How and why we yarn still presents problems for researchers in an area which has only recently been opened up to study

When Robert R Provine began studying yawning in the 1960s, it was difficult for him to convince research students of the merits of 'yawning science1. Although it may appear quirky to some, Provine's decision to study yawning was a logical extension of his research in developmental neuroscience.

The verb 'to yawn' is derived from the Old English ganien or ginian, meaning to gape or open wide. But in addition to gaping jaws, yawning has significant features that are easy to observe and analyse. Provine 'collected' yawns to study by using a variation of the contagion response*. He asked people to 'think about yawning' and, once they began to yawn to depress a button and that would record from the start of the yawn to the exhalation at its end.

Provine's early discoveries can be summanized as follows: the yawn is highly stereotyped but not invariant in its duration and form. It is an excellent example of the instinctive 'fixed action pattern' of classical animal-behavior study, or ethology. It is not a reflex (short-duration, rapid, proportional response to a simple stimulus), but, once started, a yawn progresses with the inevitability of a sneeze. The standard yawn runs its course over about six seconds on average, but its duration can range from about three seconds to much longer than the average. There are no half-yawns: this is an example of the typical intensity of fixed action patterns and a reason why you cannot stifle yawns. Just like a cough, yawns can come in bouts with a highly variable inter-yawn interval, which is generally about 68 seconds but rarely more than 70. There is no relation between yawn frequency and duration: producers of short or long yawns do not compensate by yawning more or less often. Furthermore, Provine's hypotheses about the form and function of yawning can be tested by three informative yawn variants which can be used to look at the roles of the nose, the mouth and the jaws.

i) The closed nose yawn

Subjects are asked to pinch their nose closed when they feel themselves start to yawn. Most subjects report being able to perform perfectly normal closed nose yawns. This indicates that the inhalation at the onset of a yawn, and the exhalation at its end, need not involve the nostrils - the mouth provides a sufficient airway.

ii) The clenched teeth yawn

Subjects are asked to clench their teeth when they feel themselves start to yawn but allow themselves to inhale normally through their open lips and clenched teeth. This variant gives one the sensation of being stuck mid­yawn. This shows that gaping of the jaws is an essential component of the fixed action pattern of the yawn, and unless it is accomplished, the program (or pattern) will not run to completion. The yawn is also shown to be more than a deep breath, because, unlike normal breathing, inhalation and exhalation cannot be performed so well through the clenched teeth as through the nose.

iii) The nose yawn

This variant tests the adequacy of the nasal airway to sustain a yawn. Unlike normal breathing, which can be performed equally well through mouth or nose, yawning is impossible via nasal inhalation alone. As with the clenched teeth yawn, the nose yawn provides the unfulfilling sensation of being stuck in mid-yawn. Exhalation, on the other hand, can be accomplished equally well through nose or mouth. Through thin methodology Provine demonstrated that inhalation through the oral airway and the gaping of jaws are necessary for normal yawns. The motor program for yawning will not run to completion without feedback that these parts of the program have been accomplished.

But yawning is a powerful, generalized movement that involves much more than airway maneuvres and jaw-gaping. When yawning you also stretch your facial muscles, tilt your head back, narrow or close your eyes, produce tears, salivate, open the Eustachian tubes of your middle ear and perform many other, yet unspecified, cardiovascular and respiratory acts. Perhaps the yawn shares components with other behaviour. For example, in the yawn a kind of 'slow sneeze1 or is the sneeze a 'fast yawn'? Both share common respiratory and other features including jaw gaping, eye closing and head tilting.

Yawning and stretching share properties and may be performed together as parts of a global motor complex. Studies by J I p deVries et al. in the early 1980s, charting movement in the developing foet US using ultrasound, observed a link between yawning and stretching. The most extraordinary demonstration of the yawn-stretch linkage occurs in many people paralyzed on one side of their body because of brain damage caused by a stroke, the prominent British neurologist Sir Francis Walshe noted in 1923 that when these people yawn, they are startled and mystified to observe that their otherwise paralyzed arm rises and flexes automatically in what neurologists term an 'associated response'. Yawning apparently activates undamaged, unconsciously controlled connections between the brain and the motor system, causing the paralyzed limb to move. It is not known whether the associated response is a positive prognosis for recovery, nor whether yawning is therapeutic for prevention of muscular deterioration.

