The Book of Eels, Patrik Svensson [bill gates best books .TXT] 📗

now know everything about the life and reproduction of the eel—its long journey from the Sargasso Sea, its metamorphoses, its patience, its journey back to breed and die—but even though that is all probably true and correct, much of it is nevertheless still based on assumption.

No human has ever seen eels reproduce; no one has seen an eel fertilize the eggs of another eel; no one has managed to breed European eels in captivity. We think we know that all eels are hatched in the Sargasso Sea, since that’s where the smallest examples of the willow leaf–like larvae have been found, but no one knows for certain why the eel insists on reproducing there and only there. No one knows for certain how it withstands the rigors of its long return journey, or how it navigates. It’s thought all eels die shortly after breeding, since no living eels have ever been found after breeding season, but then again, no mature eel, living or dead, has ever been observed at their supposed breeding ground. Put another way, no human has ever seen an eel in the Sargasso Sea. Nor can anyone fully comprehend the purpose of the eel’s many metamorphoses. No one knows how long eels can live for.

In other words, more than two thousand years after Aristotle, the eel remains something of a scientific enigma, and in many ways, it has become a symbol of what is sometimes referred to as the metaphysical. As it happens, metaphysics can also be traced back to Aristotle (though the concept was named only after his death). It is a branch of philosophy that is concerned with what exists outside, or beyond, objective nature, beyond what we can observe and describe with the help of our senses.

Metaphysics is not necessarily concerned with God. It is, rather, an attempt to describe the true nature of things, the whole of reality. It claims there’s a difference between existence per se and the characteristics of that existence. It also claims the two questions are separate. The eel is. Existence comes first. But what it is, is a completely different matter.

I like to think that’s why the eel has continued to be a source of fascination. Because that intersection between knowledge and faith, where knowledge is incomplete and therefore allowed to contain both fact and traces of myth and imagination, is compelling. Because even people who trust in science and an orderly natural world sometimes want to leave a small, small opening for the unknowable.

If you are of the opinion that the eel should be allowed to remain an eel, it follows that you have to allow it to remain a mystery, to some degree. For now, at least.

AND THE EEL DID REMAIN A MYSTERY. IS IT A FISH OR SOMETHING else entirely? How does it reproduce? Does it lay eggs or give birth to live young? Is it asexual? Is it hermaphroditic? Where is it born and where does it die? For centuries after Aristotle, the eel was the subject of countless theories, and every attempt to understand it was inevitably suffused with mystique. During the Middle Ages, two theories in particular were popular, often in combination: one that said the eel was viviparous, which is to say it gives birth to live young; another that said the eel was hermaphroditic, both male and female.

With the resurgence of natural science in the seventeenth century, the eel question became the subject of more methodical inquiry. Aristotle’s methods were revived—especially his insistence on the need to systematically observe nature—and as a consequence, our view of the world, and the eel, changed.

Yet even so, it would be a long time before the questions about the eel began to find answers. Aristotle had strongly argued against the theory that the eel was viviparous, but it now grew more popular. It was advocated by, among others, the English author Izaak Walton, who in 1653 published the world’s first commercially successful book on fishing, The Compleat Angler. The eel, he claimed, is viviparous and gives birth to live young, but it is also sexless. New eels were generated inside older ones without conception.

Then the Italian physician and scientist Francesco Redi, of Pisa, published the first evidence-based critique of the concept of spontaneous generation. In 1668, his experiments on flies demonstrated that eggs and fertilization are required to create life. Omne vivum ex ovo, he concluded. All life stems from the egg. He also studied eels and managed to show that the tiny wormlike creatures sometimes found inside eels, which some had taken to be unborn young, were in fact more likely parasites. The eel was in all probability not viviparous, Redi wrote, though he never did manage to find any reproductive organs or eggs and was therefore unable to give a definitive answer to the question of how the animal really reproduces.

It was in this context that a sensation landed on a table at the University of Padua in Italy. The year was 1707, and a surgeon by the name of Sancassini had visited an eel fishery in Comacchio on Italy’s east coast. There he had spotted an eel so big and fat, he had felt compelled to pick up his scalpel and cut it open. Inside the eel, he had found something that looked very much like reproductive organs, and something that resembled eggs.

He sent the dissected eel to his friend Antonio Vallisneri, a professor of natural history in Padua. Vallisneri, a sworn enemy of the notion that life can spring from nothing, was justifiably excited and sent the eel on to the University of Bologna, where many of the most prominent scientists of his day were to be found.

The Comacchio eel breathed new life into the question of the eel’s reproduction, the solving of which for a while became the central object of scientific efforts during the Enlightenment. The eel itself was not, however, as well received as Vallisneri had hoped. What had really been found, after all? Granted, it might