Ecology: the Biology of Interactions. 1.08. Properties of Complex Systems

Ukrainian language (latest version) / Russian language (updates discontinued) 1.07. Regulation of Biosystems

D. Shabanov, M. Kravchenko. Ecology: the Biology of Interactions Chapter 1. Ecology and the Biosystems It Studies

1.09. Stability of Biosystems

1.08. Properties of Complex Systems When I look at a cow grazing in a meadow, all I see is the frenzied dance of electrons. Unknown author (the quintessence of the worldview of biological reductionists) Can one, in studying systems as complex as those studied by biology, manage with the reductionist approach alone? Can one do without it? “The task of defining the object of a science is to separate it from the objects of other sciences. In the case of biology, this was hindered by numerous philosophical prejudices, still not entirely overcome. I mean the reduction of more complex forms to simpler ones and the tendency to consider these simple forms more ‘true,’ more ‘real,’ than the more complex ones. The first—the reduction of the complex to the simple—is a perfectly legitimate, indeed necessary, scientific technique. The second—the tendency to consider the products of abstraction, simple forms, more real than the things from which they were abstracted—is bad philosophy, the philosophical realism of concepts that people like to criticize in medieval scholastics but do not notice in themselves. Then electrons, atoms, molecules, and chemical processes are considered true reality, whereas the organism built out of them is granted substantially less reality; it is only an ‘epiphenomenon,’ the outward manifestation of its building blocks” (Ya. N. Danko, 2001). For several centuries, the successes of biology were associated mainly with the reductionist approach (see section 1.6). At present, reductionist methodology has to a great extent exhausted its possibilities. One manifestation of the crisis of reductionist methodology is the impossibility of an element-by-element, mosaic description of complex systems characterized by a wealth of internal interconnections. The integrity of biosystems is connected not with their having intact shells, but with the interdependence of their parts. In the twentieth century, several major scholars (for example, the Soviet zoologist and evolutionist Ivan Ivanovich Schmalhausen, as well as the French scholar and priest Pierre Teilhard de Chardin) understood that the integrity of any system is connected with the accumulation of functional differences among its parts. Simple systems can be described fairly easily. To do this, one must specify the set of initial elements and, for each of them, indicate its role in the general properties of the whole. However, even when we are dealing with not very complex technical systems, their integral properties determined by the interaction of parts come to the fore. When, for example, we consider the properties of an organism, its mosaic description turns out to be impossible. The computational means, mathematical apparatus, and even simple logic available to humans are suitable only for solving fundamentally simpler problems. The more integrated a system is, the more difficult its mosaic description becomes. The brain is so complex because it is united by a multitude of connections (a neuron in the human brain may have 100 thousand synapses). It is possible that the human brain is the most complexly organized object in the Universe (at least it could be rivaled only by the brain of a more highly developed being). Ecosystems are less integrated, and their emergent properties are not so unexpected. Nevertheless, even fairly simple systems are capable of exhibiting unexpected emergent properties, caused by the interaction of the parts of the system and irreducible to individual elements. An example is the speculative model of global regulation proposed in 1979 by J. Lovelock, which received the name “Daisyworld” (Fig. 1.9.1). [IMG_1] Fig. 1.9.1. Stages in the development of Lovelock’s “Daisyworld” Lovelock’s model is based on the assumption that stars of the same class as the Sun increase in luminosity over time. The Sun ought now to shine 40% more strongly than 4.6 billion years ago. This means that temperatures on planets around stars like the Sun should rise. Yet in the history of Earth’s biosphere, no manifestations of such warming are visible. The point is that if planets are inhabited, organisms can modify the influence of stellar radiation. The model considers a planet located near a star that gradually warms over time. On the planet there is a single life form, daisies, represented by two forms, black and white. They live only within a certain temperature range. At temperatures below the optimum, black daisies have the advantage (they warm better), whereas at temperatures above the optimum, white ones do. Under favorable temperature conditions these flowers can cover the entire surface of the planet. Black daisies are darker than the planet’s surface (and, spreading, increase planetary warming by starlight), whereas white ones are lighter (and contribute to planetary cooling). As soon as temperature at the equator reaches a value acceptable for daisies, black plants settle there, accelerating the warming of the planet. After the whole planet becomes covered with flowers, temperature will remain constant, and in response to changes in the star’s luminosity only the ratio of the two daisy forms will change. The greater the energy flow from the star, the higher the share of white daisies, and the less the planet’s surface will heat. As long as somewhere on the planet conditions suitable for daisies remain, they will alter environmental properties in the direction desirable for themselves. “Thus, even such a super-primitive biosphere, consisting of a single plant species that can do nothing more than vary the color of its petals, is capable of creating an effect of truly cosmic scale—globally changing the temperature of a planet’s surface. However, more important is not the fact of temperature change, but the fact that the planet turns into a homeostat and maintains its temperature constant in spite of external changes (in the Sun’s luminosity). Remarkable also is that the system as a whole works with negative feedback, although each of its elements works with positive feedback; this is a characteristic feature precisely of living systems (let us recall, for example, the predator–prey system)” (K. Yu. Eskov, 1999). The emergent properties of “Daisyworld” seem to arise “out of nothing.” Just think: Earth’s biosphere is far more complex and has far more degrees of freedom. Additional materials: Educational model: Daisyworld Column: A Chain of Antelope Tracks Ukrainian / Russian 1.07. Regulation of Biosystems

D. Shabanov, M. Kravchenko. Ecology: the Biology of Interactions Chapter 1. Ecology and the Biosystems It Studies

1.09. Stability of Biosystems