Is the Sahara on the move?

The southern fringe of the Sahara, known as the Sahel, is believed by some scientists to be advancing by as much as 9 miles (15km) a year. Horrifying reports of drought, starvation and death in Ethiopia, Somalia and Sudan have shocked the world. But is the Sahara really moving southwards or are the devastating crop failures being caused by politics and by bad management of land?

          
Global warming caused by increased carbon dioxide in the atmosphere from human activities is often blamed for the Sahel famines, but there is little proof. There is, however, plenty of evidence that the climate has fluctuated in log cycles over the past 2 million years. Stone Age paintings depict antelopes, elephants and lions at Tassili N’Ajjer in the Algerian Sahara. And roman cities all over North Africa, such as Leptis Magna in Libya, once ruled over the granaries of the Roman Empire where fields grew grain – without any need for irrigation – to be exported to Rome. Now the former farms are dusty plains of semi-desert. This is part of the natural climatic cycle – each cycle taking thousands of years – that is brought about by changes in the Earth’s orbit around the Sun. it is the same cycle that caused the Ice Ages, and could now be at work to cause the Sahara to march in the Sahel.

          
However, the growth of deserts can also be blamed on man’s treatment of the land. Cutting down trees and scrub to open up land for farming can expose soil to the ravages of erosion. Bad management of land on slopes, such as ploughing furrows up and down a hill instead of around it, can cause soil to be washed down or blown away. Bad farming practice in the American Midwest during the 1930s reduced an area of farm land nearly the size of England to a dust bowl. This type of soil erosion happens on the edges of the Sahara when grassland with poor oil is ploughed up to grow crops.

         
 ‘Over-grazing’ by farm animals is also alleged to cause erosion, but the evidence is inconclusive. Animals can actually encourage plant growth by fertilizing the soil with their manure. Nomadic farmers, who have roamed and flourished in the deserts for thousands of years, never stay in one place for long. They move their flocks frequently, giving grass time to grow again. Only if they are stopped from moving on will their animals over-graze the land.

         
In the short term, politics are probably as strong a factor as climate change in causing the Sahel famines. Wars in Ethiopia and Somalia have forced refugees to migrate into semi-arid land that cannot support them. Social and economic pressures, such as government settlement policies, have also forced people to give up traditional nomadic farming and change to static Western farming methods that are not suited to the land and climate, and so lead to ‘dust bowls’.

Climatic change is an easy scapegoat for countries suffering from famine, but the case has not yet been proved.

The deadly traps laid by carnivorous plants

The usual order of events in nature is that plants manufacture their own food through photosynthesis, while animals either eat plants or other animals. But more than 500 plant species are exceptions to this order: they eat animals. All grow in soil or water that contains little or no nitrogen, an element vital for plant growth, and animals provide that missing nourishment.

Pitcher plants, for example, a family of climbing vines found throughout the tropics of the Old World, grow pitcher- or urn-shaped traps, some large enough to capture a rat. Although they occasionally digest small mammals or reptiles, they are designed for eating insects, which enter the trap under the illusion that it is a flower, attracted by its scent or by a supply of false nectar. Once over the pitcher's rim, they slither helplessly down to the bottom, where downward-pointing spikes prevent escape. The plant then secretes an acid and digestive enzymes to break down the body of its victim. The pitcher plant's distinctive lid serves as a lure to flying insects and as an umbrella to prevent the pitcher from filling up with rainwater. Some species, however, do let rainwater enter their pitchers, thus drowning their prey, instead of killing it with acid.

Trigger hairs

In mechanical terms, the most sophisticated traps of all are those of the bladderworts, a successful and varied group established throughout the world. They are mainly water plants, which, depending on their size, feed on anything from single-celled protozoans to small fish. Among their branching underwater leaves grow tiny bladders, each fitted with an inward-opening trap door. Sticking out from the entrance are hairs, and any creature brushing against these make the trap fly open. As water rushes in to fill the bladder, it sucks the hapless animal in with it. The bladder then uses special glands to extrqact the water, allowing the door to close again, and leaving the animal trapped.

