The Competitive Exclusion Principle

An essay by Ron Patterson, April 2014

Evolution is all about a struggle for survival and reproduction. For predators it becomes an arms race. For hundreds of millions of years predatory animals have honed their offensive weapons while prey animals have evolved ever more effective defensive adaptations. Each animal, predator or prey, carved out their particular niche and occupied that niche until they were driven out, to another niche, or went extinct, or still occupy it today.

And that’s the way it went for hundreds of millions of years. Every species multiplying its numbers to the limit its niche or habit would support. Species waxed and waned, predator and prey maintaining a balance. When the prey numbers would expand the predator numbers would expand and when too many predators reduced prey numbers, then the predator numbers would also wane.Ron 9

For millions of years nature kept every species in check. Population explosions of any species was soon met by either an corresponding explosion of predatory animals, or in cases were there were not enough predator animals, like rat or mice plagues, starvation would ultimately reduce their numbers to what the territory would support.

Sometimes of course there would be conflicts between different species of either predatory animals of prey animals. They can of course develop a symbiotic relationship like zebras and wildebeests, zebras eat the tall tough grass and wildebeests eat the shorter tender grass. But if this doesn’t happen, one species must adapt to another niche or go extinct.

This is not a fast process, sometimes taking many thousands of years to play out, depending on the size of the territory and the lifespan of the animals involved. And over many millions of years the balance was always maintained. Every species lived in and defended its niche and life went on. Only a universal disaster, like massive volcanism poisoning the air and seas could really disrupt this balance.

Every animal had adaptations that allowed it to survive in the wild. But no animal had a “super adaptation”, that is no animal evolved an adaptation that gave it ultimate control over other animals. There was no colossus in the animal world. No matter what the adaption, no animal could be that strong.

But the first hint of such an adaptation evolved about 5 million years ago. Somewhere in Africa a species of great ape evolved that had all the other survival adaptations of other great apes plus one more, that ape was just a wee bit smarter than other apes. And among these smarter apes, some were smarter than others. These smarter apes had a slightly higher survival and reproductive rate than the ones in their own group who were not so smart. But even these “smarter” apes were not really all that smart.

Brain size, which is correlated with intelligence, increased very slowly over two and one half million years. But the ultimate competitive weapon, the weapon that would give this one great ape a huge survival weapon over all other species had begun to evolve. From this point on the fate of the earth, the fate of all other species, was set. The ultimate weapon had begun to evolve. And about 100,000 years ago modern humans appeared.

Ron12Until about 10,000 years ago, give or take, humans depended entirely on the natural world for its substance. Killing animals that they could find and gathering what fruits, roots and tubers than nature provided them. Then slowly the Neolithic Revolution started to happen. People began to plant seeds and domesticate animals. However Homo colossus had not yet appeared.

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Homo colossus appeared about 250 years ago. That was when man began to spend nature’s non renewable carbon deposits as if they were income.

William Catton: When the earth’s deposits of fossil fuels and mineral resources were being laid down, Homo sapiens had not yet been prepared by evolution to take advantage of them. As soon as technology made it possible for mankind to do so, people eagerly (and without foreseeing the ultimate consequences) shifted to a high-energy way of life. Man became, in effect, a detritovore, Homo colossus. Our species bloomed, and now we must expect crash (of some sort) as the natural sequel.

However we need to get back to the subject of this post, the competitive exclusion principle.

Wiki: The competitive exclusion principle, sometimes referred to as Gause’s Law, is a proposition that states that two species competing for the same resource cannot coexist at constant population values, if other ecological factors remain constant. When one species has even the slightest advantage or edge over another then the one with the advantage will dominate in the long term. One of the two competitors will always overcome the other, leading to either the extinction of this competitor or an evolutionary or behavioral shift toward a different ecological niche. The principle has been paraphrased into the maxim “complete competitors cannot coexist“.

The competitive exclusion principle usually describes the competition of animals for a particular niche. But humans are animals also. We have been in the competition for territory and resources for thousands of years. And we have been winning that battle for thousands of years. But it is only in the last few hundred years that our complete dominance in this battle has become overwhelming. We are winning big time, we are quite literally wiping them off the face of the globe.

The below chart was created by Paul Chefurka.

Terrestrial Vertebrate Biomass

Three very important things can be derived from the above graph. One, we are wiping out all the wild species. 10,000 years ago humans were about .1 percent of all the land vertebrate biomass of the planet. In 2000 we and our domesticated animals were about 97 percent of the land vertebrate biomass. Today it is closer to 97.5 percent. And we continue to wipe them out. The Earth has lost half its wildlife in the last 40 years.

