen), each about twice the size of the boat we were on. I will also never forget the sound and scale of the ice in Antarctica,” Savoca wrote for ZME Science.

“My life’s work is devoted to making sure people and animals have these (and ideally ever better) ecosystems of awe and plenty well into the future.”

The paper “Baleen whale prey consumption based on high-resolution foraging measurements” has been published in the journal Nature.

Cities are getting quieter: birdsong declining across the Western world

North America and Europe are becoming quieter — as far as birdsong is concerned, according to a new paper.

Image via Pixabay.

A declining trend in bird communities is making the developed world a quieter and less varied place in regards to birdsong, according to new research. While this might not sound like a pressing concern on the face of it, the findings do point to greater ecological issues brewing in the background. Songbirds perform important services in natural environments and their decline could impact the health of our immediate surroundings.

At the same time, for those living in densely urbanized environments, birdsong can be a very powerful element helping us maintain a connection to nature. Its loss could thus have important implications for public health and our overall well-being.

Songless

“The results suggest that one of the fundamental pathways through which humans engage with nature is in chronic decline, with potentially widespread implications for human health and well-being,” reads the study’s abstract.

For the study, the authors collected bird counts via annual survey data and recordings of birdsong taken over the past 25 years at various sites across North America and Europe. Data from citizen science monitoring programs across more than 200,000 sites in 22 cities in Europe, the USA, and Canada was also used.

Starting from this dataset, the team matched all recorded vocalizations to the relevant bird species in order to better understand exactly which birds inhabit which cities across the investigated area. The recordings were also used to produce a ‘composite soundscape’ for each year at each site.

All in all, this showed that the total amount of birdsong and its diversity have been steadily declining across all sites. In other words, the soundscapes most of us in the USA, Europe, or Canada experience have been getting quieter and less varied over time. This suggests that bird species are experiencing an ongoing decline both in numbers and variation across the investigated area.

The first conclusion to be drawn from these results is that, if we want to prevent further deterioration of the soundscapes we’re exposed to, we need to start conservation efforts for the birds that inhabit our cities and beyond. According to the authors, that’s definitely something we should want to do: natural soundscapes are one of the few remaining ways that city inhabitants get to connect with nature. Such experiences have a direct and beneficial effect on our well-being. The loss of soundscapes or degradation of their richness can thus have a negative effect on the well-being and quality of life for whole communities at the same time.

With half of the world now living in cities, it would be in our best interest to heed warnings like those offered by this study.

The paper “Bird population declines and species turnover are changing the acoustic properties of spring soundscapes” has been published in the journal Nature.

Baby seals can modulate the pitch of their voice, much like humans do

Credit: John O’ Connor.

In the 1980s, one of the biggest attractions at the New England Aquarium was Hoover the Talking Seal. The name says it all, as Hoover was famous for parroting human speech. The female seal was rescued as a pup by a man from Maine who took Hoover home before moving to the aquarium. During this time, Hoover remarkably learned how to imitate some of his owner’s vocal antics, including the Maine accent.

You can clearly hear the seal saying “Hoover get over here! Come on, come on!” in this 1984 recording.

Vocal learning — the ability to acquire vocalization through learning — is very rare in the animal kingdom. However, scientists are very much interested in this trait as it may reveal the evolutionary path that took our ancestors from blabbering primates to the highly articulated beings we are today, capable of conveying speech, singing, and a wide ranging vocal repertoire.

Besides humans, this ability is often restricted to birds, which are, evolutionarily-speaking, as far away from us as dinosaurs are. This is why Hoover’s story is so important since seals seem to be one of the rare examples of vocal control and plasticity in mammals. But is this quality present across the species or was Hoover just some oddball?

This inquiry inspired Andrea Ravignani from the Max Planck Institute for Psycholinguistics to conduct a new study that investigated the vocalization abilities of seals. Ravignani and colleagues studied eight harbor seal pups no older than three weeks that were held in captivity at a rehabilitation center in the Netherlands before being released back into the wild.

Over the course of several days, the pups were exposed to audio recordings of noises from the nearby Wadden Sea. These recordings were not chosen by accident. Co-author Laura Torres Borda of the University of Paris 13 went there with a microphone to record the natural noises of the sea because that’s what seal pups are used to in their natural habitat.

“The main challenge was to design the experiment in a way which would be meaningful to better understand the origins of human speech,” Ravignani said.

The recordings were played back at three volumes, varying from almost silence to 65 decibels (equivalent to the noise made by a fast car at 25 feet away), but with a similar tone to that of the seal pups’ calls.

Humans and animals alike raise their voices when there’s noise in the environment so they’re heard and understood better. This is known as the Lombard effect, and one seal clearly demonstrated this phenomenon, producing louder calls when the audio levels were higher. But that’s not all they did.

“If baby seals acted as most animals, we would just expect them to increase the intensity of their voices as noise increased. However, what seals did was lower the pitch of their voices to escape the frequency range of noise, something that only animals with good control of their larynx (including humans but potentially excluding most mammals) can do. This shows vocal plasticity in seal pups from an early age, suggesting that seals may be one of the very few mammals which, like humans when singing or speaking a tonal language, can flexibly modulate the pitch of their voices,” Ravignani told ZME Science.

The fact that seals can modulate their vocalizations spontaneously and without training is striking. Even chimps, our closest living relatives, cannot do this, which makes the origin of speech perhaps even more mysterious. Humans are the only mammals that we know of that have a direct neural connection between the cortex and the larynx (the organ at the top of the neck that is responsible for the tone of your voice). Perhaps seals share this neural connection as well, which is what scientists intend to find out.

“In general, this work is part of my larger research agenda aimed at establishing seals as prime animal model species to better understand the origins and evolution of human speech and music. While at first, they may seem an unusual model, they offer untapped potential for comparative research, being more closely related to us than the much-studied songbirds and parrots, while spontaneously showing more music-like and speech-like behaviors than say apes and monkeys,” Ravignani said.

