As the Earth turns on its axis, everything attached to it turns with it, a lovely effect of the force we call gravity. Without gravity, we’d fly off into space in less than a heartbeat.
The earth’s rotation has another beneficial effect: instead of the atmosphere circulating only between the poles (high pressure areas) and the equator (a low pressure area), circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere, resulting in curled paths. This deflection is called the Coriolis effect, named after the French mathematician Gaspard Gustave de Coriolis (1792-1843) who studied the transfer of energy in rotating systems like waterwheels.
Because of this atmospheric circulation, it’s also believed that water goes down a sink in one direction in the Northern Hemisphere and in the opposite direction in the Southern Hemisphere. Coriolis’s deflection causes weather systems to rotate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere, so it seems somewhat obvious that a sink should drain in a similar manner.
However, cyclonic systems are often more than 600 miles in diameter and may exist for several days. By contrast, a typical sink is less than four feet in diameter and drains in a matter of seconds. On this scale, the Coriolis force is miniscule – and not really observable.
But enterprising hucksters never let the impossible get in the way of yet another tourist trap. In Nanyuki, Kenya, a little town located right on the equator, proof of the Coriolis effect exists. In the burnt shell of the Silverbeck Hotel, at the exact altitude of 6389 feet, (the sign says so), a small squarish plastic sink with a very small hole in the bottom of it rests on a pinkish bucket. The gullible group I’m with stands in the southern hemisphere. The demonstration goes like this: one of the demonstrators holds the empty sink and puts his finger in the hole to plug it. Water is slowly poured into the sink, the finger removed, and the sink is carefully set over the bucket. Matchsticks are added. The water, very slowly drains and the matchsticks barely move. Then the whole enterprise is moved about twenty feet away into the Northern Hemisphere. The sink is plugged, filled from the bucket and water in the sink is allowed to settle down. Then the sink is set down and once again, matchsticks are added to the water. The matchsticks rotate counterclockwise. Moved twenty feet into the Southern Hemisphere, the matchsticks rotate clockwise. After the demonstration we’re given the golden opportunity to purchase a certificate commemorating our witnessing of the Coriolis effect, so we can prove to our friends, who may never have a chance to visit the equator, that we saw one of the wonders of the world.
Alas, the truth always gets in the way of good stories. The secret for this deception is in the shape of the sink and a little choreography. For the first demonstration right at the equator, the water in the sink behaves as it should, with no discernible matchstick rotation in either direction. For the northern part of the demonstration, the pan was filled as the demonstrator faced the equator. He then turned to his left, walked around the bucket, turned to his left again, before he pulled the plug of his finger and added matchsticks. He’s just induced counter-clockwise rotation in a non-circular pan – because of drag, water will turn as the pan does. For the Southern hemisphere he repeated his actions, but turned to the right instead of left.
Clever, eh? But, no worries. Half the world believes that sinks drain differently in different hemispheres. It fooled Michael Palin, too, on a PBS show, no less. And it’s actually true that you can demonstrate the effect with draining water, but you need a kid’s pool, 41 degrees of separation and synced cameras, like these dudes did:
Vervet monkeys chatter to each other as they jump along the branches of a Sausage tree over my head. I look up. The monkeys peer down through the tree’s large, leathery leaves. Small bits of dead flowers rain down. Brown eyes in the middle of narrow black faces stare back at me.
They wouldn’t, would they?
Last night, without any aid from the monkeys, the tree dropped a bomb next to my tent. At two feet long, six inches in diameter, and weighing nine pounds, one of the fruits dangling deli-style from the Sausage tree made quite an impressive WHUMMP! when it hit the sand. I wonder about the motives of the potential bombardiers overhead.
Light-gray thin bodies dart from branch to branch. The monkeys stop and stare, stop and stare. The bombardiers look as if they wear black oxygen masks and gray flight coats with white ruffs.
More bits of flowers and leaves rain down.
Livingston camped beneath a Sausage Tree right before he discovered Victoria Falls. What if its fruit had bonked him in the head? Stanley might have searched in vain for the famous explorer and never uttered, “Livingston, I presume?”
And what would have happened if that relentless experimenter, Isaac Newton, had been beaned with a sausage fruit instead of an apple? Would we still have the theory of gravity?
I bet that we would. After recovering from a concussion, Newton would have gone right ahead and figured out his equations. After all, this was the guy who stabbed his eye with a needle just to see what would happen.
The Vervet monkeys tire of watching me and settle higher in the tree. Thanks to the restraint of my overhead companions, I’m able to continue on without incident.
