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.
June 28, 2013
Snakes and fish do it. Cats and dogs do it. Even human babies do it inside the womb. And maybe after seeing the picture above, you’re doing it now: yawning.
Yawning appears to be ubiquitous within the animal kingdom. But despite being such a widespread feature, scientists still can’t explain why yawning happens, or why for social mammals, like humans and their closest relatives, it’s contagious.
As yawning experts themselves will admit, the behavior isn’t exactly the hottest research topic in the field. Nevertheless,
they are getting closer to the answer to these questions. An oft-used explanation for why we yawn goes like this: when we open wide, we suck in oxygen-rich air. The oxygen enters our bloodstream and helps to wake us up when we’re falling asleep at our desks.
Sounds believable, right? Unfortunately, this explanation is actually a myth, says Steven Platek, a psychology professor at Georgia Gwinnett College. So far, there’s no evidence that yawning affects levels of oxygen in the bloodstream, blood pressure or heart rate.
The real function of yawning, according to one hypothesis, could lie in the human body’s most complex system: the brain.
Yawning—a stretching of the jaw, gaping of the mouth and long deep inhalation, followed by a shallow exhalation—may serve as a thermoregulatory mechanism, says Andrew Gallup, a psychology professor at SUNY College at Oneonta. In other words, it’s kind of like a radiator. In a 2007 study, Gallup found that holding hot or cold packs to the forehead influenced how often people yawned when they saw videos of others doing it. When participants held a warm pack to their forehead, they yawned 41 percent of the time. When they held a cold pack, the incidence of yawning dropped to 9 percent.
The human brain takes up 40 percent of the body’s metabolic energy, which means it tends to heat up more than other organ systems. When we yawn, that big gulp of air travels through to our upper nasal and oral cavities. The mucus membranes there are covered with tons of blood vessels that project almost directly up to the forebrain. When we stretch our jaws, we increase the rate of blood flow to the skull, Gallup says. And as we inhale at the same time, the air changes the temperature of that blood flow, bringing cooler blood to the brains.
In studies of mice, an increase in brain temperature was found to precede yawning. Once the tiny rodents opened wide and inhaled, the temperature decreased. “That’s pretty much the nail in the coffin as far as the function of yawning being a brain cooling mechanism, as opposed to a mechanism for increasing oxygen in the blood,” says Platek.
as a thermoregulatory system mechanism could explain why we seem to yawn most often when it’s almost bedtime or right as we wake up. “Before we fall asleep, our brain and body temperatures are at their highest point during the course of our circadian rhythm,” Gallup says. As we fall asleep, these temperatures steadily decline, aided in part by yawning. But, he added, “Once we wake up, our brain and body temperatures are rising more rapidly than at any other point during the day.” Cue more yawns as we stumble toward the coffee machine. On average, we yawn about eight times a day, Gallup says.
Scientists haven’t yet pinpointed the reason we often feel refreshed after a hearty morning yawn. Platek suspects it’s because our brains function more efficiently once they’re cooled down, making us more alert as result.
A biological need to keep our brains cool may have trickled into early humans and other primates’ social networks. “If I see a yawn, that might automatically cue an instinctual behavior that if so-and-so’s brain is heating up, that means I’m in close enough vicinity, I may need to regulate my neural processes,” Platek says. This subconscious copycat behavior could improve individuals’ alertness, improving their chances of survival as a group.
Mimicry is likely at the heart of why yawning is contagious. This is because yawning may be a product of a quality inherent in social animals: empathy. In humans, it’s the ability to understand and feel another individual’s emotions. The way we do that is by stirring a given emotion in ourselves, says Matthew Campbell, a researcher at the Yerkes National Primate Research Center at Emory University. When we see someone smile or frown, we imitate them to feel happiness or sadness. We catch yawns for the same reasons—we see a yawn, so we yawn. “It isn’t a deliberate attempt to empathize with you,” Campbell says. “It’s just a byproduct of how our bodies and brains work.”
Platek says that yawning is contagious in about 60 to 70 percent of people—that is, if people see photos or footage of or read about yawning, the majority will spontaneously do the same. He has found that this phenomenon occurs most often in individuals who score high on measures of empathic understanding. Using functional magnetic resonance imaging (fMRI) scans, he found that areas of the brain activated during contagious yawning, the posterior cingulate and precuneus, are involved in processing the our own and others’ emotions. “My capacity to put myself in your shoes and understand your situation is a predictor for my susceptibility to contagiously yawn,” he says.
Contagious yawning has been observed in humans’ closest relatives, chimpanzees and bonobos, animals that are also characterized by their social natures. This begs a corollary question: is their capacity to contagiously yawn further evidence of the ability of chimps and bonobos to feel empathy?
