Name: This Is Your Brain on Parasites
Rating: 4.1 (26 reviews)
Author: Kathleen McAuliffe

What’s in it for me? Step into the hidden world of parasites.

Every year, as winter approaches, everyone seems to have it: the latest flu. These tiny viruses annually develop new strategies to get into our bodies, multiply and jump on to their next victim. They change and adapt – and they seem to know exactly what they do.

In fact, parasites, such as viruses, worms, microbes and bacteria, are much more advanced creatures than we would like them to be. They can alter human bodily functions and cognitive capacity, and, when you consider that we’ve been fighting them since the dawn of time, it could even be argued that they shape human culture!

These blinks offer some of the most astounding examples of how parasites have developed methods to pounce on other species, use them as their host and take advantage of them.

In these blinks, you’ll learn

why shrimps are pink;
why zombies really exist; and
why your brain is in your gut.

Humans have been battling a microscopic enemy for millennia.

In the history of humankind, conflict abounds; from opposing tribes to warring countries to contradictory religions, people have always found a way to fight. But there’s another type of deadly conflict that has gone practically unnoticed for thousands of years – a hidden war of microscopic proportions.

It’s the battle between humans and parasites: viruses, worms, microbes and bacteria. In fact, this fight has been so formative that it has affected the evolution of both the human physique and human behavior.

For instance, the human body has formed complex defenses to ward off intruders. The skin prevents microbes from entering; the nose and ears are lined with tiny hairs that filter out parasites and our eyes produce tears to force out invaders.

But even when a microbe does make it into the body, it’s immediately met by other defenses. There’s stomach acid, which is so strong it could burn a hole through a shoe, and mucous, a slime that traps microbes in the nose to be expelled by the next sneeze.

That being said, parasites have a few things going for them. For starters, they greatly outnumber us. They can also reproduce at an incredible rate and are both intelligent and highly adaptable.

So while the majority of them might die, a few survivors can mutate, infiltrate our system and take full advantage of the habitat our body offers.

It’s this incredible capacity for survival that has led to parasite-related deaths in the past. Just take the bubonic plague, a bacterial infection that decimated a third of Europe in the Middle Ages. Or consider Columbus’s arrival in the Americas; his landing resulted in the eradication of 95 percent of the indigenous population by way of smallpox, measles and influenza. And there’s always the Spanish flu, which claimed more lives in 1918 than World War I.

It all goes to show that, while they may be invisible to us, parasites are a powerful foe. They’re also smarter than we might imagine, which is what we’ll explore next.

Parasites alter the behavior of their hosts to their own advantage.

So parasites are bad news, but they’re not just agents of disease that attack the human body. They can actually alter human behavior to their own benefit.

In fact, parasites regularly influence the behavior of their animal hosts to complete their reproductive cycles. Just consider tapeworms, which enter brine shrimp, incite them to mate and thereby spread themselves to new hosts.

Parasites can manipulate other organisms’ brains.

You might not be ready to hear it, but the zombies you see in Hollywood movies aren’t just things of fiction. They actually exist in real life. In fact, living creatures can become zombies by way of parasitic mind manipulation.

A great example is the jewel wasp, which lives in the tropical regions of South Asia, Africa and the Pacific Islands. It gains control of its victims’ brains by essentially performing neurosurgery. Here’s how:

Our guts are home to a panoply of bacteria, which help regulate our emotions.

People tend to think of the brain as the central control mechanism of the human body. But we actually have another brain that lives in our stomach, which is home to an incredible number of microbes and bacteria.

These organisms are a part of the enteric nervous system, which has more neurons – cells that process and transmit information – than the human spine, which is why it’s often referred to as the second brain.

Humans have adjusted their culture and behavior to avoid parasites.

In Darwin’s theory of evolution, biological change is driven by natural selection, a process through which the best adapted species survive. But Darwin’s explanation doesn’t say anything about how culture evolved.

This area is still up for debate and modern biologists have found that cultural behavior might be related to the presence of parasites. For example, in 2007, biologists at the University of New Mexico began a study exploring how the evolutionary environment shapes culture.

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