October 17, 2013
In recent years, scientists have discovered that chimpanzees, our closest relatives, are capable of all sorts of human-like behaviors that go far beyond tool use.
They self-medicate, eating roughage to clear their intestines of parasites. Baby chimps use human-like gestures to convey their needs to adults. Studies suggest even that chimps have a seemingly innate sense of fairness and go through mid-life crises.
Now, new research indicates that chimps’ vocalized communications are a bit closer in nature to our own spoken languages as well. A new study published in PLOS ONE shows that, when chimps warn each other about impending danger, the noises they make are much more than the instinctive expression of fear—they’re intentionally produced, exclusively in the presence of other chimps, and cease when these other chimps are safe from danger.
This not might sound like much, but linguists use intentionality as a key hallmark of language. Those who argue that apes aren’t capable of language—and that the apes who’ve been trained in sign language are merely engaging in rote memorization, not true language acquisition—point to a lack of intentionality as one of the reasons why. So the study shows that, in their natural environment, chimps do use vocalizations in a way more similar to language than previously thought.
The researchers, led by Anne Marijke Schel of the University of York, studied a community of 73 chimps that lives in Uganda’s Budongo Forest Reserve. To simulate danger, they used the skin of a dead African Rock Python—one of the chimps’ natural predators—to create a fake python, with fishing line attached to its head so they could make it move realistically.
Over the course of nearly a year in the field, they repeatedly placed this artificial predator in the forest with a camera rolling, waiting for unsuspecting chimps—sometimes alone, sometimes with other chimps—to come upon it so they could closely study their response. Typically, when the chimps saw the snake, they were startled, and made one of two different vocalizations, which the researchers identified as ‘huus’ (softer calls, with less alarm) or ‘waas’ (louder, more alarmed calls).
When the researchers analyzed the specific responses, they found that when other chimps were around, the startled chimps were much more likely to make the ‘waas’ rather than ‘huus.’ Moreover, the chimps clearly observed the location of other chimps and whether they were paying attention, and kept sounding the alarm until the others had fled and were safe from danger. The length of time they sounded the alarm, meanwhile, wasn’t linked with their own distance from the snake, further supporting the idea that the call was an intentional warning to others.
The researchers also took note of the pre-existing relationships among chimps (within the social hierarchy, some are closer than others) and found that closer relationships were more likely to trigger alarms. “It was particularly striking when new individuals who had not seen the snake yet, arrived in the area,” Schel said in a press statement. “If a chimpanzee who had actually seen the snake enjoyed a close friendship with this arriving individual, they would give alarm calls, warning their friend of the danger. It really seemed the chimpanzees directed their alarm calls at specific individuals.”
The authors argue that these characteristics—specifically, the fact that alternate vocalizations were employed in different circumstances, that they were made with the attention of the audience in mind and that they were goal-directed, continuing until they’d successfully warned other chimps so they fled—show that the noises are more than reflections of instinctive fear. Rather, they’re a tactical, intentional form of communication.
This observation, the authors say, may also tell us something about the evolution of human language. Gestural theories on the origin of language contend that spoken language evolved from hand gestures, and cite the fact that non-human primates (a model for primitive hominids) exclusively use gestures for true communication, merely making vocalizations based on engrained instinct, rather than calculated intention.
But this discovery of intentional warnings in chimps seems to upend that idea, suggesting that primitive hominids too were able to communicate via both vocalizations and gestures. This indicates, the researchers say, that spoken language may have evolved from multiple different sources, both gestures and vocal calls.
September 3, 2013
It’s the stuff of The Hot Zone, Outbreak and Contagion: a deadly new virus has emerged from some dark corner of the jungle. While victims succumb to a horrendous death and drop like poisoned flies, virus hunters race to identify patient zero, who turns out to have recently spent time on a pig farm. Those pigs, they discover, are exposed to fruit bat droppings, which rain down from the trees above. Another animal virus made the jump to humans. And while you probably know that such jumps have happened before, brace yourself: Scientists estimate that at least 320,000 such viruses await discovery.
