by Bill Bryson
RANDOMNESS AND THE DIVERSITY OF LIFE
In the past few years, a new notion has emerged: that community structure can best be explained with a radical and at first sight absurd assumption that, in effect, all the species involved are equivalent and that their abundance turns on random fluctuations in survival and in reproduction (reviewed in Leigh 2007). This ‘neutral model’ of ecology has parallels with its equivalent in genetics, in which levels of inherited variation emerge from a balance between random mutation and the accidents of genetic drift. That model has been tested against the real world, and although it sometimes fails, at the level of DNA sequence it retains considerable explanatory power (Clark 2009). In ecology, too, a random model of communities may carry more general conviction than does a series of special cases that explain some patterns in some places but have little predictive power overall.
Darwin accepted random change when he noted that islands contain fewer species than do nearby tracts of mainland and the claim that island life is driven by the accidents of migration and extinction has held up well. The same is true in other populations, on a variety of timescales. Thus, when cataclysms strike, as in the five great extinctions of the past five hundred million years (most associated with comets or great geological upheavals), huge numbers of species of many kinds disappear through mere ill luck, and rules that might help predict their ability to withstand everyday pressures do not much apply (Jablonski 2004). Other geological events quite unrelated to the biological universe such as continental drift also have persistent effects on the diversity of communities. In the same way, the last ice age stripped Northern Europe of most life and the glaciated regions are still depauperate as the result of an ancient historical accident rather than as a response to modern conditions.
The peak of coastal marine species variety is in Indonesia and on the northern coasts of Australia (Renema et al. 2008). There, coral reefs flourish. Such places are often appealed to as an epitome of undisturbed and productive nature, in which new kinds of creature can evolve to add to the treasury of life. A closer look at the fossils and the genes shows that in fact the occupants of the reefs have moved across the globe as conditions changed. During the Eocene, marine diversity found its peak in south-west Europe and North Africa, along the Arabian Peninsula and in what is now Pakistan. As these lands were raised from the sea when Arabia crashed into Asia, many of their inhabitants migrated to more congenial places, the present Indo-Australian region included. Most of the animals supposed to have originated there have in fact an ancient and dispersed history. Global disasters of fifty million years ago have done more to shape the geography of today’s teeming reefs than have climate, food or sunlight. Evolution, that reminds us, works on a far longer timescale than does ecology.
As in genetics, there are many non-linear interactions in ecology (Andersen et al. 2009) and, as in the weather and the stock market, a small disturbance can lead to a sudden and unpredictable change in state. An attempt to shoot foxes to increase the numbers of red grouse prey backfired, for the predators normally caught only the birds most filled with parasites and once they were removed disease spread and killed many more birds than before. In a related case, an attack by one insect herbivore on a leaf often alters its attractiveness to other grazers, while plants that activate a pathway that fights fungal disease may reduce their own ability to combat insect attack with a different biochemical strategy. All these and many more multiple interactions (Strauss & Irwin 2004) emphasise that – as in genetics – many of the connections among species within a community are far from simple.
The importance of randomness first came to attention with the ‘paradox of the plankton’, the discovery that the apparently homogeneous environment of the sea was host to a vast diversity of drifting creatures all apparently in competition for the same resources, in contradiction to the supposedly fundamental principle of exclusion of species with similar demands (Scheffer et al. 2003). The plankton have become even more paradoxical with the discovery of vast numbers of new marine bacteria. The same is true of the world beneath the soil, whose organisms differ wildly from place to place, but generate roughly the same mix of nutrients. Perhaps each of those habitats really is filled with a chance assemblage of ecologically equivalent creatures, each arriving more or less by accident.
That radical notion may have a wider validity, for it seems to apply to some very different terrestrial and freshwater habitats. Fish species diversity across eight hundred tributaries in the entire Missouri–Mississippi river system can be explained by the random loss of species of varying dispersal in a pattern that diffuses from a centre of abundance into streams of smaller and smaller size (Muneepeerakul 2008) with no need for any consideration of the nutrient status of streams, of other species, or of climate. The same is true of patterns of diversity in mature forests.
Temporal shifts, too, hint at an underlying lack of order. In a somewhat heroic experiment (Beninca et al. 2008) a series of laboratory containers containing samples of plankton from the Black Sea was cultivated for seven years, in – as far as they could be attained – constant conditions. The abundance of the various species varied dramatically with time, and the relative numbers of each type could not be predicted with any confidence over any period longer than a month (which is, incidentally, the longest period for which the British weather forecast is even slightly dependable). The system was driven by something close to chaos – but, even so, most species persisted at high or low frequency within the containers.
