Is This a Kissing Blog?

wide the-princess-bride-kiss

Buttercup and Westley’s final kiss in Rob Reiner’s 1987 adaptation of William Goldman’s classic, The Princess Bride

“Since the invention of the kiss, there have only been five kisses that were rated the most passionate, the most pure. This one left them all behind.” –The Princess Bride

Ah, wuv. Twue wuv. With that record-shattering kiss, Buttercup and Westley traded vows of everlasting love, the promise of a lifetime’s “As you wish”es, and approximately 80 million bacteria.


Yes, a research group at TMO in the Netherlands investigated how kissing affects a couple’s oral bacteria and found that Valentines swap more than just spit. Just like in your intestines, stomach and skin, your mouth and airways are home to a whole host of bacteria that help keep you healthy, known as your microflora.

Oral bacteria were almost certainly the first to be viewed by humans when back in 1683, Antonie van Leeuwenhoek (the father of microbiology) scraped some tarter off his own teeth and stuck it under a microscope. As many as 600 different species of bacteria can be found in the human mouth, some of which are responsible for common problems like gum disease and tooth decay. However, keeping the bacteria living in your mouth happy and balanced helps keep out disease-causing bacteria, stops bad breath, and may even help prevent more serious diseases elsewhere in your body, including stroke, cardiovascular disease, and diabetes.

While the makeup of a person’s microflora is important, it isn’t static. The mouth is an open system, meaning that the composition of the bacteria living there can be changed by things like your genes, age, diet and who you…interact with.

princess bride grandson

INTIMATE kissing? Are you trying to kill me?


The Dutch research group that performed this study swabbed the mouths of random visitors at the Artis Royal Zoo in Amsterdam. Then, the researchers had them make out for ten seconds before re-sampling. You can’t make this stuff up.

The researchers found that among their amorous zoo-goers, romantic partners had more similar oral microflora composition pre-kiss than two people not in a relationship. In particular, partners showed the most striking similarities in the microflora associated with their tongue. The long-term couples’ microflora didn’t change much post-kiss, but this is most likely because they are in like with each other and already swap bacteria fairly regularly.


The scientists conducting the study then wanted to know precisely how many bacteria are passed around per make-out sesh. To answer that question, they gave one partner of each couple probiotic yogurt containing what they referred to as “marker bacteria” and, again, had them snog away.

They then resampled everyone’s mouths to see how much bacteria had transferred from the person who ate the yogurt to the person who did not. It turns out that on average, 80 million bacteria were swapped from one mouth to the other per 10-second make-out.

aaaaaas youuuuu wiiiiiiiiiish

Aaaaaaaaassss youuuuuuuuu wiiiiiiiiiish!


True love is not as easy as one simple kiss, however; it requires effort and real commitment. In fact, the researchers found that in order for a couples’ microfloras to really change to resemble each other, they need to kiss — intimate kissing, they specified — nine times per day.

So, friends, to have the sort of love that cannot be tracked, even with a thousand bloodhounds, that cannot be broken, even with a thousand swords, that is second only to a good MLT — remember to say those three little words every time your Valentine wants a smooch: As you wish.

Finding Vibrio

anglerfish scene gif

“…Good feeling’s gone.” Image: Disney Enterprises, Inc./Pixar Animation Studios

“Come on back here! I’m gonna getcha! I’m gonna swim with you…I’m gonna be your best friend!”

Little did Marlin and Dory know that the light — and the hungry anglerfish attached to it — already had millions of best friends without whom it couldn’t glow. Thanks to bioluminescent bacteria like Vibrio fischeri and Photobacterium phosphoreum, many species have found a way to shine in the most unlikely of habitats.


Bioluminescence is the production and emission of light by a living thing. This light has a wide variety of uses, from confusing prey, to startling predators, to attracting a mate. Bioluminescent organisms can be found on most of the branches of the tree of life, from bacteria all the way up to fish.

Bioluminescence probably originated in the ocean, and is more commonly found in marine species than in ones on land. Bioluminescent marine species live across all of the ocean depths; the greatest number of bioluminescent species can be found in the ocean’s dimly lit twilight zone, but of the organisms that have adapted to life in the ocean’s deep, dark midnight zone, about 90% are bioluminescent!


