Buzz
Spit, often dismissed, is both a curious and occasionally unsettling aspect of the human body. This frothy liquid does a lot more than you might think: it aids in hormone transfer, protects our teeth, and even carries the essence of our distant ancestors.
The realm of saliva takes an odd turn when scientists explore its potential as a vaccine or modify it into an incredibly powerful painkiller. In the darker recesses of sputum research, a strange, new life-form lurks within human saliva, while people secretly profit from trading infected samples on the black market.
10. Transforming Frog Spit
Numerous illustrations and cartoons portray frogs snatching flies with their tongues. The science behind this remarkable skill is truly fascinating. These amphibians capture their prey using a mix of rapid reflexes, precision, and a unique, sticky saliva. When a frog sights a potential meal, it shoots out a tongue that is ten times softer than a human’s, enabling it to smoothly reach every corner of an insect.
As the tongue extends and makes contact, the saliva is initially thin. Once the tongue pulls back, however, the spit becomes thicker than honey. The watery liquid that seeped into the prey’s every crevice quickly thickens, making the frog’s saliva an inescapable trap.
This process is effortless for frogs, as they don’t need to do anything particularly special. The force of the tongue launching forward and retracting swiftly takes care of everything.
To better understand the mechanics of the saliva, scientists used a rheometer to analyze mouth samples from 18 frogs. This device measures fluid properties and revealed that high concentrations of long-chain proteins were responsible for the thick, slimy texture.
9. The Role of Saliva in Reproduction
Philematology is the scientific field dedicated to the study of kissing. Researchers who delve into the world of smooching discovered something intriguing—spit plays a surprisingly important role in romance. Or at least in physical attraction.
At first glance, many people may consider saliva—particularly that swirling around in someone else’s mouth—as anything but romantic. But in reality, it plays a far more significant role in reproduction than most realize.
Scientists focused on college-aged couples, asked them to kiss, and then examined their hormone levels. The couples who simply held hands didn’t experience the same decrease in stress hormones (cortisol) or the increase in bonding hormones (oxytocin) as those who kissed.
From an evolutionary perspective, passionate kissing could serve as a way to influence these hormones, both of which are crucial to reproductive success. Previous research has also uncovered that saliva contains testosterone, a hormone that boosts libido.
Philematologists have observed that more men than women tend to enjoy a passionate, open-mouthed kiss. This could be nature’s design, as it may facilitate the transfer of testosterone from a man to his partner, possibly helping to set the mood.
8. It Can’t Quench Your Thirst
Many a thirsty adventurer in the desert, armed with knowledge of saliva, has wondered, 'Saliva is 98 percent water. Why am I still so thirsty?'
Sadly, for those stranded in the desert or for the person too lazy to get up and grab a drink, saliva doesn’t actually relieve thirst. The problem isn’t the water content but the concentration of salts and other solutes. To stay hydrated, cells need fluids that are less concentrated than the fluids already present in the body.
Freshwater is just right for this purpose. In contrast, saliva is packed with enzymes and proteins, making it much more concentrated than water. So when only saliva is available, the body ends up in a frustrating cycle of dehydration.
It begins with a few swallows, but the saliva doesn’t seem to relieve the thirst. The body dehydrates, causing the spit to become even more concentrated. While it’s 98 percent water, it’s still not watery enough to keep the body hydrated on its own.
7. Dry Mouth Syndrome
Some individuals are unable to produce enough saliva. While this may not seem like the worst problem, the repercussions are far from desirable. Saliva coats the inside of the mouth with a thin layer—just about a milliliter—but it plays a vital role in maintaining oral health.
Without this essential liquid, a condition known as “dry mouth” can occur. People affected by it often face rapid tooth decay, yeast infections, and other unpleasant oral issues.
The protective qualities of saliva stem from its rich composition. Made up of about 98 percent water, the remainder is filled with active components like mucus, electrolytes, enzymes, and antibacterial agents. Together, these elements work to break down fats and starches, aid swallowing, and shield the teeth and gums from acids, bacteria, and harmful microbes.
Saliva also has another fascinating function. Actions like chewing, jaw clenching, or teeth grinding place immense pressure on the teeth. Thanks to the proteins in saliva, teeth slide over each other rather than scraping directly against the enamel.
It may seem simple, but engineers know that high pressure makes lubrication tricky. Saliva handles this challenge seamlessly, and without it, teeth would be seriously damaged in just a few years.
6. A Morphine Alternative
Opioids, including morphine, are some of the most powerful pain relievers. While opioids can provide significant relief, prolonged use often leads to tolerance, addiction, and even fatal overdose. It's no surprise that scientists have long been searching for a new alternative—one that offers the same potency as morphine but without the harmful side effects.
In 2006, a potential substitute—a peptide known as opiorphin—was discovered in human saliva. This peptide enhances the effectiveness of enkephalin, an opioid peptide that serves as the body's natural painkiller.
Much like morphine, enkephalin binds to receptors along the spine and prevents pain signals from reaching the brain. Since both peptides are naturally occurring in the body, they don't carry the same risks associated with traditional opioids.