Found mostly in seasonally arid areas, baobabs grow very slowly as they age, except for first years of its life, when a baobab grows relatively quickly. A tree planted in Kruger National Park in South Africa grew 65 feet tall with an eleven-foot diameter in just 38 years. In contrast, an older tree described by Livingstone in 1858 grew only two feet in circumference in 110 years. Despite their early exuberance, baobabs can be cultivated as bonsai trees.
Young baobabs have only single leaves per stem. Without their crooked branches and five-leafed stems, they are difficult to recognize. Kalahari Bushmen believe the trees appear fully-grown, planted upside down by the gods, with the tree’s roots in the air. They also believe spirits inhabit the baobab’s large, waxy-white flowers, and if anyone has the audacity to pick one, they will be eaten by a lion. The flowers open just before dark, produce copious amounts of nectar and last for only 24 hours. Their heavy, carrion-like scent attracts nocturnal insects and bats, such as the Epaulleted fruit bat. The Kalahari Bushmen are right: the smell of a freshly-picked baobab flower behind your ear would make you bait for lions drawn to the carrion scent.
Older baobabs have a tendency to rot out their heartwood, but completely heal around the hollowed trunk. Rats and reptiles frequently invade them and African honeybees often establish hives in crevices of a baobab. Native to central and southern Africa the bees are actually a subspecies of the Western honeybee. A single sting from an African bee is no more venomous than a single European or American bee sting, but African honeybees respond more quickly when disturbed and send out three to four times as many workers in response to a threat. They also pursue an intruder for a greater distance from the hive – thus their reputation as “killer” bees.”
Physically unable to break open a beehive, the Honeyguide has developed a symbiotic relationship with humans, letting another species take the risk of being swarmed. A Honeyguide indicates the presence of a hive by continuously dive-bombing nearby, all the while uttering monotonous, squirrel-like chirps. Alerted by the Honeyguide, intrepid Kalahari Bushmen pound pegs into the soft bark of baobabs to climb the tree, lull the bees with smoke and obtain a sweet reward for taking that risk. Bushmen always leave honey for the birds, for if they should fail to do so, the Honeyguide will one day lead them to a lion, instead of a hive.
“Pachycaul” is a scientific term used to describe a variety of thick-stemmed plants with few branches. “Pachy” is Greek for “large” and “caul” is Latin for “trunk.” Pachyderm is a term for describing large, thick-skinned animals such as elephants. In times of drought, elephants strip the bark of the baobab and eat the spongy wood underneath, estimated to contain 40-70% water – which classifies the baobab as the world’s largest succulent. An individual baobab can store up to 32,000 gallons of water. When pachyderms meet pachycauls, it is the baobab that suffers. Sometimes, during these times of drought, elephants will completely gird a tree, leaving it standing as if on its own pedestal, and yet the baobab will still survive.
Weighted with water, baobabs barely move in the wind. Even a mild frost will kill a baobab, so they are never found at elevations over 3,000 feet. The tree is also sensitive to both flood and extended periods of drought. In Madagascar, a sugar mill diverted water onto land containing baobabs, which subsequently stood in water year-round. The trees began to rot and topple over until the land was drained and the remaining 313 baobabs upon it were declared part of a conservancy area. A highway constructed near the Nomslang Baobab in South Africa brought thousands of visitors to marvel at its size. Unfortunately, their feet trampled the earth beneath it into hardpan, making the ground impervious to rainwater and the famous baobab died. Baobabs melt into a huge, fibrous mass within a few months after their death, leaving behind mounds of stinking pulp and a pit filled with a rotting taproot. Soft spots around dead baobabs also indicate locations of its root system, which may radiate just below the surface for 300 to 1300 feet.
Some species of plants and trees emit chemical signals when under attack. I wonder if the baobab talks to its long-lived kin as it dies. Baobabs live up to two thousand years, 730,000 revolutions of daylight and darkness. Perhaps its chemical whisper is Patience, perhaps it is Eternity, perhaps it is Dream.
The most comprehensive book ever written about baobabs is The Baobabs: Pachycauls of Africa, Madagascar & Australia, Gerald Wilkins and Pat Lowe
In 1998, the Disney Corporation opened the Animal Kingdom Park in Florida. It is, in essence, a 500-acre zoo, containing 1,700 animals representing 250 species, from Abdim’s storks to African zebras. In the center of the park is a 145-foot-tall, 50-foot-wide sculpture of a baobab, representing the Tree of Life from the Disney film, The Lion King. Much larger than any known baobab, the sculpture is molded around a refitted oil platform. Its trunk is carved with 325 animals and contains a theater with 430 seats. Fixed to its branches are 103,000 leaves dyed five shades of green, made of kynar, a flexible fluoropolymer resin.
