The Mosquito Page 5
Natural selection, including our genetic buffers against malaria, is a process of trial and error. As Charles Darwin surmised, those genetic mutations that aid in the survival of a species are passed down the family tree. Those lacking these mutations, or inheriting other undesirable modifications, simply die off within the constant competitive clash for survival or what Darwin declared “the preservation of the favoured races in the struggle for life.” Individuals who possess these advantageous mutations, like sickle cell, persist or live just long enough to procreate and continue their genetic inheritance and, more important, the preservation of their species. Gradually, the adaptable survivors “breed out” those who do not possess these favorable traits—simple and uncomplicated survival of the fittest.*
The healing properties of medicines, both natural and now synthesized, are also unearthed through an experimental trial-and-error form of natural selection. When our hungry hominid ancestor perished because of eating appetizing but poisonous berries, this forbidden fruit was quickly scratched from the grocery lists of their observant and insightful companions. Over time, our hominid and human hunter-gatherer grandparents catalogued a lengthy mental Rolodex of do and do-not eats and treats. In the process, they also realized the medicinal properties of certain plants. Theirs was an austere and unforgiving existence and they experimented with the natural world around them to assuage their afflicting maladies and ward off the hungry hordes of mosquitoes.
Like the malaria parasite itself, knowledge of naturopathic remedies survived the evolutionary jump from ape to human. Chimpanzees still chew the mululuza shrub, as did our ancestors, to provide relief from malaria. It is still a common ingredient in soups and stews among the peoples of equatorial Africa, the epicenter of malaria’s stretching domain. Interestingly, the mululuza shrub comes from the same family of plants as chrysanthemums, or pyrethrum—the first known commercial pesticide. The dried and pulverized flowers found their insecticidal use in China around 1000 BCE before spreading to the Middle East around 400 BCE and acquiring the nickname “Persian Powder.” When ground and mixed with water or oil and sprayed, or applied in powdered form, the active ingredients (called pyrethrins) attack the nervous system of insects, including mosquitoes.
As a result, the symbolism associated with chrysanthemums in global cultures has been directly prejudiced by the mosquito. In countries with high historical rates of mosquito-borne disease, they are associated with death and grieving or are tendered only as funeral and gravestone offerings. Conversely, in locations largely void of mosquito-borne disease, the flower symbolizes love, joyfulness, and vitality. As evidenced in the United States, the flower has a positive connection in the North but a ghoulish connotation in the South, specifically in New Orleans, the nation’s epicenter of yellow fever and malaria epidemics until the early twentieth century. Its vast cemetery complexes are collectively known as the “Cities of the Dead” and the “Necropolis of the South” and are the primary setting for the modern vampire craze feeding on both fiction and film.
While the insecticidal properties of chrysanthemums targeted the mosquito directly, humans have also experimented with a cornucopia of organic remedies to combat mosquito-borne illness. As a result, even our taste buds have been tainted and trained by the mosquito. Cloves, nutmeg, cinnamon, basil, and onions all soften malaria’s symptoms, which may explain why, for millennia, people have added these nutritionally hollow flavorings to their diets. In Africa, coffee was also whispered to assuage malarial fevers, while in ancient China, it was alleged that tea held these same magical malaria-assailing powers.
In China, agriculture germinated both endemic malaria and also the rise of tea culture around 2700 BCE. According to tradition, Shen Nung, the second of China’s legendary emperors, is credited with the invention of the plow and industrial export agriculture as well as the discovery of numerous medicinal herbs, including the first cup of homeopathic tea to treat malaise and malarial fever. Prior to being steeped as a drink, however, boiled tea leaves fused with garlic, dried fish, salt, and animal fats were consumed as a medicinal gruel. The leaves were also chewed much like mululuza, or the stimulant amphetamine-laced coca leaves in South America and khat in the Horn of Africa. Masticated tea leaves were also applied to wounds as a dressing. Although tea is impotent against the malaria parasite, modern research has shown that the tannic acid found in tea can kill the bacteria that cause cholera, typhoid, and dysentery. Aided by Buddhist and Taoist monks who drank copious amounts of tea to enhance meditation, the drink went from an obscure medicinal beverage to the favored drink of China by the first century BCE.