However, they weren't without limitations. Opiorphin didn’t reach as many areas as morphine could. It stayed confined, bound to the locations where enkephalin was released.
In recent years, a modified version of this saliva-derived peptide has been developed to address this issue. Named STR-324, it showed promising results in rats when injected to manage postoperative pain.
5. Cat Saliva Vaccine
When investigators probed a Chicago doctor for potential malpractice, they stumbled upon something truly strange. In 2016, they uncovered that Ming Te Lin was diluting oral vaccines with two unusual ingredients. One was vodka, presumably bought at a local liquor store. The method he used to obtain the second ingredient—cat saliva—remains a mystery.
For Lin, this wasn’t a single experiment. The doctor had been administering alcoholic cat spit to his patients for over a decade. His youngest patient was just seven days old. Lin, an allergist and immunologist, believed that vodka and cat saliva could help treat allergies. Remarkably, none of his patients, or in some cases, their parents, raised any complaints.
Lin was only discovered after healthcare professionals noticed that children's vaccination records had been altered. Since the US Food and Drug Administration does not approve of using cat saliva, Lin was suspended from medical practice. He also faced serious charges for falsely claiming that the vaccines he gave to minors were the standard versions.
4. Enigmatic Prehuman Ancestor
In 2017, researchers investigated saliva samples from sub-Saharan Africa to examine mucin-7, the protein responsible for giving saliva its slippery texture, and the potential health benefits it may provide to humans.
However, something odd caught the scientists' attention. The MUC7 gene, which codes for mucin-7, showed significant variation compared to the same gene in other regions. Between 5–7 percent of the sub-Saharan African population carried this unusual variation. Remarkably, this gene was more closely related to the versions found in Denisovans and Neanderthals—both extinct human species—than to the contemporary human variant.
This led to a startling conclusion: around 200,000 years ago, the ancestors of modern humans must have interbred with something not quite human. Further tests revealed that this mysterious ancestor was even more distantly related to humans than the Neanderthals, who were the closest living relatives of humans today.
Although scientists are certain that this extinct hominid belonged to another branch of humanity, they remain clueless about what it may have looked like. Until their fossils are discovered, they hold the unique distinction of being the only extinct hominids to continue their existence, ironically, as spit.
3. Underground Saliva Market
In South Africa, saliva—particularly the saliva from tuberculosis (TB) patients—has become a black market commodity. Buyers, in good health, acquire vials of infected sputum and present them at health clinics, fraudulently claiming it as their own.
Once the clinic confirms the fluid contains TB, the scammer is given a medical card stating their diagnosis. This card is then used to apply for a disability grant from the Department of Social Development, which provides a temporary allowance of approximately R1,000 (around $75) per month.
Since scammers can exploit the system for several months, they are not hesitant to pay for the vials, which range between R50 and R100 (around $4 to $8). Though the selling price and the disability grant may seem small, the trade continues to thrive in the townships of Cape Town, where high unemployment and poverty leave many families struggling.
Once someone is diagnosed with TB, finding or keeping a job becomes even harder. So, they resort to selling their saliva. A TB patient-turned-dealer visits a clinic for treatment but actually goes there to steal the vials. The theft is easy, and the clinics that accept unsupervised spit samples make it even easier, which is why this scam remains so widespread.
2. A New Discovery
In 2016, scientists uncovered a new life-form. It wasn't an animal hiding in the forest or a fungus discovered on Mars. Instead, a microscopic creature had been quietly living in human saliva all along.
This is no friendly face. If bacteria could scream and flee from a predator, this would be the one to fear. The unnamed bacterium is the first of its kind—an organism that preys solely on other bacteria.
It was discovered attached to another strain called Actinomyces odontolyticus. When observed in the lab, it hunted down Actinomyces, latching onto its surface membrane. The parasite extracted the necessary amino acids to survive but ultimately killed its host, Actinomyces.
Scientists remain uncertain how it reproduces or moves on to its next host. The most alarming finding occurred when its DNA was discovered in elevated levels in patients with gum issues. It appears that Actinomyces, which is linked to gum disease, received one final advantage before it died. The parasite enhanced the bacterium's ability to avoid white blood cells and resist antibiotics. The parasite's DNA was also found in individuals suffering from cystic fibrosis.
1. The Lyssinum Case
In 2018, the medical community was shaken by a remedy called lyssinum. If one bothered to examine the ingredients closely, most would steer clear of the bottle. Lyssinum is made from the saliva of a rabid dog. Rabies, a disease spread through infected saliva, is almost always fatal to humans.
The uproar of 2018 came after a Canadian naturopath claimed she used the remedy on a child. The four-year-old boy, known only as Jonah, would hide under his school desk and growl at others. He had previously been bitten by a dog, which the naturopath attributed to his odd behavior.
The remedy was said to be effective, but it alarmed traditional doctors. Apart from the clear risk of infection, there is no evidence to support that lyssinum is safe or even effective.
However, those opposing the use of rabid dog saliva as a treatment for growling children face an uphill struggle. The College of Naturopathic Physicians of British Columbia stated that the remedy was acceptable in this instance. The Canadian government didn’t seem to object either.
