Tag Archives: Botswana

A Tribute to Thembi: Miles per Pound of Trees

On March 13, one of the elephants I who allowed me into her life died unexpectedly of colic and a heart attack.  I’ve written extensively about Thembi and her herd mates.  This is one of the pieces.

 

Diamond on forehead 2

Thembi, she of the evenly matched ears, long-lashed eyes, and diamond-shaped scar on the bridge of her nose, farts as she walks.  Big, burbling farts.

All the trees, grasses and leaves Thembi eats gather in her 10-gallon stomach, which is pretty much just a holding area.  From her stomach, roughage travels into her small intestine and then on into her large intestine.  Joining the two intestines is a junction called a cecum, where digestion actually takes place.  Her cecum is filled with billions of microbes, just like most mammals, including us.  The microbes break down the cellulose of leaves and trees into soluble carbohydrates Thembi can digest, but the process also gives her enough methane gas to power a car 20 miles each day.

I wonder, as I walk behind her, just how one could harness this gassy natural resource.  I live at the edge of a small town.  Twenty miles would more than cover my daily errands.  I imagine exhaust fumes smelling like fermenting grass.  I imagine driving down highways inhaling the scent of mulched trees.

I wonder, as I walk behind her, why I think of such things.

Percolating along, Thembi lifts her tail and farts again.  It’s a stupendous displacement of air.  In this just-right light, I can actually see this fart.  It looks like heat waves blasting from the back of a jet engine.

One advantage of Thembi’s size is food efficiency, miles per pound of trees.  An elephant eats four to seven percent of its body weight each day – four hundred to six hundred pounds of vegetation.  Mice eat a twenty-five percent of their weight daily and hummingbirds two times their own weight, or two hundred percent.  If hummingbirds ate trees, the forests of the world would already be gone.  Pound for pound, Thembi needs far less food than rodents or birds.  And with her size comes another advantage over smaller creatures – a longer life span.

We humans, with our penchant for measurements, have conjured up a precise formula for figuring out things like longer life spans.  The formula is called quarter-power-scaling.  A cat is about 100 times more massive than a mouse.  To calculate the cat’s age, take the square root of 100, which is ten, and then the square root of 10, which is 3.2.  The lifespan of a mouse is around 800 days, or just over two years.  Multiply 800 by 3.2.  The result is 2,560 days, or seven years, the average lifespan of a cat.

However, if a cat’s metabolic rate was 100 times faster than that of the mouse, all cats everywhere would spontaneously combust into feline fireballs.  Oddly enough, heart rate, the engine that drives the cat to chase the mouse, scales to the same formula, but in the opposite direction, to the minus quarter-power.  The resting heart rate for a mouse is 500 beats per minute.  Divide that by 3.2 and you have the average heart rate for a cat, around 156 beats per minute.

An elephant’s resting heart rate is a placid thirty-five beats per minute and a bit higher, around forty, when excited.  While the jittery mouse lives just over two years,  an elephant lives around sixty-five years, certainly long enough to power my car for the rest of my life.

 

Massive Molars

photograph by Cheryl Merrill

photograph by Cheryl Merrill

 

At birth, elephants have only two or three small cheek teeth. By the age of ten, big tectonic molars began to erupt in the back of their jaws, becoming part of a conveyer belt of teeth. As molars wear down near the front of an elephant’s mouth fragments of them break off in pieces and either fall out or are swallowed. Throughout its lifetime, an elephant will grow twenty-four molars in six sets – but only two tusks.

Each molar looks like a set of dishes drying edgewise on a rack, bonded together by enamel. The vertical ridges function like giant vegetable graters as an elephant’s lower jaw moves forward and back, rather than side-to-side like a cow. Each molar grows up to a foot long, has a maximum of ten ridges, and weighs eleven pounds apiece – perfect for grinding up tree branches.

Like human teeth, elephant teeth consist of cementum, dentine and enamel. Cementum holds the roots of a tooth in place, dentine surrounds the pulp and enamel crowns each tooth with a hard protective layer. Packed with nerves and blood vessels, the pulp cavities of elephant tusks extend two-thirds of the length of each tusk. Their teeth are as sensitive as mine are.

Doug asks Jabu to “Open up.” He curls his trunk back over his head and Doug stretches to his tiptoes, pulls his lower gums wide with his hands.

In his lifetime Jabu will have six sets of molars.  His sixth set will wear down by the time he is sixty.  Only ten percent of aging elephants grow a seventh set of molars.

“Very good, my boy. . . . veerrry good.”

Peering over Doug’s shoulder, I count four molars in his mouth, two on top and two on the bottom.

Doug lets go of Jabu’s lower jaw. “Allllright, Jabu, allllright.”

He drops his trunk but leaves his mouth open. Doug grabs a fistful of treats and slides his arm into Jabu’s mouth, all the way to his elbow. As he lets go of the treats he rubs Jabu’s tongue. He  flaps his ears.

“Elephants use their trunks to rub each other’s tongues. It’s kind of like a handshake,” Doug says.

The Mating Twirl

photograph by Cheryl Merrill

photograph by Cheryl Merrill

“Look!”

Heads swivel and eyes follow a finger pointing skyward.

Locked together, talons to talons, African fish eagles plummet toward earth in their mating dance, twirling in passionate grip with each other, taut bodies wheeling faster and faster towards earth, picking up suicidal speed. Spiraling, spiraling, feather tip to feather tip, wind streaming through their feathers.

The eagles break off a second before hitting the ground and swoop up to roost in trees opposite each other. They scream back and forth, flinging their heads over their shoulders. The female’s voice is lower, counter-point to the male’s shriek.