Tea’s popularity continued to rise and to be exported, along with its cultivation and malaria, to neighboring countries until the Mongol invasions in the thirteenth century. The Mongols banned tea in favor of koumiss (fermented mare’s milk churned into alcohol). Venetian traveler and trader Marco Polo, who spent years at the Mongol court during this time, makes no mention of tea but does contend that koumiss was “like white wine and a very good drink.” The spouted silver drinking fountain at the Mongol capital of Karakorum, intended to illustrate the extent and diversity of the vast Mongol Empire, dispensed four drinks (rice beer from China, grape wine from Persia, Slavic honey mead, and, of course, Mongolian koumiss), but no tea.
While on the topic of tea, hidden inside a 2,200-year-old Chinese medical text blandly called “52 Prescriptions” is a brief description of the medical and fever-curing benefits of consuming bitter tea made from the small, unassuming Artemisia annua, or the sweet wormwood plant. Its chemical compound of artemisinin is truly a malaria assassin. Unfortunately, the killer antimalarial properties of this invasive weedlike shrub, which can grow just about anywhere, were forgotten by the world until it was rediscovered in 1972 by Mao Zedong’s top secret Chinese medical venture code-named Project 523. This covert think tank, detailed later in our story, was sanctioned to find a solution to the dire, manpower-draining malaria rates eating away at the North Vietnamese Army and their Vietcong allies in their drawn-out war against the Americans. As one of both the oldest and the newest in the arsenal of antimalarial drugs, artemisinin, as we will learn later, is for now the antimalarial drug of choice for wealthy Western backpackers and travelers who can afford its prohibitive cost.
Not to be topped by its caffeinated companion, tea, coffee also has its roots firmly grounded in malaria. According to legend, during the eighth century, Kaldi, an Ethiopian goatherd, noticed that his sick or lackadaisical goats perked up after eating the bright caffeine-laced red berries of a specific bush. Inquisitive at their sudden vigor, and believing it could suppress his malarial fevers, Kaldi ate some himself. His euphoria prompted him to bring a handful of the berries to a nearby Islamic Sufi monastery. Thinking the shepherd foolish, the imam tossed the beans into the fire, filling the room with the billowing aroma so many of us now associate with the best part of waking up—coffee in your cup. Kaldi scooped the now roasted beans out of the fire, ground them up, and added boiling water. In the year 750, the first cup of coffee was born and brewed.
While the story of Kaldi, his goats, and his coffee is often dismissed as apocryphal, there are usually embers of truth within the smoke screen shrouding most legends. The coffee shrub is from the Rubiaceae family of plants often referred to as the madder, coffee, or bedstraw family. Coffee plants are systematically avoided by insects, which seem to possess a fierce disdain for the caffeine-laden shrubbery. Like our berry-eating hominid ancestors, through their own processes of trial and error, insects developed an ardent aversion to coffee. Caffeine, like pyrethrins, acts as a natural insecticide by disrupting the nervous system of insects, including mosquitoes. The cinchona tree, the source of the first successful antimalarial drug, quinine, is also a member of the coffee plant’s Rubiaceae family. As we will discover, quinine was administered as a suppressant by Europeans since its discovery by Spanish Jesuits in Peru (through observing the indigenous Quechua people
s) in the mid-seventeenth century.
The chronicle of Kaldi’s adventures in coffee, like his drink itself, has staying power. The Ethiopian goatherd and his animals are often featured in the names of coffee shops and roasting companies, represented by Kaldi’s Coffee Roasting Company, Kaldi Wholesale Gourmet Coffee Roasters, Wandering Goat Coffee Company, Dancing Goat Coffee Company, and Klatch Crazy Goat Coffee among others. Coffee is the world’s second most valuable (legal) commodity after petroleum, and the most widely used psychoactive drug, with Americans consuming 25% of the market share. It also provides employment for over 125 million people worldwide, with another 500 million people involved directly or indirectly with the coffee trade. In 2018, Starbucks hauled in a whopping annual revenue of $25 billion from roughly 29,000 locations in over seventy-five countries. The phenomenon that is Starbucks and the all-consuming global coffee culture has the mosquito to thank for its grip on caffeine addicts the world over. Given the properties and effects of caffeinated coffee, it certainly would have been considered a viable anti-malarial.
