Popular science writer and media theorist, Steven Johnson, recounts the history of technologies that have shaped our lives in surprising ways. Here are some of the game-changing innovations he explores.

The hummingbird effect refers to occurrences that appear completely unrelated and yet converge to create something unexpected. We see this throughout evolutionary biology. Plant reproduction patterns, for example, influenced the hummingbird’s flight mechanisms. The symbiotic relationship between plants and insects, in which the insects fertilize the plants by moving from flower to flower collecting pollen, led to the production of nectar, which made it possible for larger animals (e.g., the hummingbird) to enjoy the nectar as well. This involved the development of a wing mechanic that would enable hummingbirds to suspend themselves in midair. It’s a difficult thing for vertebrates to do, but by creating significant thrust to the upstroke as well as the downstroke, the hummingbird was able to stay aloft and enjoy the saccharine goodness stored in flowering plants.

The hummingbird effect is not to be confused with the butterfly effect—the idea that a butterfly flapping its wings in California leads to a hurricane over the Atlantic. The butterfly effect deals with chaos theory. It assumes we can’t understand the links between events. By contrast, the hummingbird effect assumes that it is possible to trace groupings of innovations and discoveries across history. Vaccinations, for example, could not have been developed without germ theory, which could not have been developed without a microscope, which could not have been invented without a refined understanding of the interactions between glass and light.

Many accounts of history revolve around the political and military actions that humans have taken over the millennia: they talk about individuals and how their decisions contributed to the fate of their civilizations or even the world. Far fewer historians look at how inventions have shaped our world.

Something remarkable occurred in the middle of the Libyan Desert 26 million years ago. There at the eastern corner of the Sahara, grains of silica reached their melting point and began to fuse, forming silicon dioxide and covering a large portion of the Libyan Desert with a substance we now know as glass.

In more recent history—10 millennia ago, give or take—a traveller through the Sahara found a large piece of it and it became the talk of early civilizations. When archeologists discovered King Tutankhamun's tomb in 1922, they found among his treasures a piece of the glass fashioned into the shape of the sacred scarab.

When the Roman Empire was at its zenith, glass became not just decorative but functional. Glass windows were first built then. Its inventors could scarcely imagine that their innovation was a precursor to the glass skyscrapers found in most of the world’s major cities. Glass became a popular vessel for drinking and bottling wine as artisans learned to make the glass less cloudy.

It was 1,000 years later that glass really became the substance we know and recognize today. The city of Constantinople was sacked in 1204. It was a colossal event, that sent shockwaves through Asia, Europe, and Africa. Maps were redrawn, religious allegiances shifted, and political arrangements irreversibly changed. But one repercussion that most historians missed was the displaced artisan class from Turkey. These refugee glassmakers fled to Venice, and the world was never the same. These Turks brought the city a reputation for beautiful luxury goods, and strengthened the Venetian economy. This came with some drawbacks, however. The artisans were heating their works to temperatures exceeding 1,000 degrees, which was a fire hazard for a city of mostly wooden structures. In order to preserve the artisan class and the economic boon, they moved the Turks to the island of Murano off the coast of Venice. This created a hub of competition but also of creative collaboration. It was the Murano glassmaker Angelo Barovier who developed the perfectly transparent glass with which we are familiar. He created cristallo by burning seaweed full of potassium oxide and manganese. When the seaweed ash was mixed with molten glass, it made the glass perfectly see-through.

From these developments came the “disks for the eyes” or “lenses” that enabled people to see the world more clearly. This invention spread from Northern Italy via the newly invented Gutenberg printing press, which allowed for the promulgation of affordable, portable reading materials. That in turn boosted literacy rates across Europe, but it also exposed widespread poor vision. The market for affordable spectacles took off, which led to a revolution in optic lenses. Inventors and glassworkers became experts in manipulating the curvature of glass to enhance images. This led to the invention of the microscope in the Netherlands in 1590, which led, in turn, to the discovery of germs and medications to fight them. This is one of the most staggering examples of the hummingbird effect in modern human history.

Another way glass  was indispensable to the creation of the modern world is that it fueled other discoveries that led to Galileo’s invention of the telescope. Improvements to Galileo’s original design have led to not only remarkable discoveries about space but, eventually, exploration of space itself. Without glass, there would be no photography, movies, or televisions. Glass aided the rise of Gutenberg’s world of literacy, but it has also transported us more recently to a world animated by images.

