Last week in class, as we viewed David Attenborough's marvelous introduction to Charles Darwin and his theory of evolution, I found myself thinking about his simple - yet profound - idea of natural selection. Natural selection states that "more offspring are born to a mother than can survive. Those that do survive are somehow stronger; better suited and "fit" to their environment. As the stronger survivors have offspring of their own, species will evolve, or adapt to their environment - ensuring a better "fit", and improving their chances for long term survival. Species evolve together, weaving balanced predator/prey relationships, and establishing balanced ecosystems that evolve as well, in order to maintain the balance of life within them.
The modern world has offered mankind many opportunities to alter the process of natural selection within ecosystems. Human have "unnaturally" selected to import, or remove any number of animals or plants within specific habitats. We have allowed invasive species to move into new, exotic environments. And we have cleared land for cultivation of our crops, and construction of our homes. This not only alters the long term process of natural selection, but more immediately, the natural ecological balance that exists within ecosystems and their food webs.
Philosophers and psychologists have long spoken of the "ghosts in the machine" - the ancient, ancestral remnants of brain/mind that continue to play a role in our mind/body relationship. We may no longer think like our "inner reptile" (well, most of us...) but these ancient parts of our brain give rise to some of our deepest, immediate responses to stumulii from our environment. (Goosebumps anyone?) We may respond with immediate fear when we see movement in a darkened room, but our modern brain knows to relax the body when it realizes that the movement was only our shadow on a wall.
Biologists have also spoken of a "ghost in the machine". In the biological sense, the ghosts exist following the unsuccessful introduction of a new species into an existing ecosystem. While the unsuccessful organism may disappear (go extinct) it's disapearance may leave an unseen impact - a ghost - on the ecological balance within that community. The extinction may allow opportunistic predators to move in. Predation may increase on particularly vulnerable smaller prey. In turn their numbers may go down. The ghost may have a domino effect throughout the ecosystem.
Biologists have tried to re-introduce species that disappear, in valiant attempts to restore, what had previously been, a natural ecological balance. Alas - this is known as the "Humpty Dumpty" effect, for like the eponymous egg (good SAT word! Look it up!) from the Mother Goose rhyme, all the king's men cannot put the ecosystem back together again. It is difficult, if not well neigh impossible, to restore ecological balance once it's gone.
Ecosystem experiments have proven extremely difficult to do. There are just so many variables. Noted evolutionary biologist Olivia Judson has written the following:
"For instance, suppose you’re interested in the question of whether individuals of different species can live together. (This is an important question, for it bears on how ecosystems form.) To keep things simple, you decide to investigate a mere six species. You want to be thorough, so you’re going to consider all combinations, from each species living alone, to all six together.
But that’s already 63 combinations. Worse, in order to be more confident about the results, you can’t just do each one once, you need to replicate them. So you set up each combination six times. That’s 378 microcosms. Worse still, ecosystems — even small and simple ones — don’t stabilize in an afternoon. You have to wait for several months before you can be sure the system has settled into a “final” form."
Judson goes on to note that the experiment has actually been done, with a success rate of about 12% with the simplest of combinations: two different species.
Natural selection takes time. Decades. Centuries. Millenia. Yet ecosystems can be irreparably damaged in a moments time. It is hard for me to think of the oil spills in the Gulf of Mexico, melting glaciers in the Arctic and Antarctic, deforestation in Africa, and population explosions in Asia, and development right here in the Upper Valley, wihtout thinking of their ecological impacts.
Ghosts and Humpty Dumpty. Sounds so childish, so innocent. Yet their very light names refer to very "heavy" ideas that govern the fragility of the world around us. I'll let Judson have the last word:
"How do ecosystems form? How much impact do invaders have? What are our chances of restoring damage done by fishing or farming? We are pushing our ecosystems to the brink. If we don’t understand how they work, we can’t hope to limit the damage. And we need to try: after all, this is our home."
13 comments:
This article has reinforced for me what I have known and dreaded about earth for a while now. When I was younger and less educated, I felt humans truly belonged in this world. But now that I have been told of the damage we have done and can do, I start to think that humans are an invasive species that has infected, if you will, the entire planet.
It's odd to think about ourselves that way, but when you compare us to all other species, it makes more sense. For instance, we have the largest cerebrum (the part of the brain that is associated with memory and learning) in the animal kingdom, which allows us to be as smart as we are. Obviously, the implications of this are that we have the capacity for extraordinary creation, but it also means we have the capacity for devastating destruction.
