Often, science and technology do not progress gradually, but evolve abruptly and in a nonlinear way. Science, like the universe, has its “big bangs.” A well-known example is Albert Einstein’s annus mirabilis of 1905, when, in a single year, the then-unknown scientist published three principles that rocked the physics world.
In optics, the laser’s emergence qualifies as a big bang; it upended the classical view of light, bringing radical change in its possibilities and uses for scientists and the public at large. Soon after the first demonstrations, seemingly in the blink of an eye, lasing extended to a variety of materials and wavelengths. The history of technology also suggests big-bang periods—such as the age of Thomas Edison, and the wealth of electrical products invented by him and others during that time.
Life on Earth, too, has had its big bangs. Perhaps the biggest was the so-called Cambrian explosion in animal evolution. The fossil record reveals that at the beginning of the Cambrian Period, some 539 million years ago, life did not evolve gradually or linearly, but very suddenly, across an interval perhaps no more than 25 million years long. In the context of the nearly 4 billion year history of life on Earth, that, too, was the blink of eye.
This rapid change puzzled Charles Darwin. But it is not surprising, and quite reasonable, if one understands the mathematics of complex systems. The nonlinear interactions of multi-body systems can lead to vast and unexpected events—not only big bangs like the Cambrian explosion, but everything from earthquakes to extreme weather to stock market crashes.
Why did the Cambrian explosion occur? Paleontologists have advanced many possible explanations, and most believe that the event did not have only one cause. Yet one particular hypothesis has always impressed me—that the evolution of the eye, nature’s optical technology, may have helped to trigger this rapid, nonlinear and remarkable change in life’s story.
While light-sensitive organs previously existed among some animals, very early in the Cambrian a number of arthropod species—including the period’s ubiquitous trilobites and other taxa—rapidly developed compound eyes, some of which are strikingly similar to those of current insects. In his 2003 book In the Blink of an Eye, the zoologist Andrew Parker argued that once these natural imaging systems appeared (with accompanying neural networks in the brain), they led to an increase in predation and, among potential prey, the evolution of camouflage and other forms of protection, all of which caused a burst of biodiversity. (One thinks of the similar impact the development of artificial “eyes” today—smartphone cameras, CCDs, computers—has had on the “big bang” of internet services and social media.)
Whether the eye’s development caused the Cambrian explosion or not, the sudden evolution of this natural optical technology clearly coincided with a remarkable flowering of the diversity of life. Almost all current animal phyla evolved during the Cambrian explosion, and no new animal phylum has emerged since then. And more than 95% of animal species today have eyes of some sort. Optics—and eyes—are amazing.
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