Gum With 5,000-Year-Old Tooth Marks
In Kierikki, Finland, researchers found chewing gum about 5,000 years old, complete with tooth imprints. It was made from birch bark tar, which is believed to have antiseptic properties. People have chewed gum in many forms since the Neolithic period, and the habit seems to have appeared separately in many early civilizations.
The Maya and Aztecs used chicle, a natural tree gum, to make a gum-like chew and to stick everyday objects together. Ancient Greeks chewed mastic, probably to keep their mouths healthy. Early chewers were not after nutrition. They wanted flavor, cleaner teeth or fresher breath.
In North America, Native peoples chewed resin from spruce trees, and New England settlers picked up the habit. In 1848, John B. Curtis sold the first commercial gum, called The State of Maine Pure Spruce Gum. Around 1850, a gum made from paraffin wax took over. To keep it sweet, chewers dipped it again and again into a plate of powdered sugar.
The Failed Rubber That Became a Hit
Modern gum began with a failed experiment. In the 1860s, former Mexican president General Antonio López de Santa Anna brought chicle to New York and gave it to Thomas Adams to use as a substitute for rubber. It flopped as rubber. But cut into strips, it sold as Adams New York Chewing Gum in 1871.
In the 1860s, Louisville pharmacist John Colgan created the first flavored gum, "Taffy Tolu", using a flavoring from a balsam tree. In 1869, Ohio dentist William F. Semple patented a gum meant to clean the teeth and strengthen the jaw. It was not a sweet treat. It contained chalk and powdered licorice root, and his patent even suggested charcoal.
Black Jack in 1884, Chiclets in 1899 and Wrigley's Spearmint Gum soon ruled the market. American soldiers in World War II got gum as part of their rations and traded it with locals, which spread it around the world. By the 1960s, US makers had switched to synthetic rubber.
Why Gum Never Dissolves
The secret is the gum base, a mix of polymers, softeners and resins. Each company's exact recipe is a trade secret known to only a few people. Its polymers are hydrophobic, meaning they repel water. Saliva dissolves the sugar and flavors but leaves the base alone, so you can chew the same piece for a long time.
That same property makes gum sticky. Water-repelling polymers attract oil, so gum bonds to oily surfaces like skin, hair, sidewalks and shoe soles. Pulling it off is hard, because the long polymers stretch instead of breaking.
Bubbles are pure physics. The air you blow pushes equally on every inner surface, so bubbles come out round. When the air pressure beats what the stretched polymers can handle, the bubble pops. Bubble gums use longer polymers that stretch further. The cool feeling of some gums comes from certain bulk sweeteners, which absorb heat as they dissolve in saliva.
A Flavor Timetable and a Friend to Teeth
Gum releases its flavors on a schedule. In the first three to four minutes, sweeteners such as sugar dissolve. From about four to six minutes, intense sweeteners and some acids follow. Wrapped-up flavors come out around 10 to 15 minutes in, or even after 30 to 45 minutes. Finally, the softeners dissolve and the gum firms up.
Gum can be good for your teeth. Sugar-free gum sweetened with xylitol reduces cavities and plaque. The American Dental Association says chewing sugar-free gum for 20 minutes after a meal helps prevent tooth decay, because the extra saliva washes bacteria away.
A 2011 review found that chewing gum before a test improved working memory and speed of perception, with the boost lasting 15 to 20 minutes. And the old claim that swallowed gum stays in your stomach for seven years? Medical opinion finds little truth in it. In most cases, swallowed gum passes through as quickly as other food.
A Quarter of a Million Blobs
Gum is very hard to clean up. It bonds strongly to asphalt and rubber shoe soles, because they are made of similar materials. In 2000, a study of London's busy Oxford Street counted a quarter of a million gum blobs stuck to the pavement. In Rome, 15,000 pieces are dropped every day, and removing each one costs the city one euro.
Singapore banned chewing gum in 1992, partly because discarded gum got stuck in the sliding doors of its MRT trains. Since 2004, sugarless gum can be sold in pharmacies if a doctor or dentist prescribes it. Singapore's pavements are perhaps unique among modern cities for being free of gum.
Some ingredients are surprising. Gum base can include polyethylene, a plastic found in shopping bags and hula hoops, polyvinyl acetate, found in white glue, and butyl rubber, used to line car tires. Designer Anna Bullus found a way to recycle old gum into plastic. Her company, Gum-tec, has turned it into shoe soles, combs and frisbees.