The second thing that is revealed in the above graph is the dramatic increase in biomass carrying capacity that has been made possible by fossil energy. Mechanical farming with tractors, combines and other farm equipment has made it possible for one farmer to cultivate hundreds of times the acreage he could just a little over a century or so ago. But that is only half the story. Fully half the people in the world are alive today because of synthetic fertilizer created from fossil fuel by the Haber-Bosch process.

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The third thing suggested by the graph is that the carrying capacity of the earth is being degraded by our massive overshoot in population.

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What no one ever talks about is the fact that the animal population is declining just as fast as our population is increasing. This means also that species extinctions are increasing as our population is increasing.

And here is the really, really bad news. Gause’s Law was never repealed. The competitive exclusion principle always applies. And instead of slowing down, the destruction of animal habitat is increasing. The wild animal population is declining at an alarming rate. Species extinction continues. And species extinction will continue until every animal that cannot coexist with man will become extinct.

Of course some animals will survive because their numbers are so great and their niche is so diverse. The rabbit and the dingo will survive in Australia and rabbits in other parts of the world will likely survive also. There is no doubt that rats and mice will survive and hopefully animals that feed on them, like the some owls and hawks will survive also.

Every large animal in Africa, the lion, the giraffe, the rhino, every great ape in Africa, will all disappear. Every large species in Asia will go also, the tiger, the elephant the orangutan, the panda and even the bears of northern Europe, Asia and North America will all become extinct. They all occupy territory and take resources that can be taken by Homo colossus and Homo colossus will take that territory because it is simply in his nature to do so.

We will kill them all.

It would eventually have happened even if not one lump of coal, one drop of oil or one whiff of natural gas had ever been discovered… but it would have taken a few thousand years longer. Our weapon, our intelligence, would have given us such a great advantage over other species that eventually the competitive exclusion principle would have prevaled and wiped them all out. Fossil fuels only enabled us to explode our own population and therefore wipe out the rest of the earth’s megafauna a lot sooner.

All this would happen even if we never have economic collapse. But when economic collapse does happen, every creature that is made out of meat will become a source of food. Economic collapse will just greatly accelerate the decline of the all that is wild.

The following was added to this page on November 17, 2016.

Of Human Extinction

Few biologists would argue with the estimate that 99 percent of all animal species that ever existed, are now extinct. Many people argue that accepting that statistic means it is quite likely that Homo sapiens will go extinct within the next few thousand years. Such people know absolutely nothing about biological evolution, or statistics either for that matter.

What is lacking here is the knowledge of why species go extinct. If we are talking about one of the five great extinctions then we are talking about some type of natural disaster. A giant meteorite and/or the massive volcanism of the Deccan Traps caused the last great extinction, the KT extinction. And the volcanism of the Siberian Traps caused the greatest of all mass extinctions, the great Permian extinction. It is possible that a great meteor strike triggered that massive volcanism but I suspect we will never know.

Some species last for many millions of years while some may last for only a few thousand years. Species, quite obviously, do not go into extinction because their allotted average time on earth is up. So the fact that 99 percent of all species that ever existed is now extinct, has no bearing on whether or not Homo sapiens are in imminent danger of extinction.

So barring some type of natural disaster, what causes species extinction?

Species are driven into extinction. That is, some other species outcompetes them for territory and resources.

Many will claim that some type of disease, virus or pestilence, can cause the extinction of a species. But that is only likely after their numbers have already been decimated, their territory shrunk and their immunity weakened by competition from another species. If their numbers are great enough, and their territory large enough, there will always be survivors. Great plagues decimate populations but not species.

Most mammalian species, as well as many foul and fish species, are now living on earth are in imminent danger of extinction. They are being driven into extinction by the evolutionary success of one great ape, Homo sapiens. But there are a few species that are in absolutely no danger of being driven into extinction. That is they are in no danger of being outcompeted by another species. That is because their numbers are so great and their territory so widespread that no competitor is likely to drive them into extinction. These, safe from extinction species, include rats, mice… and Homo sapiens.

14 Responses to The Competitive Exclusion Principle

  1. Karl says:

    I suspect some North American Megafauna (Caribou, moose, whitetail deer, polar bears, etc.) will survive in the extreme northern part of their ranges. Once we lose oil, our ability (modern industrial man) to chase after them will precipitously decline. I’ve been to Alaska, and it is both vast and sparsely inhabited. Most of the native folks have abandoned traditional ways. Human die off will (hopefully) reduce our numbers sufficiently before the survivors re-acquire the traditional skills needed to inhabit the arctic absent industrial supplies. I agree that the lower latitudes will be stripped bare of game. This was the case as recently as the 1930’s in the eastern USA, and the population is now triple what it was then.

  2. Harquebus says:

    “every creature that is made out of meat will become a source of food.”
    Humans are also made out of meat.

