Chapter 15. Language and Our Divided Brain
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
By ANDREW C. REVKIN Twenty-two months ago, I interrupted my nonstop reporting about paths toward a sustainable future for our species to focus on sustaining myself. The hiatus was not by choice, but was mandated by a stroke — the out-of-the-blue variant, the rare kind of “brain attack” (the term preferred by some neurologists) that is most often seen in otherwise healthy, youngish middle-aged people. It’s Fourth of July weekend, 2011 — a beautiful, if hot, morning for a run in the Hudson Valley woods with my son Daniel, back from brief service in the Israeli army. I’m eager to be pushed hard. I’m not even a lapsed middle-aged athlete; I’m truly negligent when it comes to exercise. We’re jogging up a steep path, and my breathing gets deeper and faster. At a particularly tough turn, I pause, hands on knees. “Come on, keep it up, Dad.” I’m panting but don’t want to disappoint. We press on. But I stop again, this time insisting that Daniel run ahead. I rest in the mottled shade and sunlight of the woods until he returns. Then I realize that through my left eye, the world appears paisley — as if I were looking through a patterned curtain. Something is really wrong. We make it back to the car. Daniel takes the wheel. Back home, I take a shower, thinking that cooling off will help. For the first time, a thought flickers. Could this be a stroke? Almost unconsciously, I take half a dozen baby aspirin. I know enough about aspirin’s blood-thinning properties to think this can’t hurt. Copyright 2013 The New York Times Company
Link ID: 18147 - Posted: 05.14.2013
by Helen Thomson "I was sitting on the toilet. I suddenly felt an explosion in the left side of my head and ended up on the floor. I think the only thing that kept me conscious was that I didn't want to be found with my pants down. Then the other side of my head went bang! I woke up in hospital and looked out of the window to see the tree was sprouting numbers. 3, 6, 9. Then I started talking in rhyme…" Ten days after having a subarachnoid haemorrhage – a stroke caused by bleeding in and around the brain – Tommy McHugh, an ex-con who'd been in his fair share of scraps, became a new man, with a personality that nobody recognised. When he was a young man, Tommy did time in prison. But after his stroke at age 51, everything changed. "I could taste the femininity inside of myself," he said. "My head was full of rhymes and images and pictures." Not only did he feel a sudden urge to write poetry, but he also began to paint and draw obsessively for up to 19 hours a day. He was never artistic before – in fact, he joked that he'd never even been in an art gallery "except to maybe steal something". Desperate to find out what was going on, Tommy wrote to several neuroscientists and end up working closely with Alice Flaherty at Harvard Medical School and Mark Lythgoe at University College London. © Copyright Reed Business Information Ltd.
by Elizabeth Norton If you've ever cringed when your parents said "groovy," you'll know that spoken language can have a brief shelf life. But frequently used words can persist for generations, even millennia, and similar sounds and meanings often turn up in very different languages. The existence of these shared words, or cognates, has led some linguists to suggest that seemingly unrelated language families can be traced back to a common ancestor. Now, a new statistical approach suggests that peoples from Alaska to Europe may share a linguistic forebear dating as far back as the end of the Ice Age, about 15,000 years ago. "Historical linguists study language evolution using cognates the way biologists use genes," explains Mark Pagel, an evolutionary theorist at the University of Reading in the United Kingdom. For example, although about 50% of French and English words derive from a common ancestor (like "mere" and "mother," for example), with English and German the rate is closer to 70%—indicating that while all three languages are related, English and German have a more recent common ancestor. In the same vein, while humans, chimpanzees, and gorillas have common genes, the fact that humans share almost 99% of their DNA with chimps suggests that these two primate lineages split apart more recently. Because words don't have DNA, researchers use cognates found in different languages today to reconstruct the ancestral "protowords." Historical linguists have observed that over time, the sounds of words tend to change in regular patterns. For example, the p sound frequently changes to f, and the t sound to th—suggesting that the Latin word pater is, well, the father of the English word father. Linguists use these known rules to work backward in time, making a best guess at how the protoword sounded. They also track the rate at which words change. Using these phylogenetic principles, some researchers have dated many common words as far back as 9000 years ago. The ancestral language known as Proto-Indo-European, for example, gave rise to languages including Hindi, Russian, French, English, and Gaelic. © 2010 American Association for the Advancement of Science.