Provine speculated that, in general, yawning may have many functions, and selecting a single function from the available options may be an unrealistic goal. Yawning appears to be associated with a change of behavioral state, switching from one activity to another. Yawning is also a reminder that ancient and unconscious behavior linking US to the animal world lurks beneath the veneer of culture, rationality and language.

Ordinary citizens have been using the internet to draw attention to the lack of healthy eating options in inner cities

Over the last few months, a survey has been carried out of over 200 greengrocers and convenience stores in Crown Heights, a neighborhood in Brooklyn, New York. As researchers from the Brooklyn Food Association enter the details, colorful dots appear on their online map, which display the specific location of each of the food stores in a handful of central Brooklyn neighborhoods. Clicking on a dot will show you the store's name and whether it carries fresh fruit and vegetables, wholegrain bread, low-fat dairy and other healthy options.

The researchers plan eventually to survey the entire borough of Brooklyn. ‘We want to get to a more specific and detailed description of what that looks like’, says Jeffrey Heehs, who leads the project. He hopes it will help residents find fresh food in urban areas where the stores sell mostly packaged snacks or fast food, areas otherwise known as food deserts. The aim of the project is also to assist government officials in assessing food availability, and in forming future policies about what kind of food should be sold and where.

In fact, the Brooklyn project represents the intersection of two growing trends: mapping fresh food markets in US cities, and private citizens creating online maps of local neighborhood features. According to Michael Goodchild, a geographer at the University of California at Santa Barbara, citizen map makers may make maps because there is no good government map, or to record problems such as burned-out traffic lights.

According to recent studies, people at higher risk of chronic disease and who receive minimal incomes for the work they do, frequently live in neighborhoods located in food deserts. But how did these food deserts arise? Linda Alwitt and Thomas Donley, marketing researchers at DePaul University in Chicago, found that supermarkets often can’t afford the amount of land required for their stores in cities. City planning researcher Cliff Guy and colleagues at the University of Leeds in the UK found in 2004 that smaller urban groceries tend to close due to competition from suburban supermarkets.

As fresh food stores leave a neighborhood, residents find it harder to eat well and stay healthy. Food deserts are linked with lower local health outcomes, and they may be a driving force in the health disparities between lower-income and affluent people in the US. Until recently, the issue attracted little national attention, and received no ongoing funding for research.

Now, more US cities are becoming aware of their food landscapes. Last year, the United States Department of Agriculture launched a map of where food stores are located in all the US counties. Mari Gallagher, who runs a private consulting firm, says her researchers have mapped food stores and related them to health statistics for the cities of Detroit, Chicago, Cincinnati and Washington, D.c. These maps help cities identify where food deserts are and, occasionally, have documented that people living in food deserts have higher rates of diet-related diseases.

The Brooklyn project differs in that it’s run by a local core of five volunteers who have worked on the project for the past year, rather than trained, academic researchers. To gather data, they simply go to individual stores with pre-printed surveys in hand, and once the storekeeper's permission has been obtained, check off boxes on their list against the products for sole in the store. Their approach to data collection and research has been made possible by technologies such as mapping software and GPS-related smart phones, Google Maps and OpenStreeMap, an open-source online map with a history of involvement in social issues. Like Brooklyn Food Association volunteers, many citizen online map makers use maps to bring local problems to official attention, Goodchild says. Heehs, the mapping project leader, says that after his group gathers more data, it will compare neighborhoods, come up with solutions to address local needs, and then present them to New York City officials. Their website hasn’t caught them much local or official attention yet, however. It was launched only recently, but its creators haven’t yet set up systems to see who’s looking at it.

Experts who visited the Brooklyn group’s site were optimistic but cautious. ‘This kind of detailed information could be very useful’ says Michele Ver Ploeg, an economist for the Department of Agriculture. To make the map more helpful to both residents and policy makers, she would like to see price data for healthy products, too. Karen Ansel, a registered dietician and a spokesperson for the American Dietetic Association, found the site confusing to navigate. ‘That said, with this information in place the group has the tools to build a more user-friendly site that could be ... very helpful to consumers’, she says. ‘The group also should ensure their map is available to those who don’t have internet access at home’, she adds. In fact, a significant proportion of Brooklyn residents don’t have internet access at home and 8 percent rely on dial-up service, instead of high-speed internet access, according to Gretchen Maneval, director of Brooklyn College’s Center for the study of Brooklyn. ‘It’s still very much a work in progress’, Heehs says of the online map. They’ll start advertising it online and by email to other community groups, such as urban food garden associations, next month. He also hopes warmer days in the spring will draw out fresh volunteers to spread awareness and to finish surveying, as they have about two-thirds of Brooklyn left to cover.