A bioluminescent jelly. Image: Joshua Lambus, Flickr

Unlike the light generated by an incandescent light bulb, bioluminescent light comes not from heat, but from energy released by a chemical reaction in the organism. All bioluminescent reactions involve a “luciferin” compound and a “luciferase” protein, both from the Latin word “lucis,” meaning “of light.” When a luciferin and a luciferase come together with oxygen and ATP (a cell’s fuel source) the reaction releases energy that we see as colored light.

Luciferins and luciferases come in many different flavors — over a dozen chemical luminescence systems are known — suggesting that bioluminescence has evolved many different times under different conditions. The luciferins and luciferases usually seen in marine bioluminescent species react to produce green or blue light, as these wavelengths of light travel well through seawater without getting absorbed or scattered.


Many bioluminescent species are able to produce light on their own, but others, like our toothy anglerfish friend, have had to get more creative. A large number of bioluminescent species are not bioluminescent in their own right, but have evolved a symbiotic relationship with bioluminescent bacteria.

A symbiotic relationship is one in which two living organisms live in or on each other in a close, physical way (from the Greek sym, “together,” and bio, “life”). Such relationships aren’t always good ones; the luminous bacteria that live symbiotically with the Tanner crab, for example, are parasitic and damage the crab’s legs. In the case of the deep-sea anglerfish and its photobacteria, however, the relationship is a mutualistic one, meaning both the fish and its glowy roommates benefit from their partnership.

Luminous bacteria living in the seawater, like Vibrio fischeri or Photobacterium phosphorum, float through pores in the bulbous sac, or esca, on the end of an anglerfish’s lure and colonize it. This lure is a completely mobile appendage whose luminescence helps female anglerfish lure charming, anthropomorphized prey to their mouths and attract their unfortunate potential mates.


Bioluminescent bacteria and algae can cause glowing red tides, as seen here in Black Point, Anglesey. Image: Kris Williams, Flickr


While photobacteria can glow on their own, they just…don’t. Before they’ll start to glow, photobacteria like V. fischeri need a little help from their friends.

Bacteria are surprisingly social organisms; instead of communicating using words or howls, bacteria send signals to each other by releasing chemicals into their environment. The more bacteria there are in an area, the more signaling molecules will be floating around them. Many bacteria regulate the production of some proteins — like those that make them glow — in response to changes in levels of these signaling molecules in their surrounding environment.

Vibrio Fischeri

Vibrio fischeri, seen plated here, are quorum-sensing bacteria that regulate their bioluminescence in response to changes in population density.

Photobacteria use this kind of communication, known as quorum sensing, as a sort of light switch. Once the number of other photobacteria reaches a certain level, the bacteria detect the resulting elevated levels of signaling molecules around them. In response, the genes that encode the luciferin and luciferase proteins get turned on and the bacteria begin to glow. If the numbers of bacteria drop, however, those genes get switched off again and the glowing stops.

Quorum sensing was first observed in V. fischeri — the glowing made it easy to see the correlation between bacterial density and regulation of the genes responsible for light production. Eventually, it became clear that the process wasn’t specific to V. fischeri and its bioluminescent abilities, but was common to the regulation of many different types of proteins across the bacterial family tree.


Whether glowing bacteria or luminescent fish, the ocean’s bioluminescent organisms are stunning, sometimes literally. The next time you’re on a deep sea adventure and see a pretty light, perhaps don’t stand in awe too long—you might just go from ardent admirer to snack in a flash.

Life on Mars

M. Dudouyt’s creepy Martians from the 1917 edition of H.G. Wells’ classic novel, The War of the Worlds

The idea that extraterrestrial life may be out there is one that has captured our species’ collective imagination for centuries. It’s possible that being able to share this incomprehensibly vast universe with someone else makes us feel a little less alone. It’s equally possible that we just want advanced alien technology without the effort and expense associated with inventing it ourselves. Perhaps that’s why the theories suggesting that there is, or ever was, bacterial life on Mars is such an attractive one to Terrestrial scientists.

The presence of even unintelligent life on a planet as nearby as Mars would mean that, however improbable it may be, life somehow found a way to exist twice in the same tiny corner of the galaxy. If that’s the case, what’s to say it’s as rare as we think it is? If life could be found just next-door, we reason, the void stretching between us and another intelligent species might not be as expansive as we previously thought.

Speculation that life could be found on the Red Planet is not a new one – from Edgar Rice Burrough’s John Carter of Barsoom to the Looney Tunes’ Marvin the Martian, little green men (or huge green men, as the case may be) have played a prevalent role in science fiction since its inception. However, it wasn’t until the mid-1990s that fantasies about Martian life began to bleed into the realm of possibility.


