The Faber Book of Science (57 page)

Scientists who work on animal behavior are occupationally obliged to live chancier lives than most of their colleagues, always at risk of being fooled by the animals they are studying or, worse, fooling themselves. Whether their experiments involve domesticated laboratory animals or wild creatures in the field, there is no end to the surprises that an animal can think up in the presence of an investigator. Sometimes it seems as if animals are genetically programmed to puzzle human beings, especially psychologists.

The risks are especially high when the scientist is engaged in training the animal to do something or other and must bank his professional reputation on the integrity of his experimental subject. The most famous case in point is that of Clever Hans, the turn-of-the-century German horse now immortalized in the lexicon of behavioral science by the technical term, the ‘Clever Hans Error.’ The horse, owned and trained by Herr von Osten, could not only solve complex arithmetical problems, but even read the instructions on a blackboard and tap out infallibly, with one hoof, the right answer. What is more, he could perform the same computations when total strangers posed questions to him, with his trainer nowhere nearby. For several years Clever Hans was studied intensively by groups of puzzled scientists and taken seriously as a horse with something very like a human brain, quite possibly even better than human. But finally in 1911, it was discovered by Professor O. Pfungst that Hans was not really doing arithmetic at all; he was simply observing the behavior of the human experimenter. Subtle, unconscious gestures – nods of the head, the holding of breath, the cessation of nodding when the correct count was reached – were accurately read by the horse as cues to stop tapping.

Whenever I read about that phenomenon, usually recounted as the exposure of a sort of unconscious fraud on the part of either the experimenter or the horse or both, I wish Clever Hans would be given more credit than he generally gets. To be sure, the horse couldn’t really do arithmetic, but the record shows that he was considerably better at observing human beings and interpreting their behavior than humans are at comprehending horses or, for that matter, other humans.

Cats are a standing rebuke to behavioral scientists wanting to know how the minds of animals work. The mind of a cat is an inscrutable mystery, beyond human reach, the least human of all creatures and at the same time, as any cat owner will attest, the most intelligent. In 1979, a paper was published in
Science
by B. R. Moore and S. Stuttard entitled ‘Dr. Guthrie and Felis domesticus or: tripping over the cat,’ a wonderful account of the kind of scientific mischief native to this species. Thirty-five years ago, E. R. Guthrie and G. P. Horton described an experiment in which cats were placed in a glass-fronted puzzle box and trained to find their way out by jostling a slender vertical rod at the front of the box, thereby causing a door to open. What interested these investigators was not so much that the cats could learn to bump into the vertical rod, but that before doing so each animal performed a long ritual of highly stereotyped movements, rubbing their heads and backs against the front of the box, turning in circles, and finally touching the rod. The experiment has ranked as something of a classic in experimental psychology, even raising in some minds the notion of a ceremony of superstition on the part of cats: before the rod will open the door, it is necessary to go through a magical sequence of motions.

Moore and Stuttard repeated the Guthrie experiment, observed the same complex ‘learning’ behavior, but then discovered that it occurred only when a human being was visible to the cat. If no one was in the room with the box, the cat did nothing but take naps. The sight of a human being was all that was needed to launch the animal on the series of sinuous movements, rod or no rod, door or no door. It was not a learned pattern of behavior, it was a cat greeting a person.

Politicians, real-estate agents, used-car salesmen, and advertising copy-writers are expected to stretch facts in self-serving directions, but scientists who falsify their results are regarded by their peers as committing an inexcusable crime. Yet the sad fact is that the history of science swarms with cases of outright fakery and instances of scientists who unconsciously distorted their work by seeing it through lenses of passionately held beliefs.

Gregor Johann Mendel, whose experiments with garden peas first revealed the basic laws of heredity, was such a hero of modern science that scientists in the thirties were shocked to learn that this pious monk probably doctored his data. R. A. Fisher, a famous British statistician, checked Mendel’s reports carefully. The odds, he concluded, are about 10,000 to 1 that Mendel gave an inaccurate account of his experiments.