Water Woes

A picturesque mountain hamlet in Meghalaya (a province in India) may hold the world record for rainfall, but water is currently the scarcest commodity. Known to the outside world as Cherrapunji, now renamed Sohra, 56 km from Shillong, this town of about 150,000 inhabitants is the world's rainiest place. Perched on the edge of a cliff 4192 feet above the sea level, Cherrapunji overlooking the plains of Bangladesh, holds various world records like highest rainfall in 12 months, 11 months, six months, one month and 15 days.
From August 1860 to July 1861, Cherrapunji recorded 26.5 metre of rainfall and during July in 1861 it was lashed by 9.3 metre of rainfall -- the two records still exist.For a majority of the people who belong to the dominant Khasi race, the fickle weather is what they look forward to. But despite the torrential rain, water is the scarcest of commodities for locals. The South-West monsoon and thunderstorms soak the village from June to September. But during winter, the natural springs and streams dry up and crops suffer. "It is an irony of sorts that the world's rainiest place is, in reality, a wet desert where people have to buy drinking water," Robert Jrwa, a Government official, said.Locals in this predominantly matrilineal society go to distant places and streams downhill to fetch drinking water during winter. Water tapped from streams and supplied through pipelines to the village is inadequate. "We often have to buy drinking water," Sweety Diengdoh, a housewife, said.A jerrycan of water costs anything between Rs 5 to Rs 10. The Guinness Book of World Records lists Mawsynram, also in the State, as getting the highest rainfall. Indian meteorologists, however, say that not only is Sohra getting the maximum rain, but it has also been getting more rainfall in the past decade. "Cherrapunji's record of being the world's rainiest place continues with the village lashed by heavier rains than before," an official of the Regional Meteorological Centre said."People are talking about global warming and there are apprehensions that Sohra might cease to be the world's rainiest place. But the rainfall data indicate that the rain God is quite happy to lash the region," the meteorologist said. But Cherrapunji is now showing signs of desertification as incessant rain wash away the thin layer of soil, leaving very little topsoil in both villages. "With no soil surface to soak the rainwater, most of the rainfall gets quickly discharged resulting in negligible base flows in the streams during winter. This leads to no stored underground water to draw from," a local soil scientist said. Due to lack of topsoil, there is no vegetation in the area. Experts say wanton destruction of the forest cover could be responsible for the yearly drought. The once-thick pine forest is lost and official figures suggest there could be less than ten per cent of the forest cover left. "By denuding the forest cover, villagers invite nature's wrath and the only way to strike a balance is by carrying on afforestation drives in the area," former Meghalaya Geology and Mining Minister DP Iangjuh said. For close to 180 years, it was known as Cherrapunji to the outside world.Now the State Government, under sustained lobbying for decades by the nearly 150,000 tribal Khasi inhabitants, decided to rename Cherrapunji as Sohra -- locals always referred to it as Sohra, expect for official communications. "Sohra is the actual name of this village, but the British rulers tweaked the local name unable to pronounce it correctly and started saying as Cherra....some of the Bengali bureaucrats later added 'punjo,' which means a cluster, to make it Cherrapunji," 82-year-old Marbaniang, a retired schoolteacher, said. Lighting his antique tobacco-filled pipe near the famous Mawsmai cave, five km off Sohra, Marbaniang said the fight to get the original name back was more of a sentimental issue for the locals. "How would you feel if someone for the sake of convenience changes your name from Tom to Harry? If I am Tom call me Tom and not Harry," he said. The British had made Sohra their regional headquarters in the 1830s with the area resembling very much like Scotland with rains and fogs enveloping this quaint little village. Meghalaya, meaning the land of the clouds, later earned the sobriquet from the British as the Scotland of the East for its cool clime. It would take time for the Guinness Book of Records to correct the name, but this village is listed as getting the highest rainfall.

