Being freed from superstition isn’t enough for science to grow. One must also have the idea of interrogating Nature, of doing experiments. There were some brilliant examples -Eratosthenes’s measurement of the Earth’s diameter, say, or Empedocles’s clepsydra experiment demonstrating the material nature of air. But in a society in which manual labour is demeaned and thought fit only for slaves, as in the classical Graeco-Roman world, the experimental method does not thrive. Science requires us to be freed of gross superstition and gross injustice both. Often, superstition and injustice are imposed by the same ecclesiastical and secular authorities, working hand in glove. It is no surprise that political revolutions, scepticism about religion, and the rise of science might go together. Liberation from superstition is a necessary but not a sufficient condition for science.
At the same time, it is undeniable that central figures in the transition from medieval superstition to modern science were profoundly influenced by the idea of one Supreme God who created the Universe and established not only commandments that humans must live by, but laws that Nature itself must abide by. The seventeenth-century German astronomer Johannes Kepler, without whom Newtonian physics might not have come to be, described his pursuit of science as a wish to know the mind of God. In our own time, leading scientists, including Albert Einstein and Stephen Hawking, have described their quest in nearly identical terms. The philosopher Alfred North Whitehead and the historian of Chinese technology Joseph Needham have also suggested that what was lacking in the development of science in non-western cultures was monotheism.
And yet, I think there is strong contrary evidence to this whole thesis, calling out to us from across the millennia . . .
The small hunting party follows the trail of hoofprints and other spoor. They pause for a moment by a stand of trees. Squatting on their heels, they examine the evidence more carefully. The trail they’ve been following has been crossed by another. Quickly they agree on which animals are responsible, how many of them, what ages and sexes, whether any are injured, how fast they’re travelling, how long ago they passed, whether any other hunters are in pursuit, whether the party can overtake the game, and if so, how long it will take. The decision made, they flick their hands over the trail they will follow, make a quiet sound between their teeth like the wind, and off they lope. Despite their bows and poison arrows, they continue at championship marathon racing form for hours. Almost always they’ve read the message in the ground correctly. The wildebeests or elands or okapis are where they thought, in the numbers and condition they estimated. The hunt is successful. Meat is carried back to the temporary camp. Everyone feasts.
This more or less typical hunting vignette comes from the IKung San people of the Kalahari Desert, in the Republics of Botswana and Namibia, who are now, tragically, on the verge of extinction. But for decades they and their way of life were studied by anthropologists. The IKung San may be typical of the hunter-gatherer mode of existence in which we humans spent most of our time, until ten thousand years ago, when plants and animals were domesticated and the human condition began to change, perhaps forever. They were trackers of such legendary prowess that they were enlisted by the apartheid South African army to hunt down human prey in the wars against the ‘front-line states’. This encounter with the white South African military in several different ways accelerated the destruction of the IKung San way of life. It had, in any case, been deteriorating bit by bit over the centuries from every contact with European civilization.
How did they do it? How could they tell so much from barely more than a glance? Saying they’re keen observers explains nothing. What actually did they do? According to anthropologist Richard Lee:
They scrutinized the shape of the depressions. The footprints of a fast-moving animal display a more elongated symmetry. A slightly lame animal favours the afflicted foot, puts less weight on it, and leaves a fainter imprint. A heavier animal leaves a deeper and broader hollow. The correlation functions are in the heads of the hunters.
In the course of the day, the footprints erode a little. The walls of the depression tend to crumble. Windblown sand accumulates on the floor of the hollow. Perhaps bits of leaf, twigs or grass are blown into it. The longer you wait, the more erosion there is.
This method is essentially identical to what planetary astronomers use in analysing craters left by impacting worldlets: other things being equal, the shallower the crater, the older it is. Craters with slumped walls, with modest depth-to-diameter ratios, with fine particles accumulated in their interiors tend to be more ancient, because they had to be around long enough for these erosive processes to come into play.
The sources of degradation may differ from world to world, or desert to desert, or epoch to epoch. But if you know what they are you can determine a great deal from how crisp or blurred the crater is. If insect or other animal tracks are superposed on the hoofprints, this also argues against their freshness. The subsurface moisture content of the soil and the rate at which it dries out after being exposed by a hoof determine how crumbly the crater walls are. All these matters are closely studied by the IKung.
The galloping herd hates the hot Sun. The animals will use whatever shade they can find. They will alter course to take brief advantage of the shade from a stand of trees. But where the shadow is depends on the time of day, because the Sun is moving across the sky. In the morning, as the Sun is rising in the east, shadows are cast west of the trees. Later in the afternoon, as the Sun is setting toward the west, shadows are cast to the east. From the swerve of the tracks, it’s possible to tell how long ago the animals passed. This calculation will be different in different seasons of the year. So the hunters must carry in their heads a kind of astronomical calendar predicting the apparent solar motion.
To me, all of these formidable forensic tracking skills are science in action.
Not only are hunter-gatherers expert in the tracks of other animals; they also know human tracks very well. Every member of the band is recognizable by his or her footprints; they are as familiar as their faces. Laurens van der Post recounts,
[M]any miles from home and separated from the rest, Nxou and I, on the track of a wounded buck, suddenly found another set of prints and spoor joining our own. He gave a deep grunt of satisfaction and said it was Bauxhau’s footmarks made not many minutes before. He declared Bauxhau was running fast and that we would soon see him and the animal. We topped the dune in front of us and there was Bauxhau, already skinning the animal.
Or Richard Lee, also among the IKung San, relates how when briefly examining some tracks a hunter commented, ‘Oh, look, Tunu is here with his brother-in-law. But where is his son?’
Is this really science? Does every tracker in the course of his training sit on his haunches for hours, following the slow degradation of an eland hoofprint? When the anthropologist asks this question, the answer given is that hunters have always used such methods. They observed their fathers and other accomplished hunters during their apprenticeships. They learned by imitation. The general principles were passed down from generation to generation. The local variations – wind speed, soil moisture – are updated as needed in each generation, or seasonally, or day-by-day.
But modern scientists do just the same. Every time we try to judge the age of a crater on the Moon or Mercury or Triton by its degree of erosion, we do not perform the calculation from scratch. We dust off a certain scientific paper and read the tried-and-true numbers that have been set down perhaps as much as a generation earlier. Physicists do not derive Maxwell’s equations or quantum mechanics from scratch. They try to understand the principles and the mathematics, they observe its utility, they note how Nature follows these rules, and they take these sciences to heart, making them their own.
Yet someone had to figure out all these tracking protocols for the first time, perhaps some palaeolithic genius, or more likely a succession of geniuses in widely separated times and places. There is no hint in the IKung tracking protocols of magical methods -examining the stars the night before or the entrails of an animal, or casting dice, or interpreting dreams, or conjuring demons, or any of the myriad other spurious claims to knowledge that humans have intermittently entertained. Here there’s a specific, well-defined question: which way did the prey go and what are its characteristics? You need a precise answer that magic and divination simply do not provide, or at least not often enough to stave off starvation. Instead hunter-gatherers – who are not very superstitious in their everyday life, except during trance dances around the fire and under the influence of mild euphoriants – are practical, workaday, motivated, social, and often very cheerful. They employ skills winnowed from past successes and failures.