Tuesday, August 3, 2010

Are We Redundant?

We all know the age-old process of plants capturing the sun's solar energy, creating chemical energy which animals then consume to generate waste etc etc. To add to this we've just read about how it's actually the order or energy 'quality' that is consumed in cyclic process where energy is radiated in, used then radiated out (See Diagram 1.2).

My question is, if the Earth consisted of only plants, would the 'biosphere' still be maintained?

One could argue that we evolved simply to soak up this excess 'ordered' energy that the plants produce; that we in fact are responsible for maintaining the Earth in a stable cyclic system. We consume the plant products and generate more radiative heat that escapes the Earth. In doing so not only are we maintaining the carbon dioxide supply that plants also rely on but also preventing the planet from becoming first an overgrown jungle followed by a dead rock depleted of the necessary supplies for life.

On the other hand we could be considered as parasites that consume the energy wealth of plants; and without our interference that they would be perfectly able to maintain the ordered biosphere of the planet.

Of course considering egotism the former option would be preferrable. Considering evolution however it is doubtless that plants would have become equipped to complete this energy cycle if animals did not exist.

But it comes down to whether this energy cycle is necessary for life to be maintained. Are we actually completing a vital and elegant process or are we providing a redundant service? Would life on Earth still be balanced without the usage of plant matter and the production of animal waste?


  1. This comment might be off topic but your post made me think of it. It is strange comparing life to other physical processes. For some reason the formation of stars and other cosmological things seems inevitable. Can the same be said about life? Is it inevitable under the right conditions? To answer this question I suppose we would need to observe other instances of life and narrow down the conditions that are common.

  2. Good question. I think that is something Biologists have been trying to answer for years. I definitely think that for life to occur it requires very specific conditions. Whether or not having those conditions makes it inevitable...?

  3. Well, the inevitability of something depends on the time scale it has to occur on. As I hae indicated in previous posts, as long as the probability of an event occuring is not zero, if you leave it long enough, it is inevitable. The question is, is the age of the universe, before it decays into a warm hydrogen soup, long enough?

  4. Good question Heather (referring to the main blog). I personally think that it is quite possible, but there are a number of things to consider if this occurs.
    1) The diversity of plants will decrease most likely, as a number of plants rely on animals to transfer their genetic material around to create more plants.
    2) More diversity could arise through mutations of plants or evolution (survival of the fittest)
    3) Without animals, the breakdown of dead trees would take a lot longer to achieve, to the point where the dead trees would be covering viable land, preventing new sprouts from coming through
    4) We would really have to know exactly how much energy plants take in, what they release, and what they give back when they breakdown at the end of their life cycle. or as a simpler point, is there an energy source they relies on animal existance to stay in enough supply to meet the demand.

  5. This touches on my earlier mention of Charley Lineweaver's talk. He was advocating a paradigm shift from "we eat food" to "food created us so that we could eat it". The idea is that there is an enormous free energy gradient waiting to be discharged, and that the structures that discharge this gradient increase their complexity to accelerate its discharge. In this sense, both plants and us evolved from some common ancestor because this lead to a faster discharge of the gradient.

    Of course, it is easy to follow Lineweaver's arguments too far: one could equally say that since CO2 is a high-entropy form of carbon, anthropogenic global warming is a fulfillment of our natural purpose! I don't advocate using this as a basis for policy.

    At the end of Lineweaver's talk, I asked him: "Would you prefer cremation, burial, or alkali hydrolysis?". This was a personal question, probing his own relationship to the gradient which spawned him. The options are:

    1. Cremation. You are moved quickly into a state of low free energy through burning (again CO2 is a high-entropy form of carbon). You move down the gradient fast.
    2. Burial. Your free energy is approximately constant at short times. You don't move down the gradient (at short times, and assuming a closed and isolated coffin).
    3. Alkali Hydrolysis. You are heated under pressure, and emerge as a good source of fixed nitrogen. This pushes you back up the gradient at short times. This is popular in Canada.

    He elected not to answer. Fair enough - it was a personal question.