The following ideas have lived in my head for a long time and were initially invoked as a result of understanding the compelling hypothesis put forth by James Lovelock and Lynn Margulis, the so-called Gaia Hypothesis which states that the cumulative effect of the metabolic, physical and chemical properties of living systems on Earth is a cybernetic system with homeostatic tendencies, tightly coupled to the planet's physical surface properties such as atmosphere and geology.
It occurred to me that not only was the core idea of this Gaian system plausible on Earth, but it was probably a signature of a class of life that exists in potentially large numbers of other worlds in the universe. It is unfortunate that a substantial segment of the scientific community still prefers to think of life as a consequential phenomenon with the advent of biological systems being extraterrestrial in origin and the impact life has on sustained planetary habitability and evolution as insignificant. The accepted idea seems to be that life on Earth exists as a result of some cosmic "seeds" planted on Earth during the age of bombardment (early on in Earth's history it was heavily pummeled by asteroids, some presumably carriers of life's essential chemical ingredients) coupled with randomly perfect conditions for "germination".
I, and others, disagree with this notion. Life, as amazing and wonderful as it truly is, is a planetry surface property that is bound both in advent and evolution to the planet upon which it happens. By looking at life in this way (from a systems as well as planetary perspective), the possibility of finding living systems (of the same class as Earth's) throughout the galaxy is very good. In the next 5-10 years we will have the instrumentation to start searching our galaxy for "life like ours" utilizing techniques of atmospheric spectral analysis combined with new telescopes.
In earlier posts I've briefly touched on Lovelock's approach to the detection of life on other planets. Does this life really need to be like ours? If so, to what extent? I argue that there are classes of life that exhibit similar behavior, but need not be composed of similar ingredients or design (like cellular genetic systems). So, then how do you define "life like ours"? Good question.
Life like ours can be defined as an autochthonous geobiological autopoietic cybernetic system. What?
In a nutshell: life like ours is a dynamic system, an adaptive planetary surface property, originating on the planet where it is found (tied to planetary formation and evolution), provides regulatory feedback mechanisms that ensure planetary habitability, and is remotely detectable via atmospheric spectral analysis due to dynamic atmospheric chemical exchange (life like ours perturbs atmospheres as a consequence of the processes associated with the daily business of living). Our class of life is a planetary-scale system composed of sub systems (animals, plants, microbes, cells, viruses, dna) that cumulatively, some more than others, act to ensure that Earth remains habitable for life. For this class of life, the particular composition and associated behaviors of sub systems are implementation details. Again, life like ours is a planetary surface property, just like the atmosphere, land and oceans. Astronomers like to say, and correctly so, that we are made of stars. Narrowing the scope a bit, it can also be said that we are made of Earth.
Can the Earth be used as a general model for rocky planets possessing autochthonous geobiologic surface properties?
Can a planet's surface be favorable for life without supporting autochthonous life forms?
Look into the light.
> This is the Faint Young Sun paradox and
> Lovelock used it to explain the notion
> of life-mediated temperature regulation
> in a Gaian system.
Oh great! I can hear the republicans now. "Screw Kyoto!" they'd say. It's the Gaian system. We're meant to produce CO2. What's wrong with a little global warming? What? You want another ice age?
P.S. I do believe in life affecting the atmosphere also. But mother earth didn't select liberals for no good reasons.
Posted by: Anonymous Coward | February 17, 2005 at 03:08 AM
> is remotely detectable via atmospheric spectral analysis
I think it's just a hopeful wish. What about Saturn's Europe? We still believe there's life under the icy surface and we CANNOT detect via spectral analysis...
Posted by: ikari | February 17, 2005 at 08:18 AM
the Screw Kyoto comment is even less funny that it might be. how right you are. the total symbiosis of everything is almost shocking. Have you heard of global cooling - that is the effect of visible particles in the air that serve to lower global temperatures. without global cooling, so a BBC documentary recently argued, global warming would have *really* screwed us up. Turns out that since Europe got better about reducing emissions temperatures *increased*... in other words our polluting has led to global cooling *and* global warming - thus a rough equilibrium. but if we cut emissions global warming may get really out of hand...
maybe we can just leave it to the coral...
Posted by: James Governor | February 17, 2005 at 09:27 AM
ikari, you are correct that spectral detection of geobiologic activity is impossible on a place like Jupiter's Europa. Remember that I am talking about classes of life. On worlds without atmospheres that have salty subsurface oceans beneath icy surfaces, well that would be a place that harbors a different implementation of life, however the life would still be autochthonous. For Earth-like planets with geobiologic systems, (rocky, significant and dynamic atmospheres perturbed by surface-dwelling life forms) atmospheric spectral analysis is a good detection mechanism.
Posted by: Carmine | February 17, 2005 at 12:32 PM
The earth has the appropriate temperature, protection from the sun, and resources (water supply), that it may have attracted life. Prehistoric paintings show, not only adeptly drawn animals, but images of unknown origin that approximate today's flying vehicle reports. It is not popular to surmise a directed seeding of the planet, but there is too much to suggest that we are a Garden with gardeners. -- Cathetel, Angel of the Garden.
Posted by: Healing the Body | May 15, 2008 at 03:56 PM
This is both srteet smart and intelligent.
Posted by: Shanna | December 21, 2011 at 03:36 AM