Broca's Brain: The Romance of Science

by Carl Sagan

  There are still many people in the United States who believe that if a thing appears in print it must be true. Since so much undemonstrated speculation and rampant nonsense appears in books, a curiously distorted view of what is true emerges. I was amused to read-in the furor that followed the premature newspaper release of the contents of a book by H. R. Haldeman, a former presidential assistant and convicted felon-what the editor in chief of one of the largest publishing companies in the world had to say: “We believe a publisher has an obligation to check out the accuracy of certain controversial non-fiction works. Our procedure is to send the book out for an objective reading by an independent authority in the field.” This is by an editor whose firm has in fact published some of the most egregious pseudoscience of recent decades. But books presenting the other side of the story are now becoming available, and in the section below I have listed a few of the more prominent pseudoscientific doctrines and recent attempts at their scientific refutation. One of the contentions criticized-that plants have emotional lives and musical preferences-had a brief flurry of interest a few years ago, including weeks of conversations with vegetables in Gary Trudeau’s “Doonesbury” comic strip. As an epigraph to this chapter (on the death struggle of the snapdragon) shows, it is an old contention. Perhaps the only encouraging point is that it is being greeted more skeptically today than it was in 1926.

  SOME RECENT BORDERLINE DOCTRINES

  AND THEIR CRITIQUES

  While many recent borderline doctrines are widely promoted, skeptical discussion and dissection of their fatal flaws are not so widely known. This table is a guide to some of these critiques.

  Bermuda Triangle::The Bermuda Triangle Mystery-Solved,

  Laurence Kusche, Harper & Row,1975

  Spiritualism::A Magician Among the Spirits,Harry Houdini, Harper, 1924

  The Psychic Mafia,M. Lamar Keene, St. Martin’s Press,

  1976

  Uri Geller::The Magic of Uri Geller,James Randi, Ballantine, 1975

  Atlantis and other “lost continents”::Legends of the Earth: Their GeologicOrigins,Dorothy B. Vitaliano, Indiana UniversityPress, 1973 Lost Continents,L. Sprague de Camp, Ballantine,1975

  UFOs::UFOs Explained,Philip Klass, Random House, 1974

  UFOs: A Scientific Debate,

  Carl Sagan and Thornton Page, eds.,

  Norton, 1973

  Ancient Astronauts::The Space Gods Revealed: A Close

  Look at the Theories of Erich von Däniken,

  Ronald Story, Harper & Row, 1976

  The Ancient Engineers,

  L. Sprague de Camp, Ballantine, 1973

  Velikovsky:::Scientists Confront Velikovsky,

  Worlds in Collision ::Donald Goldsmith, ed., Cornell

  University Press, 1977

  The Emotional Lives of Plants::“Plant ‘Primary Perception,’ ”

  K. A. Horowitz and others, Science,

  189: 478-480 (1975)

  A FEW YEARS AGO a committee of scientists, magicians and others was organized to provide some focus for skepticism on the border of science. This nonprofit organization is called “The Committee for the Scientific Investigation of Claims of the Paranormal” and is at 923 Kensington Avenue, Buffalo, N.Y. 14215. It is beginning to do some useful work, including in its publications the latest news on the confrontation between the rational and the irrational-a debate that goes back to the encounters between Alexander the Oracle-Monger and the Epicureans, who were the rationalists of his day. The committee has also made official protests to the networks and the Federal Communications Commission about television programs on pseudoscience that are particularly uncritical. An interesting debate has gone on within the committee between those who think that all doctrines that smell of pseudoscience should be combated and those who believe that each issue should be judged on its own merits, but that the burden of proof should fall squarely on those who make the proposals. I find myself very much in the latter camp. I believe that the extraordinary should certainly be pursued. But extraordinary claims require extraordinary evidence.

  Scientists are, of course, human. When their passions are excited they may abandon temporarily the ideals of their discipline. But these ideals, the scientific method, have proved enormously effective. Finding out the way the world really works requires a mix of bunches, intuition and brilliant creativity; it also requires skeptical scrutiny of every step. It is the tension between creativity and skepticism that has produced the stunning and unexpected findings of science. In my opinion the claims of borderline science pall in comparison with hundreds of recent activities and discoveries in real science, including the existence of two semi-independent brains within each human skull; the reality of black holes; continental drift and collisions; chimpanzee language; massive climatic changes on Mars and Venus; the antiquity of the human species; the search for extraterrestrial life; the elegant self-copying molecular architecture that controls our heredity and evolution; and observational evidence on the origin, nature and fate of the universe as a whole.

  But the success of science, both its intellectual excitement and its practical application, depend upon the self-correcting character of science. There must be a way of testing any valid idea. It must be possible to reproduce any valid experiment. The character or beliefs of the scientist are irrelevant; all that matters is whether the evidence supports his contention. Arguments from authority simply do not count; too many authorities have been mistaken too often. I would like to see these very effective scientific modes of thought communicated by the schools and the media; and it would certainly be an astonishment and delight to see them introduced into politics. Scientists have been known to change their minds completely and publicly when presented with new evidence or new arguments. I cannot recall the last time a politician displayed a similar openness and willingness to change.

