Lesson 1 Tiny and Mighty
The Mosquito: The Worst Bug on the Planet?
Part1 The Nuisance
You are on a camping trip with your family or friends.
After a long day of hiking, you take a quick shower, sit in your favorite camping chair, pick up a soda, and let out a deep, contented sigh.
Right at that moment, you hear that annoying and familiar buzzing sound.
Beating its wings as fast as 600 times per second, a mosquito sneaks in and pierces your skin with its straw-like mouthparts.
Next, it fills its belly with blood and then escapes quickly, leaving behind an itchy red bump.
This is a mild allergic reaction to the mosquito’s saliva.
The more you scratch the bump, the more it itches.
But how do mosquitoes find their victims anyway?
Carbon dioxide, which humans and other animals breathe out, is actually a key signal to mosquitoes that a nice meal is near.
They are highly sensitive to CO2 and can detect it from far away.
That’s not the only cue they use to find their victims.
When you sweat, you release certain chemicals that attract them.
Moreover, they can easily notice that your body temperature has risen.
Why do they want our blood in the first place?
It turns out that only females bite us; they need protein to produce eggs.
If our blood did not contain protein, they would not bother us.
After the mosquito successfully takes a blood meal of up to three times her own body weight, she quickly lands on the nearest vertical surface.
With the aid of gravity, she drains off the water from the blood she took.
Using this concentrated blood, she develops her eggs over the next few days.
She then lays roughly 200 floating eggs on the surface of a small pool of water.
Part 2 The Predator
If you had to choose our greatest predator in nature, which would you pick?
Sharks, lions, or bears?
According to history professor Timothy Winegard, it is actually the mosquito.
Mosquitoes can pass on deadly diseases like malaria and yellow fever.
Over a million people worldwide die of these diseases every year.
Throughout history, Winegard estimates that mosquitoes have killed more people than any other single cause—about fifty two billion people, nearly half of all humans who have ever lived.
Winegard claims that mosquitoes also played a role in shaping the history of several countries.
Take the Roman Empire, for example.
The fall of the Western Roman Empire was gradual, spanning over centuries.
Here are commonly cited reasons for the fall of the empire: invasions by outside forces, economic troubles, and corruption.
Diseases like malaria, however, also contributed.
Rome, the capital of the empire, was once surrounded by a huge stretch of wetland.
This was an ideal breeding ground for mosquitoes and hence a hot spot for malaria.
On the one hand, mosquitoes helped protect the city against the armies coming to attack it.
However, they eventually spread the disease not only throughout the city, but also throughout the empire, crushing much of the population.
Here is another reason why Winegard considers the mosquito a powerful agent of historical change.
In 1698, five ships set sail from Scotland, carrying twelve hundred settlers and valuable trade goods.
They headed for the Darien region of Panama, where Scotland planned to create a trading center.
After struggling through years of a food crisis, Scotland had hoped this would help raise its economic prospects.
The ambitious plan, however, was brought down by the local diseases: yellow fever and malaria.
Virtually no one from Scotland had ever encountered any of these diseases before.
After six months, nearly half of them died, and the survivors returned to their ships and fled.
If their immune systems had been much stronger, they would not have lost so many lives in such a short time.
Surprisingly, human beings lived with and died of these diseases for thousands of years without understanding how they were spread.
It was not until the end of the nineteenth century that we found out that mosquitoes spread malaria.
Before this finding, no one imagined that these tiny annoying insects might be affecting our lives so deeply.
Now we all know that human history is not free from the workings of the natural world.
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