Eight species of living baobabs exist: six in the dry deciduous forests of Madagascar, one in Australia and one which grows in West, East and Southern Africa. Baobabs on the Arabian Peninsula are the result of human settlements. All baobabs are deciduous. Nude limbs, entangled as a root system, seem to search for moisture from the sky. Kalahari Bushmen believe the trees appear fully-grown, planted upside down by the gods, with the tree’s roots in the air. They also believe spirits inhabit the baobab’s large, waxy-white flowers, and if anyone has the audacity to pick one, they will be eaten by a lion.
Hollow baobabs have a long history of creative uses by humans. During World War II, a baobab in Namibia was fitted with a toilet. The toilet is still there, but the tree has grown around the door, which no longer opens. On the lower Zambezi River, the Kayila Lodge has an operational toilet tree, used more for photo opportunities than necessity. And on a private farm in Sunland, South Africa, an enormous baobab contains a wine cellar and bar, complete with draft beer, a dartboard, stools, and a wooden bench along the wall. This tree is possibly the oldest baobab in existence – it has been radiocarbon-dated to the end of the Stone Age, around six thousand years ago.
In Kasane, Botswana, a baobab was used as women’s prison in the early twentieth century. Incarceration with potential rat and reptile cellmates might make any criminal think twice. Although that baobab died in 1967, an offshoot now grows next to the remains of the jail. Throughout Africa, hollow baobabs have served various purposes – as hiding places during tribal warfare, as shops, storage shelters, barns, chapels, burial sites, post offices, even a bus stop.
Almost every part of the baobab is edible. Fresh leaves are eaten as spinach and condiments. The shoots from germinating seeds taste like asparagus. Bulbs from its roots make porridge. Fluid extracted from the bark of the baobab is used to dilute milk. The ash from a burnt tree is a good substitute for salt. Pulp and seeds of its fruit contain potassium acid tartrate as well as citric acid, an effective substitute for cream of tartar, and resulting in the Afrikaans name “Kremetartboom.” Early settlers also used fruit pulp in place of yeast and added baobab leaves to speed up the fermentation process in winemaking. The fruit pulp has the highest known concentration of Vitamin C. It makes a slightly acidic, but refreshing drink when mixed with water. Baobab seeds have the same protein value as domestic nuts and can also be roasted and ground into a substitute for coffee.
The baobab is often called “the Monkey-bread tree,” because baboons and monkeys eagerly consume its fruits. Nearly all four-legged browsers eat the baobab’s fallen leaves and flowers. The flowers open just before dark, produce copious amounts of nectar and last for only 24 hours. Their heavy, carrion-like scent attracts nocturnal insects and bats, such as Peter’s Epaulleted Fruit Bat. In times of drought, elephants strip the bark of the baobab and eat the spongy wood underneath, estimated to contain 40-70% water – classifying the baobab as the world’s largest succulent. An individual baobab can store up to 32,000 gallons of water and weigh 266,880 pounds – or one hundred and twenty-one tons. A bull elephant weighs up to 16,000 pounds or seven tons. If you stacked elephants one upon the other, it would take seventeen or eighteen elephants to equal the weight (if not the mass) of the water stored in a large baobab.
The name baobab derives from North African Arabic, bu-hibab, “fruit of many seeds.” Within life spans that reach six thousand years, the baobab nourishes countless species, takes in tons of carbon dioxide and releases equal amounts of oxygen. Used and re-used, a baobab cycles and recycles, measures seasons by dropping its leaves, measures centuries by the blur of life beneath its limbs, unaware of that strange human notion of time.
Across the grassy lagoon is a rare tree species for this part of the Okavango Delta: an African Baobab, Adansonia digitata – digitata for the five leaves it has per stem. The baobab is deciduous, naked this time of year. Its prehistoric appearance conjures up primeval landscapes full of odd plants and the crawling creatures that existed in the ages before the dinosaurs.
Adansonias are named after the French naturalist, Michel Adanson (1727-1806), who spent five years in Senegal, brought home a huge plant collection, and published a paper on Digitata after his return. He also wrote a masterwork of natural history, L’Ordre Universel de la Nature, but it was based on his own system of classification, a system totally different from that of his contemporary, Carl Linnaeus (1707-1788). Linnaeus’s Systema Naturae introduced binomial nomenclature – using an organism’s Genus, Adansonia, followed by a descriptive modifier such as digitata. Systema Naturae classified 4,400 species of animals and 7,700 plants.