Just last week, researchers from the same Max Planck Institute for Psycholinguistics found that a type of lemur from Madagascar, known as the indri, has songs that exhibit a kind of rhythm only previously seen in humans. Together with seal vocalizations, these findings suggest that various building blocks for human speech may be found across different animal species. It’s just that we’ve somehow been lucky enough to put them all together.

“By finding another mammal who can modulate the pitch of its voice, we can start building an evolutionary tree of building blocks of speech, and show that some of these are not in fact uniquely human,” Ravignani said.

The findings appeared in the journal Philosophical Transactions of the Royal Society B Biological Sciences.

Honeybees also use social distancing to protect themselves from pathogens

A new study found that honeybees, just like humans, spread themselves out in the hive when exposed to a common parasite — and this can help them withstand the outbreak.

Image credits: Boba Jaglicic.

When the COVID-19 pandemic first struck, the world became familiar with the words “social distancing“. While the term is somewhat unfortunate (physical distancing is probably better), it sent a clear message: staying farther away from one another can help stop the spread of this virus.

This distancing approach has been reported several times in very different types of species, from baboons that stay clear of individuals with gastrointestinal infections to ants infected with a pathogen that relegate themselves to the outskirts of the anthill. Vampire bats, mandrills, and guppies also do it. Now, this type of behavior has been reported in honeybees for the first time.

“For several years, we have been researching the behavioral defenses used by honeybees to fight parasites and pathogens. We believe that this line of research can provide useful insights to improve the health status of honeybees,” study author Alberto Satta told ZME Science. Satta works at the Dipartimento di Agraria, University of Sassari, Italy.

Bees are social creatures and they spend a lot of time huddled close to each other inside the hive. They also have complex social structures that require them to divide up responsibilities. Previous research has suggested that bees can modify their social network to limit the dispersal of a pathogen, and researchers from the University of Sassari, Italy, wanted to see if they also practice social distancing.

The researchers analyzed how honeybees changed their parasite when exposed to the ectoparasite mite Varroa destructor — one of the most common and devastating parasites bees can get.

Honeybee colonies are essentially divided into two main compartments: the inner one, inhabited by the queen, brood, and nurses, and the outer one, occupied by foragers. This distribution protects the inner circle from exposure to intruders or parasites, and there is limited interaction between the queen and the foragers that routinely go out of the hive and are more exposed — which is why they stay on the periphery.

This distribution becomes even more pronounced when bees are exposed to parasites. When a colony was exposed to a parasite, the outer circle moved even closer to the periphery, while the inner circle moved even closer to the middle.

“Our study shows that honeybees can modify their social organization in the presence of a parasite suggesting a strategy implemented to mitigate the effects of parasitosis,” Satta explained in an email.

Lead author Dr. Michelina Pusceddu, from the same university, said that this is a somewhat surprising but very efficient adaptation.

“Their ability to adapt their social structure and reduce contact between individuals in response to a disease threat allows them to maximize the benefits of social interactions where possible, and to minimize the risk of infectious disease when needed.

Developing this type of behavior takes a lot of time and is shaped by evolution, Satta adds.

“Social behaviors have evolved in animals as they increase reproductive success throughout life. In the case of honeybees and other social insects, the pattern of interactions among colony members across space and time, has evolved under the need to ensure efficient functioning, that selects dense and interconnected societies, and the exposure to parasite pressure that favors mechanisms that limit interactions between individuals to reduce the risk of disease spread. The trade-off between these two factors shapes the structure of the social organization.”

Unfortunately for honeybees, they don’t have access to the same defense mechanisms as we do — there’s no face mask or vaccine for bees. However, bees could be making their own medicine to protect themselves. Specifically, researchers are investigating the use of natural substances (propolis) with antimicrobial and anti-parasitic properties as a means to counteract the Varroa destructor mite.

We hypothesized that bees can engage in self-medication against this parasite by using the propolis they produce in the hive. Recently, we have acquired evidence that this substance induces beneficial effects on parasitized bees, prolonging their life span, and that it has negative effects on the fitness of the mite. A further paper on these subjects will be published shortly,” Satta concludes.

The study was published in Science Advances.

Fossil Friday: the story of how tusks evolved from teeth

What, exactly, makes a tusk a tusk? And how did they come to be? New research by U.S. paleontologists sheds light on both of these questions.

Left side of the skull of a dicynodont Dolichuranus fossil used in the study. The tusk is visible at the lower left. Image credits: Ken Angielczyk.

Multiple animal species today have tusks. From elephants to walruses, however, one thing they all have in common is that they’re mammals. This wasn’t always the case, new research reveals. The history of tusks, according to a team of paleontologists at Harvard University, the Field Museum, the University of Washington, and Idaho State University started with an ancient relative of mammals that lived before the age of the dinosaurs.

Those relatives were dicynodont (meaning “two canine teeth), a species that shared some of the characteristics of mammals but also reptiles — including sporting a turtle-like beak.

Tooth or tusk?

“For this paper, we had to define a tusk, because it’s a surprisingly ambiguous term,” said lead author Megan Whitney, a postdoctoral researcher at Harvard University and a UW doctoral alum, in a press release. “Enamel-coated teeth are a different evolutionary strategy than dentine-coated tusks. It’s a trade-off.”

For this study, the team defined tusks as being teeth not covered in enamel (i.e. they’re entirely made of dentine), that extend out past an animal’s mouth, and keep growing throughout the individual’s lifetime. Using this definition, the authors set out to determine the evolutionary history of such appendages. They worked with thin slices cut out from the teeth of several fossil species in order to determine when tusks first appeared. They investigated these using micro-CT scans, to determine how the teeth were attached to the skulls of the animals, and to check for signs of continuous growth around their roots.

Dicynodonts lived from 270 to 201 million years ago, roughly, so they’re quite ancient animals. As a group, they were very diverse, ranging in size from a rat to a modern elephant. They got their name from the two distinctive teeth in their upper jaws, teeth which were the focus of this study.

According to the findings, some dicynodont teeth were indeed tusks. One important finding is that there wasn’t a clear-cut transition between the two. The team analyzed 19 different dicynodont specimens comprising 10 species, finding that tusks evolved independently several times in this extinct clade. Another important hint that we’re looking at the first evolution of tusks was that the earlier dicynodont species only showed teeth, whereas tusks started making an appearance among the later species to arise in this clade.