Ben
I think that the idea of natural selection is interesting and, of course, accurate (who am i to question Darwin?) Anyway, what i do think is a little ironic is the idea that those that survive after birth and into adult hood would be stronger than those who dont survive. Um...duh. They obviously died for a reason, however; i do not understand why we would assume had they survived they would be weaker than the others; that is ludicrous.
I also thought that the section on attempting to re-introduce species into ecosystems where they have become extinct was interesting. The ecosystem would have slowly adjusted as the population of that species decreased into oblivion and, therfore, would have been adjusted to life without the creature making that species an outcast in its old home. Having the species back would alter the ecosystem too fast (where the other change was slower) and make it more susceptable to changes and predators because the ecosystem was not as adjusted or sound as it previously was.
Also, on the re-introducing extinct species, i thought that it showed us the value of protecting our earth now and not later. Later, is too late and we will not succesfully re-introduce species that used to have a positive effect on the earth. It is like cells in the brain- you can destroy them but you cannot get them back. At this point we can stop furthur harm to our planet but we cant fix it so that it is back to the way it was.
Sydney
~ "Only the fittest survive" ~
Everyone in our school has probably heard this phrase, but what exactly does it mean? I immediately thought of this quote when I read the beginning of Mr. Engler's post. Charles Darwin helped introduce this idea through his discovery of "natural selection." If only the "fittest" and strongest survive, then clearly, (as Sydney said), we are all survivors. But expanding further on this idea is where it becomes interesting. Because we have already determined that the ones who survive are the strongest, how does one determine which of those survivors are stronger? How can one person say they are stronger than another? Likewise, how can one species?
Well, to start off with, as Mr. Engler’s post mentioned, humans have a distinct brain and are smarter than other species on our planet. Mr. Engler writes: “Species evolve together, weaving balanced predator/prey relationships, and establishing balance ecosystems that evolve as well, in order to maintain the balance of life within them.” Although in theory this is an ideal collaborative effort of different species, this is not the way our world works. As Mr. Engler mentions in his second paragraph, humans have altered this way of life into something similar to a dictatorship – and we are the leaders.
It is saddening to think of how humans have taken over the world (as Ben pointed out). If we all do have an “inner fish” or an “inner reptile” it is unfair for us to not appreciate where we came from. The fish and reptiles were first. Humans control the world we live in now, but we all evolved from the same animals. Why does it become so easy for humans to forget this? As Mr. Engler said, there are “so many variables” that one has to consider in this whole process. As saddening as it is, the way humans have evolved, enables us to be smarter and more controlling than any other species.
I think that what Ben said has some value. Although I don't know that we can call ourselves an invasive species, I would argue that we are too smart for our own good. As Ben said, we have the largest cerebrum and this has lead to countless wonderful inventions that extend our lifespan. That is the problem, though. Because we are living longer, and because more people are surviving childhood and living to the age where they can reproduce, we have far exceeded our planet's carrying capacity for humans.
So, while I generally agree with the Theory of Natural Selection, I think that we have, as a species, have decided that it no longer applies to us. We have created a species, on the backs of a few exceptional individuals, where it is not only the fitest who survive. We have actually reversed it, now only the absolute weekest of our species die, and, in fact, many of the weekest survive.
On another note, the idea of a biological "ghost in the machine" reminds me of something that was done many years ago in Puerto Rico. Many years ago, when explorers first came to the island, rats were accidentaly introduced and quickly infested the island. To get rid of one invasive species, they introduced another, snakes, and then another, mongeese. eventually, all of the rats and snakes were gone, but the islanders were still left with a mongoose infestation. I cannot say for sure how the islanders delt with the mongeese, but whatever they did, I'm sure it wasn't easy. I am inclined to believe that this is the situation we have put ourselves in all over the planet, only we are the proverbial mongeese, and there is no one left to get rid of us for the good of the island.
I've enjoyed reading these first 4 responses - the good thinking and cross-referencing to other responses is exctly what I hope to read! Good job!
Ben - thanks for getting the ball rolling. Yes indeed - this dichotomy between mankind's capacity for both creation and destruction is a philosophical conundrum!