The media is currently abuzz with talk of the MERS coronavirus, which might have originated in bats and then used camels as an additional host. Before that, we had SARS (from small mammals); Nipah virus (fruit bats and pigs); and swine flu. Zoonoses–or illnesses that originate in animals and cross over into humans–account for around 70 percent of all emerging viral diseases, including HIV/AIDS, West Nile and Ebola. Zoonoses originating from mammals are especially problematic. They tend to prove the most readily transmittable to people because the viruses that evolved to exploit our closest furry relatives tend to be most adept at navigating our own warm-blooded bodies. As we encroach upon new tracts of forest where dangerous pathogens may lurk, and then jet-set around the world with the pathogens hitching a ride, the rate of such emerging infectious disease outbreaks is only increasing.
Yet we know very little about “virodiversity,” or the number, types and abundance of viruses in the world. We don’t even have a handle on how many viruses may exist in any given animal species, despite those viruses potentially posing the greatest threat to our lives and economies.
In an ambitious new study from the American Society for Microbiology’s online journal mBio, more than 20 leading virus hunters got together to try and solve this mystery. Rather than just tackle a single species, they decided to take on an entire class of animals: mammals. Collecting samples from all 5,500 known mammals wasn’t an option, so they chose a representative species, the Indian flying fox–a type of bat that is the largest flying mammal in the world and is the carrier of the Nipah virus–to supply their viral data, from which they could then extrapolate to estimate broader diversity among all mammals.
They collected nearly 2,000 samples from flying foxes trapped in Bangladesh (they let the bats go afterwards, unharmed, and wore protective gear to make sure they themselves did not become infected with the next Nipah virus), then performed nearly 13,000 genetic analyses to test for viral traces in those samples. They discovered 55 viruses from nine different families, only five of which–two bocaviruses, an adenovirus, a betacoronavirus, and a gammacoronavirus–were already known to science. Ten of the newly discovered viruses were in the same family as the deadly Nipah virus.
Additionally, a commonly used statistical test allowed the researchers to estimate that their sampling most likely missed three other, more elusive viruses, bringing the flying foxes’ tally to an estimated 58 viruses. From there, they extrapolated this figure to all mammals, calculating that, at minimum, around 320,000 viruses await discovery in these animals.
While several hundred thousand may sound like a lot, that number is much more manageable than the millions of viruses that some researchers supposed might be out there. In fact,, a species richness estimation program they used, called the Chao 2, indicated that samples from just 500 more animals would be needed to discover 85 percent of those 320,000 viruses. On the other hand, discovering the remaining 15 percent, which accounts for only the rarest of the viral bunch, would require more than ten times as many samples. The team calculated that the 85 percent effort would require about $1.4 billion in funding, which sounds like a lot but is only a fraction of the $16 billion that a single disease pandemic, SARS, has cost over the last ten years in economic impacts. Divided over a 10 year period, we could put the mystery of mammalian viruses to rest for just $140 million per year, they write.
“For decades, we’ve faced the threat of future pandemics without knowing how many viruses are lurking in the environment, in wildlife, waiting to emerge,” Peter Daszak, the study’s lead author, said in a statement. “Finally we have a breakthrough–there aren’t millions of unknown virus, just a few hundred thousand, and given the technology we have it’s possible that in my lifetime, we’ll know the identity of every unknown virus on the planet.”
The researchers did make several assumptions in their study. They assumed that 58 is a reasonable estimate for the number of viruses harbored by every mammal species. that viruses are not shared by different hosts. that mammalian viruses only belong within nine families. and that their tests for viral diversity were dependable. They acknowledge that their initial calculation is only a rough estimate, and they plan to repeat the experiment in primates in Bangladesh and bats in Mexico to add more robustness to their figure. Unfortunately, they predict that their estimate of total viral diversity will likely increase with more data.