The enamel layer on this Diictodon caniform (the colorful ring on the cross-section) makes it resemble teeth more than tusks. Image credits Megan Whitney.

“We were able to show that the first tusks belonged to animals that came before modern mammals, called dicynodonts,” said co-author Ken Angielczyk, a curator at the Field Museum in Chicago. “Despite being extremely weird animals, there are some things about dicynodonts — like the evolution of tusks — that inform us about the mammals around us today.”

The authors further report on some adaptations dicynodonts had to go through to enable the evolution of true tusks. These include flexible ligaments connecting the tusks to their jaws, and a reduced overall rate of tooth replacement. The roots of their tusks were hollow, as well, to allow for fresh dentine to be continuously added over time.

Apart from the findings of this study, the team’s classification of what exactly constitutes a tusk and how they’re different from regular teeth is more broadly applicable to other species. In particular, it gives us insight into the different tasks these structures are meant to serve.

The enamel layer on the surface of our teeth is harder than dentine, making it more resilient to wear and tear. But it’s also much harder to heal damaged enamel than it is to heal dentine. Its presence also prevents teeth from growing continuously, as tusks do. Animals with tusks use them for fighting or rooting through the ground, so they’re much more exposed to damage than teeth. A complete enamel covering would be impractical in this situation, as it would present a liability. Since tusks regrow, damaging or losing a tusk isn’t a death sentence. If they had the same structure as teeth, however, they couldn’t be replaced, and any damage would constitute a direct and significant threat to an individual’s survival.

An example of a true tusk in the dicynodont Lystrosaurus, with a hollow pulp cavity in its root where fresh dentine would have been created. Image credits Megan Whitney.

“Tusks have evolved a number of times, which makes you wonder how — and why? We now have good data on the anatomical changes that needed to happen for dicynodonts to evolve tusks,” said co-author Christian Sidor, a UW professor of biology and a curator at the UW’s Burke Museum of Natural History & Culture. “For other groups, like warthogs or walruses, the jury is still out.”

Most of the dicynodont fossils analyzed in this study were unearthed in Tanzania and Zambia. They’re currently stored in a range of museums in the U.S., and are scheduled to be returned to the National Museum of Tanzania and the Livingstone Museum in Zambia after the conclusion of the research project.

The study “The evolution of the synapsid tusk: insights from dicynodont therapsid tusk histology” has been published in the journal Proceedings of the Royal Society B.

Illegal wildlife trade is much more damaging than we think

Species are targeted around the globe by illegal and unsustainable wildlife trade, leading to biodiversity loss and extinction. So far, nothing new — but the effects of trade on targeted species are actually the tip of the iceberg, with repercussions that affect ecosystems and society in more ways than we thought, a new study warns.

“Illegal or unsustainable wildlife trade is growing at a global level, pervading our daily lives, and affecting our well-being. It threatens targeted and non-targeted species, promotes the spread of invasive species, the loss of ecosystem services, the spread of diseases across geographic areas and taxa, and disrupts local to global economies,” the researchers wrote.

Image credit: Flickr / Hari K Patibanda.

Implications of trade

The main consequence of trade on species is population depletion, the researchers explain. About 60% of traded birds, mammals, and reptiles show a decline in abundance — they’re being exploited unsustainably. The rarer a species becomes, the higher its price often becomes, creating an increased incentive for wildlife trading.

This comes at a huge cost for the species. FOr instance, increasing market value for fish has had devastating effects on some populations, especially those relying on spawning aggregations, leading to loss of healthy populations. The legal and illegal shark finning has led to a decline in shark species that were previously abundant, while the totoaba (Totoaba macdonaldi) is extensively fished for its swim bladder, considered a delicacy in China.

Bycatch, incidental capture of non-target species, accounts for 80% of marine catches, either dumped or sold illegally. Fishing can have a negative effect on diverse species from mammals to jellyfish. For example, the vaquita, (Phocoena sinus), has seen a decline of 98.6% of its population between 2011 and 2019 due to bycatch in gillnets intended for the totoaba. 

Plants are also not spared — about 15,000 species frequently used and traded as medicinal as now threatened with extinction.

With trade, comes a set of incidental effects on other species within impacted ecosystems, the researchers wrote. Overharvesting of wildlife can disrupt ecosystem structure and species composition, functioning, and services, such as pollination. In marine fisheries, for example, bottom trawling affects species composition, most non-targeted. This means that exploiting one species can have cascading effects across the ecosystem.

“Wildlife trade can also impact the area where traded species are introduced. Invasive species cost up to an estimated US$162.7 billion per year,” the researchers wrote in the paper. “Wildlife trade-facilitated invasions include snakes introduced in Florida, trout species around the globe, and pine trees in many austral countries.”

Not only does illegal trade have ecological consequences, but it’s also negative for societies as it weakens the rule of law. People engage in wildlife crime for many reasons, from profit and sports to social and cultural reasons. Despite the impacts, some governments still see illegal trade as just a conservation problem, and not as a truly criminal activity. 

Meanwhile, some local communities rely at least in part on wildlife trade for subsistence, either as a food source or for income. In China, for example, wildlife farming is valued at US$8 billion and helps to alleviate poverty. Hunting is also a significant food source in many countries. Nevertheless, wildlife trade as an economic activity is still unreliable, the researchers argued. 

Global legal trade generated annual revenue of US$2.9 to US$4.4 trillion from 1997 to 2016. Meanwhile, the revenue estimates for illegal wildlife trade widely vary from US$4 to US$23 billion up to US$48 to US$216 billion if illegal logging and fishing are included. Governments lose up to US$12 billion annually in potential revenues from illegal wildlife trade. 

The researchers highlighted a set of approaches and tools available to curb the illegal trade, including setting up bans, protected areas, and quotas as well as creating. awareness and education programs. Adam Toomes from the University of Adelaide, a study co-author, called for policy and enforcement that considers the livelihoods and communities that depend on trade. 