By BILL PENNINGTON BOSTON — The drumbeat of alarming stories linking concussions among football players and other athletes to brain disease has led to a new and mushrooming American phenomenon: the specialized youth sports concussion clinic, which one day may be as common as a mall at the edge of town. In the last three years, dozens of youth concussion clinics have opened in nearly 35 states — outpatient centers often connected to large hospitals that are now filled with young athletes complaining of headaches, amnesia, dizziness or problems concentrating. The proliferation of clinics, however, comes at a time when there is still no agreed-upon, established formula for treating the injuries. “It is inexact, a science in its infancy,” said Dr. Michael O’Brien of the sports concussion clinic at Boston Children’s Hospital. “We know much more than we once did, but there are lots of layers we still need to figure out.” Deep concern among parents about the effects of concussions is colliding with the imprecise understanding of the injury. To families whose anxiety has been stoked by reports of former N.F.L. players with degenerative brain disease, the new facilities are seen as the most expert care available. That has parents parading to the clinic waiting rooms. The trend is playing out vividly in Boston, where the phone hardly stops ringing at the youth sports concussion clinic at Massachusetts General Hospital. “Parents call saying, ‘I saw a scary report about concussions on Oprah or on the ‘Doctors’ show or Katie Couric’s show,’ ” Dr. Barbara Semakula said, describing a typical day at the clinic. “Their child just hurt his head, and they’ve already leapt to the worst possible scenarios. It’s a little bit of a frenzy out there.” © 2013 The New York Times Company
by Lizzie Wade If you were a rat living in a completely virtual world like in the movie The Matrix, could you tell? Maybe not, but scientists studying your brain might be able to. Today, researchers report that certain cells in rat brains work differently when the animals are in virtual reality than when they are in the real world. The neurons in question are known as place cells, which fire in response to specific physical locations in the outside world and reside in the hippocampus, the part of the brain responsible for spatial navigation and memory. As you walk out of your house every day, the same place cell fires each time you reach the shrub that's two steps away from your door. It fires again when you reach the same place on your way back home, even though you are traveling in the opposite direction. Scientists have long suspected that these place cells help the brain generate a map of the world around us. But how do the place cells know when to fire in the first place? Previous research showed that the cells rely on three different kinds of information. First, they analyze "visual cues," or what you see when you look around. Then, there are what researchers call "self-motion cues." These cues come from how your body moves in space and are the reason you can still find your way around a room with the lights out. The final type of information is the "proximal cues," which encompass everything else about the environment you're in. The smell of a bakery on your way to work, the sounds of a street jammed with traffic, and the springy texture of grass in a park are all proximal cues. © 2010 American Association for the Advancement of Science.
By Christie Wilcox What does your voice say about you? Our voices communicate information far beyond what we say with our words. Like most animals, the sounds we produce have the potential to convey how healthy we are, what mood we’re in, even our general size. Some of these traits are important cues for potential mates, so much so that the sound of your voice can actually affect how good looking you appear to others. Which, really, brings up one darn good question: what makes a voice sound sexy? To find out, a team spearheaded by University College London researcher Xi Yu created synthetic male and female voices and altered their pitch, vocal quality and formant spacing (an acoustics term related to the frequencies of sound), the last of which is related to body size. They also adjusted the voices to be normal (relaxed), breathy, or pressed (tense). Through several listening experiments, they asked participants of the opposite gender to say which voice was the most attractive and which sounded the friendliest or happiest. The happiest-sounding voices were those with higher pitch, whether male or female, while the angriest were those with dense formants, indicating large body size. As for attractiveness, the men preferred a female voice that is high-pitched, breathy and had wide formant spacing, which indicates a small body size. The women, on the other hand, preferred a male voice with low pitch and dense formant spacing, indicative of larger size. But what really surprised the scientists is that women also preferred their male voices breathy. “The breathiness in the male voice attractiveness rating is intriguing,” explain the authors, “as it could be a way of neutralizing the aggressiveness associated with a large body size.”