Aside from elucidating the wondrous diversity of the natural world, discovering and classifying all of these viruses could significantly help humans. Rather than flounder for months trying to discover the origins of a virus–as scientists are still struggling to do with MERS–a central database based on extensive surveys of animals would expedite the process of identifying any new virus that emerges in humans. Knowing where a virus comes from is important for cutting off the source of infection, as demonstrated in the culling of hundreds of thousands of chickens, civets and pigs and other animals in recent viral outbreaks. But snagging the source quickly may allow animal handlers to better isolate tainted populations of animals, allowing the rest to be spared and keeping humans away from those tainted few.
Unfortunately, knowing what viruses are out there cannot prevent an emerging viral disease from striking a wide swath of people. But it can help lessen the blow, for example, by giving researchers more time to develop rapid diagnostic tests for disease intervention and control.
“To quote Benjamin Franklin, an ounce of prevention is worth a pound of cure,” said W. Ian Lipkin, director of the Center for Infection and Immunity at Columbia University’s Mailman School of Public Health and the study’s senior author. “Our goal is to provide the viral intelligence needed for the global public health community to anticipate and respond to the continuous challenge of emerging infectious diseases.”
June 26, 2013
Humans have a number of special abilities not shared by other primates. Being capable of walking continuously on two legs might be the first that comes to mind. The ability to speak, produce written language and engage in complex reasoning are a few more.
One of our most remarkable skills, though, might be one that you rarely consider outside of sporting contexts: the ability to throw small objects fast and hard.
Chimpanzees, after all, are roughly twice as strong as humans, pound for pound, and can jump about a third higher than our finest athletes, but can only throw an object about 20 miles per hour—far slower than an average person, let alone a professional baseball player (who commonly throw in the 90s or even 100s).
Why are our bodies particularly suited to throwing things? A new study published today in Nature by researchers from Harvard and elsewhere suggests that our ancestors evolved this uncommon ability roughly two million years ago as a way of improving their hunting prowess. The newly-evolved skill likely helped early hominids to more effectively hurl rocks or sharpened pieces of wood at prey.
The study began with a biomechanical analysis of what exactly goes on during the human throwing motion, which was conducted using an infrared motion capture system (the same technology often used to create realistic human movements in video games) to look at the deliveries of 20 college-level baseball players as they threw 8-10 pitches. While throwing a ball, a person’s shoulder can rotate extremely fast—at 9000 degrees per second, it’s the fastest movement found in the human body—and the researchers’ previous calculations had shown that this speed couldn’t be explained by the energy stored in the shoulder muscles alone.
Their analysis showed that the remarkable level of speed generated during the throwing motion wouldn’t be possible without the flexible tendons and ligaments that surround the shoulder. “When humans throw, we first rotate our arms backwards away from the target. It is during this ‘arm-cocking’ phase that humans stretch the tendons and ligaments crossing their shoulder and store elastic energy,” Neil Roach, a biological anthropologist and lead author of the study, said in a press statement. “When this energy is released, it accelerates the arm forward, generating the fastest motion the human body produces, resulting in a very fast throw.” In a sense, these stretchy tendons and ligaments act like the rubber band in a slingshot, gradually storing energy and then releasing it all at once.
The researchers also found that we’re able to use our shoulder tendons and ligaments in this way because of several anatomical features that we all have—and don’t share with any other primates. For one, our low, outward-facing shoulders allow a greater range of motion than chimpanzees’ high, inward-facing ones. Additionally, our high, mobile waists also allow us to rotate our torsos more easily, enabling us to cock our throwing arms farther back, relative to our legs.
The importance of these features and the overall significance of a wide range of motion in producing fast throws was confirmed when the researchers put shoulder braces on the baseball players and let them pitch. With their flexibility reduced, the speed of their throws declined by an average of 8 percent.
