Before you swat, take a moment to admire the ingenious, audacious mosquito.
She is exquisitely engineered to steal your blood – an act of theft that is the essence of high risk/high reward. The fact that only female mosquitoes bite us, which they do not do to feed themselves but to nourish their offspring, further heightens the all or nothing nature of their existence. “If she wasn’t the cause of so much death, disease and suffering, we might actually be able to appreciate how amazing this animal is from an evolutionary standpoint,” says Timothy Winegard, author of The Mosquito: A Human History of Our Deadliest Predator. Recently shortlisted for the final RBC Taylor prize, which will be awarded on March 2, the book is a lively journey through the ages that builds the case for mosquitoes as shapers of world events.
“If you removed mosquitoes from the planet across our existence, our world would be unrecognizable,” Winegard says.
A professor of history and political science at Colorado Mesa University, Winegard grew up in Sarnia, Ont., and spent his summers on the shores of Lake Huron. He knows, firsthand, that mosquitoes are an irritating but inescapable piece of the Canadian experience. A legion of tormented campers and distracted wedding guests can relate. And whether or not we’re ready to “appreciate” mosquitoes, it’s clear we are fascinated by them.
Winegard could hardly have found a better venue for his message than at the Royal Ontario Museum in Toronto, which has mounted Bloodsuckers, an impressive original exhibition about blood predators and parasites.
The show, which he visited last month and runs until March 22, draws on science, medicine, popular culture and the supernatural to explore its central theme. Here, the mosquito is just one of the stars in a much larger cast of squirm-inducing creatures that are united by their quest for the liquid lunch that flows through our veins.
When I met with Winegard and the curators to tour the exhibition, it felt like a gathering of blood brothers. Sebastian Kvist and Douglas Currie are research scientists at the ROM and world experts on leeches and black flies, respectively. Bloodsuckers has been their labour of love, a chance to show museum-goers why they are so passionate about a diverse class of lifeforms – from ticks to lampreys to vampire bats – that most of us would prefer to give a wide berth. Their enthusiasm is infectious.
Fittingly, we entered the exhibition like corpuscles, passing through a stylized recreation of a human artery. We were soon face to fang with a myriad of species that make their living by feasting on the blood of others.
What may come as a surprise to many visitors is that every major animal group has its representative bloodsuckers. That includes birds (I found the vampire ground finches of the Galapagos Islands particularly unsettling). But, even in this vast ecological landscape, mosquitoes hold a dubious distinction. In the course of hunting for our blood, they have become ideal vectors for a suite of diseases. Through their bites, they have claimed more lives than any other adversary. In 2018 alone, mosquitoes are credited with some 830,000 deaths, mostly through malaria. And that’s a huge improvement compared with earlier times.
Fossil mosquitoes preserved in amber show that the insect’s origins reach back at least 100 million years – deep into the age of the dinosaurs and long before anything close to humans was on the scene. When homo sapiens showed up a mere 200,000 years ago, mosquitoes were already there to meet us, feed on us and, through the microbes they carry, channel our development.
In his wide-ranging exploration, Winegard focuses on two chief perpetrators of human misery. One is the mosquito genus Aedes, carrier of diseases such as yellow fever, dengue and West Nile, to name a few. The species Aedes aegypti is currently the most notorious member of the group thanks to its role in the 2016 outbreak of Zika virus. An old-world import, Aedes aegypti is thought to have reached the Western Hemisphere through the slave trade and it’s been making trouble ever since. Until recently, Canada has been too cold a country for it, but climate change has degraded our defences. In 2016, the species was spotted in Windsor, Ont., for the first time.
Far more deadly in global terms is the genus Anopheles. It is Anopheles alone that transports the single-celled organisms that cause malaria in humans. While malaria is fortunately not a public-health issue in Canada today, it was a different story in the 18th and 19th centuries, when hundreds of settlers in Upper Canada died of the mosquito-borne disease. It’s possible that British troops who were rotated into the area after serving in the Caribbean were also disseminating malaria into the local population with the mosquitoes’ help.