  3. Petro says:

    when you first posted this in early April, among other word concoctions, I articulated the following:
    “…great posting, Ron!
    This belongs on the header of this site alongside of: “Of fossil fuels and human destiny” and ” The grand illusion”.”
    -I am happy that you followed my advice!
    If it is not so, It feels nice to think I somehow influenced your decision.
    In any case, I am glad you moved it to the header where it deservedly belongs, for otherwise, it would have been “obscured” somehow by the “…commenting on Ron’s next posting…” feverish crowd.

    Along with ” Energy and human evolution” and “The grand illusion” is one of those interesting mind “teasers”, one rarely finds/reads nowadays!

    Be well,


  4. MarbleZeppelin says:

    The great hunter gatherer tribes have again risen. This time they hunt and gather minerals, metals and fossil fuels. All of which provide them with food, shelter, clothing and a plethora of other things.

  5. Revi says:

    I read Diane Dumanowski’s book The End of the Long Summer, and one of the most interesting things she says is that our particular species doesn’t have any idea how to conserve resources. We wiped out the Neanderthals who had coexisted with their prey animals for hundreds of thousands of years and moved into Europe. We are not a species which knows how to live within limits. Fortunately until now we have been able to push back on them with the help of fossil fuels, but maybe we have hit the end of that game now. I saw a drilling rig that was off the coast of Maine being taken down to Brazil, and I thought that 10,000 years ago people were probably standing right near there lamenting the end of the mammoth. There we were lamenting the end of the Fossil Fuel economy as we watched a huge rig moving offshore.

  6. Do you have any estimate of how many years worth of reserves exist to support the Haber-Bosch process?

  7. Nathanael says:

    Species can also go extinct when their food supply runs out, or their climate becomes inhospitable to them.

    This is pretty standard for apex predators (where nobody eats them and nobody competes with them directly).

    This is the most likely way for humans to go extinct. We’re actually quite fragile compared to rats and mice: low birth rate, long time as juveniles, restricted food supply (we can’t really eat trees or most algae, for example). A combination of losing the ocean food chain and half the land food chain would be very hard to survive and would create genetic bottlenecks which would leave us prone to disease attacks.

    • You cannot compare the likely survival of humans to rats and mice. Rats and mice have no chance of going extinct within the next few thousand years. Humans have about a one in a million chance of going extinct within the next few thousand years, far higher than rats or mice.

      What you seem to not understand is extinction means everyone everywhere.

  8. Josie Wales says:

    Do you fundamentally or substantially repudiate the (reasoning or science behind the) assertions of Dr. Guy McPherson regarding rapid warming scenarios, and the prospect, which he and others raise, of a planet simply so warm that large warm-blooded animals such as homo colossus would be incapable of adequate thermoregulation to survive over much of the mid latitudes where human populations and their agricultural food base are presently concentrated?

    • I do not support anything Dr. Guy McPherson says. He is just a little too far out to warrant any serious consideration. His idea that human extinction is imminent is just stupid.

  9. CM says:

    I think this proposition that only other species can drive humans to extinction is rather simplistic. This is becoming evident now as our exploding numbers, rapacious nature and myopic outlook are terraforming our planet to one not suited to most life currently on it and that includes humans

    • Hey, if all life on earth goes extinct then of course humans will also go extinct. But when most people talk about humans going extinct they are not talking about all life. and neither was I. They will say something like “99 percent of all species that ever lived is now extinct. Why should humans be an exception?” And that is really just a very stupid comment.

      Except for extinctions caused by a natural disaster, like a comet hitting the earth or some other natural disaster, then all species that ever went extinct were driven into extinction by being out-competed by another species.

      However, with all that being said, I think the odds that humans will destroy all life on earth is the real simplistic idea. That is just not going to happen. No matter what we do to the earth, and I agree we are destroying it, there will be survivors. Humans are the most adaptable megafauna on earth! No matter what kind of rubble or desert we turn the earth into, there will be survivors. Even if only one in every 1,000 survived, that would still leave 1.4 million people alive. Or if only one in 10,000 survived, that would still leave 740,000 people alive. After the eruption of Toba, some 74,000 years ago, only from 5,000 to 10,000 people were left on earth. (Some estimates are a lot lower.) We would still have that many survivors if only one in one million survived.

  10. Ed says:

    You have labelled the y-axis of your first graph wrongly. It states “Total energy consumption (TW)” and “Energy per capita (kW)”. TW and kW are not the units for energy, they are the units for power.

    Its is like saying “Total amount of miles (mph)” . Obviously wrong.

    May I suggest that you omit the units and the scale on the y-axis. After all it is the overall behaviour between the qualities that you are trying to convey by the graph.

  11. Ed says:

    The great writer John Wyndham explored the Competitive Exclusion Principle in this 1957 fiction book The Midwich Cuckoos. In his book, a super human species is introduced to the world and homo sapiens are acutely aware what the Competitive Exclusion Principle would means for them.

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