Coffee is first mentioned in a tenth-century Arabian medical text written by the renowned Persian physician Rhazes. The “Wine of Arabia,” as it was once known, quickly spread to Egypt and Yemen and, in a short time, conquered Muslim lands. The prophet Muhammad, the founder of Islam, professed that with the stimulating inspiration and medicinal virtues of coffee, he could “unhorse forty men and possess forty women.” Soon after Kaldi’s revelations, coffee went viral across the Middle East and, upon its European discovery in the mid-sixteenth century as a result of the African slave trade, coffee sailed on the winds of the worldwide Columbian Exchange.
The coffee-malaria-mosquito connection filters throughout our story. Coffee added a dash of revolutionary flavor to America and France. It became the favored drink of intellectual Europe during the Scientific Revolution. Coffeehouses, fittingly conceived in Oxford, England, in 1650 and in the colonies in Boston in 1689, became the hotbed of avant-garde conversation, and steeped an unprecedented period of academic advancement across Europe, and revolutionary philosophies in the American colonies. In short, coffeehouses provided the medium for the exchange and dialogue of information and ideas.
The mosquito’s infusion of coffee, however, brewed a far more sinister and enduring bond. As the drink went global, and coffee plantation colonies percolated throughout the post-Columbian world, coffee became invariably connected to the African slave trade and to the spread of mosquito-borne diseases. As we will see, the transatlantic slave trade introduced Africans and deadly mosquitoes and their diseases to the Americas. These African slaves, fortified with their hereditary genetic immunities to malaria, including sickle cell, withstood the wrath of mosquitoes as compared to defenseless and vulnerable European laborers and indentured servants. Enslaved Africans became a valuable commodity on colonial outposts and plantations in the Americas. Africans survived mosquito-borne diseases to produce profit, thereby becoming profitable entities themselves.
Ryan Clark’s personal struggle with sickle cell is a tiny aftershock of the mosquito’s seismic entry onto the global platform and our attempts through genetic design to persevere against her persistent bombardment of disease. His individual story is embedded within the larger historical events that occurred in and out of Africa. Prior to European imperial mercantilist expansion in the mid-fifteenth century, Africans had always lived in Africa. During the Columbian Exchange, African slaves and their genetic shields against malaria were carried to distant fields across the Americas. For those currently living and contending with sickle cell in the United States, like Ryan Clark, this is not history at all. For them, it is everyday routine and reality. The influence and impact of the mosquito is not confined to the pages of history, and straddles all stages and ages of humanity. The first appearance of sickle cell in Bantu yam farmers, for example, kick-started a chain of sweeping events in which Ryan Clark was caught up, with influential echoes that are still reverberating today.
The advent of sickle cell had immediate impacts and enduring repercussions for Africa and its people. Mosquito populations boomed with the emergence of Bantu-speaking plantain and yam farmers in West Central Africa around 8000 BCE. Devastating year-round falciparum malaria quickly took root. Human natural selection countered by affording Bantu peoples protection through hereditary sickle cell. As malaria spread and began to raze nonimmune populations, the Bantu, armed with their immunological advantage and iron weapons, slashed south and east across Africa. The yams they cultivated also reinforced their genetic resistance to the malaria parasite. Yams release chemicals that inhibit the reproduction of falciparum malaria in the blood.
During two large Bantu migrations between 5000 and 1000 BCE, they drove the malaria-ridden survivors of hunter-gatherer groups with limited or no immunities, such as the Khoisan, San, Pygmy, and Mande peoples, to the fringes and peripheries of the continent. This land did not suit Bantu agricultural requirements, nor was it suitable for grazing their itinerant wealth in the form of cattle. The ousted Khoisan survivors found refuge on the Cape of Good Hope at the tip of Africa. “The immunological fence that P. falciparum built around the Bantu repelled incursions by outsiders as effectively as a standing army,” decodes malaria researcher Sonia Shah. “The Bantu villagers didn’t have to be bigger or stronger to beat back the nomads: a couple bites from their mosquitoes did the trick.” The mosquito and the Bantu genetic adaptations to her malarial disease carved out mighty, southern African empires for the Xhosa, Shona, and Zulu. The ecological interference by human pastoral pursuits, embodied by the Bantu plotline, was the key to unlocking Pandora’s Box, letting loose deadly plagues of gleaning and reaping mosquitoes.