Posted by Christy Ullrich Elephants may use a variety of subtle movements and gestures to communicate with one another, according to researchers who have studied the big mammals in the wild for decades. To the casual human observer, a curl of the trunk, a step backward, or a fold of the ear may not have meaning. But to an elephant—and scientists like Joyce Poole—these are signals that convey vital information to individual elephants and the overall herd. Biologist and conservationist Joyce Poole and her husband, Petter Granli, both of whom direct ElephantVoices, a charity they founded to research and advocate for conservation of elephants in various sanctuaries in Africa, have developed an online database decoding hundreds of distinct elephant signals and gestures. The postures and movements underscore the sophistication of elephant communication, they say. Poole and Granli have also deciphered the meaning of acoustic communication in elephants, interpreting the different rumbling, roaring, screaming, trumpeting, and other idiosyncratic sounds that elephants make in concert with postures such as the positioning and flapping of their ears. Poole has studied elephants in Africa for more than 37 years, but only began developing the online gestures database in the past decade. Some of her research and conservation work has been funded by the National Geographic Society. “I noticed that when I would take out guests visiting Amboseli [National Park in Kenya] and was narrating the elephants’ behavior, I got to the point where 90 percent of the time, I could predict what the elephant was about to do,” Poole said in an interview. “If they stood a certain way, they were afraid and were about to retreat, or [in another way] they were angry and were about to move toward and threaten another.” © 1996-2012 National Geographic Society.
By Lucy Wallis BBC News Abby and Brittany Hensel are conjoined twins determined to live the normal, active life of outgoing 20-somethings anywhere. They have been to university, they travel, they have jobs. But how easy is it for two people to inhabit one body? Like most 23-year-olds Abby and Brittany Hensel love spending time with their friends, going on holiday, driving, playing sport such as volleyball and living life to the full. The identical, conjoined twins from Minnesota, in the United States, have graduated from Bethel University and are setting out on their career as primary school teachers with an emphasis on maths. Although they have two teaching licences, there is one practical difference when it comes to the finances. "Obviously right away we understand that we are going to get one salary because we're doing the job of one person," says Abby. "As maybe experience comes in we'd like to negotiate a little bit, considering we have two degrees and because we are able to give two different perspectives or teach in two different ways." "One can be teaching and one can be monitoring and answering questions," says Brittany. "So in that sense we can do more than one person." Their friend Cari Jo Hohncke has always admired the sisters' teamwork. "They are two different girls, but yet they are able to work together to do the basic functions that I do every day that I take for granted," says Hohncke. BBC © 2013
Link ID: 18072 - Posted: 04.25.2013
By Meghan Holohan Need to remember some important facts for that big presentation at work? Clench your right hand while preparing to remember. When giving that talk, ball up your left hand and you’ll call to mind those details, no problem. That’s the finding from a new study authored by Ruth Propper, an associate professor and director of the cerebral lateralization laboratory at Montclair State University. Propper has long been intrigued by how body movements impact how the brain works. While most people realize that the brain influences the body (the brain tells your arm there is an itch, and you feel it), less is understood about how the body sways the brain. Past research suggests that clenching our hands can evoke emotions. When people ball up their right hands, for example, the left sides of their brains become more active, causing what’s known as “approach emotions,” feelings such as happiness or excitement. By squeezing the left hand, people engage the right side of the brain, which controls “withdrawal emotions” such as introversion, fear, or anxiety. (It probably seems like these might be less useful, but they come in handy in dangerous situations.) Propper theorized that if clenching hands impacted feelings, these gestures might influence the brain in other ways. © 2013 NBCNews.com
by Tanya Lewis, The lip-smacking vocalizations gelada monkeys make are surprisingly similar to human speech, a new study finds. Many nonhuman primates demonstrate lip-smacking behavior, but geladas are the only ones known to make undulating sounds, known as "wobbles," at the same time. (The wobbling sounds a little like a human hum would sound if the volume were being turned on and off rapidly.) The findings show that lip-smacking could have been an important step in the evolution of human speech, researchers say. "Our finding provides support for the lip-smacking origins of speech because it shows that this evolutionary pathway is at least plausible," Thore Bergman of the University of Michigan in Ann Arbor and author of the study published today (April 8) in the journal Current Biology,said in a statement. "It demonstrates that nonhuman primates can vocalize while lip-smacking to produce speechlike sounds." NEWS: Lip Smacks of Monkeys Prelude to Speech? Lip-smacking -- rapidly opening and closing the mouth and lips -- shares some of the features of human speech, such as rapid fluctuations in pitch and volume. (See Video of Gelada Lip-Smacking) Bergman first noticed the similarity while studying geladas in the remote mountains of Ethiopia. He would often hear vocalizations that sounded like human voices, but the vocalizations were actually coming from the geladas, he said. He had never come across other primates who made these sounds. But then he read a study on macaques from 2012 revealing how facial movements during lip-smacking were very speech-like, hinting that lip-smacking might be an initial step toward human speech. © 2013 Discovery Communications, LLC.