Tree Grown From 2,000-Year-Old Seed

Just over three years old and about four-feet tall, Methuselah is growing well. "It's lovely," Dr. Sarah Sallon said of the date palm, whose parents may have provided food for the besieged Jews at Masada some 2,000 years ago.
The little tree was sprouted in 2005 from a seed recovered from Masada, where rebelling Jews committed suicide rather than surrender to Roman attackers.
Radiocarbon dating of seed fragments clinging to its root, as well as other seeds found with it that didn't sprout, indicate they were about 2,000 years old -- the oldest seed known to have been sprouted and grown.
Sallon, director of the Louis L. Borick Natural Medicine Research Center at Hadassah Medical Organization in Israel, updates the saga of Methuselah in Friday's edition of the journal Science.
One thing they don't know yet is whether it's a boy or girl. Date palms differ by sex, but experts can't tell the difference until the tree is six or seven years old, Sallon said.
She hopes there's a chance to use it to restore the extinct Judean date palm, once prized not only for its fruit but also for medicinal uses.
The researchers have had a look at the plant's DNA, however, and found it shares just over half its genes with modern date cultivars.
"Part of our project is to preserve ancient knowledge of how plants were used," Sallon said in a telephone interview. "To domesticate them so we have a ready source of raw material."
Her Middle Eastern Medicinal Plant Project is working to conserve and reintroduce plants to the region where they once lived.
"Many species are endangered and becoming extinct. Raising the dead is very difficult, so it's better to preserve them before they become extinct," she said.
The oldest documented seed to be grown previously was a 1,300-year-old lotus, Sallon said.

Source : Associated Pess

Photo Courtesy : Science Magazine

Olympic Swimmers Learn From Sharks, Dolphins

When winning an Olympic gold medal in swimming is the goal, it helps to take inspiration from some of the best swimmers in the world -- sharks and dolphins -- and that is exactly what U.S. Olympic team swimmers have been doing as they train.

From suits to strokes, coaches, researchers and other advisers are making sure that their athletes benefit from fish and marine mammals' natural swimming abilities.

"Some of our athletes are now wearing what are called 'shark skin suits,'" Russell Mark, biomechanics coordinator for U.S.A. Swimming, told Discovery News.

"These aren't made of actual shark skin, of course, but they are slippery in feel, like sharks, and they make the wearer move faster than normal in the water by reducing friction and drag," he explained.

Mark also indicated that excelling at the dolphin kick can make or break a swimmer's race.
"This is when swimmers push off walls and swim underwater without moving their arms, very similar to how a dolphin swims," he said.

The move emulates how dolphins zoom through water by moving their flipper in an up and down motion. Sharks, in contrast, move side to side. Humans are mammals like dolphins and the up and down undulating motion propels people as it does dolphins. The dolphin kick is one of the most powerful moves among professional swimmers.

The move begins when an individual raises the hips, and then follows with a knee bend with flexed ankles. Put together, the sequence creates an undulating, whipping motion that runs all along the legs to the toes, minimizing water resistance and smoothly zooming the person forward.

"Our top swimmers -- Michael Phelps, Natalie Coughlin, Ryan Lochte and others -- all excel at dolphin kicking," Mark said. "Phelps is among the best in the world and probably gets as close to anyone as also having a more shark-like finesse in the water."

Sharks are some of the world's fastest swimmers. One impressive species is the shortfin mako, which has been reliably clocked at 31 miles per hour underwater. Everything about this fish is designed for swimming in short bursts of perfection. It has a streamlined body, a crescent-shaped tail supported by keels and a water-cutting, pointed snout.
Sharks, as fans of B-horror movies know, can also be quite hefty and large, yet still move quickly in the water.

"I think it has to do with surface area to volume ratio and drag," Neil Hammerschlag, University of Miami marine biologist, told Discovery News. "That is perhaps why larger, longer boats and longer airplanes move quicker."

Hammerschlag explained that big volumes have a smaller surface area to volume ratio and can move in a speedier fashion as a result, since surface drag can cause a boundary layer of water to sort of stick to the individual, potentially holding them back.

Over the years, Olympic swimmers have been beefing up by incorporating weight training into their schedules. This not only helps to combat drag, but also to simply improve power. Australian Libby Trickett, for example, has a powerful upper body, which may be behind her success in the butterfly stroke.

Rajat Mittal, associate professor in the Department of Mechanical and Aerospace Engineering at George Washington University, has worked with Mark by providing information about swimming mechanics inspired by dolphins. Mittal recently even created a computer model of a dolphin to better understand its movements.

Mittal said basic anatomical differences, such as lack of a totally flexible spine, joint structure, the nature of human musculature and the need to frequently breathe, keep humans way out of the range of shark and dolphin swimming records.

"To win, our Olympians must go all out and swim in what is essentially an inefficient manner," Mittal said. "Dolphins and sharks, by contrast never compromise their speed with efficiency. They are truly among nature's best swimmers."