On December 27th, 1984, the scientific community received the best Christmas present it had been given in a long time when a National Science Foundation team found a meteorite in the Allan Hills of Antarctica. The meteorite, now named ALH84001, was described by the team as being grayish-green, highly-shocked, and the rarest find of that season. Additional remarks in the field notes include simply, “Yowza-yowza.”

Nine years of analysis revealed that the meteorite was both of Martian origin and incredibly ancient; radiometric dating determined that ALH84001 is approximately 4.1 billion years old, meaning it formed very shortly after Mars itself came into being. After an impact event launched it from Mars’ surface, ALH84001 had spent nearly 16 million years dancing out in space before crash-landing in Antarctica somewhere around 13,000 years ago.

In 1996, ALH84001 found its way into the spotlight when NASA scientist David McKay reported a shocking discovery: this meteorite may hold evidence of ancient microbial life on Mars.

The carbonate disks found in ALH84001, rimmed with black magnetite rings. Image: Thomas-Keprta et al. (2009)

The carbonate disks found in ALH84001, rimmed with black magnetite rings.
Image: Thomas-Keprta et al. (2009)


While examining the meteorite, McKay’s group found that ALH84001 contains flat carbonate disks rimmed with rings of tiny magnetite crystals. Magnetite is a commonly occurring iron oxide that is a natural magnet. Terrestrial magnetite is known to form in igneous and metamorphic rock when under pressure in high temperatures. However, some magnetite is of biogenic origin – it is created by living organisms.

In 1975, Richard Blakemore discovered a group of magnetite-producing bacteria that he named “magnetotactic bacteria.” Magnetite derived from magnetotactic bacteria is very distinct; they produce very fine (as small as 0.000000005 meters!) magnetite crystals bound by intracellular membranes. These tiny organelles are called “magnetosomes.”

The magnetosomes of magnetotactic bacteria are aligned in chains that act like a bacterial compass needle – they orient the bacteria into perfect alignment with the Earth’s geomagnetic field. The bacteria use this process, called “magnetotaxis,” to narrow their search for an ideal growing environment.

Interestingly, magnetotactic bacteria exist in numerous forms in as many varied locations around the planet. Magnetotactic cocci, rods, vibrios, spiriella, and even multicellular forms have been found in diverse aquatic environments, from oceans to lakes to rice paddies. The only things these tiny, living magnets seem to have in common is that they are all Gram-negative, contain magnetosome chains, and live in watery habitats.

A transmission electron micrograph of a magnetotactic bacterium. The dark spheres are the magnetosomes, lined up in a chain along the bacterium's axis. Image: Nature Education

A transmission electron micrograph of a magnetotactic bacterium. The dark spheres are the magnetosomes, lined up in a chain along the bacterium’s axis.
Image: Nature Education

The magnetite from magnetotactic bacteria is so finely, purely, and consistently produced, that to date, no lab has been able to synthesize magnetite of the quality made by magnetotactic bacteria. However, scientists have been able to use both magnetotactic bacteria and isolated magnetosomes in a variety of medical and scientific applications.


That magnetite was found in ALH84001 is in itself not very exciting; magnetite is made all the time near terrestrial volcanoes and hydrothermal vents. In fact, about 75% of the magnetite crystals ringing ALH84001’s carbonate disks may have been produced by those same processes. What excited the scientific community were the unique chemical and physical properties of the remaining 25% of the crystals.

These magnetite crystals are chemically pure and very fine, measuring a tiny tens of nanometers in size. In terms of size, shape, purity, and magnetic properties, these crystals match the characteristics of magnetite produced by terrestrial magnetotactic bacteria – the same properties that neither humans nor geological processes could imitate.

Many experts therefore believe that these magnetite crystals are a Martian biosignature: a physical or chemical marker of the presence of life. If this is true, these Martian bacteria are the earliest forms of life known to man.

A side-by-side comparison showing the similarities between magnetite crystals found in ALH84001 and those produced by the Earth magnetotactic bacterium strain MV-1. Image: Kathie Thomas-Keprta, NASA Johnson Space Center

A side-by-side comparison showing the similarities between magnetite crystals found in ALH84001 and those produced by the Earth magnetotactic bacterium strain MV-1.
Image: Kathie Thomas-Keprta, NASA Johnson Space Center


Whether or not these magnetite crystals were actually made by ancient Martian magnetotactic bacteria is a subject of hot debate. Other potential Martian biosignatures exist, though none so definitive as a mineral of biogenic origin. Methane found in Martian rock samples may imply active biological processes are taking place on Mars, perhaps just below the planet’s surface.