By Janice Lynch Schuster, My grandmother, who is 92, recently reported that she’d seen three giraffes in her Midwest back yard. She is otherwise sharp (and also kind and funny), but the giraffe episode was further evidence of the mild cognitive impairment that has been slowly creeping into her life. The question for my family has become: How should we respond? One of my sisters tried humor. (“Grandmom, I didn’t know you drank in the middle of the day!”) My father suggested that they were deer (to which she replied, “I’m 92 years old, and I know a giraffe when I see one.”) I tried to learn more about what, exactly, the giraffes were doing out there. (She didn’t seem to know, saying only that “the light shimmered.”) Communicating with a family member who has cognitive impairment can be frustrating and disheartening, even downright depressing for patient and caregiver alike. And it’s a problem faced by a growing number of Americans. According to a report published last week, about 4.1 million Americans have dementia. Alzheimer’s, one of the many forms of dementia, is the most expensive disease in the United States, costing $157 billion to $215 billion a year — more than heart disease and cancer, according to the study, which was sponsored by the National Institute on Aging. As baby boomers reach old age, these numbers are expected to increase dramatically. A number of techniques can not only reduce the frustration but also create new ways of connecting. Among the most effective and popular among experts is the “validation method,” a practice pioneered by geriatric social worker and researcher Naomi Feil in the 1980s. © 1996-2013 The Washington Post
By Bruce Bower Babies take a critical step toward learning to speak before they can say a word or even babble. By 3 months of age, infants flexibly use three types of sounds — squeals, growls and vowel-like utterances — to express a range of emotions, from positive to neutral to negative, researchers say. Attaching sounds freely to different emotions represents a basic building block of spoken language, say psycholinguist D. Kimbrough Oller of the University of Memphis in Tennessee and his colleagues. Any word or phrase can signal any mental state, depending on context and pronunciation. Infants’ flexible manipulation of sounds to signal how they feel lays the groundwork for word learning, the scientists conclude April 1 in the Proceedings of the National Academy of Sciences. Language evolution took off once this ability emerged in human babies, Oller proposes. Ape and monkey researchers have mainly studied vocalizations that have one meaning, such as distress calls. “At this point, the conservative conclusion is that the human infant at 3 months is already vocally freer than has been demonstrated for any other primate at any age,” Oller says. Oller’s group videotaped infants playing and interacting with their parents in a lab room equipped with toys and furniture. Acoustic analyses identified nearly 7,000 utterances made by infants up to 1 year of age that qualified as laughs, cries, squeals, growls or vowel-like sounds. © Society for Science & the Public 2000 - 2013
by Sid Perkins The electric fields that build up on honey bees as they fly, flutter their wings, or rub body parts together may allow the insects to talk to each other, a new study suggests. Tests show that the electric fields, which can be quite strong, deflect the bees' antennae, which, in turn, provide signals to the brain through specialized organs at their bases. Scientists have long known that flying insects gain an electrical charge when they buzz around. That charge, typically positive, accumulates as the wings zip through the air—much as electrical charge accumulates on a person shuffling across a carpet. And because an insect's exoskeleton has a waxy surface that acts as an electrical insulator, that charge isn't easily dissipated, even when the insect lands on objects, says Randolf Menzel, a neurobiologist at the Free University of Berlin in Germany. Although researchers have suspected for decades that such electrical fields aid pollination by helping the tiny grains stick to insects visiting a flower, only more recently have they investigated how insects sense and respond to such fields. Just last month, for example, a team reported that bumblebees may use electrical fields to identify flowers recently visited by other insects from those that may still hold lucrative stores of nectar and pollen. A flower that a bee had recently landed on might have an altered electrical field, the researchers speculated. Now, in a series of lab tests, Menzel and colleagues have studied how honey bees respond to electrical fields. In experiments conducted in small chambers with conductive walls that isolated the bees from external electrical fields, the researchers showed that a small, electrically charged wand brought close to a honey bee can cause its antennae to bend. Other tests, using antennae removed from honey bees, indicated that electrically induced deflections triggered reactions in a group of sensory cells, called the Johnston's organ, located near the base of the antennae. In yet other experiments, honey bees learned that a sugary reward was available when they detected a particular pattern of electrical field. © 2010 American Association for the Advancement of Science