  Many of the belief systems at the edge or fringe of science are not subject to crisp experimentation. They are anecdotal, depending entirely on the validity of eyewitnesses who, in general, are notoriously unreliable. On the basis of past performance most such fringe systems will turn out to be invalid. But we cannot reject out of hand, any more than we can accept at face value, all such contentions. For example, the idea that large rocks can drop from the skies was considered absurd by eighteenth-century scientists; Thomas Jefferson remarked about one such account that he would rather believe that two Yankee scientists lied than that stones fell from the heavens. Nevertheless, stones do fall from the heavens. They are called meteorites, and our preconceptions have no bearing on the truth of the matter. But the truth was established only by a careful analysis of dozens of independent witnesses to a common meteorite fall, supported by a great body of physical evidence, including meteorites recovered from the eaves of houses and the furrows of plowed fields.

  Prejudice means literally pre-judgment, the rejection of a contention out of hand, before examining the evidence. Prejudice is the result of powerful emotions, not of sound reasoning. If we wish to find out the truth of a matter we must approach the question with as nearly open a mind as we can, and with a deep awareness of our own limitations and predispositions. On the other hand, if after carefully and openly examining the evidence, we reject the proposition, that is not prejudice. It might be called “post-judice.” It is certainly a prerequisite for knowledge.

  Critical and skeptical examination is the method used in everyday practical matters as well as in science. When buying a new or used car, we think it prudent to insist on written warranties, test drives and checks of particular parts. We are very careful about car dealers who are evasive on these points. Yet the practitioners of many borderline beliefs are offended when subjected to similarly close scrutiny. Many who claim to have extrasensory perception also claim that their abilities decline when they are carefully watched. The magician Uri Geller is happy to warp keys and cutlery in the vicinity of scientists-who, in their confrontations with nature, are used to an adversary who fights fair; but is greatly affro
nted at the idea of performances before an audience of skeptical magicians-who, understanding human limitations, are themselves able to perform similar effects by sleight of hand. Where skeptical observation and discussion are suppressed, the truth is hidden. The proponents of such borderline beliefs, when criticized, often point to geniuses of the past who were ridiculed. But the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown.

  The best antidote for pseudoscience, I firmly believe, is science:

  There is an African fresh-water fish that is blind. It generates a standing electric field, through perturbations in which it distinguishes between predators and prey and communicates in a fairly elaborate electrical language with potential mates and other fish of the same species. This involves an entire organ system and sensory capability completely unknown to pretechnological human beings.

  There is a kind of arithmetic, perfectly reasonable and self-contained, in which two times one does not equal one times two.

  Pigeons-one of the least prepossessing animals on Earth-are now found to have a remarkable sensitivity to magnetic-field strengths as small as one hundred thousandth that of the Earth’s magnetic dipole. Pigeons evidently use this sensory capability for navigation and sense their surroundings by their magnetic signatures: metal gutters, electrical power lines, fire escapes and the like-a sensory modality glimpsed by no human being who ever lived.

  Quasars seem to be explosions of almost unimaginable violence in the hearts of galaxies which destroy millions of worlds, many of them perhaps inhabited.

  In an East African volcanic ash flow 3.5 million years old there are footprints-of a being about four feet high with a purposeful stride that may be the common ancestor of apes and men. Nearby are the prints of a knuckle-walking primate corresponding to no animal yet discovered.

  Each of our cells contains dozens of tiny factories called mitochondria which combine our food with molecular oxygen in order to extract energy in convenient form. Recent evidence suggests that billions of years ago the mitochondria were free organisms which have slowly evolved into a mutually dependent relation with the cell. When many-celled organisms arose, the arrangement was retained. In a very real sense, then, we are not a single organism, but an array of about ten trillion beings and not all of the same kind.

  Mars has a volcano almost 80,000 feet high which was constructed about a billion years ago. An even larger volcano may exist on Venus.

  Radio telescopes have detected the cosmic black-body background radiation, the distant echo of the event called the Big Bang. The fires of creation are being observed today.

  I could continue such a list almost indefinitely. I believe that even a smattering of such findings in modern science and mathematics is far more compelling and exciting than most of the doctrines of pseudoscience, whose practitioners were condemned as early as the fifth century B.C. by the Ionian philosopher Heraclitus as “night-walkers, magicians, priests of Bacchus, priestesses of the wine-vat, mystery-mongers.” But science is more intricate and subtle, reveals a much richer universe, and powerfully evokes our sense of wonder. And it has the additional and important virtue-to whatever extent the word has any meaning-of being true.

  CHAPTER 6

  WHITE DWARFS AND LITTLE GREEN MEN

  No testimony is sufficient to establish a miracle,

  unless… its falsehood would be more

  miraculous than the fact

  which it endeavors to establish.