Further, analysis of the carbonate disks in ALH84001 showed that they were formed during what is known as the Noachian epoch on Mars, when high numbers of asteroid and meteorite impacts formed the oldest Martian surfaces that exist today, and water was possibly an abundant resource on Mars. These disks precipitated 3.9 billion years ago in a shallow, sub-surface watery environment near a temperature of 18°C. This means that this magnetite was produced in an environment similar to ones where some terrestrial magnetotactic bacteria are found.

Some experts believe that, rather than being made by bacteria, the magnetite may have been produced by the geological process of thermal decomposition, as often seen on Earth. However, experiments have shown that none of the currently proposed scenarios for geological production of these crystals could have resulted in magnetite crystals with these properties. This doesn’t prove that the crystals definitely resulted from a biological process; it just means that we still can’t rule out the possibility that they did.


It may not be a giant face on the surface of Mars, but ALH84001 has brought us closer to finding extraterrestrial life than ever before. Will our search for neighbors somewhere in the cosmos prove fruitless, or miraculously reveal that we are not alone in this vast universe? We may never know for sure, but at least the clues hidden in ALH84001 have given mankind a real reason to hold on to hope, and Congress a real reason to give NASA funding. Perhaps that’s a big enough miracle in itself.

You Know Plenty, John Snow

Dr. Jon Snow, the Father of Epidemiology, and his impressive sideburns.

An 1856 autotype portrait of Dr. John Snow, the Father of Epidemiology, and his impressive sideburns.
Image: Wikimedia Commons

Even the most casual Game of Thrones fan knows Jon Snow, the illegitimate son of the late fan favorite, Ned Stark. As a man of the Night’s Watch, Jon Snow is charged with defending Westeros from the terrors beyond the Wall, including keeping Wildling invasions and the terrifying Others (White Walkers) at bay.

However, many of you have probably not heard of another John Snow who went down in history as a great defender of men. Now known as the Father of Epidemiology, this John Snow was a 19th century doctor and revolutionary thinker who bucked the established paradigm of then-modern thought.


In the mid-1800’s, Soho in London’s West End was not exactly the height of fashion. It was a squalid, densely populated working-class neighborhood that was largely neglected by the well-to-do of London. At this time, Soho’s residents depended on poorly maintained cesspits or the River Thames for waste disposal, rather than a well-planned sewage system.

The poor quality of Thames drinking water, depicted in William Heath's 1828 cartoon, A monster soup, commonly called Thames Water. Image: Wellcome Images

The poor quality of Thames drinking water depicted in William Heath’s 1828 cartoon, A monster soup, commonly called Thames Water.
Image: Wellcome Images

This lack of basic water and sanitation infrastructure meant that the many residents of Soho were swimming in their own filth. Accounts from this time describing cellars three feet deep in human excrement and nearly opaque drinking water the color of green tea feel ripped from Martin’s pages on Flea Bottom, with the glaring difference that these accounts are not works of fiction.

A member of both the Royal College of Surgeons of England and the Royal College of Physicians, John Snow not-of-Winterfell fought to combat poor hygiene and disease. Though he was by training an anesthesiologist (he personally administered chloroform to Queen Victoria during the birth of her two youngest children), recent cholera outbreaks in Soho attracted his attention. The end of August 1854 had brought with it a particularly bad bout of this disease, killing 127 people within the first three days of the outbreak.

A transmission electron microscopy image of the bacterium that causes cholera, Vibrio cholerae. Image: Tom Kirn, Ron Taylor, Louisa Howard - Dartmouth Electron Microscope Facility

A transmission electron microscope image of the bacterium that causes cholera, Vibrio cholerae.
Image: Tom Kirn, Ron Taylor, Louisa Howard – Dartmouth Electron Microscope Facility


Today, we know that cholera is spread through food and water contaminated with feces containing the bacterium Vibrio cholerae. In 1854, however, the idea that living, microscopic organisms cause infectious diseases, called the “Germ Theory of Disease,” would not have been accepted by the medical profession, as Louis Pasteur did not come up with it until 1861.

The “Miasma Theory of Disease” that pervaded at that time had existed since medieval times. It stated that foul, poisonous air made people sick; in fact, this idea was how the disease malaria got its name, being medieval Italian for “bad air.”