Brother Mendel was a Roman Catholic priest who lived in an abbey in Brünn, now part of Czechoslovakia. More than a century ago, working alone in a monastery garden, he found that his plants were breeding according to precise laws of probability. Later, these laws were explained by the theory of genes (now known to be sections along a helical DNA molecule), but it was Brother Mendel who laid the foundations for what later was called Mendelian genetics. His great work was totally ignored by the botanists of his time, and he died without knowing he would become famous.

Most of the monk’s work was with garden peas. Seeds from dwarf pea plants always grow into dwarfs, but tall pea plants are of two kinds. Seeds from one kind produce only tails. Seeds from the other
kind produce both tails and dwarfs. Mendel found that when he crossed true-breeding tails with dwarfs he got only tails. When he self-pollinated these tall hybrids he got a mixture of ¼ true-breeding tails, ¼ dwarfs, and ½
tails that did not breed true.

Today one says that tallness in garden peas is dominant, dwarfness is recessive. Mendel’s breeding experiment is like shaking an even mixture of red and blue beads in a hat, then taking out a pair. The probability is ¼
you will get red-red, ¼
you will get blue-blue, and ½
you will get red-blue. These, however, are ‘long-run’ probabilities. Make such a test just once, with (say) 200 evenly mixed beads, and the odds are strongly against your getting
exactly
25 red pairs, 25 blue, and 50 mixed. Statisticians would be deeply suspicious if you reported results that precise.

Mendel’s figures are suspect for just this reason. They are too good to be true. Did the priest consciously fudge his data? Let us be charitable. Perhaps he was guilty only of ‘wishful seeing’ when he classified and counted his tails and dwarfs.

Geologists find strange things in the ground, but none so strange as the ‘fossils’ unearthed by Johann Beringer, a learned professor of science at the University of Würzburg. German Protestants of the early eighteenth century, like so many American fundamentalists today, could not believe that fossils were the relics of life that flourished millions of years ago. Professor Beringer had an unusual theory. Some fossils, he admitted, might be the remains of life that perished in the great flood of Noah, but most of them were ‘peculiar stones’ carved by God himself as he experimented with the kinds of life he intended to create.

Beringer was ecstatic when his teen-age helpers began to dig up hundreds of stones that supported his hypothesis. They bore images of the bodies of strange insects, birds, and fishes never seen on earth. One bird had a fish’s head – an idea God had apparently discarded. Other stones showed the sun, moon, five-pointed stars, and comets with blazing tails. He began to find stones with Hebrew letters. One had ‘Jehovah’ carved on it.

In 1726 Beringer published a huge treatise on these marvelous discoveries. It was written in Latin and impressively illustrated with engraved plates. Colleagues tried to convince Beringer he was being bamboozled, but he dismissed this as ‘vicious raillery’ by stubborn, establishment enemies.

No one knows what finally changed the professor’s mind. It was said that he found a stone with his own name on it! An inquiry was held. One of his assistants confessed. It turned out that the peculiar stones had been carved by two peculiar colleagues, one the university’s librarian, the other a professor of geography.

Poor trusting, stupid Beringer, his career shattered, spent his life’s savings buying up copies of his idiotic book and burning them. But the work became such a famous monument to geological gullery that twenty-seven years after Beringer’s death a new edition was published in Germany. In 1963 a handsome translation was issued by the University of California Press. Beringer has become immortal only as the victim of a cruel hoax.

Was Paul Kammerer the victim of a similar hoax, or was he himself the perpetrator? In any case, when someone applied India ink to (or perhaps injected it into) the feet of several of Kammerer’s frogs, the career of one of the most respected of Viennese biologists was brought to an inglorious end.

Kammerer was the last great champion of a theory of evolution called Lamarckism. In this view, named for the French naturalist Jean Lamarck [see p. 58], acquired traits are somehow passed on to descendants: when giraffes stretched their necks to nibble high leaves, their offspring were born with longer necks. Darwin himself was a Lamarckian. Modern genetics discards this theory, replacing it with the Mendelian view that natural selection operates on variations produced by random mutations.