In contrast to Linnaeus, Adanson proposed a “natural” system that took many features of the plant into account, which included structure along with function, growth, evolution and distribution. His system was ignored because it was too unwieldy. Adanson’s masterwork was huge, just like the baobab: 27 large volumes with a 150-volume index that contained an alphabetical treatment of 40,000 species, and a vocabulary listing of 200,000 words, 40,000 drawings and 30,000 specimens. It was never published, but is preserved in the Hunt Institute for Botanical Documentation, at Carnegie Mellon University, in Pittsburgh, Pennsylvania. At least his life’s work was not lost.
Elephants (you knew I’d get around to them, right?) love the bark of the baobab because of its moisture content. As insurance against harsh drought, the swollen trunk of a single baobab stores up to 32,000 gallons of water, an amount weighing around one hundred and twenty-one tons. A big bull elephant weighs up to 16,000 pounds, or seven tons. If you stacked elephants upon a scale, it would take seventeen or eighteen elephants to equal the weight (if not the mass) of the water stored in a large baobab.
The wood of the baobab is soft, spongy and fibrous. A plank cut from a baobab will decrease in volume by 40% and shrink in length by 15% while it dries. Sometimes, during times of drought, elephants will completely gird a tree, leaving it standing as if on its own pedestal, and yet the baobab will still survive.
The bark on the baobab across the lagoon is smooth, pinkish-gray, and untouched by elephants, possible due to its proximity to the Okavango’s permanent water channels. I estimate this tree is about 22 feet in diameter and 70 feet tall. Mature baobabs have trunk diameters of 23 to 36 feet and reach heights of 98 feet. The Glencoe baobab, near Hoedspruit in the Limpopo Province of South Africa, is considered the largest specimen alive, with a circumference of 154 feet. In 2009 it split into two still-living parts, revealing an enormous hollow in its middle. The date 1893 is carved into its trunk.
Although the Glencoe baobab is thought to be two thousand years old, baobab wood does not produce annual growth rings and it actually shrinks during times of drought, so size is not an indicator of age. The baobab across the grass lagoon is probably – my best guess – around 600 years old, or perhaps even older, taking root about the time Eric the Red colonized Greenland (985), or later – perhaps the year Gutenberg invented the printing press (1439). This tree, this timepiece, probably first dropped its leaves during the Middle Ages, and will continue dropping them, annually, for several thousand years more.
I wish I could slip sideways into the life of this nearly eternal tree, and, time-lapsed, witness the swirl of life around it as it fattened and grew. While I’m at it, why not wish for an added one or two thousand years more to my life? Eternity is often defined as an endless length of time. Are two thousand more years enough time to witness this amazing world and the lives it contains? After two thousand years would I want more?
Swollen by November rains, the Okavango River floods south from Angola, arrives in Botswana in May or June, fans out, and then stops when it bumps into a barrier of fault lines near Maun. Landlocked, the river penetrates deep into the Kalahari Desert before it dies in the sand. Not a single drop reaches the sea.
As the river pushes south, it creates an oasis, a floodplain the size of Massachusetts, containing an ark-full of animals: the Okavango Delta, a flat maze of islands and water.
The river descends less than 200 feet in 300 miles. Bracketed by fault lines, sediments deposit elevation changes of less than seven feet. Islands that rise above the floodplains tend to be long and sinuous, following old channel routes, linking to other uplifted channels, and creating large dry fingers of land that will be outlined by next season’s floods. Water loving trees such as the Jackalberry, Mangosteen, Knobthorn and Sycamore Fig fringe these larger islands.
The Delta contains more than 50,000 islands; their landmass roughly equals that of water. Paths cross some of the islands; roads cross others; water surrounds the rest. All of the islands carry the mixed vegetation of the Kalahari sand plains. Approached by foot in this maze, every island looks like the next one and the next one and the next, especially during the low flood season, when boundaries between them evaporate with the water, when footpaths end in walls of thick bush, and roads take every opportunity to wander off in a new direction.
Sometimes you’ll wade to an island; sometimes the water is over your head. Near the southern end of the Delta, some of the islands are larger sandveldt tongues, extensive areas of the Kalahari that penetrate deep into the flood. In the Okavango’s vast delta of uncounted islands, a few inches here or a few inches there separate wet lagoons from dry land. If I turn one way, I’m lost in a maze of floodplain islands, now high and dry. Turn the other, and I’ve entered into a maze of Kalahari woodland. Until I’ve gone a few miles, it’s hard to tell the difference since the same vegetation covers both.