Natural ecosystems can also remain stable until a threshold is reached and then collapse. The effect is familiar to fisheries managers, for a trophic cascade may be set off by overfishing, with unpredictable results. In the Black Sea itself, there was, from the 1970s on, a shift from large (and valuable) fish to anchovies that feed on plankton, and then to gelatinous creatures such as jellyfish and ctenophores, which now teem in huge numbers and have, within a few decades, replaced what seemed a stable ecosystem. A similar shift in the Pacific from sardines to anchovies and back twice in the second half of the twentieth century may also have turned on small changes in climate in a regime poised on the edge of stability that moves unpredictably from one to another. There have been dozens of climate shifts from cool to warm and back again every few hundred or thousand years, in the past hundred thousand years, each of which was no doubt accompanied by sudden upheavals in what might have seemed like stable ecosystems. Even on a much shorter timescale, the numbers of birds and mammals in a particular place when studied for long enough swing wildly for no obvious reason (as in the collapse of the British house-sparrow). Unexpected outbreaks can also destroy whole ecosystems (as in Dutch Elm disease, which appeared from almost nowhere and killed millions of trees). Such fluctuation might maintain a complex community with no external driver, in which case the paradox of the plankton (and, by extension, of land-based ecosystems too) could be explained in terms of random change.
A recent review claims that ‘ecological surprises’ of this kind have proved to be almost universal (Doak et al. 2008). Not only do they reveal our ignorance of the laws behind biodiversity, but they hint that chaos and complexity may be the rule rather than the exception. Darwin himself was well aware of the difficulties of disentangling the patterns of nature. The term ‘complexity’ appears in The Origin almost fifty times, and ‘innumerable’ and ‘endless’ almost as often (although ‘inextricable web of infinities’ makes it just once). The tension between order and disorder remains unresolved and more than a century and a half since that remarkable work we may understand rather less (although we know considerably more) about the patterns of nature than we imagined just a decade ago.
* Full references can be found in Further Reading on page 488.
13 PHILIP BALL
MAKING STUFF: FROM BACON TO BAKELITE
Philip Ball is a science writer. He worked at Nature for over 20 years, first as an editor for physical sciences (for which his brief extended from biochemistry to
quantum physics and materials science) and then as a consultant editor. He is author of numerous non-fiction works including Universe of Stone: Chartres Cathedral and the Triumph of the Medieval Mind, The Devil’s Doctor, Elegant Solutions: Ten Beautiful Experiments in Chemistry and Critical Mass: How One Thing Leads to Another. His latest books form a trilogy – Nature’s Patterns: A Tapestry in Three Parts, individually titled Shapes, Flow and Branches.
FRANCIS BACON’S VISION OF A SCIENCE DRIVEN BY THE URGE FOR ‘THE EFFECTING OF ALL THINGS POSSIBLE’ HAS BEEN ASTONISHINGLY PRODUCTIVE FOR NEARLY FOUR HUNDRED YEARS. ARE WE GRATEFUL? ASKS PHILIP BALL. ANSWER: YES AND NO. THE REASONS FOR THIS TAKE A BIT OF TEASING OUT.
C.P. Snow’s 1959 Rede Lecture is remembered as a critique of the cultural divide then perceived between the scientific and the literary worlds. But there were more than two cultures identified in his discussion. ‘I think it is fair to say’, he wrote, ‘that most pure scientists have themselves been devastatingly ignorant of productive industry, and many still are.’
It is permissible to lump pure and applied scientists into the same scientific culture, but the gaps are wide. Pure scientists … wouldn’t recognise that many of the problems [of engineering] were as intellectually exacting as pure problems, and that many of the solutions were as satisfying and beautiful. Their instinct … was to take it for granted that applied science was an occupation for second-rate minds.
Snow wasn’t alone in this perception. Writing at much the same time, the English biologist Peter Medawar spoke of Francis Bacon’s division of experimental science in the seventeenth century into ‘Experiments of Use’ and ‘Experiments of Light and Discovery’. Bacon’s distinction, said Medawar, ‘is between research that increases our power over nature and research that increases our understanding of nature, and he is telling us that the power comes from the understanding’ – Bacon’s famous maxim that ‘knowledge is power’. But, Medawar went on:
Unhappily, Bacon’s distinction is not the one we now make when we differentiate between the basic and applied sciences. The notion of purity has somehow been superimposed upon it, and in a new usage that connotes a conscious and inexplicably self-righteous disengagement from the pressures of necessity and use. The distinction is not now between the empirically founded sciences and those whose axioms were supposedly known a priori; rather it is between polite and rude learning, between the laudably useless and the vulgarly applied, the free and the intellectually compromised, the poetic and the mundane.
‘All this’, he added, ‘is terribly, terribly English.’
I believe that this situation can’t be ignored when looking at the development of the applied sciences over the past several centuries. When several rather austere-sounding books from the post-war years, with titles such as Metals [or Plastics] in the Service of Man, served up to lay audiences a triumphalist celebration of materials technologies, they rather took it for granted that the general public felt indebted to these wondrous advances. But as Snow and Medawar intimated, not even scientists themselves had yet found an accommodation between scientific discovery and its applications. This is scarcely surprising, however, since such ambivalence towards what the Greeks called techne – the art of making things – can be discerned throughout history, and pervades not just science and technology but culture in the broad sense.
Many scientists, for instance, will agree with biologist Lewis Wolpert that ‘technology is not science’. Science, says Wolpert, ‘originated only once in history, in Greece’ – although he acknowledges that ‘those who equate science with technology would argue differently’. Indeed they do.