Leaving science behind

It is a cruel and poignant certainty that the children who died in the wreckage of their school during the earthquake this week in Dujiangyan, China, knew all too well that their country once led the world in the knowledge of the planet's seismicity.

They would have been taught, and proudly, that almost 2,000 years ago an astronomer named Chang Heng invented the world's first seismoscope. It was a bizarrely imagined creation, with its centerpiece a large bronze vessel surrounded by eight dragons, each holding a sphere in its mouth.

A complex system of internal levers ensured that if an earthquake ever disturbed the vessel, a ball would drop from a dragon's care into the mouth of a bronze frog positioned underneath. By observing which dragon had dropped its ball, Chang Heng could ascertain the location of the quake. And always, as the emperor for whom Chang Heng fashioned the device noted, the earthquakes came from the mountains in the west, where Dujiangyan lies.

As we watch with mounting melancholy the devastation from Sichuan, a question lingers, and troublingly. Why, if the Chinese had come to know so much about earthquakes so early on in their immensely long history, were they never able to minimize the effects of the world's contortions - to at least the degree that America has? Why did they leave the West to become leaders in the field, and leave themselves to become mired, time and again, in the kind of tragic events that we are witnessing this week?

The question applies to very much more than the science of earthquakes. In almost every area of technology the Chinese were once supreme, without competition. The stirrup, so hugely important in peace and war, was invented by the Chinese. Printing, gunpowder, the use of the compass - the three inventions that Francis Bacon once said defined the modern world - are all thought to have been first made in China. So too, many think, were vaccination, toilet paper, segmental arch bridges, iron chains and perhaps chess - the list seems endless.

And yet, in the 16th century China's innovative energies inexplicably withered away, and modern science became the virtual monopoly of the West. There had been any number of Chinese Euclids and Archimedes but there was never to be a Chinese Newton or Galileo. The realm fell steadily behind, century by century; it became impoverished, backward and prey to the caprices of nature.

There is a peculiar paradox in the Sichuan disaster. Dujiangyan is known as the site of one of China's greatest ancient wonders. In 256 B.C. an engineer named Li Bing, concerned about the catastrophic annual flooding of the Min River, completed a huge water diversion and irrigation scheme. It involved cutting a long trench through a granite mountainside - achieved by burning grass bonfires on top of the rocks and pouring cold water until the granite cracked. It took decades, but Li Bing's 2,300-year-old project still stands less than a mile from the town's ruined school, and it still works.

And yet, did the Chinese continue with their early expertise in flood prevention? Just as with Chang Heng's seismic mastery, Li Bing's expertise counted for nothing; year upon year, thousands of Chinese die in immense inundations in the great rivers that course across the country; some 400 dams sustained damage in this week's quake.

Historians have long debated why the Chinese so signally failed to exploit their early promise. Lack of internal competition, some suggest. Others blame the long-held central ambition of every young Chinese man to become a Confucian mandarin, a bureaucrat, rather than an engineer or scientist.

Not a few others, however - admirers of China and optimists in the main - say that in the long sweep of Chinese history, a mere 400 or 500 dark, non-scientific years are a mere blip, a hiccup, and that China's innovative energies are now roaring back, with the universities and scientific institutions brimming as they did back in the golden ages of the great dynasties.

That had better be the case. China, in its headlong attempts to modernize, has often demonstrated a dismayingly cavalier attitude toward the well-being of its people: Skyscrapers are built with little attention to safety standards and are invariably far from earthquake-resistant; huge dams - not least the monstrosity that has so ruined the Three Gorges of the Yangtze - are erected in a slapdash fashion; subways, like the system burrowing through the waterlogged alluvium beneath Shanghai, are built with incautious haste; freeway tunnels are bored through earthquake fault zones.

If the country does not occasionally stand back and pause for breath, then its future - at least so far as nature's occasional moments of seismic madness are concerned - will continue to be marked by calamity. Until this week Dujiangyan was a place of which China could be proud; today its wreckage stands as a tragic monument to a culture that turned its back on its remarkable and glittering history.



Source : International Herald Tribune

New variant of rare flower found in Camerons

CAMERON HIGHLANDS: It is a plant with an awful stench but its beauty is enough to stop nature-lovers in their tracks.