“Trade regulations that do not take this into consideration could increase vulnerability and poverty in certain areas that depend on it for food and income,” Toomes said. “With large differences in legislation, cultural drivers of trade and availability of species, there is no one-size fits all strategy. Each unique context warrants a variety of disciplines and actors dedicated to ensuring trade occurs sustainably.”

The study was published in the journal Biological Conservation. 

Great White sharks may mistake humans for seals, explaining attacks

Shark attacks are exceedingly rare when you consider the sheer number of beachgoers that cross paths with these apex predators. Every year, there are no more than a couple dozen unprovoked shark attacks with an annual average of just four unprovoked fatalities. While every death is a tragedy, it’s worth bearing in mind that three times more people are killed by vending machines and about 30 times more are killed by falling coconuts than sharks.

What’s more, on the very rare occasion that sharks attack people, it may all be due to a case of mistaken identity. According to researchers from Australia, sharks can’t see very well, so they may not be able to distinguish swimmers at the water’s surface from their natural prey. In other words, sometimes humans just happen to look like their usual food.

Mistaken identity

This insight was gained after researchers looked at various silhouettes from the shark’s point of view. They recorded and compared video footage of swimmers, people paddling surfboards, and seals as a shark would see them from right below the water, with sunlight in the background.

“Surfers are the highest-risk group for fatal shark bites, especially by juvenile white sharks,” says lead author Dr. Laura Ryan, a post-doctoral researcher in animal sensory systems at Macquarie University’s Neurobiology Lab.

In order to truly put themselves in the sharks’ fins, the researchers employed their knowledge of the great whites’ retinal structure and brain visual systems to estimate their visual acuity. The focus was on the retina of great white juveniles, which are responsible for the majority of attacks on humans. These young sharks tend to have poorer vision than adults and are also more likely to venture inside habitats frequented by humans.

The footage was fed into modeling programs to simulate the way a paddling human or swimming seal might look through the eyes of a shark. “I didn’t realize being a scientist would involve quite so much coding,” Ryan said, which reminds us that modern science is becoming increasingly interdisciplinary and coding has become a must-have skill in any researchers’ toolkit, regardless of their field.

The analysis suggests that sharks, which are believed to be color blind, are ill-equipped to tell apart the silhouette shapes of humans or their motion cues from those of seals. As the sharks grow larger, their retinas also improve. Experience may also help adults better tell apart seals from humans, learning what’s good or bad to eat as they age, the researchers claim in their study published in the journal Royal Society Interface.

“We found that surfers, swimmers and pinnipeds (seals and sea-lions) on the surface of the ocean will look the same to a white shark looking up from below, because these sharks can’t see fine details or colors,” Ryan said.

It’s not sharks’ fault we look like food

These findings confirm a long-standing theory that great whites and other sharks responsible for rare attacks on humans do not actively seek us as prey.

Unfortunately for sharks, they have a bad rep due to their fierce appearance and skewed portrayals in popular media (i.e. Jaws films). Meanwhile, humans kill millions of sharks every year for their fins, cartilage, and oil. And our fear of sharks has also led to the widespread installation of shark nets and drumlines, which further threaten sharks, as well as other marine life. Great whites are now classed as endangered.

Credit: Pixabay.

How a unique facial muscle makes those ‘puppy dog eyes’ irresistible to humans

Credit: Pixabay.

Credit: Pixabay.

When a dog needs something from its human, it needs only to raise its eyebrows. Faced with those big “puppy dog eyes”, the human has little choice but to yield. This canine trait and the power it has in human-dog dynamics is, of course, no accident. According to a new study, dogs have evolved muscles around the eyes that allow them to be more expressive; muscles which wolves, dogs’ closest living relatives, lack.

Researchers at Howard University compared the facial anatomies of six domestic dogs and four gray wolves, along with behavioral changes in nine wolves and 27 shelter dogs. The researchers discovered that all the dogs had a muscle that pulls the lateral corner of the eyelid toward the ears when contracted. This very thin muscle, called the levator anguli oculi medialis, doesn’t exist in wolves, which can only mean that it appeared as a byproduct of canine domestication. It happened relatively fast too, over tens of thousands of years.

“We show that, in only 33,000 y, domestication transformed the facial muscle anatomy of dogs specifically for facial communication with humans. Based on dissections of dog and wolf heads, we show that the levator anguli oculi medialis, a muscle responsible for raising the inner eyebrow intensely, is uniformly present in dogs but not in wolves,” the authors wrote in the journal PNAS.

In order to study how dogs use their extra eye muscle, the researchers exposed the participating canines to humans for a couple of minutes. Compared to wolves, the dogs raised their inner eyebrows more frequently and with greater intensity than wolves.

Red highlights the anatomical differences in ocular musculature between the two species. Credit: PNAS.

Red highlights the anatomical differences in ocular musculature between the two species. Credit: PNAS.

The extra muscle allows dogs to be more expressive, and the researchers believe that it appeared as a result of human preference for traits that facilitate eye contact between dogs and humans. In time, dogs that were more emotionally expressive were selected by humans and bred more often than less expressive dogs.

“We know that humans favor dogs that show paedomorphic (infant-like) anatomical features like a large forehead, large eyes, and so on; in studies asking people to select pictures presenting dog (or cat) faces, people prefer the faces that present paedomorphic features over others,” the authors said.

Video: eye muscle intensity in wolves. 

Video: eye muscle intensity in shelter dog. 

Studies have shown that when a dog makes “puppy dog eyes”, humans are more likely to desire to look after them. Shelter dogs who widen their eyes and raise their eyebrows more often are also more likely to be adopted compared to dogs that are less expressive. In other words, we’ve manipulated dogs to the point that they evolved features to our liking. But, the tables have since turned. It is now dogs who manipulate us instead, with their irresistible adorable eyes.

Critically endangered primate sings with rhythm, much like humans

Credit: Filippo Carugati.

A cute, long-limbed lemur native to the rainforest of Madagascar is recognized as one of the few ‘singing’ primates in the world. Their lovely songs or terrible roars — depending on whom you ask — play important roles in the myths and legends of the Malagasy people. But their status may be even grander.