  DAVID HUME,

  Of Miracles

  HUMANITY HAS already achieved interstellar spaceflight. With a gravitational assist from the planet Jupiter, the Pioneer 10 and 11 and the Voyager 1 and 2 spacecraft have been boosted into trajectories that will leave the solar system for the realm of the stars. They are very slow-moving spacecraft despite the fact that they are the fastest objects ever launched by our species. They will take tens of thousands of years to travel typical interstellar distances. Unless some special effort is made to redirect them, they will never enter another planetary system in all the tens of billions of years of future history of the Milky Way Galaxy. The star-to-star distances are too large. They are doomed to wander forever in the dark between the stars. But even so, these spacecraft have messages attached to them for the remote contingency that at some future time, alien beings might intercept the spacecraft and wonder about the beings who launched them on these prodigious journeys. [3]

  If we are capable of such constructions at our comparatively backward technological state, might not a civilization thousands or millions of years more advanced than ours, on a planet of another star, be capable of fast and directed interstellar travel? Interstellar spaceflight is time-consuming, difficult and expensive for us, and perhaps also for other civilizations with substantially greater resources than ours. But it surely would be unwise to contend that conceptually novel approaches to the physics or engineering of interstellar spaceflight will not be discovered by us sometime in the future. It is evident that for economy, efficiency and convenience, interstellar radio transmission is much superior to interstellar spaceflight, and this is the reason that our own efforts have concentrated strongly on radio communication. But radio communication is clearly inappropriate for contact with a pretechnological society or species. No matter how clever or powerful the transmission, no such radio message would have been received or understood on Earth before the present century. And there has been life on our planet for about four billion years, human beings for several million, and civilization for perhaps ten thousand.

  It is not inconceivable that there is a kind of Galactic Survey, established by cooperating civilizations on many planets throughout the Milky Way Galaxy, which keeps an eye (or some equivalent organ) on emerging planets and seeks out undiscovered worlds. But the solar system is very far from the center of the Galaxy and could well have eluded such searches. Or survey ships may come here, but only every ten million years, say-with none having arrived during historical times. However, it is also possible that a few survey teams have arrived recently enough in human history for their presence to have been noted by our ancestors, or even for human history to have been affected by the contact.

  The Soviet astrophysicist I. S. Shklovskii and I discussed this possibility in our book, Intelligent Life in the Universe, in 1966. We examined a range of artifacts, legends and folklore from many cultures and concluded that not one of these cases provided even moderately convincing evidence for extraterrestrial contact. There are always more plausible alternative explanations based on known human abilities and behavior. Among the cases discussed were a number later accepted by Erich von Däniken and other uncritical writers as valid evidence for extraterrestrial contact: Sumerian legends and astronomical cylinder seals; the Biblical stories of the Slavonic Enoch and of Sodom and Gomorrah; the Tassili frescoes in North Africa; the machined metal cube allegedly found in ancient geological sediments and said to be displayed in a museum in Austria; and so on. Over the years I have continued to look as deeply as I am able into such stories and have found very few that require more than passing attention.

  In the long litany of “ancient astronaut” pop archaeology, the cases of apparent interest have perfectly reasonable alternative explanations, or have been misreported, or are simple prevarications, hoaxes and distortions. This description applies to arguments about the Piri Reis map, the Easter Island monoliths, the heroic drawings on the plains of Nazca, and various artifacts from Mexico, Uzbekistan and China.

  And yet, it would be so easy for an advanced extraterrestrial civilization to leave a completely unambiguous calling card of their visit. For example, many nuclear physicists believe that there is an “island of stability” of atomic nuclei, near a hypothetical superheavy atom with about 114 protons and about 184 neutrons. All chemical elements heavier than uranium (with 238 protons and neutrons in it
s nucleus) spontaneously decay in cosmically short periods of time. But there is reason to think that the binding between protons and neutrons is such that stable elements would be produced if nuclei having about 114 protons and 184 neutrons could be constructed. Such a construction is just beyond our present technology, and clearly beyond the technology of our ancestors. A metal artifact containing such elements would be unambiguous evidence of an advanced extraterrestrial civilization in our past. Or consider the element technetium, whose most stable form has 99 protons and neutrons. Half of it radioactively decays to other elements in about 200,000 years, half of the remainder is gone in another 200,000 years, and so on. As a result, any technetium formed by stars with the other elements billions of years ago must all be gone by now. Thus, terrestrial technetium can only be of artificial origin, as its very name indicates. A technetium artifact could have only one meaning. Similarly, there are common elements on Earth that are immiscible; for example, aluminum and lead. If you melt them together, the lead, being considerably heavier, sinks to the bottom. The aluminum floats to the top. However, in the zero g conditions of spaceflight there is no gravity in the melt to pull the heavier lead down, and exotic alloys such as AL/Pb can be produced. One of the objectives of NASA’s early Shuttle missions will be to test out such alloying techniques. Any message written on an aluminum/lead alloy and retrieved from an ancient civilization would certainly commend itself to our attention today.