The Amorphophallus bufo, a rare species found in tropical and sub-tropical areas, sparked interest when news of its discovery here broke last year.

But there is fresh excitement now with the sighting of a new variant with reddish and pinkish flowers.

Local environmentalist and orchid enthusiast Embi Abdullah, 60, said he and his friend N. Madi were trekking when they spotted the reddish bloom in the jungles of Gunung Jasar, Tanah Rata, here.

Most Amorphophallus bufo flowers were brown with white spots, he said.

Within just a week, Embi and several others came across a colony of more than 10 of the plants, five of them in bloom.

“You only get to see these flowers once every five or six years,” Embi said in Brinchang here.

He added that the highlands Amorphophallus bufo, measuring about 1.5m in height, was unusually tall and dwarfed other Amorphophallus species.

“The Amorphophallus is also a plant found in warmer lowlands, so the Cameron Highlands species is even more unique,” he added.

Embi said a group of them planned to approach the district officer or the state forestry department with a proposal to set up an Amorphophallus conservatory.

“The Amorphophallus might have some medicinal value and the conservatory could be used for research and maybe tourism purposes.

“In India, the tuber of one Amorphophallus species has even been used as food,” he added.

The group also hoped to consult fellow environmentalist Datuk Seri Lim Chong Keat, who recently led a group of scientists in finding another variety of the plant during a Forest Research Institute of Malaysia expedition.

Source : TheStar online

Frog With No Lungs Found

A frog has been found in a remote part of Indonesia that has no lungs and breathes through its skin, a discovery that researchers said Thursday could provide insight into what drives evolution in certain species.

The aquatic frog Barbourula kalimantanensis was found in a remote part of Indonesia's Kalimantan province on Borneo island during an expedition in August 2007, said David Bickford, an evolutionary biologist at the National University of Singapore. Bickford was part of the trip and co-authored a paper on the find that appeared in this week's edition of the peer-reviewed journal Current Biology.

Bickford said the species is the first frog known to science without lungs and joins a short list of amphibians with this unusual trait, including a few species of salamanders and a wormlike creature known as a caecilian.

"These are about the most ancient and bizarre frogs you can get on the planet," Bickford said of the brown amphibian with bulging eyes and a tendency to flatten itself as it glides across the water.

"They are like a squished version of Jabba the Hutt," he said, referring to the character from Star Wars. "They are flat and have eyes that float above the water. They have skin flaps coming off their arms and legs."
Bickford's Indonesian colleague, Djoko Iskandar, first came across the frog 30 years ago and has been searching for it ever since. He didn't know the frog was lungless until they cut eight of the specimens open in the lab.

Graeme Gillespie, director of conservation and science at Zoos Victoria in Australia, called the frog "evolutionarily unique." He said the eight specimens examined in the lab showed the lunglessness was consistent with the species and not "a freak of nature." Gillespie was not a member of the expedition or the research team.

Bickford surmised that the frog had evolved to adapt to its difficult surroundings, in which it has to navigate cold, rapidly moving streams that are rich in oxygen.
"It's an extreme adaptation that was probably brought about by these fast-moving streams," Bickford said, adding that it probably needed to reduce its buoyancy in order to keep from being swept down the mountainous rivers.

He said the frog could help scientists understand the environmental factors that contribute to "extreme evolutionary change" since its closest relative in the Philippines and other frogs have lungs.

Bickford and Gillespie said the frog's discovery adds urgency to the need to protect its river habitat, which in recent years has become polluted due to widespread illegal logging and gold mining. Once-pristine waters are now brown and clogged with silt, they said.

"The gold mining is completely illegal and small scale. But when there are thousands of them on the river, it really has a huge impact," Bickford said. "Pretty soon the frogs will run out of the river."





Source : Associated Press

A matter of give and take

Most flowering plants produce seeds that have a built-in food supply to help the young seedling in the early stages of its life. But the orchid Dactylorchis purpurella is an exception. Its seeds are so tiny that there is no room for a food store. The seed of this flower survives only because of its relationship with a particular kind of fungus, which feeds it and helps it to germinate.