According to a new study, the Indri indri lemurs are not only capable of hitting notes, their songs also exhibit rhythm. This would make them part of a select musical club in the animal kingdom, mostly composed, until now, of songbirds and humans.

This primate’s got rhythm — all the more reason to cherish it

Many great composers have often described music as ‘having a conversation’. Indeed, what we commonly refer to as bird and whale “songs” are actually communication systems, which leads us to language. Humans are the only primates capable of both acquired vocalization (speech) and musicality, which begs the question of how these traits evolved and how interconnected they are.

Biologists have often turned to our closest living primate relatives for clues. The natural communication of apes may hold clues about language origins, especially because apes frequently gesture with limbs and hands, a mode of communication thought to have been the starting point of human language evolution.

However, musicality is much more mysterious. Let’s just say other apes aren’t that interested in tunes, which is all the more intriguing since music seems to have been an integral part of the human experience since prehistoric times. The oldest musical instrument is a flute carved from cave bear bones by Neanderthals some 50,000 years ago.

This is why the indri, a black-and-white primate about the size of a dog, is so fascinating. In 2016, researchers found that indris co-sing certain parts of their song with other group members, effectively forming a choir.

Now, researchers at the University of Turin and the Max Planck Institute for Psycholinguistics have gone a step further, showing the primates possess categorical rhythm. This type of rhythm refers to intervals between sounds that have exactly the same duration (1:1 rhythm) or doubled duration (1:2 rhythm). Even when sung at different tempos, the categorical rhythm is what allows songs to be easily recognizable.

“Despite its preponderance in our lives, the existence of music is biologically puzzling, as the selective advantage of musicality in humans is highly debated. We know that human musical behaviors exhibit a few ‘rhythmic universals’, and the presence of categorical rhythms is one of them. Since indris’ songs are composed of notes that are organized in phrases, we wanted to understand if they would share the same categorical rhythms that are typical of human music. We indeed found that indris’ songs possess the same categorical rhythms that can be found in the intro of “we will rock you”, by the famous band Queen!” first author Chiara de Gregorio told ZME Science.

Credit: Filippo Carugati.

These findings are the result of twelve years worth of painstaking fieldwork in the rainforest of Madagascar. During this time, the researchers recorded songs from twenty indri groups, comprising 39 individuals, in their natural habitat.

“Indris live all their life up in the canopy of Madagascar’s rainforest, jumping from tree to tree up and down the hills. So, for many years, we have followed them in the humid forest in every weather condition! Some days you find yourself totally soaked, with leeches on your face, slippering down a hill as the ground is covered in mud. And it’s not unusual to find yourself stuck in some big holes created by trees’ roots!” de Gregorio recounted.

But all the hard work eventually paid off. Eventually, de Gregorio and colleagues had enough data that showed the indri songs had rhythmic categories (1:1 and 1:2), as well as the ritardando rhythm (slowed down rhythm typical of some ethnic music). Although male and female songs had different tempos and pitches, their rhythm was the same. Previously, the only non-human animals which exhibited these rhythms were songbirds.

“Rhythm is not something necessarily related to music: it can be considered as the intervals between certain phenomena. We have a circadian rhythm, for example, and hour heart has a particular beat. But when we take “notes” into account, then we can refer to musical rhythm. Indris are among the few species of singing primates, that are primates that communicate with songs. Like birds’ songs, primates’ songs too may have musical features, but we have demonstrated that indris’ songs not only are composed of notes that are organized in phrases but also that they possess categorical rhythms, a musical universal considered typical of human music. Further research will investigate if other singing primates may share this rhythmic feature with humans,” de Gregorio told ZME Science.

It’s not clear why the indris possess this universal rhythm and whether other primates share this ability. But considering humans and indris last shared a common ancestor some 77 million years ago, the researchers speculate that the ability must have evolved independently. Both species likely found that rhythm helps them produce and process songs easier.

There are only a couple hundred of these musical lemurs left in the wild. Their extraordinary abilities provide all the more reasons to protect them, especially from their biggest threats: hunting and habitat loss. There are no indris in captivity because they can only survive in the wild.

“Our team is not focused only on scientific research but also works very hard for indris’ conservation. We have a long history of collaboration with GERP, a Malagasy association that manages our field site, to enhance habitat protection, biodiversity conservation, capacity building, and improving living conditions of people inhabiting villages around the forest. We really think that scientific research and conservation are the two sides of the same coin,” de Gregorio said.

The findings were reported in the journal Current Biology.

Elephants are evolving to lose their tusks due to poaching pressure

Tusks are usually a big plus for elephants, as they can use them to dig for water, strip bark for food, and joust with other elephants. But those big incisors can also be a liability amid intense ivory poaching. Now, researchers have found that elephants in Mozambique have evolved towards tusklessness in an area affected by poachers. 

Image credit: Flickr / Juraj

Mozambique went through a civil war from the late 1970s to the early 1990s, with both sides of the conflict targeting elephants for ivory to finance their war efforts. As a result, elephant population dropped more than 90% in what’s now the country’s Gorongosa National Park, going from 2,000 animals when the conflict started to about 250. 

Many of those who survived shared one key characteristic: over 30% of the females were naturally tuskless, meaning they couldn’t develop tusks, while before the war only 18% lacked tusks. Genes are behind whether elephants inherit tusks from their parents. So after the war the tuskless surviving females passed their genes with surprising results. 

“Our study shows how a sudden pulse of civil unrest can cause abrupt and persistent evolutionary shifts in long-lived animals even amid extreme population decline. In Gorongosa, recovery of both elephant abundance and ancestral tusk morphology may be crucial for ecosystem restoration,” the researchers wrote in the journal Science. 

An elephant’s evolution

Researchers from Princeton University worked with colleagues in Mozambique to further understand how ivory trade had tipped the scales of natural selection. They observed over 800 elephants in the Gorongosa national park over several years and created a catalogue of mothers and offspring by collecting blood samples from them. 

As tuskless elephants were female, the team decided to focus on the X chromosome. While males have an X and Y chromosome, females have two X. They also believed that the relevant gene was dominant (a female needs only one altered gene to be tuskless) and when passed to male embryos it could alter their development phase. 