The evolution of the anatomical traits that set our throwing skills apart from chimps can be traced to roughly two million years ago, the researchers say, when our ancestors still belonged to a different species (Homo erectus). While it’s impossible to know exactly which selective pressures led to their evolution, the researchers have an idea. “We think that throwing was probably most important early on in terms of hunting behavior, enabling our ancestors to effectively and safely kill big game,” Roach said. “Eating more calorie-rich meat and fat would have allowed our ancestors to grow larger brains and bodies and expand into new regions of the world—all of which helped make us who we are today.”
Eventually, the development of technologies that made hunting easier—starting with bows and arrows, then nets, blades, and eventually firearms—made our skill at hurling objects largely unnecessary. But if the authors are correct, our capacity for such invention stems from the evolutionary advantage given by high-speed throwing. In a sense, throwing javelins, hurling Hail Mary passes, and striking out batters—athletic feats that attest to our physical prowess as a species—are just an evolutionary vestige from our ancestors, retained by our modern selves.
June 6, 2013
Thirteen years after the release of On the Origin of Species, Charles Darwin published another report on the evolution of mankind. In the 1872 book The Expression of the Emotions in Man and Animals, the naturalist argued that people from different cultures exhibit any given emotion through the same facial expression. This hypothesis didn’t quite pan out—last year, researchers poked a hole in the idea by showing that the expression of emotions such as anger, happiness and fear wasn’t universal (PDF). Nonetheless, certain basic things—such as the urge to cry out in pain, an increase in blood pressure when feeling anger, even shrugging when we don’t understand something—cross cultures.
A new study, published today in the journal Frontiers in Psychology, compares such involuntary responses, but with an added twist: Some observable behaviors aren’t only universal to the human species, but to our closest relatives too—chimpanzees and bonobos.
Using video analysis, a team of UCLA researchers found that human, chimpanzee and bonobo babies make similar gestures when interacting with caregivers. Members of all three species reach with their arms and hands for objects or people, and point with their fingers or heads. They also raise their arms up, a motion indicating that they want to be picked up, in the same manner. Such gestures, which seemed to be innate in all three species, precede and eventually lead to the development of language in humans, the researchers say.
To pick up on these behaviors, the team studied
hree babies of differing species through videos taken over a number of months. The child stars of these videos included a chimpanzee named Panpanzee, a bonobo called Panbanisha and a human girl, identified as GN. The apes were raised together at the Georgia State University Language Research Center in Atlanta, where researchers study language and cognitive processes in chimps, monkeys and humans. There, Panpanzee and Panbanisha were taught to communicate with their human caregivers using gestures, noises and lexigrams, abstract symbols that represent words. The human child grew up in her family’s home, where her parents facilitated her learning.
Researchers filmed the child’s development for seven months, starting when she was 11 months old, while the apes were taped from 12 months of age to 26 months. In the early stages of the study, the observed gestures were of a communicative nature: all three infants engaged in the behavior with the intention of conveying how their emotions and needs. They made eye contact with their caregivers, added non-verbal vocalizations to their movements or exerted physical effort to elicit a response.
By the second half of the experiment, the production of communicative symbols—visual ones for the apes, vocal ones for the human—increased. As she grew older, the human child began using more spoken words, while the chimpanzee and bonobo learned and used more lexigrams. Eventually, the child began speaking to convey what she felt, rather than only gesturing. The apes, on the other hand, continued to rely on gestures. The study calls this divergence in behavior “the first indication of a distinctive human pathway to language.”
The researchers speculate that the matching behaviors can be traced to the last shared ancestor of humans, chimps and bobonos, who lived between four and seven million years ago. That ancestor probably exhibited the same early gestures, which all three species then inherited. When the species
diverged, humans managed to build on this communicative capacity by eventually graduating to speech.
Hints of this can be seen in how the human child paired her gestures with non-speech vocalizations, the precursors to words, far more than the apes did. It’s this successful combination of gestures and words that may have led to the birth of human language.