Along with being contagious, yawning is highly suggestible, meaning that for English speakers, the word “yawn” is a representation of the action, a symbol that we’ve learned to create meaning. When we hear, read or think about the word or the action itself, that symbol becomes “activated” in the brain. “If you get enough stimulation to trip the switch, so to speak, you yawn,” Campbell says. “It doesn’t happen every time, but it builds up and at some point, you get enough activation in the brain and you yawn.”
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.
November 19, 2012
Stereotypically, people experiencing a mid-life crisis desperately seek to justify their lives through superficial means, perhaps by buying an expensive sports car or getting into a relationship with a younger romantic partner. Although their behavior looks rather different, a new study says that chimpanzees and orangutans go through a mid-life nadir in overall well-being and happiness that roughly resembles our own.
A team led by psychologist Alexander Weiss of the University of Edinburgh asked zookeepers and researchers around the world to keep track of the well-being of resident chimpanzees and orangutans—508 animals in total. The results of all that record-keeping, published today in the Proceedings of the National Academy of Sciences, show that, like humans, these great apes generally experience a U-shaped pattern of happiness and well-being, starting off with high ratings for happiness as adolescents, declining gradually during middle age (bottoming out in their late 20s or early 30s), and then rising back up again in their elder years.
Although popular conceptions of human mid-life crises focus on material acquisitions, psychologists believe they’re driven by an underlying decline in satisfaction and happiness as we go through middle age, and reflected by increased antidepressant use and suicide risk. In this sense, the primates studied went through a similar pattern:
Of course, unlike with humans, no one can directly ask chimps and orangutans how they are feeling. Instead, the researchers relied upon surveys, filled out by zookeepers and caretakers, that rated the animals’ mood and how much pleasure they took from certain situations. They acknowledge the ratings are necessarily subjective, but they feel that the size of the dataset and consistency in the trends as reported from the different zoos with different animals suggests that the pattern is legitimate.
Weiss’ group originally embarked on the ape study to answer the question of why mid-life dissatisfaction is so common in humans. “We hoped to understand a famous scientific puzzle: why does human happiness follow an approximate U-shape through life?” Weiss said in a statement.
Although many are apt to blame external cultural factors such as disappointing careers or mounting bills as the cause, Weiss felt it was something more fundamental. By showing that a similar pattern exists in other primates, he argues that his team has dispelled the notion that these types of external factors are solely responsible. “We ended up showing that it cannot be because of mortgages, marital breakup, mobile phones or any of the other paraphernalia of modern life,” he said. “Apes also have a pronounced midlife low, and they have none of those.”
Instead of these cultural factors, Weiss suggests that this pattern is rooted in biological or evolutionary factors. It might have been the case, for example, that the human ancestors who had an innate tendency for happiness and satisfaction at the stages of life when they were most vulnerable (youth and old adulthood) might have been less likely to venture into risky and potentially harmful situations in the pursuit of more resources.
October 13, 2011
You’ve probably laughed at a commercial or television show featuring a chimpanzee dressed like a little kid. They’re cute animals, so how could you resist? But a new study in PLoS ONE provides startling evidence that turning chimps into entertainers makes us care less about them as a species.
Researchers at Duke University had human participants watch a series of television ads (for products like tooth paste and soda) in which they included either a commercial for chimp conservation featuring Jane Goodall, a bit of footage of chimpanzees in the wild or a commercial that had a chimp dressed like a human. The participants were then given a questionnaire that asked about the suitability of chimps as pets, their presence in the media and their status in the wild. They were also asked if they would like to purchase a soda or a tube of toothpaste or to donate to the Red Cross or a conservation organization.
People who saw the chimps dressed as humans were more likely to view the animals as being suitable as pets or in entertainment and were the least likely to donate to the conservation organization. The researchers write:
Advertisers only use easily manageable young chimpanzees in commercials but based on our survey viewers believe these chimpanzees were adults—leaving them unaware of how dangerous these animals can be when fully grown. Such a frivolous use of chimpanzees also leads those watching chimpanzee commercials to overestimate their population size in the wild. Clearly, chimpanzee commercials violated participants’ expectations about how perilously endangered animals are treated. This confusion likely explains why those watching commercials including entertainment chimpanzees donated the least of their experimental earnings to a conservation charity.
“Nobody has measured this sort of thing before, but [our study] clearly shows that the portrayal of endangered species on television can alter viewers’ behaviors and decrease one’s willingness to donate,” says graduate student Kara Schroepfer, the study’s lead author. “This is a clear indication that we need to reevaluate media practices and conservation priorities.”
And the impact of using chimps as entertainers goes beyond the money issue. If people think that chimps make good pets—which is seriously misguided—then more young chimpanzees may be captured in the wild, their mothers killed, so they can be sold into the pet trade. And there is a sad history of chimps being abandoned or killed when they get too old and too dangerous to be cute.