After sequencing the genomes, the researchers identified a dominant gene that may explain the tusklessness, called AMELX. The gene is passed from mothers to offspring on the X chromosome — remarkably, humans have it too. In people, the gene disruption causes brittle teeth in females. But in human males a disrupted gene usually means death. 

For the researchers, this could also be true of African elephants. If a male gets a disrupted AMELX gene, he likely dies. But the mutated gene leads just to tusklessness in a female elephant. Not having tusks might not seem like a critical issue, but this could actually have a snowball effect on the whole ecosystem of the African elephants.

If an elephant doesn’t have tusks, it means that their behavior changes. They don’t push for trees anymore because they can’t strip their bark, for example. This affects other animals too. Once elephants push over tees, this opens new space for other grassland plants, which creates habitats to other species. A decline in tusked elephants alters that process. 

Ultimately, while this may allow elephants to survive the poaching crisis, it could have long-term cascading effects for the entire ecosystem.

“A population-wide increase in tusklessness may have downstream impacts such as reduced bioturbation, shifts in plant species composition, reduced spatial heterogeneity, and increased tree cover—any of which could affect myriad other ecosystem properties. Elsewhere, evolution in species that perform key ecological functions has exerted potent effects,” the researchers wrote

The study was published in the journal Science. 

Not this time: climate change, not humans, wiped out wooly mammoths

Credit:Daniel Eskridge.

Human activity is responsible for an alarming decline in insects, vertebrates, plants, and just about almost any living thing you can think of. Extinction rates are up to 1,000 times greater than during pre-human times, which is why scientists refer to this rapid loss of biodiversity as the “sixth mass extinction”, alongside other mass extinctions owed to dinosaur-killing asteroids, massive planet-wide volcanic explosions, and catastrophic sea-level rise.

Given this ignoble track record, it’s not that surprising that whenever a species was found to have gone extinct around the same time people were also around, the finger was quickly pointed towards us as the dastardly culprits. Such has been the narrative, for instance, surrounding the extinction of the iconic Pleistocene megafauna, with the wooly mammoth’s sudden disappearance often serving as a prime example of humans’ wicked ways since prehistoric times.

After all, there is ample evidence that humans hunted mammoths, with butchered mammoth bones found in various caves known to be occupied by prehistoric hunter-gatherers. Some groups even used the sturdy mammoth bones to construct peculiar, occult-like circular structures, some made from the remains of dozens of individuals.

But studies from the last decade or so, supported by various climatological and genetic evidence, have painted a different picture, suggesting that mammoths may have gone extinct regardless of whether or not humans ever existed. A new study, perhaps the most comprehensive of its kind, absolves humans, concluding that rapid climate change owing to the end of the last Ice Age doomed the mammoths with no chance of appeal.

Whilst the last mammoths survived up until 4,000 years ago on the remote Wrangel Island in the Arctic Ocean, the vast majority of mammoths living in the rest of the world were wiped out around 10,000 years ago.

The mammoth decline was fast, on a geological time frame, starting around 12,000 years ago when glaciers that covered vast ranges of the Northern Hemisphere melted. That’s no coincidence, according to the findings of decade-long research led by Professor Eske Willerslev, a Fellow of St John’s College, University of Cambridge, and director of The Lundbeck Foundation GeoGenetics Centre at the University of Copenhagen.

Wilerslev and colleagues analyzed the DNA of biological samples collected over a period of 20 years from over 200 sites across the Arctic region where mammoth remains were found. The samples span the last 50,000 years and included plant and animal remains, including urine, feces, and skin cells. The same technique had been previously used to detect and track COVID-19 cases indirectly from the sewage of human populations.

This massive dataset of environmental DNA was compared with genetic information from 1,500 modern plant genomes that were sequenced by the international team.

This analysis showed that as the glaciers melted, the onset of a much warmer and wetter climate rapidly displaced the brush vegetation that mammoths used to graze on, replacing it with trees and wetland plants. This change occurred much faster than the mammoth herds could adapt to, thereby ending an evolutionary legacy spanning four million years.

 “Scientists have argued for 100 years about why mammoths went extinct. Humans have been blamed because the animals had survived for millions of years without climate change killing them off before, but when they lived alongside humans they didn’t last long and we were accused of hunting them to death,” Professor Willerslev said.

“We have finally been able to prove was that it was not just the climate changing that was the problem, but the speed of it that was the final nail in the coffin—they were not able to adapt quickly enough when the landscape dramatically transformed and their food became scarce.”

The mammoth extinction did not occur instantly. Instead, their numbers slowly trickled down as food became increasingly scarce. In time, their genetic diversity also suffered since there were fewer individuals, leading to an increase in inbreeding. The loss of genetic diversity made them even more vulnerable to wild shifts in temperature, food resources, and diseases.

“When the climate got wetter and the ice began to melt it led to the formation of lakes, rivers, and marshes. The ecosystem changed and the biomass of the vegetation reduced and would not have been able to sustain the herds of mammoths. We have shown that climate change, specifically precipitation, directly drives the change in the vegetation—humans had no impact on them at all based on our models,” said Dr. Yucheng Wang, first author of the paper and a Research Associate at the Department of Zoology, University of Cambridge.

Although other extinct megafauna did not constitute the object of the present study, it is likely that the same environmental forces may explain the demise of other species, such as the woolly rhinoceroses and Pleistocene horses. Many of these species’ demise were also previously associated with overkilling by humans.

“This is a stark lesson from history and shows how unpredictable climate change is—once something is lost, there is no going back. Precipitation was the cause of the extinction of woolly mammoths through the changes to plants. The change happened so quickly that they could not adapt and evolve to survive,” Willerslev said.

In September, scientists in the field of genetic engineering proposed resurrecting the wooly mammoth under a new project called Colossal.

All hopes to save the northern white rhinos now rest on a single female

Researchers will stop harvesting eggs from one of the two remaining northern white rhinoceros in the world, according to a Thursday announcement by BioRescue, according to the AFP.

A southern white rhino mother and calf. Image credits Hein Waschefort via Wikimedia.

