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According to Wikipedia, "all known types of organism are capable of some degree of response to stimuli, reproduction, growth and development and self-regulation via homeostasis." Further, watching a video like the "Earth Breathes as Seasons Change" (which is from NASA) - superficially gives the sense that the "Earth is alive" so to speak.

Is Earth an organism? Since there is no unequivocal definition of life, the current understanding is descriptive. To define Earth as an organism, your answer most show either via observed phenomena or theoretically observable phenomena that Earth exhibits all or most of the following traits: Homeostasis, Organization, Metabolism, Growth, Adaptation, Response to stimuli, and Reproduction.

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    $\begingroup$ A label is just a name. Anybody can name the Earth how they want. Do you perhaps mean a model? $\endgroup$ – gerrit Apr 26 '14 at 2:59
  • $\begingroup$ Review aspects of Upper-atmospheric lightning, Schumann resonances and various upper-atmospheric phenomena, and try to imagine that region as a kind of cerebral cortex of a planetary-scale nervous system and the phenomena as nervous discharges. We might learn to "communicate" with the Earth as a very long-lived, slow-living 'organism' someday. "It's alive!" $\endgroup$ – user2338816 Apr 26 '14 at 3:24
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    $\begingroup$ my main issue with this question is that it seems purely philosophical to me: let say you can label it as an organism, will that bring anything to our understanding of earth? or our understanding of organisms for that matter? $\endgroup$ – plannapus Apr 26 '14 at 15:00
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    $\begingroup$ The Earth is somewhat like an organism, in the sense of the Gaia hypothesis. But you seem to be asking "is the Earth literally an organism", in the same way that cows and trees and bacteria are organisms. The only reasonable answer to this is "no, obviously not." It's like asking "is the Sun a coffee cup?" You don't think it is, nobody else thinks it is, and nobody sane ever said it was - so what's the point of the question? $\endgroup$ – Nathaniel May 4 '14 at 7:00
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    $\begingroup$ -1. As has been noted there is no clear definition of life, so there can be no clear answer to this question (except perhaps the common sense one of "of course not!"). As such this is asking for opinions, and is off-topic. And also, frankly, it's more about philosophy than earth science, and is thus doubly off-topic. $\endgroup$ – Semidiurnal Simon May 5 '14 at 20:05
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[I am going to preface this by saying that I am not in one camp or the other in this discussion, as I think there are pros and cons to each side]

This links to the "Gaia Theory" proposed by James Lovelock, wherein the Earth is considered a self regulating organism.

In this hypothesis, Earth is an organism in that it will try to maintain certain conditions. These conditions include temperature (within a range suitable for life as we currently understand it), oxygen content of the atmosphere, water availability etc.

This does not mean that the ball of rock we are flying through space on is a living organism as we understand it, but rather that the various spheres of life (These are usually the biosphere (ecosystems), the atmosphere, the cryosphere (the poles, and other ice-bound areas), the hydrosphere(oceans), and the pedosphere(soil)) interact with each other in such a way that optimal conditions are maintained.

Whilst the theory as a whole is not used today, it is recognised that feedbacks and interactions between different spheres occur, and are an important part of understanding Earth systems, and is studied in an area of science known as Earth System Science

One of the initial arguments for this theory was that our atmosphere is not in chemical equilibrium, and that there must therefore be processes active to maintain oxygen levels at a steady state outside of equilibrium.

This is a difficult topic, as it is important to stress that the Gaia hypothesis does not state the Earth is some sentient being consciously doing anything, rather that a complex set of interactions, abiotic and biotic, combine to maintain and regulate the planets temperature and atmospheric composition.

An example of this regulation is chemical weathering, whereby carbon dioxide in the atmosphere falls in rain, and reacts with rocks, to form calcium bicarbonate, removing carbon from the short term carbon cycles. The more surface rocks there are which are capable of this reaction, the more CO2 is removed from the atmosphere. There is a hypothesis which says that at least once, the Earth has been covered largely in ice and snow, and this reaction (known as carbonation) is suspected to have played a part in the recovery of Earth. The hypothesis (Snowball Earth) goes like this:

The Earth became cooler, whether due to Milankovich cycles, volcanic activity, or solar output changes. As this happened, ice began to form at the poles, changing the albedo, and reflecting more radiation back to space, this caused local cooling, and allowed for the growth of the ice sheets. As they spread, the albedo became higher on a larger scale, and the ice sheets eventually covered the two hemispheres, with a band of open ocean at the equator. The earth was now very cold, but not completely empty of life, or without volcanic activity. Life continued to respire CO2, and volcanoes continued releasing CO2. Without rocks to remove it from rain, or ocean to absorb it, Carbon dioxide began to build up in the atmosphere. As it built up (over millions of years), it began to warm the planet, which in turn began to melt the snow. As the snow and ice began to retreat to the poles, rocks, and open ocean were again available to remove the carbon dioxide from the atmosphere, and more photosynthetic organisms were able to survive, and remove more CO2 through photosynthesis.

This lead to a stabilisation of the planets systems again, although, it may have gone too far, and swung back to a glacial period (although not a frozen earth), then moving back to a warm period before stabilising due to the tectonic movement of the continents northwards The break-up of Rodinia, birth of Gondwana, true polar wander and the snowball Earth

I hope this long ramble illustrates how there are a number of complex systems which all interact with each other to maintain conditions. Whether we consider the sum of these systems an organism is an ongoing discussion, but, all organisms have the ability to regulate via various systems, and each of these systems has the potential to lead to chaotic positive feedbacks, and spiral out of control, although negative feedbacks usually keep everything running as normal.