In 1910 Lamarckism was still the ‘establishment’ view, but the new Mendelian theory was rapidly gaining ground. Eager to defend the older theory (he had written a book about it called
The
Inheritance
of
Acquired
Characteristics
)
,
Kammerer devised a simple experiment with a species of frog known as the ‘midwife toad.’

Most toads mate in water. To keep a firm grip on the female’s slippery body, the male toad develops dark ‘nuptial pads’ on his feet. The male midwife toad, which mates on land, lacks such pads. Kammerer’s scheme was to force midwife toads to copulate under water for several generations, then see if they develop nuptial pads. It was a stupid experiment, because, had it succeeded, Mendelians would have explained it as no more than a revival of a genetic blueprint. Nothing so complicated as a nuptial pad could have developed in just a few generations.

But Kammerer went ahead with his plan and soon reported it to be a huge success. The black pads had indeed appeared. The news was sensational, especially in Russia where Lamarckism then completely dominated biology. Russian scientists were so impressed that they offered Kammerer a post at the University of Moscow.

No sooner had Kammerer accepted this offer than it was discovered that his toad specimens had been crudely faked. It was the biggest science scandal of the decade. Kammerer blamed it all on an assistant, but nobody believed him. In 1926, at age 46, he took a pistol and shot himself through the head.

Kammerer continued to be a great hero in the Soviet Union throughout the period when Joseph Stalin and the plant-breeder Trofim Lysenko, both enthusiastic Lamarckians, saw to it that Mendelian geneticists were banished to Siberia. Now that Lysenko is dead and Soviet genetics has gone Mendelian, it is hard to find a biologist anywhere in the world who takes Lamarckism seriously.

The physics of motion provides one of the clearest examples of the counter-intuitive and unexpected nature of science. Most people not trained in physics have some sort of vague ideas about motion and use these to predict how an object will move. For example, when students are presented with problems requiring them to predict where an object – a bomb, say – will land if dropped from an aircraft, they often get the answer wrong. The correct answer – that the bomb will hit that point on the ground more or less directly below the point at which the aircraft has arrived at the moment of impact – is often rejected. The underlying confusion partly comes from not recognizing that the bomb continues to move forward when released and this is not affected by its downwards fall. This point is made even more dramatically by another example. Imagine being in the centre of a very large flat field. If one bullet is dropped from your hand and another is fired horizontally from a gun at exactly the same time, which will hit the ground first? They will, in fact, hit the ground at the same time, because the bullet’s rate of fall is quite independent of its horizontal motion. That the bullet which is fired is travelling horizontally has no effect on how fast it falls under the action of gravity…

Science also deals with enormous differences in scale and time compared with everyday experience. Molecules, for example, are so small that it is not easy to imagine them. If one took a glass of water, each of whose molecules were tagged in some way, went down to the sea, completely emptied the glass, allowed the water to disperse through all the oceans, and then filled the glass from the sea, then
almost certainly some of the original water molecules would be found in the glass. What this means is that there are many more molecules in a glass of water than there are glasses of water in the sea. There are also, to give another example, more cells in one finger than there are people in the world. Again, geological time is so vast – millions and millions of years – that it was one of the triumphs of
nineteenth-century
geology to recognize that the great mountain ranges, deep ravines and valleys could be accounted for by the operation of forces no different from those operating at present but operating over enormous periods of time. It was not necessary to postulate catastrophes.

A further example of where intuition usually fails, probably because of the scale, is provided by imagining a smooth globe as big as the earth, round whose equator – 25,000 miles long – is a string that just fits. If the length of the string is increased by 36 inches, how far from the surface of the globe will the string stand out? The answer is about 6 inches, and is independent of whether the globe’s equator is 25,000 or 25 million miles long.