April 26, 2013
You probably haven’t heard of the world’s second rarest ape, the cao vit gibbon. Scientists know of only one place the species still lives in the wild. In the 1960s, things got so bad for the cao vit gibbon that the species was declared extinct. But in 2002, to the surprise and elation of conservationists, the animals—whose shaggy coats can be a fiery orange or jet black—turned up along Vietnam’s remote northern border. Several years later, a few gibbons were found in China, too.
Also known as the eastern black-crested gibbon, the cao vit gibbons once covered an expanse of forest spanning from southern China and northern Vietnam just east of the Red River, but today only about 110 individuals survive. This gibbon is highly inclined to stick to the trees—in a previous study, during more than 2,000 hours spent observing gibbons in the field, researchers saw only once and very briefly one young male cao vit gibbon come down from the canopy and walk on a rock for a few seconds. Population surveys based on watching the animals in the branches reveal that the gibbons live in 18 groups scattered throughout the area. That makes it the second least populous species of ape, just after the Hainan gibbon, another type of extremely rare gibbon living in the same area of Asia.
In 2007 and 2009, Vietnam and then China hustled to establish special protected areas dedicated to preventing the cao vit gibbon’s extinction. Much of the area surrounding the remaining populations of gibbons is quickly being converted to agricultural fields and pasturesor cut down to make charcoal to sell and use at home, a common practice in the area. Hunting—though illegal—is also an issue, as exotic wild meat dinners are popular with locals in the region.
For an endangered species to recover rather than just survive, it needs to grow in numbers. But any given patch of land can only support so many animals given the amount of food and space that’s available. If populations exceed this threshold—called a carrying capacity—then animals will either starve, get picked off by predators or have to move somewhere else.
Researchers from Dali University in Yunnan, the Chinese Academy of Sciences in Kunming and the Chinese Research Academy of Environmental Sciences in Beijing wanted to find out how much of the protected forest the cao vit gibbons had expanded into, and also how many animals that pocket of land could eventually support. To answer this question, they turned to high-resolution satellite images, describing their results in the journal Biological Conservation.
Once they acquired aerial images of the gibbons’ habitat, they classified it into forest, scrub, shrub land and developed areas. This was important because gibbons can only live high in forest canopies, meaning the latter three categories were out of bounds for potentially supporting the animals. Overall, the area could be divided into five different zones that were split apart by either roads or rivers. From there, the researchers plugged the data into computer models that ranked possible gibbon habitat from high to low quality.
Their results revealed several bits of news, some good and some bad. First, from the models it seems that 20 groups of gibbons could eventually live in the protected forest areas before the population reaches its carrying capacity threshold. However, as human development creeps closer and closer, that disturbance could lower that figure. As things stand, the gibbons will likely reach their carrying capacity in the current habitat in 15 years, which doesn’t bode well for building up the species’ numbers.
There are a couple options. The protected area isn’t all great habitat, it turns out. Some of it is just mediocre for gibbons. If that span of forest could be improved, it could eventually support up to 26 groups of animals. The researchers also identified two other potential areas where gibbons could live if they could somehow manage to travel there (no gibbon has ever been known to cross a river or a road). But these patches of welcoming forest, located in Vietnam, are not protected, so they likely will not remain forests for long. If the government decided to protect those areas, the researchers write, they could serve as places for cao vit gibbons to live in the future, especially if narrow corridors of trees connecting the two areas were protected and restored as well.
If these patches of forest were protected, gibbons would not be the only species to benefit. Numerous other species of primates and monkeys, civets, pangolins, porcupines, birds, bats and many more depend upon those last remaining jungle habitats for survival. “In summary, the last remaining population of cao vit gibbon is nearing its carrying capacity in the current remaining forest patch,” the authors write. “Forest protection and active forest restoration using important food tree plantings to increase habitat quality and connectivity should be the most critical part of the ongoing conservation management strategy.”