Sidney - Yes, re-introduction of species has its consequences. Did you ever see Jurassic Park 2? :)
Oriana - I suppose it is sort of a dictatorship - I had never thought of it in those terms before! Daniel Quinn, author of Ishmael, breaks it down into the LEavers and the Takers. While other predators leave enough food/prey to re-generate or rebound, only humans are "Takers" who continue to over-harvest, over-hunt, taking into account only what they need, rather than what is required to maintain this "circle of life".
Aiden - I would agree (and in fact, was having this same conversation at home several nights ago) that human have changed the equation. Modern medical technology has assured that not only the fittest survive. (Which begs the question, "are we (as Oriana stated) all survivors"?) Your example of the Puerto Rico experiment is a good example of the "ghost" in the machine. As to hitting earth's carrying capacity - well, some argue that we're not there yet. Others have taken the extreme position that epidemics and global pandemics should be allowed to run their course, in order to allow nature to "clean house" every few centuries (i.e., the Black Plague). Few, however, would take so draconian an approach.
Cheers -
Mr E
I agree with the idea of natural selection. Obviously it makes sense that a creature who is stronger would outlast the one who is weaker. There are some cases where one might just get lucky, but overall the strongest surviving makes the most sense.
I think Ben makes a very good point in his opinion of humans being and invasive species that has infected the planet. I do not think humans are necessarily an invasive species, I think we got here on purpose somehow just like every other creature meant to be living on this planet.
However I do believe that due to our intelligence and ability to use our resources around us, we started having a feeling of entitlement to the earth around us only because we believed we were smarter and more important than other creatures we share it with. This entitlement continued to get worse until we ended up where we are now, in a time where we have selfishly destroyed used up the earth for our pleasure and not left much for other creatures who deserve the same share as we should have had.
If we had taken only what we needed and not whatever we wanted we would not be in the situation we are now.
-Sarah
I remember not too long ago, maybe 5 years ago, the year before my brother's graduation, he had a great love for Charles Darwin. If you look in the TA yearbook of 2007, his senior page is a Darwin quote and a drawing representing Darwin's theory of evolution. Of course, me being a 12-13 year old, I didn't see what the huge fuss was about.
It's interesting to look at the destruction of "our" planet in terms of Darwin's theories. It's interesting to take a step back and think about the theories of a man who lived BLANK years ago. Obviously his theories have always been of great importance to education, but they also give us a good - should I say - image on what exactly we're doing. It makes you think about how much work was put into building "our" home and what is being slowly killed in, really, only centuries (maybe even decades). As so many people around the world have tried to point out, we need to do something. It is sad that we didn't realize the damage and do something BEFORE it got this bad.
"Humpty Dumpty" showed us exactly that. The amount of work that mankind (and scientists) need to do to bring back just ONE extinct species is incredible. The ratio between the seconds it takes to destroy an ecosystem with a bulldozer and the months/years/people needed to recover a species just doesn't seem remotely just.
I also would like to say that I really appreciated what Ben said. It is crazy to think that humans, said to be some of the smartest animals on the planet, could also be responsible for its destruction.
Notice throughout my response, I have been putting the word "our" in quotation marks. I hear "our planet" used so often but in no way does planet Earth belong to the humans. It goes all the way back to single-celled organisms.
-Molly
After reading this article, all I could think about was how when I used to watch the speicals on National Geo. on tv, there always seemed to be some helpless animal like a baby seal who lost its mom. When I was younger I would get so upset that the guys filming would never help the poor baby out. The narrartor would always say something like "oh we can't get involved with nature. We have to let it take its course." Of course thats not what I wanted to be hearing. But now that I am older I understand that it is all about natural selection. This idea that the animals we see today are the strongest and best fitted to be out and about, is truly sobering. Because as we look at our own population, we do not see that. Yet we are animals ourselves. We have cheated the system. Maybe not even for the better. By advancements in health care, we have created mega virus's and new found heath issues. We humans no longer have to worry about natural selection. We have a bad heart we sign up to hopefully get a new one. We break our back we try to get surgry for it. Now if we were being filmed we would never have a narrartor be saying something like "oh that one is an orphain we can do anything about because nature has to take its course." Because we are nature. We seem to control the course it takes on us. After reading this it has made me wonder that if it was possible to look at the human race, and be completly unbais, would I be agreeing with this method of living? This method that we have no natural selection, we are over popluated and takers rather then givers on the world, and the organisums below us suffer as a result. I'm not sure I would.. And thats scary.
