Before Luigi Galvani jumpstarted his first frog, the mystery of how human beings are able to wiggle our fingers and toes was impervious to science. To say of a mid-18th century scientist that his understanding of this motive force was stuck in the dark ages would have been an understatement—it had gotten stuck a lot earlier than that.
The dominant theory had not been significantly updated since the second century, when the Roman philosopher and physician Claudius Galen concluded that the nerves are hollow tubes that send man's will to be executed in the limbs and muscles, by way of ineffable substances he christened “animal spirits.” When these flowed from the brain to the muscles, they created contractions. No one was able to pin it down much further after Galen, so apart from increasingly baroque refinements—and even after we had developed detailed maps of the nerves that infiltrate every extremity of the body—the story of “animal spirits” largely remained unchallenged for 1500 years.
By the 18th century, this had become a source of acute pain to scientists, who were routinely lampooned by satirists—including in rude cartoons—for their inability to provide the most rudimentary explanations of the motive force. Expectations had changed: so many other myths and puzzles had yielded under the interrogating blaze of the Enlightenment. Newton had cracked gravity; Galileo had plucked us from the center and set us into an unremarkable corner of the universe.
Galvani was well placed to unpick the mystery of animal spirits. By all accounts, he was a driven polymath, an anatomist, and obstetrician given to obsessive digressions into the workings of the human body (his highly lauded doctoral thesis examined the structure and function of bone). More importantly, though, he was at the University of Bologna, which was among the first institutions of higher learning to investigate the brand-new phenomenon of electricity. The 17th century had delivered an entirely new concept within which Galvani could reframe the human motive force: this notion of a fluid that was not a liquid, that traveled as fast as light, and whose action faded at a distance like gravity.
To prove his idea, Galvani famously flayed dead frogs and connected their exposed leg nerves to each other (immortalized in the famous sketch on the cover). When this made the legs twitch, he had his proof that a biological electrical current was flowing to cause it. Thus, Galvani found the first serious evidence of a kind of electricity specific to the animal body that flowed through the limbs to animate them. In 1791 he published these findings and, to great fanfare, launched the study of bioelectricity that leads directly here today with the launch of a journal specifically dedicated to its study.
Today we may think of Galvani's lasting contributions to science as inevitable, a fait accompli. What many do not know is that he died penniless, his theory of biological electricity in tatters. His experiments stirred up a scientific war whose viciousness has been compared to the French revolution. It began as a disagreement about interpretation with Alessandro Volta, the “Newton” of electricity.
From Volta's perspective—molded by his experience as a physicist—Galvani's experiments showed no such thing as a biological electrical fluid. Instead they looked like evidence that artificial electricity can flow whenever sufficiently dissimilar metals (or really materials of any kind) meet. Volta claimed that the wires Galvani was using to connect the frog legs were introducing this external spark, accounting for the twitchy legs.
Galvani worked tirelessly to counter this claim, and a publication war ensued between the two men which would go on to rope in every reputable scientist in Europe. Galvani's final salvo was an experiment that showed conclusively that two exposed frog nerves—biological materials that were the same in every way—placed in contact with one another, would pass enough of the inherent electrical impulse between them to cause a dead frog's leg to jump. No wires were necessary to connect them. No “artificial” electricity was involved. Biology alone could pass a current.
Even as his allies praised the experiment as “one of the most beautiful and valuable of the eighteenth century Physics,” however, Volta doubled down, and stunned the world by unveiling the first-ever battery based on his theory of dissimilar metals.
It was a third scientific giant who grasped the truth (although not in time for Galvani): Alexander von Humboldt set off to Paris with an army of dead frogs in tow to prove that the men had both been right. But it was too late. The discrediting of his life's work contributed to Galvani losing his university position and income. He became ill, and soon after, he was dead.
After the loss of its progenitor and patron, the field of bioelectricity died too. Its formal study was abandoned to quacks and mountebanks whose sham experiments would poison the field for decades.
Today Galvani's reputation has been fully restored: he rests in the scientific canon as the father of electrophysiology among many other plaudits. And despite languishing for 40 years after Galvani's death, the discipline was also resurrected. It may be more accurate to say it was shocked back to life by a replication experiment straight out of a body horror movie. Carlo Matteucci killed multiple frogs, chopped them into half, flayed their legs, and connected them all together into a grotesque biological battery.
Then, using a newly developed galvanometer, he demonstrated that the more frog legs you added to this amphibian stack, the more current you could detect flowing through it. He had effectively created a meat battery. It proved once and for all that the electricity intrinsic to animals was undeniably biological in origin.
Over the next centuries, proof piled upon proof that Galvani had been right about the electrical nature of muscular and nerve function. They carry information around the nervous system by way of electrical signals. Innate electrical signals are responsible for muscle contraction and nerve conduction in all living animals; they tell a cell when to take out the rubbish, for example, or demand more fuel. Today these ideas are incontrovertible.
But even 200 years after the end of the scientific war between artificial and biological electricity, echoes remain. The field of bioelectric medicine holds enormous promise across a breathtaking range of the human experience, from stopping cancer to starting regenerative medicine. And yet many of the experiments that are reported in the general press are received with a familiar disbelief or skepticism. The same can even be true before publication, when two reviewers may look at the same phenomenon from two different distant perspectives. Like Galvani and Volta, each will see something different.
With the launch of Bioelectricity, we will provide a place where those different perspectives can lead to insights in the tradition of von Humboldt, rather than to fruitless wars between interpreters who do not realize they are on the same side.
About the Author
Sally Adee is an independent science and technology writer and editor. From 2010 to 2017, she was a features and news editor at New Scientist magazine, where she commissioned and wrote articles about medical technology, artificial intelligence, and the rest of the Venn diagram where the human mind and body intersect with the machines we create. Before that, she was on the microchips beat at IEEE Spectrum magazine in New York. She has received awards from the National Press Club and British Telecommunications, and has reported from China, DARPA headquarters, and the Estonian cloud. She blogs at the science website (www.lastwordonnothing.com).