Long before malaria’s arrival in the Americas, it was a scourge of the ancient world. Here, readers should be warned that Winegard takes at face value an often-repeated estimate that malaria has killed half of all people who have ever lived. While the figure has been in circulation since at least the 1980s, there is ample reason to be skeptical of it.
More central to the book is Winegard’s historical argument that malaria is a serial game-changer in human affairs. Descriptions from the period suggest it halted Alexander the Great’s armies and the young conqueror himself may have succumbed to the disease. Malaria similarly helped to secure the rise of Rome, thanks to the Pontine Marshes, a year-round source of mosquitoes. In Winegard’s telling, the marshes get at least partial credit for discouraging Hannibal from laying siege to the eternal city.
Fast forward to the Middle Ages and it is “General Anopheles” that keeps Western Europe from being overrun by the Mongol forces led by the descendants of Genghis Khan. An exceptionally wet spring in 1242 coincides with the Mongols turning around and heading for home. Was it simply a matter of too much soggy ground, or was the water-loving mosquito Europe’s secret weapon?
The evidence is more persuasive when Winegard considers the American Revolution. That conflict took a fateful turn in 1779 when Britain decided to shift focus from New England and the mid-Atlantic and relocate troops to the swampy southern colonies. For two years, the British were ravaged not only by patriots but by the malaria-carrying Anopheles mosquito. Winegard points to correspondence from the British commander, Lord Charles Cornwallis, complaining of the need to find “healthy ground” on which to fight. While both sides were susceptible to malaria, the British regulars, often men from the north of England or Scotland, had no prior experience with the disease. Fans of the musical Hamilton are familiar with what happened next, if not the underlying cause. By the time Cornwallis surrendered to French and American forces at Yorktown in 1781, more than half of his men were too sick to stand and fight.
The mosquito’s hidden hand is finally exposed in 1897, when it is shown to be the carrier of malaria. The 20th century becomes a period of open warfare, during which malaria is eradicated from the developed world but continues to exact a shocking toll on populations elsewhere. Back at the ROM, the conversation turns to the latest development in the struggle: the possibility that the genetic editing technology known as CRISPR may soon make it possible to wipe out entire species of disease-carrying mosquitoes.
For entomologists such as Currie, it’s a thorny issue. While the chance to eliminate a major public-health threat may justify the measure of deliberate extinction, there remains a matter of unintended consequences. To underscore the point, evidence published last September found that attempts to suppress mosquitoes through genetic modification in Brazil did not work as planned and have instead led to modified genes circulating in the wild population.
One of the strengths of Bloodsuckers is how it demonstrates the ecological and scientific value of the creatures it puts in the spotlight. Black flies, for example, are not known as disease carriers. And while they may torment us on the hiking trail, they also play an indispensable role as filter feeders during their aquatic larval stage, turning tiny bits of organic debris into handy fecal pellets that sustain an entire ecosystem.
Kvist shows even more love for the leeches he studies, reaching into a tank and pulling out some live specimens so that we can take a closer look. (A nearby video that shows how a leech feeds features Kvist’s willing arm.) There is plenty of time to avoid a grisly scene. Unlike mosquitoes, leeches don’t always latch on right away. Once they do, they are insatiable, ingesting up to three times their body weight in blood. To pull this off, they carry nature’s strongest anticoagulants, which prevent the blood from clotting as they feed. This biochemical adaptation is the reason why medicinal leeches are still used in hospitals today. With the task of producing the exhibition behind him, Kvist has now turned his attention back to the lab. He is part of an international team that in the next several weeks expects to publish the genome of the medicinal leech for the first time, helping to unlock the evolutionary secrets of nature’s most prolific bloodsucker.
Meanwhile, Winegard is trying out a video game developed by the ROM’s exhibit team. It invites visitors to play the role of a mosquito searching for a human to bite amid a jumble of distractions and false leads. “You were quick,” Kvist says, genuinely impressed at how efficiently Winegard finds his target.
Sometimes it’s useful to have a bloodsucker’s perspective.
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