The fungus, a species of the Rhizoctonia family, penetrates the seed and provides it with nutrients from the soil until it has grown leaves that can produce their own food through photosynthesis. As the orchid develops, the fungus takes nourishment from the orchid's roots. The two plants live side by side, in what at first appears to be a mutually beneficial relationship.

But as the orchid takes the nutrients it needs, it actually eats away at the fungus. Eventually, when the orchid can depend on its leaves to provide enough food, it devours its life-giving partner completely.

The array of senses that make owls supreme night hunters

The circles of feathers around an owl's eyes do not, as you might expect, help it to see; they help it to hear. Known as facial discs, the circles have tightly packed feathers around their rims. The feathers channel high-frequency sounds, such as the squeak of a mouse, into the owl's ears, which lie behind the discs. They perform essentially the same function as they fleshy external ears of mammals such as rabbits and cats.

With their enormous eyes, owls are particularly well-equipped for hunting in dim light. But their remarkable vision cannot help them in the complete darkness they encounter under trees at night. They then have to rely on their extremely acute hearing.

Owls locate sounds much as we do; a sound from the right reaches the right ear fractionally before it reaches the left, and their brains analyse this tiny difference to give the direction of the sound. In the same way, some species of owl can sense the exact height a sound is coming from, as one of their ears is higher than the other. Owls turn their heads to balance a sound in both ears - this gives them the precise direction of a sound, and allows them to pinpoint their prey with complete accuracy in total darkness.

As if all this was not enough, owls have extremely soft plumage, allowing them to make their final gliding assault in almost complete silence. A mouse scuttling through the undergrowth has very little chance of escape.

Desert frying pan

Death Valley - This desert frying pan holds not one record but three - it is the the hottest, driest and lowest place in North America

Deadman Pass, Dry Bone Canyon, Funeral Mountains - the very place names of California's Death Valley are sinister. This is North America's hottest, driest area - a place of baking summer heat where a whole year can pass without a drop of rain.
On summer days, the thermometer routinely rises to 43degreeC (110degreeF), and temperatures raching more than 49degreeC (120degreeF) have been recorded daily for a period of just over six weeks. When rain comes, it is often in sudden downpours that flood the heat-baked ground with torrents of water and mud.
Death Valley claims another record at its lowest point, 282ft (86m) below sea level, it is the lowest place on the North American continent. It formed when huge blocks of land sank downwards along fault lines, while adjacent blocks rose to form the neighbouring mountains. This deep trench, with its very low-lying floor, acts as a sheltered sun trap within an area that is already hot and dry, and in the rain shadow of the Sierra Nevada mountains.
Everywhere there is evidence that the climate was once much wetter. Canyons cut into the valley walls were created by torrents of running water, and there are great fans of sediment that was washed down from the surrounding peaks. Salt deposits on the valley floor were left behind after lakes evaporated, and at the Devils Golf Course salt has been eroded by wind and rain into jagged spires.
Yet despite the hostile surroundings, Death Valley is far from devoid of life. Bighorn sheep can live on very little water, sidewinder snakes move in 'jumps' that keep their bodies clear of the hot ground, and the stems and leaves of the rare, white-flowered rocklady are covered with hairs that insulate them from the desiccating wind. Even the few brackish streams and ponds support life - tiney pupfish that can cope with salty water.
A party of gold prospectors bound for California visited Death Valley by accident in 1849, and their experiences gave the place its name. They left the trail, hoping to find a short cut, but instead found themelves struggling down a barren, almost waterless valley which had no obvious way out. One woman wrote later of how her little boys 'bore up bravely, though they could barely talk, so dry and swollen were their lips and tongues'.
Two of the group found a route out of the valley and returned to guide their companions to safety. As they left, one of them delivered the parting shot 'Goodbye, Dealth Valley'.
A myth grew up about the horrors of Death Valley. Greatly embellished stories were told of wagon trains of people dying in torments of thirst, yet prospectors were still drawn there by rumours of gold and silver.
In the boom and bust days that followed, fortunes were made, but more often lost, in short-lived mining ventures. Settlements mushroomed and were deserted a few years later when the mines ran out - Skidoo, site of a very profitable gold mine, had 500 inhabitants at its peak in the early 1900s. It had a telephone link with Rhyolite, just outside the valley, which in 1906 had a swimming pool, an opera house and 56 saloons where prospectors could enjoy their profits. By 1911 Rhyolite had been abandoned, and slowly decayed into a ghost town.
Though gold mining had little long-term succes in Dealth Valley, the same was not true of borax. During the 1880s, the 'white gold', one of whose many uses was in pottery glazes, was scraped from the valley floor. Mule teams then hauled it to the railhead, 165 miles (265km) away from the harsh, yet austerely beautiful Dealth Valley.