Though John Snow knew as little about infectious microbes as anyone else at the time, his observations about the patterns of the spread of disease led him to believe that bad air had nothing to do with it. He traveled from house to house, collecting data on the sick and the deceased in order to map out the source of the outbreak.

By asking questions about people’s habits and behavior, he found that the common connection between many of the sick was that their main source of drinking water was a water pump that sat on the corner of Broad Street and Cambridge Street.

ghost map

John Snow’s map of cholera cases in Soho. Each black bar represents one case of cholera. The Broad Street pump is marked in the center of the map.
Image: John Snow, M.D., On the Mode of Communication of Cholera

By the time the Board of Guardians of St. James’s Parish met on September 7th, 1854, nearly 500 people had died from the cholera outbreak that was sweeping through Soho. Firmly believing the Broad Street pump to be the center of the outbreak, John Snow testified in front of the Board, urging them to remove the pump’s handle in order to stop further spread of the disease.


Though the Board was skeptical of his claims, they took his advice and mandated that the handle be removed from the Broad Street pump to block the source of the disease. The outbreak waned shortly after the handle was removed, but few really believed Snow’s theory.

The fact was that nobody wanted to believe that the disease was being spread through drinking water contaminated with human feces; despite the obvious evidence that the water was filthy, this thought was too vile to be readily accepted. The end of the outbreak did not help his case, either – Snow was the first to admit that the outbreak had already been on the decline before they took action.

Despite this reluctance to believe Snow’s theory that disease is contagious, evidence kept piling up in his favor against the claims of those who believed in the Miasma Theory of Disease.

Afjeowi caption

George Pinwell’s 1866 cartoon, Death’s Dispensary, depicting the Broad Street Pump as the source of the 1854 Soho Cholera outbreak.
Image: CDC


Snow set out to find more convincing evidence for the connection between contaminated water and cholera infection, and discovered that those who avoided drinking from the Broad Street Pump did not become infected.

Just one block away from the Broad Street pump, workers in a local brewery and monks from a nearby monastery did not become ill, despite being surrounded by the sick. It turned out these men took a page out of the Lannister playbook; rather than drinking water, they exclusively drank alcohol, specifically the beer they brewed within their own walls.

Further investigation found that of the 535 malnourished inmates living in the terrible living conditions of a Soho workhouse, only 5 became ill. This workhouse had its own, independent source of water.

With the help of fellow contagionist Dr. Joseph J. Whiting, Snow extended his inquiries by asking residents around South London which company supplied their drinking water. They were particularly suspicious of the Southwark and Vauxhall Water Company, which could have caused cases later in the outbreak by pulling water from the Thames downstream of where cholera-contaminated sewage was dumped into the river.

A table from John Snow's 1856 paper, Cholera and the water supply in the south districts of London, 1854, showing the connection between the Southwark and Vauxhall company's water and deaths due to cholera.

A table from John Snow’s 1856 paper, Cholera and the water supply in the south districts of London, 1854, showing the connection between the Southwark and Vauxhall company’s water and deaths due to cholera.

When they compared these findings to the incidence of cholera in Soho, Snow found that 286 of the victims of the most recent outbreak drank Southwark and Vauxhall water, whereas only 14 drank water from another company that pulled water upstream of the sewage inputs (it was unknown which company provided water to the remaining 34.)

Despite the evidence in favor of John Snow’s theory, the Miasma Theory prevailed until Louis Pasteur’s development of the Germ Theory a decade later.


He may not have killed a White Walker, fought off a Wildling invasion, or even managed to convince people that disease is contagious. Still, John Snow’s impact was profound. Snow’s investigations established a new way of thinking about disease; by trying to understand human behavior and find patterns surrounding the outbreak, he laid the foundation for the field of epidemiology as we know it today.

And so – it seems it’s safe to say that in spite of the staunch opposition of the Miasmatists, you know plenty, John Snow.

Should Auld Acquaintance Be Forgot

Ms. Pelletier's American Literature and Knife-Wielding 101. Image: AMC

Ms. Peletier’s American Literature and Knife-Wielding 101.
Image: AMC

I think we can all agree that there are many drawbacks to life in the post-apocalyptic world of the Walking Dead. The lack of resources, collapse of basic infrastructure, limited medical care, and the ever-present, ravenous undead make even the simplest tasks a struggle. Let’s not even get started on traveling up Atlanta’s Downtown Connector – between the buildup of abandoned cars and flamed-out tanks, traveling through Atlanta could only be harder if there was an inch of snow on the ground.

