Humans unique to the universe?

nannoh

Are humans unique to the universe? This is a question being asked by SETI, the Search for Extraterrestrial Intelligence.

Are we alone? Are humans unique in the universe, or is our existence the natural outcome of universal processes that produced complex life on Earth and elsewhere? As we observe the universe beyond Earth, we find that we are fundamentally a part of it. Carl Sagan eloquently describes our intimate relationship with this larger universe:

The fate of individual human beings may not now be connected in a deep way with the rest of the universe, but the matter out of which each of us is made is intimately tied to the processes that occurred immense intervals of time and enormous distances in space away from us. Our Sun is a second- or third-generation star. All of the rocky and metallic materials we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interiors of a red giant star. We are made of star-stuff. -- The Cosmic Connection, 1973, pp. 189-90

http://www.seti.org/site/apps/nl/con...4993&ct=221048

It has been argued that the human organism is a unique product of the universe. The conditions and criteria for the emergence of a human population are so rare and seemingly unrepeatable in the universe that humans are thought by some to be a one time affair.

Could there be approximations that come close to a human organism elsewhere in the universe? What would be some of the predominant features of such an organism?

berkeman

I learned a fascinating point about the probabilities involved in advanced organisms evolving on other planets on a recent Nova or Nature program. They made the point that in order to have enough *time* for more advanced organisms to evolve, the solar system with the Earth-like planet in the correct orbital range also needs to have a large planet like our Jupiter to help deflect incoming asteroids. Without a large planet in the solar system, the frequency of large environmentally-altering impacts is too high to allow enough time for advanced animals to evolve.

I'd never heard that point before, but it seems to make sense. Anyway, to your question, I'd guess that there are a number of candidate solar systems where mammal-like organisms can evolve. Whether they make the step to self-awareness and other human-like qualities, and start broadcasting RF energy off their planet.....that's a harder question.

D H

Many factors may preclude the development of intelligent life. The Drake equation implies a large number of intelligent civilizations could be present in our galaxy. The Fermi paradox asks "why haven't we seen or heard them?" The Rare Earth hypothesis (see http://en.wikipedia.org/wiki/Rare_Earth_hypothesis) answers the Fermi paradox by saying that we are more-or-less unique.

russ_watters

Quote by nannoh

Are humans unique to the universe? This is a question being asked by SETI, the Search for Extraterrestrial Intelligence.

It has been argued that the human organism is a unique product of the universe. The conditions and criteria for the emergence of a human population are so rare and seemingly unrepeatable in the universe that humans are thought by some to be a one time affair.

Be careful with preconceptions. At the moment, we have nowhere near enough information about what is going on in other solar systems to say with any conviction that the conditions on earth are either rare or unrepeatable.

Could there be approximations that come close to a human organism elsewhere in the universe?

"Could" is a very general word, so the answer is an unequivocable (and utterly meaningless) yes.

What would be some of the predominant features of such an organism?

It is difficult to know, but we have good reasons to believe that they would have some features in common with us. And I don't mean hands and feet, I mean biology and chemistry.

JimTKirk

Quote by berkeman

I learned a fascinating point about the probabilities involved in advanced organisms evolving on other planets on a recent Nova or Nature program. They made the point that in order to have enough *time* for more advanced organisms to evolve, the solar system with the Earth-like planet in the correct orbital range also needs to have a large planet like our Jupiter to help deflect incoming asteroids. Without a large planet in the solar system, the frequency of large environmentally-altering impacts is too high to allow enough time for advanced animals to evolve.

I'd never heard that point before, but it seems to make sense. Anyway, to your question, I'd guess that there are a number of candidate solar systems where mammal-like organisms can evolve. Whether they make the step to self-awareness and other human-like qualities, and start broadcasting RF energy off their planet.....that's a harder question.

I think I've seen that program too. I also recall a program on Discovery about the Moon that eluded to its presence contributing to life on our planet (tides and deflecting incoming asteroids, if I remember right).

berkeman

Quote by JimTKirk

I think I've seen that program too. I also recall a program on Discovery about the Moon that eluded to its presence contributing to life on our planet (tides and deflecting incoming asteroids, if I remember right).

Oh yeah, that's right. I forgot about that point. I'm pretty sure it was in the same show. They showed some simulations that implied that the Earth would not spin stably like it does now if it didn't have the Moon. That implied no climatic stability, and therefore no reasonable expectation of advanced evolution. Thanks for reminding me of that! That was a pretty interesting show.

JimTKirk

You're right... I think it was the same program.

nannoh

Quote by berkeman

I learned a fascinating point about the probabilities involved in advanced organisms evolving on other planets on a recent Nova or Nature program. They made the point that in order to have enough *time* for more advanced organisms to evolve, the solar system with the Earth-like planet in the correct orbital range also needs to have a large planet like our Jupiter to help deflect incoming asteroids. Without a large planet in the solar system, the frequency of large environmentally-altering impacts is too high to allow enough time for advanced animals to evolve.

I'd never heard that point before, but it seems to make sense. Anyway, to your question, I'd guess that there are a number of candidate solar systems where mammal-like organisms can evolve. Whether they make the step to self-awareness and other human-like qualities, and start broadcasting RF energy off their planet.....that's a harder question.