Rocks that slide

A track over parched ground leads to a boulder and stops. This track is straight; others trace wandering curves or zigzag over the ground. The tracks are on a dried lake bed called the Racetrack, where randomely scattered boulders have all moved over a completely level surface. The most likely explanation is that the ground becomes slippery after rain, strong winds push the boulders along and paths form in their wake.

Survivors in a tough world

Plants that grow in the frozen land north of Brooks Range must have special qualities to survive the cold, wind and low rainfall. All plants grow close to the ground, minimising the battering effects of cold. desiccating winds - the polar willow (Salix polaris), for example, grows flat on the ground. Heat is trapped in clumped plants - the temperature in the centre of a clump of moss campion may 22 degree C (40 degree F) higher than the surrounding air. Moss campion's narrow leaves cut down moisture loss, and so do leaves pressed close to a stem, such as the arctic bell heather's. Only at flowering time do stems reach above the tundra carpet, and then they bend in the wind.

Lakes tinted with changing colours

An Indonesian island's lakes are said to be the resting place of souls

The souls of sorcerers, the people of Flores say, live high in the mountains of their Indonesian island home, in a lake where the water looks black. The green lake close by is the home of sinners' souls, and the souls of virgins and infants rest in a third lake coloured a much paler green.
The three lakes lie more than 5200ft (1600m) up, cradled in the craters of Keli Mutu, one of Flore's many extinct volcanoes. The island also has 14 active volcanoes - and frequent earthquakes.
Lakes of improbable colours lying side by side are surprising enough, until you hear that not many years before, their waters were a different trio of colours - black, maroon and blue. In the 1960s they were cafe au lait, red, brown and blue. Thirty years before that the colours were much as they are now.
No one has yet discovered the reason for the lakes' colours, let alone why they change. They lie enigmatically in once fiery hollows while unknown proceses brew up the next colour change.

Liquid Engineering

In the human world, hydraulic-fluid power offers competition to both electrical and mechanical power. Fluids are used in vehicle braking and transmission systems, in mass-production units, and even structurally, as in large rockets, whose thin skins are given more 'body' by internal fluid pressure.

But, as so often, Nature got there first. The structural role of fluids can be seen in a cut flower, which droops if left without water. This is because its stem is composed of highly flexible cellulose fibres stressed by the internal pressure of sap. When this dries out, the pressure lessens and the flower wilts. The same effect can be seen on the foliage of trees after prolonged drought.

Sweat Reason

You might not expect a bird and a badger to have much in common, but in tropical Africa an unusual collaboration between the two assists both creatures to obtain one of their favourite foods: honey.

The small bird known as the honey guide is remarkably adept at finding the nests of wild bees, but it cannot get into them and is wary of being stung. Its 'accomplice', the ratel, or honey badger, on the other hand, has powerful claws that easily break the nest open, and it is well protected from the bees' stings by a tough hide and a thick layer of fat.

Bees are less active in the cooler parts of the day, and it is then that the honey guide sets out on its search. When the bird finds a nest, it flies off in search of a ratel, attracting its attention with a distinctive song. Then, fluttering and singing, it leads the ratel through the forest, making shorter and shorter flights as it nears the nest site.

The bird waits while the ratel plunders the nest and devours the honey. Then it takes its turn, feasting on the larval bees and the wax of the honeycomb that is left behind.

Unfortunately, perhaps, for the ratel, the honey guide will provide the same service for any honey-fancier capable of breaking into a hive. People, too, have learned the significance of the bird's distinctive call, and have used it to lead them to nests, where they gather the honey that might have gone to the bird's traditional partner the ratel. In recognition of this service, scientists have given the bird the Latin name of Indicator.

How Crystals May Help The Firefly To Survive

In parts of tropical Asia, you can see trees glowing in the dark - single trees where waves of light ripple from top to bottom and back again, and rows of trees where the light leaps from one tree to another.