Huge earth and rock mounds rise out of the desert of the Supe Valley near the coast of Peru in South America. These immense mounds appear simply to be part of the geographical landscape in this arid region squeezed between the Pacific Ocean and the Andes mountains.But looks deceive. These are actually human-made pyramids strong evidence indicates they are the remains of a city known as Caral that flourished nearly 5,000 years ago. It true, it would be the oldest known urban center in the America and among the most ancient in the world.

Research undertaken by Peruvian archaeologist Ruth Shady suggests that the 150-acre plex of pyramids, plazas and residential buildings was a thriving metropolis when Egypt's great pyramids were still being built. Though discovered in 1905, for years Caral attracted little attention, largely because archaeologists believed the structures were rainy recent. But the monumental scale of the pyramids had long interested Shady, who began excavations at the site in 1996, about 22 kilometers from the coast and 190 kilometers north of Peru's capital city of Lima.

Shady and her crew searched for broken remains of the pots and containers that most such sites contain. Not finding any only made her more excited: it meant Caral could be what archaeologists term pre-ceramic, that is, existing before the advent in the area of pot-firing techniques. Shady's team undertook the task of excavating Piramide Mayor, the largest of the pyramids. After carefully clearing away many hundreds of years' worth of rubble and sand, they identified staircases, walls covered with remnants of colored plaster, and brickwork. In the foundations, they found the remains of grass-like reeds woven into bags. The original workers, she surmised, must have filled these bags with stones from a nearby quarry and laid them atop one another inside retaining walls, gradually giving rise to the pyramid's immense structure. Shady had samples of the reeds subjected to radiocarbon dating and found that the reeds were 4,600 years old. This evidence indicated that Caral was, in fact, more than 1,000 years older than what had previously been thought to be the oldest urban center in the Americas.

What amazed archaeologists was not just the age, but the complexity and scope of Caral. Piramide Mayor alone covers an area nearly the size of four football fields and is 18 meters tall. A nine-meter-wide staircase rises from a circular plaza at the foot of the pyramid, passing over three terraced levels until it reaches the top. Thousands of manual laborers would have been needed to build such a project, not counting the many architects, craftsmen, and managers. Shady's team found the remains of a large amphitheater, containing almost 70 musical instruments made of bird and deer bones Clearly music plaved an important role in Caral's society. Around the perimeter of Caral are a series of smaller mounds and various buildings. These indicate a hierarchy of living arrangements: large, well-kept rooms atop pyramids for the elite, ground-level quarters for shabbier outlying dwellings for workers

But why had Caral been built in the first place? Her excavations convinced Shady that Caral once served as a trade center for the region, which extends from the rainforests of the Amazon to the high forests of the Andes. Shady found evidence of a rich trading environment, including seeds of the cocoa bush and necklaces of shells, neither of which was native to the immediate Caral area. This environment gave rise to people who did not take part in the production of food, allowing them to become priests and planners, builders and designers. Thus occupational specialization, elemental to an urban society, emerged.

But what sustained such a trading center and drew travelers to it? Was it food? Shady and her team found the bones of small edible fish, which must have come from the Pacific coast to the west, in the excavations. But they also found evidence of squash, sweet potatoes and beans having been grown locally. Shady theorized that Caral's early farmers diverted the area's rivers into canals, which still cross the Supe Valley today, to irrigate their fields.But because she found no traces of maize, which can be traded or stored and used in times of crop failure, she concluded that Caral's trade leverage was not based on stockpiling food supplies.

It was evidence of another crop in the excavations that gave Shady the best clue to Caral’s success. In nearly every excavated building, her team discovered evidence of cotton - seeds, fibers and textiles. Her theory fell into place when a large fishing net made of those fibers, unearthed in an unrelated dig on Peru's coast, turned out to be as old as Caral. 'The farmers of Caral grew the cotton that the fishermen needed to make their nets, Shady speculates. And the fishermen gave them shellfish and dried fish in exchange for these nets.' In essence, the people of Caral enabled fishermen to work with larger and more effective nets, which made the resources of the sea more readily available, and the fishermen probably used dried squash grown by the Caral people as flotation devices for their nets.