Efforts to bring the species back from the brink of extinction are still underway. Currently, BioRescue is focusing on extracting eggs from the two remaining northern white rhino females. However, the scientific consortium announced on Thursday that one of the females, 32-year-old Najin, will be retired as a donor from the project.

Although Najin has been a valuable participant, and despite all the care being taken during its various procedures, BioRescue simply feels like the risks to Najin outweigh the benefits she could bring to the program at this point.

Hard choice to make

“Weighing up risks and opportunities for the individuals and the entire species rendered this decision without an alternative,” BioRescue said in a statement.

The only other northern white rhino on Earth, and Najin’s daughter, Fatu, has thus remained the sole egg donor for the program. Using her cells, researchers will try to develop viable embryos. Neither Fatu nor Najin are able to carry a pregnancy to term, so surrogate mothers from the closely-related southern white rhino subspecies will be used.

This assisted reproduction programme has been underway since 2019.

Harvesting of the eggs involved a high-risk procedure. Although it was carried out by an international team of excellent veterinarians, it still required the animals to be anesthetized for almost two hours, and the extraction process involved the use of specialized techniques — all of which means that there was an unavoidable level of risk involved in the programme.

Thankfully, the process was successful. The eggs were then taken to a lab in Italy for fertilization, development into embryos, and preservation. Frozen sperm from two (now-deceased) male northern white rhinos was used for this step.

So far, the programme has resulted in the creation of three embryos of the northern white rhino subspecies. But these were all developed from eggs harvested from Fatu. As such, it simply doesn’t make sense to keep risking Najin’s wellbeing.

“She will remain a part of the programme, for example by providing tissue samples for stem cell approaches, which can be performed with minimal invasion,” said Jan Stejskal, director of international projects at Safari Park Dvur Kralovs, where Najin was born in 1989.

It’s safe to say that programmes such as this one are the subspecies’ last shot at avoiding extinction. Sudan, the last male northern white rhino, died at the Ol Pejeta Conservancy in Kenya in 2018. Najin and Fatu are currently living under permanent guard at the same location.

Those guards are not meant to protect the animals from predators. Rhinos only need to fear precious little threats in the wild. Their populations were decimated, instead, by poachers over the last 5 decades or so.

Amazing 100-million-year-old crab found perfectly preserved in amber

Artistic reconstruction of Cretapsara athanata, whose name translates to ‘the immortal Cretaceous spirit of the clouds and waters.’ Credit:  Franz Anthony, courtesy of Javier Luque.

More than 100 million years ago, while dinosaurs still roamed the Earth, a tiny crab wandered out to the shore. Unlucky for it, the crab got stuck in resin and perished. But lucky for us, that resin fossilized into amber, preserving not just the crab’s body parts but also soft tissues like antennas and even its bulgy eyes.

“It’s not missing a single hair on the body, which is remarkable,” said Javier Luque, a postdoctoral researcher in the Department of Organismic and Evolutionary Biology at Harvard University.

The spectacular specimen is, in fact, the most complete crab fossil ever discovered. The ancient crab, which scientists have christened Cretapsara athanata, originated in northern Myanmar. Researchers from the Longyin Amber Museum in China bought the fossil from local miners in 2015 and remained in the museum’s collection somewhat idly until Luque heard about it.

Credit: Lida Xing.

Luque is one of the world’s foremost authorities on crab evolution, so naturally, he was invited to become part of an international collaboration that included researchers from China, Canada, and the United States.

When Luque first laid eyes on the amber fossil, one of his first thoughts was what the heck was a crab doing stuck in fossilized tree resin.

“In a way, it’s like finding a shrimp in amber,” the researcher said. “Talk about wrong place, wrong time.”

Credit: Javier Luque and Lida Xing.

Using micro-CT scans, Lida Xing of the China University and colleagues reconstructed a 3D model of the ancient crab, allowing the researchers to study the specimen in minute detail, including the fine hairs the lined its body.

Credit: Elizabeth Clark and Javier Luque.

By the looks of these scans, the 100-million-year-old specimen closely resembled modern crabs that scuttle around shores across the world today. Judging from its tiny size, which measures only 5 millimeters across, it was likely a baby crab. Although the oldest-ever crab fossils date back to the Jurassic, more than 200 million years ago, previously discovered crab fossils were incomplete, largely consisting of claw fragments.

The new specimen also predates previous crab-like fossils by 25 to 50 million years and perfectly agrees with molecular reconstructions of the crab tree of life. Such molecular DNA analyses predicted that nonmarine crabs split from their marine ancestors more than 125 million years ago. Thus, this amazing Cretaceous crab bridges the gap between theoretical predictions and the actual fossil record.

Writing in the journal Science Advances, the authors note that the amber fossil shows that crabs made the leap from sea to land much earlier than thought, during the dinosaur era rather than during the age of mammals.

But it’s not clear whether or not Cretapsara athanata was a land lover, judging from its incomplete lungs that weren’t adapted to fully terrestrial life. Instead, the scientists believe the ancient crab likely flourished in freshwater or perhaps brackish water. Some of the crab’s preferred habitats may have been puddles on the forest floor, which explains how this particular specimen may have met its doom.

“They are all over the world, they make good aquarium pets, they’re delicious for those of us who eat them, and they’re celebrated in parades and festivals, and they even have their own constellation,” Luque said. “Crabs, in general, are fascinating, and some are so bizarre-looking — from tiny little pea-shaped crabs to humongous coconut crabs. The diversity of form among crabs is captivating the imagination of the scientific and non-scientific public alike, and right now people are excited to learn more about such a fascinating group that are not dinosaurs. This is a big moment for crabs.”

Update (03 November, 2021): Fixed a dishonorable but funny typo. Thank you all in the comments :)

Horse domestication traced to 4,200 years ago in the Western Eurasian steppe

Credit: Pixabay.

The domestication of wild horses has had a huge impact on human history, offering important advantages in terms of mobility, nutrition, and warfare, among other things. But there are still many unknowns with regards to when and where humans’ affinity for horses first began. These questions may have finally been answered by a new genetic study that traced the earliest domestication of horses to the Pontic-Caspian steppes, northern Caucasus, around 4,200 years ago.

