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Living energies mini-series
The secret of life is not to be found in the molecular nuts and bolts in
living organisms. Instead, it may be in how organisms use energy. This
mini-series will hint at what lies in store, which gives concrete meanings to
renewable living energy and sustainability. A selection of the articles in the
series will be circulated.
To see the entire series, please
subscribe
to Science in Society magazine or become a Member of ISIS.
Details here. These
articles appear in issue 21.
- No System in Systems
Biology
- Biology’s Theory of Everything
- Energy, Productivity & Biodiversity
- Why Are Organisms So
Complex – A Lesson in Sustainability
ISIS Report 24/01/04
Why Are Organisms So Complex?
A Lesson in Sustainability
Complexity is linked to productivity and sustainability.
Dr. Mae-Wan Ho explains.
Sources
for this report are available in the ISIS members site.
Full details here
The organism is like an ecosystem in many respects. It is highly
complex. And like the ecosystems, it is useful to look at its complexity is in
terms of organised, nested heterogeneity. The simplest kind of nested
heterogeneity is a fractal structure – with fractional dimensions
in between the usual 1, 2 or 3 - that is similar on many, if not every scale.
Fractal geometry offers a ready mathematical description of the simplest kind
of organised complexity.
Some years ago, I showed how such a system is optimised for storing and
mobilising energy. In other words, it captures and stores useful coherent
energy, and mobilises it most efficiently and rapidly. The rigorous arguments
involves formal thermodynamics, a discipline that deals with energy
transformation; but can be stated in a much more intuitive form, which I shall
reproduce here.
How organisms make a living
‘Sustainability’ has become a buzzword, but it is difficult to
say exactly what it means. Rather than indulge in getting a correct definition,
I want to show that there is a lot we can learn about sustainability by
studying how organisms sustain themselves, or keep alive.
The pre-requisite for keeping away from thermodynamic equilibrium –
death by another name – is the ability to capture energy and material from
the environment to develop, to grow and to recreate oneself from moment to
moment during one’s life time. The organism not only sustains itself
dynamically, it also reproduces future generations, which is part and parcel of
sustainability.
An organism needs, first of all, physical barriers that separate inside
from the outside, though not completely. It also needs a dynamic structure that
enables it to store as much energy and material as possible, and to use
the energy and material most efficiently and rapidly, with the least amount of
waste and dissipation. Dissipation means the loss of useful energy from the
system.
The organism has solved those problems over billions of years of
evolution. It has an obviously nested physical structure. Our body is enclosed
and protected by a rather tough skin, but we can exchange energy and material
with the outside, as we need to, we eat, breathe and excrete. Within the body,
there are organs, tissues and cells, each with a certain degree of autonomy and
closure. Within the cells there are numerous intracellular compartments that
operate more or less autonomously from the rest of the cell. And within each
compartment, there are molecular complexes doing different things, such as
transcribing genes, making proteins and extracting energy from our food. And
all those compartments are perfectly orchestrated.
The organism is indeed so perfectly coordinated that an actively mobile
animal typically appears liquid crystalline under the polarising microscope,
due to the coherent motions of all its molecules (see Fig. 1). This perfect
coordination depends to a large extent on how energy is mobilised within the
organism.
Figure 1. Inside the liquid crystalline brine-shrimp (200X).
It turns out that energy is mobilised in cycles, which can be
thought of as dynamic boxes, and they come in all sizes, from the very fast to
the very slow, from the global to the most local. Biologists have long puzzled
over why biological activities are predominantly rhythmic or cyclic, and much
effort has gone into identifying the centre of control, and more recently to
identifying master genes that control biological rhythms, all to no avail.
Cycles make sense
The organism is full of cycles possibly because cycles make
thermodynamic sense. Cycles involve perpetual returns to the same states, they
give dynamic stability as well as autonomy to the organism. Cycles also enable
the activities to be coupled, or linked together, so that those yielding energy
can transfer the energy directly to those requiring energy, and the
direction can be reversed when the need arises. These symmetrical,
reciprocal relationships are most important for sustaining the system.
That’s how our metabolism and physiology is organised: closing the cycle
and linking up.
