The course of human evolution has been punctuated by a long succession of chance discoveries and accidental inventions; and in fact, experts estimate that between 30 and 50 percent of of all scientific discoveries are in some way accidental. The ability to swiftly recognize the utility in something unexpected is one of the profound things that sets us apart from other animals. Whether that’s a good thing or not remains to be seen; some serendipitous discoveries have spawned such staggering success that they’ve become a bit unwieldy. (Hello, plastic and antibiotics.) But whether banes or boons, the following accidental inventions from the past two centuries have changed the world in one way or another.

1. Matches

Match stick headMany of us wonder what life was like before electricity or the Internet (shudder), but imagine life before matches. We’re talking magnifying glasses and flint. For those of us who like to create controlled flame from time to time with the strike of a match, we can thank a British pharmacist and his dirty mixing stick. In 1826, John Walker noticed a dried lump on the end of a stick while he was stirring a mix of chemicals. When he tried to scrape it off, voila, sparks and flame. Jumping on the discovery, Walker marketed the first friction matches as “Friction Lights” and sold them at his pharmacy. The initial matches were made of cardboard but he soon replaced those with three-inch long hand-cut wooden splints; the matches came in a box equipped with a piece of sandpaper for striking. Although advised to patent his invention, he chose not to because he considered the product a benefit to mankind — which didn’t stop others from ripping off the idea and taking over the market share, leading Walker to stop producing his version.

2. Mauveine (aniline purple dye)

Before the 1850s, the general palette of common clothing was decidedly drab. Dyes and paints were made from natural materials. Plants, leaves, roots, minerals and insects were used to create lovely hues, but most often they were subtle, inconsistent and impermanent. All this changed in 1856 when 18-year-old chemistry student William Perkins was working to create an artificial quinine to help treat malaria, and instead came up with a muddy coal tar residue. Upon closer inspection, he noticed a stunning color: mauve. And just like that, Perkins had stumbled across the world's first aniline dye, a dye that would consistently produce a vivid and uniform shade that paved the way for synthetic colors as we know them today. (The 1980s thank you, Mr. Perkins.) The royal court fell head over heels for mauve, as did all of London and much of the world. But aside from the mauve madness, the first commercial application of a chemistry discovery created a paradigm shift. Organic chemistry became exciting and profitable — and as a result, it enticed many young minds to pursue industrial applications of chemistry, ultimately leading to important advances in medicine, perfume, photography and explosives.

A lab technician prepares penicillin in 19433. Penicillin
Although antibiotics may get a bum rap for their prevalence and overuse, life before them was fraught with untamable infection and few defensive tools. Penicillin was the first antibiotic, a discovery that happened in 1929 when a young bacteriologist, Sir Alexander Fleming, was tidying up his lab. After having been on vacation, he returned to work to find that a petri dish of Staphylococcus bacteria had been left uncovered; and he noticed that mold on the culture had killed many of the bacteria. He identified the mold as penicillium notatum, and upon further research found that it could kill other bacteria and could be given to small animals without ill effect. A decade later, Howard Florey and Ernst Chain picked up where Fleming left off and isolated the bacteria-killing substance found in the mold – penicillin. The three won the Nobel Prize in medicine in 1945 "for the discovery of penicillin and its curative effect in various infectious diseases.” At right, a laboratory worker measures purified penicillin into bottles. In this process, the substance was freeze-dried and the ice evaporated off under vacuum. The powder left behind was penicillin.

4. Microwave oven

Of all the newfangled, ultra-mod, sci-fi kitchen appliances of the future, few are as notable as the microwave oven. Baking a potato in eight minutes must have seemed beyond imagination before this. The technology that promised to revolutionize the load on housewives everywhere, not to mention bachelors, was discovered in the 1940s when the U.S. company Raytheon was working on wartime magnetron tubes used in radar defense. Percy Spencer, an engineer at the company, was working on a magnetron when he noticed that a candy bar in his pocket had started to melt due to the microwaves. Eureka! Spencer developed a box for cooking and found that indeed, when food was placed in the box with the microwave energy, it cooked quickly. Raytheon filed a U.S. patent for the process and the first microwave oven was placed in a New England restaurant for testing. The first home microwave oven was introduced in 1967 by Amana (a division of Raytheon), to the delight of Jane Jetson wannabes everywhere.