Ludovic Orlando, a molecular archaeologist from France’s CNRS research agency in Toulouse, was among the first researchers to study the horse genome. His lab houses the world’s largest collection of wild and tamed horse DNA, some as old as 50,000 years old. This massive trove of genetic data helped him and his colleagues have a much clearer understanding of how humans shaped equine evolution. But it was only recently that Orlando and a team of more than 160 international scientists have been able to pinpoint the origin of domestic horses as we know them today.

Initially, the researchers turned their attention to Kazakhstan, where excavations of ancient Botai settlements had suggested these herders were among the first to domesticate horses. Yet although these 5,500-year-old horses from Botai showed signs of domestication, their DNA proved without a doubt that they were not the ancestors of modern domestic horses. So, the researchers moved to other possible origin spots like Anatolia, Siberia, and even the Iberian Peninsula, which each ultimately proved to be dead ends.

“We knew that the time period between 4,000 to 6,000 years ago was critical but no smoking guns could ever be found,” said Orlando in a statement.

In response, Orlando and colleagues went back to the drawing board and opted for a new strategy. They widened their net to compare the genomes of 273 horses that lived between 52,000 and 2,200 years ago.

This strategy eventually paid off, showing that horses in Eurasia suffered a dramatic change between 4,200 and 4,000 years ago. A single genetic profile, which was previously confined to the Pontic steppes of the North Caucasus, spread very fast beyond its native region, eventually replacing all the wild horse populations from the Atlantic to Mongolia in the span of only a few centuries.

“That was a chance: the horses living in Anatolia, Europe, Central Asia, and Siberia used to be genetically quite distinct,” notes Dr. Pablo Librado, first author of the study published today in the journal Nature.

“The genetic data also point to an explosive demography at the time, with no equivalent in the last 100,000 years,” Orlando added. “This is when we took control over the reproduction of the animal and produced them in astronomic numbers.”

This particular early population of domesticated horses introduced two key genomic regions (GSDMC and ZFPM1.) with desirable adaptations that made them appealing to humans. One is linked to more docile behavior, while the other helps horses develop a stronger backbone. In time, these advantageous characteristics were further selected and helped domestic horses spread from the Western Eurasian steppe.

These genetic characteristics surfaced at the same time as archaeological evidence suggests spoke-wheeled chariots and Indo-Iranian languages started to spread throughout Asia. The combination of technology and culture helped the new horse breed to replace all other previous populations across Eurasia, showing how history and science can converge to reveal

These early domestic horse ancestors suffered further important domestications. For instance, after the Arabs expanded into Europe in the 7th-century, Arabian stallions outcompeted males from other breeds, which transferred their Y chromosomes to all modern horses alive today. Today’s horses are much faster and stronger than their counterparts from 1,000 years ago, let alone those that lived 4,000 years ago. At the same time, their genetic diversity is much smaller than it ever has been, allowing more potentially deleterious mutations to accumulate and lead to a higher risk of genetic disease. 

Koala vaccination campaign kicks off as species battles chlamydia epidemic

This year seems to be all about vaccination — not just for humans, but for koalas as well. However, they’re not doing it for COVID-19. 

As part of a trial, about 400 koalas will be vaccinated against chlamydia — a sexually transmitted disease (STD) also found in humans that has spread widely among the furry animals in some areas of Australia. The researchers behind the initiative hope the roll-out of the vaccine will significantly improve the survival and reproduction of the animals.

Image credit: Creative Commons.

Wild koalas can get infected with chlamydia through sexual contact and newborns can contract it by eating pap, a nutritious type of feces excreted by infected mothers (yes, koalas do that). It’s not really clear why the animals are so vulnerable to the disease, with previous studies suggesting a virus in the same family as the human immunodeficiency virus (HIV) could be the reason. 

While humans are affected by the bacterium Chlamydia trachomatis, koalas are targeted by the Chlamydia pecorum — a different ‘breed’ of chlamydia, though both can cause infertility and permanent blindness if left untreated. Antibiotics used in humans can also work for koalas, but the success rate varies and some antibiotics produce harmful side effects, disrupting the koalas’ gut bacteria. 

The diet of wild koalas is based on eucalyptus leaves. While nutritious, leaves have a compound called tanning that can be highly toxic if it’s not broken down by gut bacteria — and the antibiotics seem to be causing just that, leaving koalas unable to process their meals. That’s why new antibiotics and even a vaccine have been long searched for. 

Trying out the new vaccine

The vaccine was developed by researchers at the University of the Sunshine Coast (USC) in Australia. Professor Peter Timms spent the past decade investigating the impact of chlamydia in koalas and sequencing the koala genome, which has now led to the vaccine. It has already passed Phase 1 and Phase 2 trials, with over 250 koalas vaccinated. 

Timms argues the vaccine is completely safe, with a good immune response and a decrease in the levels of chlamydia infection identified in the trials. Now, for phase 3, the plan is to vaccinate 400 animals, starting at the Australia Zoo Wildlife Hospital, the Moggill Koala Rehabilitation Center, and the RSPCA Wildlife Hospital and then continuing with animals in the wild. 

“We are now at the exciting stage of being ready to roll out the vaccine as part of large Phase 3 trials,” Timms said in a statement. “While this vaccination will directly benefit each of the animals, the trial will also have a focus on the protection provided by vaccination. All koalas will be microchipped and the hospital will record any animals that return for any reason.”

Ambert Gillett, a veterinarian at the Australia Zoo Wildlife Hospital involved in the research, said chlamydia is a “cruel disease” for koalas, causing conjunctivitis, bladder infections, and infertility. Having a vaccine will largely help to prevent infection, she added. Chlamydia is the most common reason for koala admission to the Australia Zoo Wildlife Hospital. 

As well as chlamydia, koalas are also threatened by global warming and tree-clearing. Climate change is leading to the koala range being reduced in Australia because of fewer nutritious eucalyptus leaves available. At the same time, the expansion of agriculture means koalas have to spend a longer time on the ground moving from tree to tree.