I have linked the Gaia theory webpage, and if you search for Daisyworld model, you will find a model which you can run to simulate feedbacks It is up to you whether you think this collection of feedback systems is an organism, and this debate will likely run for decades more.

Gaia Theory Site

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    $\begingroup$ The gaia hypthosis says that the earth is a complex self regulating organism, it does not reproduce, no. $\endgroup$ – Rhiaden Apr 26 '14 at 15:24
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    $\begingroup$ If Earth does not reproduce, it is not an organism. In my opinion, there's no need to post an answer about the gaia hypothesis, since it does not answer the question; meaning the gaia hypothesis does not claim that the Earth is an organism. In fact, there's no reference at all in your answer as it relates to means of observing and classifying the reproductive behavior of Earth, right? $\endgroup$ – blunders Apr 26 '14 at 15:30
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    $\begingroup$ you could be a little more positive about it: you asked a frankly peculiar question and Rhiaden took the time to give you a detailed, interesting answer that (as you feel, and it's your right) doesn't cover everything (because honestly how are you supposed to bring contradictory evidences to such an extraordinary claim as the reproduction of Earth) but is totally relevant (i honestly thought you were querying about the Gaia theory as well, after reading your question). I think it's a little unfair to shun him down, when you could have just said "thanks but what about the reproduction aspect?". $\endgroup$ – plannapus Apr 26 '14 at 16:36
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    $\begingroup$ @SlippD.Thompson: Thanks, though unable to find anything to support that "there's little condemnation on SE for off-topic answers" - have any supporting links on the topic? $\endgroup$ – blunders Apr 27 '14 at 1:40
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    $\begingroup$ @blunders, If you define "organism" as something able to reproduce, then the question is clearly nonsense. I'm fairly certain that there is no conceivable mechanism by which the earth meaningfully "reproduce" in the way that living organism do. $\endgroup$ – naught101 May 1 '14 at 7:22
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Interesting question. I think many issues of self-regulation and so forth have been addressed but what is really up for debate is whether the Earth can reproduce.

I answer with yes it is possible the Earth is an organism because it is possible for it to reproduce. Through intelligent life that is able to develop technology, this life is able to reproduce the Earth (assuming living creatures are part of the Earth - like cells of the Earth). We can think of the inanimate features of the Earth (e.g. atmosphere) like the blood of the organism that must supply the right Milieu intérieur for it's cells, the living creatures of the Earth. The humans are analogous to the planets sex cells, because through humans, the most intelligent of Earth's species, the Earth is able to replicate itself through technology in the ways listed below:

There are two potential ways that humans can be used to replicate the Earth. The first way, is that because humans have adapted to fit in with the inanimate features of the Earth, if humans are to inhabit another existing planet, they must transform this planet into another Earth with the same properties of the Earth, that are compatible with human life, in order for that planet to be suitable for them. Humans have evolved to be suited the Earth's conditions, and therefore any planet they wish to inhabit must have these same features of Earth. It is a neat method of reproduction - evolve a species to need you, so it will later be forced to reproduce you. This effectively replicates the Earth. The second way humans could replicate the Earth is directly producing another planet that has the same features of Earth using technology.

While at present we have no record of living creatures having replicated a planet it is certainly plausible, and therefore it is plausible that the Earth is a living organism, given that it is possible for it to reproduce and self regulate through negative feedback mechanisms observable in nature.

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    $\begingroup$ Re: "It is a neat method of reproduction..." Yep. Humans are as much a part of Earth as our brain cells are part of us. $\endgroup$ – user2338816 Apr 27 '14 at 2:52
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    $\begingroup$ This kind of works if you apply it to the biosphere, but not the earth as a whole. And we're heading way out into science fiction here, and quickly leaving science behind.. $\endgroup$ – naught101 May 1 '14 at 7:25
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    $\begingroup$ When ants move from a tree onto a new tree, this does not make the tree reproduce. $\endgroup$ – Nicolas Barbulesco May 3 '14 at 18:47
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    $\begingroup$ @NicolasBarbulesco, that is because ants are not byproducts of the tree, but humans and ants are byproduct of the Earth. So if the Earth generates humans, and humans generate a new Earth, then Earth has reproduced. And just as animals can use existing proteins and molecules to reproduce themselves, planets can use existing floating lumps of rock to reproduce themselves, via humans, the cells of the Earth. $\endgroup$ – Kenshin Sep 30 '14 at 5:33
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Answer is no, Earth not an organism. Key reason being that life without reproduction is not life, and there is no logical proof that Earth reproduces using a type of reproduction never observed, or is proof that life does not require reproduction.

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    $\begingroup$ is an infertile human a life form? $\endgroup$ – Kenshin May 21 '14 at 3:19
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    $\begingroup$ Bit vague, but I'll attempt to respond. In my opinion, an infertile "species" is not a life form, which is to say, without reproduction being present within a species, the species would not exist. Ants would be a great example of where some members of the species by "design" do not directly reproduce, though the species does. $\endgroup$ – blunders May 21 '14 at 3:26
  • $\begingroup$ +1 Succinct and to the point. $\endgroup$ – Jack Aidley Nov 20 '14 at 17:13
  • $\begingroup$ perhaps the answer proper would gain more attention if it included the "species" comment $\endgroup$ – nilon May 31 '17 at 16:36

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