5. Plastic

Bakelite banglesAlthough earlier plastics had relied on organic material, the first fully synthetic plastic was invented in 1907 when Leo Hendrik Baekeland accidentally created Bakelite. His initial quest was to invent a ready replacement for shellac, an expensive product derived from lac beetles. Baekeland combined formaldehyde with phenol, a waste product of coal, and subjected the mixture to heat. Rather than a shellac-like material, he inadvertently created a polymer that was unique in that it didn’t melt under heat and stress. The new thermosetting plastic was used for everything from phones to jewelry to clocks. It was also the first synthetic material to really stand on its own; it wasn’t used to mimic a natural material like ivory or tortoise shell, ushering in a era of new synthetic materials that has yet to subside.

6. Potato chips

Behold the potato chip: the salty, greasy, crispy wisp of tuber for which Americans dole out more than $7 billion a year. The life of the potato chip didn’t start out as an accident, more of a prank, but its imminent success took its inventor by surprise. As legend has it, in 1853 Saratoga Springs restaurant cook George "Speck" Crum was annoyed with the complaints of a wealthy patron who repeatedly returned his thickly cut French style potatoes, a common preparation at the time. After the third return, the exasperated Crum sliced the potatoes as thinly as he could, fried the daylights out of them, and covered them in what he assumed to be a prohibitive amount of salt. Much to his surprise, and perhaps initial chagrin, the patron adored them and ordered another round. They quickly became the house specialty, and the history of snacking was changed forever. So much so, in fact, that a major study by Harvard University recently revealed that the potato chip is the number one reason for weight gain in the United States. (We can't blame Chum for that.)

7. X-rays

In 1895, German physicist Wilhelm Conrad Röntgen was tinkering with a tube of cathode rays, the phosphorescent stream of electrons used today in everything from televisions to fluorescent light bulbs, when he noticed that a piece of paper covered in barium platinocyanide began to glow across the room. He knew that the flickering he saw was not being created by the cathode rays because they would not travel that far. Not knowing what the rays were, he named it X-radiation signifying the unknown nature. Upon further research he discovered a host of materials transparent to the radiation and that the rays could affect photographic plates. He took an X-ray photograph of his wife's hand that showed her bones and a ring; the image aroused great interest and ensured his place in the history of medicine and science. He was awarded the Nobel Prize in physics in 1901.

8. Safety glass

Laminated safety glassBack in the early days of automobiles, before seatbelts and airbags were part of the package, one of the gravest dangers was injury from shards of shattered windshield glass. We can thank French artist and chemist Édouard Bénédictus for chancing upon the invention of laminated glass, also known as safety glass. While in his lab, a glass flask dropped and broke but didn’t shatter, Bénédictus realized that the interior was coated with plastic cellulose nitrate that held the now-harmless broken pieces together. He applied for a patent in 1909 with a vision of increasing the safety of cars, but manufacturers rejected the idea to keep costs down. However, the glass became standard for gas mask lenses in World War I. With its success on the battle field, the automobile industry finally ceded and by the 1930s most cars were equipped with glass that didn’t splinter into jagged pieces upon impact.

9. Viagra

Much like the fountain of youth, humans have long sought magic ingredients that promise to boost the libido and enhance sexual function. But the breakthrough that gave us Viagra (sildenafil) didn’t occur when researchers were looking for ways to make men manly; rather, they were testing sildenafil as a cure for hypertension and heart disease. After two phases of testing, researchers came to the conclusion that the drug failed to show promising results for the heart, but test subjects noted that … well, you know what part of the body it did wonders for. Bingo! Pfizer patented Viagra in 1996 and it was approved for use in erectile dysfunction by the U.S. FDA in 1998. Sales of Viagra continue to exceed well more than $1 billion per year. Bonus tip: Researchers have also found that 1 milligram of sildenafil dissolved in a vase of water can make fresh cut flowers, um, "stand at attention" for up to a week beyond their natural life span.

A small stack of chocolate chip cookies10. Chocolate chip cookies

Not all chance discoveries came at the hands of scientists fiddling in labs. Sometimes they happened to cooks twiddling in kitchens — and sometimes in the kitchens of restored tollhouses. Case in point: The beloved Toll House Cookie. Ruth Wakefield and her husband owned and operated the Toll House Inn in Massachusetts where Ruth cooked for the guests. According to legend, one day in 1937 while making cookie dough, she realized she was out of melting baker’s chocolate and instead used a chocolate bar that she chopped into bits, hoping it would melt as well. It didn’t, and thus was born America's favorite cookie. Did the chocolate chip cookie change the world? Probably not, unless you calculate the combined moments of pleasure derived from biting into one fresh from the oven. They’ve certainly been responsible for changing a lot of moods.

Related stories on MNN:

Photos: funadium/Flickr; Imperial War Museum/Wikimedia Commons; Wikimedia Commons; holisticmonkey/Flickr; ginnerobot/Flickr