In the eighteenth and nineteenth centuries, natural goods like sugar cane, coffee, tea, and cotton were in high demand, but these products typically thrive in the world’s tropics and subtropics. This created a niche that a young entrepreneur from New England saw and leveraged to lucrative ends. Global trade was built by importing items plentiful in one part of the world to regions where those goods were scarce. In high-energy climates where traders, entrepreneurs, and plantation owners were moving to sell coffee and sugar, ice was what they needed—even though many in the Caribbean and other tropical regions had never even seen ice before!

Frederic Tudor lived in Massachusetts, where there was plenty of ice during the winter. Over the course of the early 1800s, Frederic Tudor became an exceedingly wealthy man by setting up an ice shipping business that took enormous blocks of ice to the remotest corners of the globe where the heat bordered on unlivable. At the time of his death in 1864, he’d accrued a fortune to the tune of $200 million dollars. This was possible because of the double-barriered chambers that Tudor created to keep the ice from interacting with sunlight and melting. The ice business is actually mentioned in Henry David Thoreau’s famous Walden Pond. Thoreau recalls watching Tudor’s employees removing large blocks of ice from the pond by his Massachusetts cabin. It was a surreal thought for the poet that the inhabitants of not just Charleston and New Orleans, but Bombay and Calcutta would be drinking Walden’s waters.

Thoreau’s imagination was only scratching the surface of the changes that transporting cold would bring to the world. The fact that the southern United States is far more likely to offer iced drinks than European countries is a continuation of the Tudor legacy, but even more significantly, his ice industry gave rise to the invention of air conditioning.

The ice-shipping industry was gradually replaced with machines that could artificially produce ice—what later became known as a refrigerator. This revolutionized shipping industries, as meat and produce could be preserved over long distances. Chicago began shipping pork and beef across the Midwest, but within a few decades, it was shipping meat across four continents. The cooling systems became increasingly efficient and were eventually small enough to fit comfortably in a kitchen.

Air conditioning came around through an accident in 1902, when a 25-year-old engineer named Willis Carrier tried to develop a cooling mechanism for a printing press in a Brooklyn publishing house. He found that the dehumidifying process he’d designed had also cooled the space and he went about designing a system that could cool interior spaces. Among other things, his air-conditioning made summer blockbusters possible. In 1925, he asked the Paramount Pictures’ owner to witness a demonstration of his invention at work; thus, central air-conditioning was introduced into the theater—and then numerous other commercial spaces. Before then, such buildings would have been intolerably sweltering.

Carrier’s company remains one of the biggest air conditioning companies in the world. It’s radically changed migration patterns across the world. From 1925-1950, air-conditioning was found mostly in commercial—non-residential—spaces. But once the unit’s size shrank from the size of a truck to an appliance that could fit on a window sill, air conditioning became a common feature in homes.

Places that were sweltering and humid were suddenly bearable. The century-long post-Civil War migration trend from southern states to the northern states slowed and then reversed. Demographics then influenced politics. The change in migration patterns broke up the long-time division of Southern Democrat and Northern Republican, creating entirely new political dynamics. The more Republican presence from the North aided the civil rights movement by breaking up the “Dixiecrat” stronghold. Interestingly enough, the shift also led to a string of leftist reforms in Congress.  For the first half of the twentieth century, all but two men elected president were from the North. Between 1952 and 2008, almost all of the US presidents elected were from the South.

The impact of air-conditioning extends around the world now. The world’s megacities used to be  New York, London, Paris, and Tokyo—all in relatively temperate zones. The list of the megacities now includes cities that endure blistering heat waves. Not everyone in these cities has air conditioning, of course, but it’s prevalent enough that political-economic systems are booming in places like Rio de Janeiro, Bangalore, Chennai, Manila, and Dubai. Within the next decade there will be a billion more people invading these hot cities.

The known uses of sound go back tens of thousands of years. In the primeval Arcy-sur-Cure cave network in modern-day France, the Neanderthals would navigate its tunnels by making noises and listening to the timbre of the corresponding echoes. In more recent history, the phonograph, telegraph, and radio made information more readily available because sound could be transported previously unheard-of distances.