Michael Corballis, professor of cognitive neuroscience and psychology at the University of Auckland in New Zealand, responds: Although teaching people to become ambidextrous has been popular for centuries, this practice does not appear to improve brain function, and it may even harm our neural development. Calls for ambidexterity were especially prominent in the late 19th and early 20th centuries. For instance, in the early 20th century English propagandist John Jackson established the Ambidextral Culture Society in pursuit of universal ambidexterity and “two-brainedness” for the betterment of society. This hype died down in the mid-20th century as benefits of being ambidextrous failed to materialize. Given that handedness is apparent early in life and the vast majority of people are right-handed, we are almost certainly dextral by nature. Recent evidence even associated being ambidextrous from birth with developmental problems, including reading disability and stuttering. A study of 11-year-olds in England showed that those who are naturally ambidextrous are slightly more prone to academic difficulties than either left- or right-handers. Research in Sweden found ambidextrous children to be at a greater risk for developmental conditions such as attention-deficit hyperactivity disorder. Another study, which my colleagues and I conducted, revealed that ambidextrous children and adults both performed worse than left- or right-handers on a range of skills, especially in math, memory retrieval and logical reasoning. © 2013 Scientific American
By ANAHAD O'CONNOR Slurred and incoherent speech is one of the classic signs of a stroke. But new research finds that another symptom may be garbled and disjointed text messages, which could provide early clues to the onset of a stroke. In Detroit, doctors encountered a 40-year-old patient who had no trouble reading, writing or understanding language. His only consistent problem was that he had lost the ability to type coherent text messages on his phone. An imaging scan showed that he had suffered a mild ischemic stroke, caused by a clot or blockage in his brain. The case represents at least the second instance of what doctors are calling “dystextia.” In December, a report in The Archives of Neurology described a 25-year-old pregnant woman whose husband grew concerned after she sent him a series of incoherent text messages. Doctors found that the woman had also been experiencing weakness in her right arm and leg, and that she had earlier had difficulty filling out an intake form at her obstetrician’s office. The case in Detroit was particularly unusual because garbled texting appeared to be the only conspicuous problem, at least initially, said Dr. Omran Kaskar, a senior neurology resident at Henry Ford Hospital who treated the patient in late 2011. “Stroke patients usually present with multiple neurologic deficits,” he said. The findings suggest that text messaging may be a unique form of language controlled by a distinct part of the brain. And because texts are time-stamped, they may potentially be useful as a way of helping doctors determine precisely when a patient’s stroke symptoms began. The patient was a businessman who had traveled to southeast Michigan one evening for a work trip. Shortly after midnight, the man sent text messages to his wife that were disjointed and nonsensical – and not because he was using shorthand. Copyright 2013 The New York Times Company
Coaches should pull athletes with a suspected head injury immediately until a health professional trained in concussions checks them out, according to new medical guidelines. The American Academy of Neurology updated its guidelines on Monday for evaluating and managing athletes with concussion. It’s the group's first update since 1997. Demonstration of a test with patients that have suffered concussions. It's likely that concussion risk is greater for female athletes playing soccer, according to new guidelines.Demonstration of a test with patients that have suffered concussions. It's likely that concussion risk is greater for female athletes playing soccer, according to new guidelines. (Keith Srakocic/Associated Press) "If in doubt, sit it out," said Dr. Jeffrey Kutcher with the University of Michigan Medical School in Ann Arbor and a member of the academy, in a release. "Being seen by a trained professional is extremely important after a concussion. If headaches or other symptoms return with the start of exercise, stop the activity and consult a doctor. You only get one brain; treat it well." Players should return to the rink, field or pitch slowly and only after acute signs and symptoms, such as headache, sensitivity to light and sound or changes in memory and judgment, are gone. For ice hockey, the guidelines said bodychecking is likely to increase the risk of sport-related concussion. In peewee hockey, bodychecking is likely to be a risk factor for a more severe concussion that prolongs the return to play. © CBC 2013