This extraordinary effect is caused not by the trees themselves, but by the synchronised flashing of thousands of fireflies that have gathered in the branches. Look closely and you will find that each tree harbours a different species of these luminescent insects.


Why these mass displays occur is not fully understood. But biologists do know why fireflies flash when flying alone, and how they produce light.


Fireflies glow in order to find a mate. The male of one common species of North American firefly, Photinus pyralis, flashes regularly while flying. The female, watching from the ground, flashes back in a rhythm unique to its own species. The male recognises this signal and drops towards a new mate.


It is possible that the flashing light also serves as a warning mechanism, reminding would-be predators of the firefly's bitter taste. But it does not always work - certain frogs eat so many fireflies that they themselves glow.


Firefly 'lanterns' contain oxygen and a substance called luciferin. The chemical reaction between the two produces light. An enzyme called luciferase helps to speed up the process, and this in turn intensifies the light.


Where do crystals come into all of this? In the lantern is a layer of ammonium urate crystals, behind the light emitting luciferin. These crystals help to scatter the light and increase the effectiveness of this remarkable natural signalling system.

Plant Ballistics

Long before armies devised means of hurling projectiles at one another, plants had already devised catapults, guns and other mechanisms to help them disperse seed.

One such is the seed capsule of sphagnum moss, which, as it ripens, contracts to about a quarter of its size, and compresses the air within it to about double the pressure of a car tyre. Towards the end of the contraction, the lid blows off and the spores within are fired out with a pop, as though by an air gun, 1 ft (30 cm) or so into the air - no mean achievement for a 2 mm gun.

The Mediterranean squirting cucumber, Ecbellium elaterium, is recorded as shooting forth a stream of juice and seeds under pressure to a range of 12 yd (11 m) at a muzzle velocity of 20 mph (32 km/h) or more. A rather different method has been adopted by an American form of pumpkin, Cyclanthera explodens. Its fruit consists of two shells clamped together about a curved lever, held down under pressures that are at least ten times greater than that within a car tyre. When ripe, the shells spring apart and the lever flies out like a sling, projecting the seeds up to 3 yd (2.7 m).

Building To Last

Reinforced concrete is perhaps the most characteristic component of modern building. Yet this invention was not the work of an architect or engineer, but of a French gardener, Joseph Monier, who in 1867, having studied the skeletal structure of plants, converted some of their patterns into steel. The skeleton of a dead saguaro cactus, for example, closely resembles the reinforcing cage of a ferro-concrete column. This cactus also has a pleated outer skin, which marvellously expands to store water against periods of drought. The fibrous material of many other plant skeletons also share the same steely characteristics of elasticity and resilience. It is these for instance that enable a corn stalk, standing 5 ft (1.5 m) high though less than 1/2 in (13 mm) thick, to bear the weight of the plant's head while it whips back and forth at the behest of the wind.

Botanic Architecture

The rib structure of the huge leaves - 7 ft (2 m) across - of the giant South American water lily, Victoria amazonica, can support the weight of a child. These leaves were Joseph Paxton's inspiration for the pattern of the cast-iron ribs of the Crystal Palace, built for the Great Exhibition of 1851 in London. Further models may be found in the many tall tress that grow in the shallow soils of the rain forests. These push out aerial roots from their trunks for additional anchorage and support, giving them the appearance of the flying buttresses that rise from piers to support upper walls and towers are added to prevent the soaring structure from collapsing outwards under the weight of a vaulted roof.

Pumping Power

A manufactured suction pump can raise water no more than 33ft (10 m) before the weight of the water counteracts the atmospheric pressure, so breaking the lift. But a tree can raise water to ten times this height. The tree's 'pump' is powered by the sun - as water evaporates from the leaves, so more is drawn up to take its place through myriad tiny tubes in trunk and branches. These tubes are very thin, which prevents the rising column from breaking, and the chemicals taken up on the way adds to its cohesion. In this way, a medium-sized oak may draw up as much as 140 gallons (637 litres) of water in a day.

By contrast, the aerial roots of some orchids, in contact with neither soil nor water, are covered in a thick tissue called velamen. When dry, this is white and easily compressed. But, like blotting paper , it absorbs the slightest touch of damp, and in the rain it darkens and fills to capacity, channelling moisture to the aerial roots.