The derivation of our escalating war with mosquitoes was the relatively recent human shift from small hunter-gatherer clan-based cultures to larger densely populated settled societies based upon the domestication of plants and animals during the Agricultural Revolution. “The past 200 years, during which ever increasing numbers of Sapiens have obtained their daily bread as urban labourers and office workers, and the preceding 10,000 years, during which most Sapiens lived as farmers and herders,” explains Yuval Noah Harari in his bestseller Sapiens: A Brief History of Humankind, “are a blink of an eye compared to the tens of thousands of years during which our ancestors hunted and gathered.” Husbandry and its human interference and manipulation of local environments brought early farmers face-to-face with deadly mosquitoes while inadvertently expanding their living space through deforestation and land clearance. The addition of irrigation and the deliberate diversion of waterways maximized the mosquito’s ability to procreate, generating the perfect storm for the proliferation of mosquito-borne disease. While agriculture led to a bounty of advancements across human sociocultural systems, including the written word, it also tampered with and unleashed nature’s biological weapon of mass destruction—the mosquito. Cultivation was shackled to a corpse.
By 4000 BCE, intense agriculture was being practiced in the Middle East, China, India, Africa, and Egypt, giving rise to all the trappings of modern civilization. As author H. G. Wells put it, “civilization was the agricultural surplus.” This was the principal contributor to the commencement of the war of our world between man and mosquitoes. In fact, between 12,000 and 6,000 years ago, there were at least eleven independent sites of agricultural origin.
This agricultural ripening, which led to the expansion of mosquito habitats and breeding sites, also required beasts of burden, quickly followed by other barnyard livestock, including sheep, goats, pigs, fowl, and cattle. These animals were teeming reservoirs of disease. As Alfred W. Crosby argues, “When humans domesticated animals and gathered them to the human bosom—sometimes literally, as human mothers wet-nursed motherless animals—they created maladies their hunter and gatherer ancestors had rarely or never known.” Domesticated animals that did not require intimate human management, such as donkeys, yaks, and water buffalo, did not
make many, if any, zoonotic contributions. Those animals that were collected and nurtured within the human environment, however, delivered with dire consequences. To inventory just a few examples, horses conveyed the common cold virus; from chickens came “bird flu,” chickenpox, and shingles; pigs and ducks donated influenza; and from cattle arose measles, tuberculosis, and smallpox.
While farming flourished in South and Central America as early as 10,000 years ago, as we will see, unlike the rest of the world, it was not accompanied by extensive domestication of livestock or by the unimpeded conquest of disease. In the Americas, the farming package, or pairing of agriculture and animals, did not occur. As a result, zoonosis was incompatible with their pastoral practices, and indigenous peoples of the Americas remained sheltered from the storm of all zoonotic diseases, including those rained down by the mosquito. While the Western Hemisphere was swarming and abuzz with the largest mosquito populations on the planet, these New World mosquito species followed a self-determining evolutionary path for 95 million years, one that liberated them from the burden of vectoring disease—for the time being. Throughout the rest of the pre-Columbian world, however, malaria was the only mosquito-borne disease to yet escape the clutches of Africa.
Mirroring the Bantu in Africa, the evidence we have from antiquity authenticates this intersection between the rise of agriculture and the domestication of animals, and the proliferation of mosquito-borne diseases. Japan, for example, imported both rice agronomy and malaria from China around 400 BCE. “Both falciparum and vivax probably emerged as truly chronic infections with expanding cultural and economic consequences,” acknowledges historian James Webb, “only when human beings began to settle in the earliest subtropical and tropical river basins—along the banks of the Nile, the Tigris-Euphrates, the Indus, and the Yellow rivers—and founded the first great seed-based societies.” Human domestication of plants and animals accelerated the mosquito’s ascent to global domination and presented her diseases with beckoning untapped frontiers and unblemished horizons of opportunity.