Keyword: Brain Injury/Concussion
Link ID: 17917 - Posted: 03.19.2013
By Jon Lieff Traditionally, we have understood the immune system and the nervous system as two distinct and unrelated entities. The former fights disease by responding to pathogens and stimulating inflammation and other responses. The latter directs sensation, movement, cognition and the functions of the internal organs. For some, therefore, the recent discovery that left-sided brain lesions correlate with an increased rate of hospital infections is difficult to understand. However, other recent research into the extremely close relationship between these two systems makes this finding comprehensible. A study, published in the March 2013 issue of Archives of Physical Medicine and Rehabilitation, looked at more than 2,000 hospital patients with brain lesions from either stroke or traumatic brain injury. They looked at how many of these brain-injured patients contracted infections within 2 to 3 days of admission. Of those patients who developed infections, 60% had left-sided lesions. The authors concluded that an unknown left-sided brain/immune network might influence infections. But why would the left side of the brain affect immunity? The nervous and immune systems are quite different in their speed and mode of action. The two major immune systems, innate and adaptive, are both wireless—they communicate through cell-to-cell contact, secreted signals, and antigen-antibody reactions. The innate system is the first responder, followed by the slower adaptive response. The nervous system, on the other hand, is wired for much more rapid communication throughout the body. It turns out that the two work surprisingly closely together. © 2013 Scientific American
By Dwayne Godwin and Jorge Cham Dwayne Godwin is a neuroscientist at the Wake Forest University School of Medicine. Jorge Cham draws the comic strip Piled Higher and Deeper at www.phdcomics.com. © 2013 Scientific American
SAN FRANCISCO (AP) — The future is unclear for a heart device aimed at preventing strokes in people at high risk of them because of an irregular heartbeat. Early results from a key study of the device, Boston Scientific’s Watchman, suggested it is safer than previous testing found, but may not be better than a drug that is used to prevent strokes, heart-related deaths and blood clots in people with atrial fibrillation in the long term. Atrial fibrillation, a common heart arrhythmia that affects millions of Americans, causes blood to pool in a small pouch. Clots can form and travel to the brain, causing a stroke. The usual treatment is blood thinners like warfarin, sold as Coumadin and other brands. But they have their own problems and some are very expensive. The Watchman is intended to be a permanent solution that would not require people to take medication for the rest of their lives. It is a tiny expandable umbrella that plugs the pouch of blood, and is inserted without surgery, via a tube pushed into a vein. A study four years ago indicated the device was at least as good at preventing strokes as warfarin, but the procedure to implant it led to strokes in some patients. The Food and Drug Administration required another test of its safety and effectiveness. The new study was led by Dr. David Holmes Jr. of the Mayo Clinic in Rochester, Minn. He and the clinic have a financial stake in the device. © 2013 The New York Times Company
Link ID: 17886 - Posted: 03.11.2013
by Lizzie Wade With its complex interweaving of symbols, structure, and meaning, human language stands apart from other forms of animal communication. But where did it come from? A new paper suggests that researchers look to bird songs and monkey calls to understand how human language might have evolved from simpler, preexisting abilities. One reason that human language is so unique is that it has two layers, says Shigeru Miyagawa, a linguist at the Massachusetts Institute of Technology (MIT) in Cambridge. First, there are the words we use, which Miyagawa calls the lexical structure. "Mango," "Amanda," and "eat" are all components of the lexical structure. The rules governing how we put those words together make up the second layer, which Miyagawa calls the expression structure. Take these three sentences: "Amanda eats the mango," "Eat the mango, Amanda," and "Did Amanda eat the mango?" Their lexical structure—the words they use—is essentially identical. What gives the sentences different meanings is the variation in their expression structure, or the different ways those words fit together. The more Miyagawa studied the distinction between lexical structure and expression structure, "the more I started to think, 'Gee, these two systems are really fundamentally different,' " he says. "They almost seem like two different systems that just happen to be put together," perhaps through evolution. One preliminary test of his hypothesis, Miyagawa knew, would be to show that the two systems exist separately in nature. So he started studying the many ways that animals communicate, looking for examples of lexical or expressive structures. © 2010 American Association for the Advancement of Science.