But when the sun sets, magic begins. The sky turns pink; water lilies fold into perfect imitations of floating candles; papyrus along shorelines become golden sentries; and the spell of water over a desert casts its memories into your dreams.
Melting from yellow to orange the swirled, stained-glass sun hangs round and unfastened, rolling down a line of bush. The last hot breath of the day exhales and in a single moment the sun drops and is gone.
A lemon sky turns violet. Moisture thickens as plants exhale and shadows deepen. As light fades, smells condense – the cold iron of stars, the ancient, clean smell of cold sand under my feet, sage on my fingertips, smoke in my hair.
Palm trees fan black silhouettes against the stars.
I look up at a sky filled with diamonds where the giant, gem-studded belt of the Milky Way girdles the full belly of the night. By its light alone I pick my way to my tent.
The moon sails west, round and immense, shining a clean, pure light that has a whiff of blue about it. The brush is full of crickets, each one singing in a different rhythm. I hear a few individuals among the many – soloists. I hear collective phrasing – the choir. And right before I sleep I hear them singing even more loudly to the sizzling stars.
I turn my head toward the sun’s white-hot eye. Behind my closed eyelids burn a thousand childish sketches of red suns. I hear one of the regular camp staff scratching around my feet for crumbs: a Red-billed Francolin, who believes his territory includes the kitchen shelter and its surroundings. The color of his legs, feet and bill match, but they look more orange than red to me. He’s plump as a pillow, with a bright yellow circle around each eye – but woe to any other francolin who trespasses. The resulting chases are explosive, noisy, and continue until he’s satisfied the intruder is back in the bush where he belongs. Male francolins have spurs on their legs, and they don’t hesitate to use them in fights. When he’s this close I can see the tiny black claws at the end of his toes, and hear his soft chuckles when he finds another crumb.
A metal pail hangs over my head, fixed by a rope and pulley to the limb of a tree. The bottom of the pail has a showerhead with a spigot to control water flow. I stand on sand within a rectangle of stones while a loose, slat-sided fence protects my modesty. Vines climb up and around and through the slats. Sunlight filters through the overhanging tree while the sky above it snaps blue, blue, blue with the upbeat tempo of a jazzy song.
Naked, my skin softens as buttery light melts into my pores. Naked, I create my own breezes as I wash. Naked, I smell saltish, metallic, as if newly risen from the sea. Naked, I am clothed in myself.
Cool water the color of weak tea trickles down my neck and across the landscape of my body. Each sluice takes a different path: one rivulet down an arm, another makes it all the way to my ankle. The water becomes darker and turns into rivers full of dust as it washes away islands of soap. A small puddle gathers around my feet and sinks immediately into the sand.
As I dry off insect noise boils shrill as a teapot. I dress and step around the edge of the fence.
The afternoon hunkers down and sits on its heels – occasionally fanning itself with a short breeze,perfumed with the faint scent of hot, dry wood. Faint whisperings rustle through the grass, prayers for rain. If there were clouds I would lie on my back and watch them.
I sip hot oxygen in tiny gulps, panting.
Life, perishable life, rests in the shade, its thin legs tucked under, safe for the moment, waiting, even-eyed, for the predators of the dark to awaken.
Not far from here jungles of papyrus lean their feathery seed heads over the clear blue channels of the Okavango River, tall stands of reeds that line the permanent footprint of the Delta. The river is inching southward, breaking the boundary between water and desert. Soon it will flush this lagoon, scouring out the sweet muck at its bottom to spread among grassy floodplains.
With the river will come crocodiles and hippos and other denizens of its deep, running water. When the river reaches this part of the Delta, a new population of birds will arrive with it: Wattled cranes, Egyptian geese, Reed cormorants, Darters, Avocets, Black crakes, Red-knobbed coots, Sacred ibis, Hamerkops, Fish eagles, and Saddle-bill storks.
Standing shoulder to shoulder on a mat of trampled reeds, two elephants blow a concert of bubbles, bassoons under water. They shower their spines, poke their trunks into the back of their throats and release gallons of water at a time. Corkscrew spirals spill from their mouths, patter like rain on the surface of the lagoon. Sky-blue ripples spread from one edge to another, bounce back images of a thousand suns.
Believe me: you could spend the rest of your life watching this.