At the beginning of the twentieth century, inventors also began to utilize sound where light was not sufficient to guide ships through difficult passages. A lighthouse is least visible on the nights when it’s most needed—when thick mists, heavy rains, and tumultuous waves swallow the guiding beams. In 1901, the Submarine Signal Company capitalized on the discovery that sound travels four times as quickly through water than through air by creating hydrophones. These devices would bounce a sound wave between stations and ships that installed the same technology, warning of dangerous passages or giving them some kind of reference point. This, of course, only worked for vessels that acquired the technology, and was only useful for ships that happened to be in proximity to the stations.

Canadian inventor Felix Fessenden improved this technology and demand for it grew in the wake of the Titanic tragedy of 1912. His device allowed vessels to create their own electric-powered sonar signals to which people could listen and discern foreign shapes in the nearby vicinity—similar to how dolphins use echolocation. Fessenden’s invention helped us navigate icebergs and German U-boats, but he could not have imagined how his technology would transform world populations.

Felix Fessenden’s invention of the first sonar has given rise to more complex and compact devices that allow fishermen to determine depths and plenitude of fish, to discover remains of sunken vessels and natural resources thousands of feet below the ocean’s surface.

Ironically, one of the most significant uses of sound came not from what it enabled us to hear but what it enabled us to see. Fessenden’s designs led to sonar imaging, which uses sound frequencies to render images. He saved lives not only on the high seas, but also in hospitals. The sonogram has helped doctors identify complications in pregnancy and saved countless lives of mothers.

The dark side of this technology is sex-selective abortions in countries like India and China. Even decades after the Chinese government banned the use of sonograms to determine the baby’s sex in the 1980s, the birth rate of males to females in Chinese hospitals was still 110 boys to every 100 girls, as people found surreptitious ways to obtain sonograms and have abortions.

This is one of the most tragic instances of the hummingbird effect: that our ability to listen to sound waves ricocheting off icebergs in the beginning of the twentieth century is being used by the end of the twentieth century to eliminate millions of female babies in-utero. Technology’s impact is never entirely positive. There’s not a single technology in which that has been the case. The point here is that the use of sound has had unexpectedly profound consequences for humanity.

If an alien race in a galaxy far, far away were trying to discern the presence of intelligent life forms on earth, they might have remained unsure for almost all of earth’s existence—continents and glaciers drifted imperceptibly over the millennia, but nothing to write home about. That all changed about a century ago when artificial lights were developed. Today, satellite imaging reveals glowing nodes across the world. The night skies are 6,000 times brighter than they were in the mid-1800s.

Artificial light has utterly rearranged our lives, from the times we work and sleep to the global communication networks we’ve been able to create. Our dealings with artificial light began a long time ago with fire. Until the late 1800s, we relied on candles and lamps to light the way, but oil was expensive and candle making was a time-consuming process. Candle-makers were part of a thriving trade.

The transition from candle to light bulb would not have been possible without the head of a 100,000-pound whale. The sperm whale is so-named because of the copious amounts of spermaceti contained in its head. (The skull of one full-grown sperm whale can house about 500 gallons!) Some scientists believe that it enables echolocation while others theorize that it is related to the creature’s buoyancy. In either case, it looks like seminal fluid and was terrific fuel for lamps: long-lasting and clean.

It was in the late-1800s that Thomas Edison (and several dozen others across Europe and North America) began developing carbon filaments that would create light and an alternative to the expensive oils. (George Washington actually estimates that he spent about $15,000 in today’s money on spermaceti.)

Today, people are taking what we’ve learned about light bulbs and thermodynamics to see if we can create not only artificial light but an artificial light source by utilizing nuclear fusion technology. The National Ignition Facility in northern California is home to the largest and most energy-intensive laser system in the world. One of the projects underway is an attempt to replicate the conditions of the Sun’s core. It’s hard to sustain energy levels of that intensity for more than a few seconds, and there are plenty of naysayers who doubt that nuclear fusion will ever create more energy than it expends.

Of course, people were probably dismissive of the idea that oil from a 50-ton marine animal would be able to create clean, reliable artificial light. That same dogged spirit of experimentation and innovation, building on a growing corpus of discoveries keeps us chasing breakthroughs in the uses of light. The light bulb has, after all, become symbolic of new ideas.