I have drawn a diagram to represent the nested cycles that span all
space-time scales, the totality of which make up the life cycle of the organism
(Fig. 2). I have also proposed that the life cycle has a self-similar fractal
structure, so if you magnify each cycle, you will see that it has smaller
cycles within, looking much the same as the whole.
The system effectively stores and mobilises energy over all space-times
that are coupled together, so energy can get from any space-time compartment to
every other, from the local to the global and vice versa. This complex
dynamical structure is the secret of how the system can sustain itself as a
whole.
In the ideal, the system is always tending towards a dynamic balance,
expressed in another diagram (Fig. 3). The simple equation, S DS = 0, inside the cycle, says there is an
overall internal balance and compensation of energy so that the system
organisation is maintained, and the necessary dissipation (entropy,
S, made up of degraded, incoherent energy) is exported to the outside,
S DS > 0. But that’s the abstract
ideal. In practice, dissipation within the system goes to a minimum, not quite
zero. In other words, the system does grow old and eventually die, but only
very slowly.
energy flow.
Minimum dissipation means in one sense that energy (as well as material)
going into the system is used many times over before it is exported to the
outside. Intuitively, one can see that the more complex the dynamical
structure, the more cycles there are, the longer the energy remains in the
system, and the least amount is dissipated. In other words, increase in
space-time differentiation leads to increase in the energy that can be stored
in the system.
Sustainable systems as organisms
Can we look at a sustainable ecosystem, and ultimately the sustainable
global ecosystem in the same way? I have suggested that we can some years
ago.
Since then, evidence has been accumulating in ecology that productivity
– rate of production of biomass – generally, though not always goes
up with biodiversity (see "Energy, productivity & biodiversity", this
series), although the precise causal relationship is still uncertain.
In my theory based on energy storage, productivity and the complexity of
space-time differentiation – a correlate of biodiversity - are completely
linked: the more complex the space-time differentiation, the greater the energy
stored, which is productivity by another name.
It also explains why greater energy input doesn’t necessarily
increase productivity: if the energy is supplied at a rate greater than the
space-time differentiation of the system can assimilate, then no further
increase in productivity can occur. An over-abundant supply of energy can
indeed unbalance the system, leading to a decrease in space-time
differentiation, and hence a fall in productivity (hence the unimodal
relationship between diversity and productivity, see "Energy, productivity
& biodiversity").
Evidence linking productivity and biodiversity has also emerged in
agriculture. David Tilman and his colleagues in the University of Minneapolis
in the United States have recently produced the best experimental evidence that
biodiverse fields are more productive, although the precise explanation is
still hotly debate. Other ecologists are also rediscovering how it is the
symbiotic reciprocal relationships, rather than competition, which sustain the
ecosystem as a whole. It is a case of closing circles and joining up to build a
more complex space-time differentiation in the ecosystem.
Sustainable farming across the world relies on cultivating a diversity
of crops and livestock to maximise internal input, which effectively closes up
cycles and maximises the nested, space-time structure of the system. This
wisdom has informed traditional indigenous farming systems for millennia, in
marked contrast to the high external input monoculture of industrial farming,
which breaks cycles and destroys space-time differentiation, and is proving
unsustainable in many respects.
These findings also explode the myth of constant ‘carrying
capacity’ that have been used to estimate how many people a piece of land,
or the earth as a whole, can support.
In recent years, African farmers all along the edge of the Sahara, in
Nigeria, Niger, Senegal, Burkina Faso and Kenya, have been working miracles,
pushing back the desert, and turning the hills green, simply by integrating
crops and livestock to enhance nutrient recycling, by mix-cropping to increase
system diversity, and reintroducing traditional water-conservation methods to
overcome drought. Yields of many crops have tripled and doubled, keeping well
ahead of population increases.
In fact, high local population densities, far from being a liability,
are actually essential for providing the necessary labour to work the land
properly, digging terraces and collecting water in ponds for irrigation, and to
control weeds, tend fields, feed the animals and spread manure. In some areas,
the population density or carrying capacity went up fivefold, but the land is
far more productive than ever before.
Organisms are the most energy-efficient ‘machines’ by far, a
point lost on policy-makers bent on increasing efficiency by getting rid of
workers and introducing other unsustainable ‘labour-saving’ measures.
It is high time policy-makers learn thermodynamics.
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