The notion that science is distinct from technology would have sat comfortably with the ancient Greek philosophers, most of whom displayed a reluctance to get their hands dirty. Both Plato and Aristotle elected for a top-down approach to understanding the world, launched from the kind of a priori axioms that Medawar mentions. Aristotle, it is true, advocated close observation of nature, and in the Middle Ages Aristotelian natural philosophers such as Roger Bacon and his mentor Robert Grosseteste instigated a methodology in which experiment played a central role. But one must be careful when speaking of ‘experimental science’ before the Enlightenment, for it often meant demonstrating what one already knew to be the case – and if experiment seemed to contradict axiomatic reason, so much the worse for experiment. In any event, Aristotelianism became rigid dogma in the medieval universities, and Bacon’s advocacy of a new, ‘experimental philosophy’ was a reaction to it: a call for a reformation in how science was conducted.
Meanwhile, what we might now call applied sciences and technologies were commonly conducted by artisans who had no formal university training: metallurgists and alchemists, miners, dye-makers, brewers and bakers, textile makers, barber-surgeons. Their trades were systematically excluded from the academies, where they were often derided as ignorant labourers and recipe-followers (sometimes, it must be said, with good reason).
So it is interesting that, for Wolpert, one of the people confused about the relation between science and technology was Francis Bacon himself. That claim warrants a little examination – for isn’t Bacon often credited with the germinal vision of a body of scientific savants like the Royal Society? What was it, exactly, that Bacon would have such an organisation do – science, or something else?
BROTHERHOODS OF SCIENCE
The blueprint for this new philosophy was laid out in Bacon’s Instauratio Magna (The Great Instauration) of 1620. This was a mere fragment, the introductory episode of an unrealised dream to summarise all of human knowledge and to explain how it should be extended and applied. The Latin noun instauratio means a renewal or restoration. It has a Biblical connotation, referring to a rebuilding of the House of the Lord like that accomplished in the renovation of Solomon’s Temple.
As an addendum to the same volume, Bacon published Novum Organum (The New Organon), which explains the shortcomings of earlier natural philosophy. Bacon decries both the sterility of academic Aristotelianism, which he compares with spiders weaving tenuous philosophical webs, and the blind fumblings of uninformed practical technologies, which are like the mindless tasks of ants. True scientists, he said, should be like bees, which extract the goodness from nature and use it to make useful things.
Seven years later, Bacon offered a vision of how this new experimental philosophy might unfold. In The New Atlantis he presented a utopian fable in which a group of travellers in the Pacific Ocean encounters a land called Bensalem, run by a sect of scholar-priests in an institution called Salomon’s House. Here were Bacon’s scientist-bees, engaged in ‘the production of wonderful operations’. This is evidently not a scientific body that is content to sit and ponder. It creates marvellous devices and structures: artificial lakes, furnaces, engines, caves where alchemy mimics the natural production of metals. Nature is not merely observed, classified and understood in the manner of some Aristotelian taxonomist – it is dominated, modified, ‘improved’. According to the scholars of Salomon’s House:
We make, by art … trees and flowers to come earlier or later than their seasons; and to come up and bear more speedily than by their natural course they do. We make them also by art greater much than their nature; and their fruit greater and sweeter and of differing taste, smell, colour and figure, from their nature … We have also parks and enclosures of all sorts of beasts and birds, which we use not only for view or rareness, but likewise for dissections and trials … We also try all poisons and other medicines upon them … By art likewise we make them greater or taller than their kind is, and contrariwise dwarf them and stay their growth. We make them more fruitful and bearing than their kind is, and contrariwise barren and not generative. And we also make them differ in colour, shape, activity, many ways. We find means to make commixtures and copulations of different kinds, which have produced many new kinds, and them not barren, as the general opinion is.
Bacon’s programme was championed in England during the stormy
1640s by the Prussian exile Samuel Hartlib, one of a clutch of progressive thinkers that included the mathematician William Petty, the chymist Robert Boyle and the Bermudan alchemist George Starkey. During the English Civil War and its aftermath, such ambitions were politically charged: the ‘new philosophy’ had a distinctly Puritan slant that challenged the traditionalism of the Royalists. But Cromwell’s Protectorate was wary of anything that smelled of the utopian, and it was not until the Restoration of Charles II in 1660 that permission was granted for Boyle, Petty and colleagues to found what became, by royal charter two years later, the Royal Society.
Bacon’s thinking infused this project. The poet Abraham Cowley, whose pamphlet The Advancement of Experimental Philosophy in 1661 was of a distinctly Baconian flavour, wrote an ode to the Royal Society in 1667 in which he hailed Bacon as the liberator who, like Moses, ‘led us forth at last’ to a ‘Promis’d Land’. In fact, in its early days the members of the Royal Society seemed to take so closely to heart Bacon’s advocacy of Experiments of Use that its early historian Thomas Sprat complained in 1667 that ‘we are not able to inculcate into the minds of many men, the necessity of that distinction of my Lord Bacon’s, that there ought to be Experiments of Light, as well as of Fruit’. It was as though they were all intent on creating without delay the technological miracles of a New Atlantis.