Bare Bones Biology 243 – No More Games

Repost of Limiting Factors, BBB 035

 

If we decide we really want to save our ecosystem for future generations, we need to organize our opinions around the unchangeable facts of Life in a way that will save us.  About five years ago, I described the most important facts on this blog, and since that time I’ve been trying to sort out the most important ones that most people don’t know about.  At the top of that list is Limiting Factors.

141215-Snow-ASC_3244RLSs To a professional biologist, Limiting factors are those conditions that prevent any population from growing beyond the ability of the ecosystem to support it.   Limiting factors are complex and they fluctuate, and every organism is somewhat different, so let’s invent an organism and compare it with ourselves, the human organism.

 

Suppose we invent a mouse living in Texas and we say its first limiting factor is water.  I mean a species of mouse, not one individual mouse.  So this mouse species cannot live in areas where there is not as much water as it requires.  Also, as global warming increases, the amount of water will be less in its home range, and there are fluctuations year by year.  The mouse population is responsive to all these changes, mostly in terms of how many baby mice they can raise in any given area and year.  The mouse can’t raise babies in areas that have not enough water.  For humans, up to now, we have taken care of the water problem by building dams and water pipes.  Most of us bypassed that limiting factor.

 

But back to the mouse, supposing there is enough water, but the temperature limits the number of mice in any area.  We humans make heaters and air conditioners.

 

So maybe all the conditions were great for the mouse one year and they raised a skizzilion babies, until they are so crowded that a disease spreads through the whole population and wipes out half of them.  That year the mouse limiting factor is disease; humans invented flu shots.

 

Mouse populations are constantly balanced against the predator populations.  If there are five different species that eat mice, then there is a constant automatic balancing of both the predators and the prey so that the predators never eat all the mice and there are always enough mice to eat.  If something happens to the mice, the numbers of predators will be affected.  All these things are limiting factors both to predators and to prey.

 
The bottom line limiting factor is that every living cell and organism and ecosystem requires food energy to stay alive.  Food energy is made by photosynthesis in plants and other green organisms.  If the major food of mice is a particular kind of grass seed, and if the mice become too populous, so that they eat up all the seeds, then all the mice will starve, and so will the predators.

  

 

Survival of the Biosystem is NOT basically a story of individual survival of the fittest; it is a story of balancing millions of biological interactions so that the SYSTEMS can survive together within the limiting factors of all the millions of species that make available the air, water, earth and energy that are required for the survival of the whole Biosystem.

 

Human technologies can increase efficiency, but there is nothing humans can do to actually make food for ourselves, so the bottom line fact is that food energy (chemical energy) is a limiting factor that humans cannot exceed on Earth .   And that is the limiting factor we now face.   Or actually we are not facing it, because we’ve gotten a bit big-headed.  We’ve used technology to get around all our limiting factors for all these millennia up to now, and we’ve forgotten that the only reason we could do that is because the earth was making more food than we needed to feed ourselves, and our machines, and now our corposystem.

 

That is no longer the case.

 

People have learned to grow their own food.  Cattle.  And corn.  And the like.  But we have now reached the point where we and our machines and our corposystem are all competing with the ecosystem for food energy. 

 

Another thing we sometimes forget is that the ecosystem is not growing that food just for us; the ecosystem needs food for all its populations of millions of organisms because all those OTHER organisms do make available the air, water, soil and food energy that we and they, and therefore the entire Biosystem, require to stay alive and healthy. 

 

So we need to pay attention to the fact that we have hit the bottom-line limiting factor for humans on this earth.  That is one of our facts that we cannot change.  We cannot change how the Biosystem functions to prevent overpopulation by any species.  Overpopulation by definition is when the species hits the final limiting factor.  Normally, at that point in overpopulated species, the population continues to grow until it eventually eats up all the food and then it dies.  The population of humans on this earth has already surpassed the limit and is beginning its descent.

 

What we decide to do about this situation will determine whether or not we survive as a species, and how many people must suffer for our big-headedness.  Whatever happens, our population will not grow beyond its final limiting factor because no technology can change the second law of thermodynamics.  We could, however, change our behaviors so that we stay within the biological limits.

 

This is Bare Bones Biology, a production of http://FactFictionFancy.Wordpress.org and KEOS radio, 89.1 FM in Bryan Texas

A copy of this podcast can be downloaded at:

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