P.S the article above mr. E is Amelias.(the seal one)
Invasive species and how they impact the environment around them is something that I am actually very interested in. This article is more about the larger effect of how natural selection can be impacted by humans, while I am more into the local species. The unnatural selection caused by humans is something I've thought about quite a bit. When I read articles like this it makes me think that we, as humans, need to drastically change out lifestyles.
I think we humans are the only species that don't need to compete to carry on our DNA. It's very hard to "fix" problems in our environment. Sometimes I think when we try to do things like introduce species that are endangered I feel like it is going against nature, but then again humans are probably the reason that animal is endangered. Altering the ecosystems is very important and I think studying and understanding how these ecosystems work is very important. Most of the time I find that articles like this end up leaving me with more questions than I had before I read them.
This article and your own thoughts on it have made me consider many different things.
The idea that we have grown to think that only the fittest survive is a scary thought. We don't take everyone into consideration. You may be a hard worker and someone who works hard to stay healthy and you could never be sick one day in your life. Your neighbor on the other hand could also be a hard worker and someone who works hard to stay healthy, but your neighbor is the one who gets diagnosed with cancer. All of a sudden your neighbor is the one who fights to stay alive everyday, and who struggles to get through every painful moment. Once they fight off the cancer aren't they in turn the fittest? They were the one who was the weakest, but in the end they prevailed. I don't think we think about things like that when we make statments such as "survival of the fittest".
The investigation that was tested to see if whether individuals of differnt species can live together apalled me. Why would someone want to test that, or feel that they can test that when we as humans haven't even been able to master that? I suppose it's just the way we have learned to think over many generations. The thought that we can fix something else, when really we need to fix oursleves before we can move on. I don't know how that hypothesis was supposed to be tested if the scientists didn't have anything to compare it to such as ourselves.
This article just made me think of the way our thought process has developed over the years, and sometimes just how irrational it can be. Admitting that there is a problem is the first step to finding a cure. So humans need to admit that they are wrong before we can go on fixing other things. We would have a greater understanding if we did.
-Marley
When I read this it brought to my mind what I learned in an environmental science class I had. The idea that humans can live in a sustainable and non-harmful way just isn't possible. With the population of humans on the planet at somewhere between 6 and 7 billion and the "habitats" that we create for ourselves there is no way we won't impact the planet.
While it's true that all animals impact the planet in some way our impacts are non-reversible. Most animals impact the planet in such small ways that it can heal, like a how our bodies can deal with a paper cut without it affecting the rest of the body. However, humans seem to think that because the planet can heal from tiny wounds it can also heal from giant ones. As we know this is not so.
For proof of this you have to look no farther than your own back yard. At one time it was probably a forest teeming with different kinds of life. However, i seriously doubt that many people now have a backyard full of forest creatures.
The reason for this is that we decided we were the fittest to survive. In order to be the dominant species on the planet we must constantly destroy. This is evident when you look at an old building. If you don't cut the ivy it will eventually pull down the walls. If we don't keep destroying we'll lose our dominance, and because of everyone's unconscious (or conscious) drive for dominance we will keep destroying until there is no one left to challenge us.
Sarah and Molly - It's interesting to think of humans as an "invasive species". The term refers to the introduction of a non-native species to new environments. Since humans are native to Africa......
As for the issue of Earth being "our planet", it's true, humans have determined that they can, and should, express their lordship over all other organisms. It is a sad state of affairs. But how many of us would give up our homes in order to allow the land beneath them to revert back to its natural state?
Cole - having more questions in mind than you originally started with is one of the greatest complements you can pay any writer! Real reflection!
Marley - is the modern day cancer survivor a true "survivor" in the Darwinian sense? Or someone who may have been "naturally selected out" by nature, without our modern medical intervention? (Not that I'd ever suggest we NOT intervene medically)
Jacob - Fortunately, the earth's capability to repair itself following man's intervention is superb. Man may not survive, but the earth undoubtably will. There's a great book about that called World Without Us that I'd love to lend you if you're interested in reading it.
Sarah - your response definitely hits home. I can't tell you how many nature documentaries I've seen over the years where I've thought "How can they just watch that happen and not intervene?" Especially during one particularly harsh scene in the Blue Planet series. It's hard.
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