One of the guides shakes his head. “I have never seen that before.”

Like the bald eagles in North America, African fish eagles have chestnut bodies, long yellow beaks, yellow feet, pure white heads, white tails and white chests, although their bibs are larger.

They have the same habits – they mate for life and build huge stick nests in trees, nests twelve feet wide and ten feet deep. They dwell in the same habitats – rivers, lakes, creeks, lagoons, estuaries, sea coasts and man-made reservoirs. Both carry fish caught near the water’s surface in their grasping talons, carry the fish headfirst for lesser wind resistance, one claw behind the other, surfing, riding a fish through waves of air.

Holding to their tree with fierce feet, the eagles continue to scream at each other, perhaps in excitement from their mating twirl, or perhaps because they are dizzy. Eagles have somewhat the same structure in their inner ears as humans, including the looping canals for balance. Ah, that instinct, the one that will sweep you off your feet, twirl you around, make you dizzy, breathless, and, for the moment, drop you down totally in love.

Dear Madame Elephant

photograph by Cheryl Merrill

photograph by Cheryl Merrill

Chobe River, 2012

Dear Madame Elephant:

There is a hole in the space between us, filled with thrown dust. You stare down your nose with a don’t-mess-with-me look, but I am describing things in my language, not yours. Yours is a language of thunder, trombones, and a low, rumbling growl. Your breasts are full; your child hides behind you. We have come knockata-knockata noisy around the corner in a vehicle now halted before you. How quickly we became silent and supplicant, waiting with immobile slightly bowed heads, as you sample the scent of our intentions. We are watchers watching each other. Your eyes are deep brown pools. Your benevolence is the most important thing to us. We hope you will bestow it upon us. Dear Madame Elephant, what would you tell us in our language, if you could. Or did you already tell us: your forbearance louder than our beating hearts, louder than words.

Sincerely,

A Thankful Human

Baobabs, Part Two, Utility

photograph by Cheryl  Merrill

photograph by Cheryl Merrill

 

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.

 

Baobabs, Part One, Eternity

Baobab sunset reflect

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?

Islands in the Okavango Delta

photograph by Cheryl Merrill

photograph by Cheryl Merrill

 

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.

Why Don’t Elephants Get Cancer?

 

photograph by Cheryl Merrill

photograph by Cheryl Merrill

 

This collared elephant, photographed in Botswana’s Chobe National Park, has a large breast mass – most likely mastitis, an inflammation or abscess of breast tissue often caused by blocked milk ducts. Although harmful bacteria may be present in her milk, nursing might relieve her mastitis symptoms. I don’t know the outcome for this mother, but it’s highly unlikely her breast mass was cancer related. Why? For elephants, the overall lifetime chance of dying from cancer is less than 5%. The mortality rate for humans is 20%.

Why should a mammal with 100 times more cells than we do have such a low cancer rate? Oddly enough, there is little relationship between cancer rates and body size of mammals – even though the cells of elephants will divide many more times throughout their lifetimes than ours will, simply because they have so many more of them. Elephants ought to have a greater quantity of random mutations predisposing them to cancer than we do.  But they don’t.

Studies using the autopsy reports of 36 mammals at the San Diego Zoo (ranging in size from mice to elephants) and the database of 644 captive Asian and African elephants confirmed that the relationship of cancer to body size did not matter. But those studies also found something highly unusual in the blood cells of elephants. African elephants have twenty TP53 genes (and therefore 40 alleles of that gene); Asian elephants have fifteen. TP53 is sometimes called the “guardian of the genome” for its ability to create a protein that suppresses tumors.

Humans have just one gene and two alleles of TP53. (An allele is basically a copy of a specific gene at the same position on a chromosome.   Chromosomes are located in the nucleus of cell and contain DNA, the genetic instructions that make mice mice and elephants elephants.) In humans, one allele is inherited from each parent – both crucial to prevent cancer. Having only one allele causes Li-Fraumeni syndrome, which is characterized by a more than 90% lifetime risk of cancer.

TP53 codes for the protein p53, a crucial tumor suppressor that stops cells with damaged DNA from dividing. TP53 goes into action when cells suffer DNA damage, churning out copies of its associated p53 protein and either repairing the damage or killing off the cell. But instead of repairing DNA damage, compromised elephant cells have evolved to always commit suicide rather than pass on potentially harmful mutations acquired in trying to repair itself. Once the damaged cell is dead and gone, it can’t turn into cancer.

Most of the elephant TP53 genes are retrogenes, which evolved into their genome at a later time than the original gene. Two factors explain why elephants developed more TP53 genes: a long gestation period (22 months) and a reproductive lifespan that lasts well into their 50s (elephants live 60+ years in the wild). Unlike mice, elephants don’t reproduce often – thus they pass along the extra copies of TP53 even in old age, and their progeny benefit.

In contrast, humans reproduce only into to middle age and most of our cancers are diseases of aging. We are the legacy of short-lived ancestors (compared to modern life expectations), who mostly didn’t get cancer throughout their years of reproduction and raising children. As modern humans age, our chances of contracting cancer become greater since we have less suppressing genes than elephants do. And any cancer-fighting mutations within our genes don’t get passed along in our older years.

Do elephant genes hold the secret of a cure for cancer? Researchers are investigating. Meanwhile, elephants are being slaughtered for their ivory, for short-term gains. What if elephants were our saviors, our partners in longer, healthier lives? What if elephants were worth much more alive than dead? #worthmorealive Spread the word.

 

Camp Staff

photograph by Cheryl Merrill

photograph by Cheryl Merrill

 

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.

Drinking It In

Photograph by Cheryl Merrill

Photograph by Cheryl Merrill

 

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.

 

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