While adjusting to the new world can be tough for many survivors, there are some surprising benefits for the children of the apocalypse: an education that includes both Tom Sawyer and knife-wielding skills, the opportunity to develop a pretty forgiving palate, and, surprisingly, an immune system that’s trained better than a Navy SEAL.

What gives little Judith Grimes a biological edge over even Michonne and her katana? Simply put, she will have grown up caked in dirt and, well…grime.


Farmer Rick’s pig, Violet, taking immune health very seriously.
Image: AMC


In the modern world, if something is dirty, you clean it. Whether your home, your body, your car, or your pet, clean is the norm and dirty should be an exception that is remedied as soon as possible. Dirt is the enemy, and cleanliness is healthy and good.

In the last quarter century, however, doctors have begun to realize that this idea is not necessarily true. Though the incidence of childhood infections has decreased since the advent of modern medicine and sanitation, more and more people are developing health problems like allergies, asthma, and autoimmune diseases.


We so often talk about threats our immune systems need to recognize and fight that we tend to forget an equally important part of the immune system’s job is to not recognize other things that are harmless. The question is, how do we teach our immune system to tell the difference between the good guys and the bad guys?

Enter what scientists call “immune tolerance.” Immune tolerance is the process by which the immune system keeps the immune cells that respond to actual threats and get rid of those that respond to things that should be ignored, like the body’s own cells.

By developing proper immune tolerance, we avoid both autoimmune diseases and chronic inflammatory diseases caused by a poorly trained, trigger-happy immune system. If the immune system constantly activates in response to things that don’t actually need to be killed, the collateral damage to the body’s own tissue is very high.

Nasty but nice - even microbes that can cause mild disease, like tapeworms, are considered "old friends" microbes. Image: Hubert Ludwig

Nasty but nice: even microbes that can cause mild disease, like this tapeworm, are considered “old friends” microbes.
Image: Hubert Ludwig


When the human immune system was first evolving back in our hunter-gatherer days, we were far from clean. People would have had regular contact with their microbial neighbors that live in the soil, water, and everywhere else, for that matter – so-called “old friends” microorganisms.

By reducing our regular contact with these “old friends,” the modern urban lifestyle that predominates in most of the developed world is associated with the uptick in both chronic inflammatory diseases, like asthma and hay fever, and autoimmune diseases, such as multiple sclerosis and Crohn’s disease.

In fact, treatment with antibiotics within the first six months of life, effectively killing off an infant’s microbes, is associated with an increased risk of such diseases. Even being born by Cesarean section increases the chances a child will develop these diseases by interfering with the colonization of the infant by its mother’s microbes during natural birth (so maybe Judith is at a slight disadvantage there…)

It appears that these interactions between humans and microbes in the dirt were so constant that as our immune system developed, it evolved a special role for these “old friends.”

Are they dirty because they're badasses, or are they badasses because they're dirty? Yes. Image: AMC

Are they dirty because they’re badasses, or are they badasses because they’re dirty? Yes.
Image: AMC


The biological reasoning behind this idea, better known as the Hygiene Hypothesis, is fairly simple.

Much like Rick’s mental state, the immune system exists in a delicate balance. One arm serves to call immune cells to action, while the other arm activates the production and release of antibodies. If one arm or the other gets too active, either autoimmune diseases or allergies can develop.

The improbable rise of autoimmune and inflammatory diseases in the 20th century puzzled scientists for some time, as they indicated problems on both arms of the immune system. How could one problem affect each arm differently from person to person?

It turns out the problem wasn’t with these different arms themselves, but with the immune cells in charge of keeping them in line. Regulatory T cells are the police force of the immune system, playing an important role in immune tolerance. When these regulatory cells find an immune cell that responds to harmless things, it hog-ties and gets rid of it before it can do more damage.

That constant contact with our “old friends” microbes gives the regulatory cells the guidebook they need to tell the Governor from good-guy Aaron. Without being able to sample these microbes and learn from them, regulatory cells don’t develop properly and can’t recognize immune cells that need to be stopped.


While proper hygiene and sanitation are very important at blocking infection with enemy microbes, they are also keeping out friendly ones that we need. In order to get around this Catch-22, many scientists are considering purposefully introducing our old friends to polite society via a different route, such as in our food or as a medication (think probiotics!)

In the meantime, our old friends will ensure little Judith and other kids rolling around in the post-apocalyptic dirt are well equipped to handle whatever the Walkers, Kirkman, or Nicotero throw at them.