Very good point. Recently, Jupiter deflected Shoe-Maker Levy very nicely. The point about the time we got between major catastrophies is a pertinent one as well. We've had a relative 65 million years to evolve from rodents to humans without the hinderance of carnivorous, 8 ton dinos. And the later comments about the moon inducing the tides is extremely important. It perhaps supplied the transitional environment of tidal pools where organisms evolved the capability to withstand open air along with being submerged in water. Incidently our moon is comparitively unique to its parent planet, earth, in our solar system.

Russ Watters, I agree, we really don't have enough information about what's going on in other solar systems to make an educated quess about "intelligent life" on other planets. Its only when you tally up the conditions that have surrounded our planet and our evolution that it begins to look almost impossible that such a synergy of conditions have happened elsewhere. However, personally and statistically, I believe that if it has happend once (as in here) it will have happened elsewhere. I really wonder what the outcome, elsewhere, looks like!

Chris Hillman

Quote by russ_watters

At the moment, we have nowhere near enough information about what is going on in other solar systems to say with any conviction that the conditions on earth are either rare or unrepeatable.

Exactly! This is perhaps the single most important point which could be made in discussions of this kind: we are talking about informed speculations, and not, strictly speaking, about science. History suggests in the most compelling fashion that when you haven't yet looked at what actually happens in Nature, preconceived notions are generally wrong. In this case, we have not yet examined very many biospheres, so it seems perilous indeed to attach much weight to alleged generalizations about biospheres in general.

(Some of us feel that NASA has its priorities all upside down, at least for "the forseeable future". In my view, intensive robotic exploration of Titan is a far more reasonable thing to be planning than the insane notion of transporting humans to Mars, much less getting them back alive. Robotic exploration is far more cost effective, and thus yields far more useful data for a given amount of money spent, plus we don't run the risk of dismantling an agency like NASA entirely if voters become disillusioned after numerous tragedies involving the loss of successive crews, as seems likely, given the extreme risks involved, at least not unless the U.S. spends itself into bankruptcy, which would presumbably result in the dismantling of far more than NASA. The Moon landing was a great romantic adventure, there's no denying that, but the most important thing it accomplished, politically speaking, was producing an undeniably striking picture http://en.wikipedia.org/wiki/Blue_marble which could however have been taken just as easily, and a great deal more cheaply, by a robotic spacecraft. From a scientific standpoint, IMHO, Voyager and Pioneer were truly epochal; those accomplishments of the Moon landings which could not have been readily achieved by robot explorers, such as scooping up and returning Moon rocks, were comparatively trivial.)

Don't misunderstand: speculation hath its place. In particular, it can help clarify how we might go about exploring a possible biosphere years before we actually start sending missions.

nannoh

Quote by Chris Hillman

Exactly! This is perhaps the single most important point which could be made in discussions of this kind: we are talking about informed speculations, and not, strictly speaking, about science. History suggests in the most compelling fashion that when you haven't yet looked at what actually happens in Nature, preconceived notions are generally wrong. In this case, we have not yet examined very many biospheres, so it seems perilous indeed to attach much weight to alleged generalizations about biospheres in general.

(Some of us feel that NASA has its priorities all upside down, at least for "the forseeable future". In my view, intensive robotic exploration of Titan is a far more reasonable thing to be planning than the insane notion of transporting humans to Mars, much less getting them back alive. Robotic exploration is far more cost effective, and thus yields far more useful data for a given amount of money spent, plus we don't run the risk of dismantling an agency like NASA entirely if voters become disillusioned after numerous tragedies involving the loss of successive crews, as seems likely, given the extreme risks involved, at least not unless the U.S. spends itself into bankruptcy, which would presumbably result in the dismantling of far more than NASA. The Moon landing was a great romantic adventure, there's no denying that, but the most important thing it accomplished, politically speaking, was producing an undeniably striking picture http://en.wikipedia.org/wiki/Blue_marble which could however have been taken just as easily, and a great deal more cheaply, by a robotic spacecraft. From a scientific standpoint, IMHO, Voyager and Pioneer were truly epochal; those accomplishments of the Moon landings which could not have been readily achieved by robot explorers, such as scooping up and returning Moon rocks, were comparatively trivial.)

Don't misunderstand: speculation hath its place. In particular, it can help clarify how we might go about exploring a possible biosphere years before we actually start sending missions.

Speaking of Titan, is there any chance that neucleotides can form in a methane rich environment then actually lead to a life form? Are there any experiments going on that research this possibility? I agree that the search for life elsewhere requires such an open mind that you almost just have to wait for the discovery before considering it. But, as you say, if we don't explore the possiblilities, we may not recognize the phenomenon as a life form.

Its looking more and more as though mars has water present on its surface.

http://news.nationalgeographic.com/n...ars-water.html

Water has always been the "well spring" of life from the perspective of the life on this planet (which is 3/4s covered with water). But, how necessary is water to the formation of life? There are indications that viruses could well be the first form of life on earth. Do viruses need water to replicate and or mutate? Check out this article

Unintelligent Design

A monstrous discovery suggests that viruses, long regarded as lowly evolutionary latecomers, may have been the precursors of all life on Earth
By Charles Siebert
Photography by Jörg Brockmann
DISCOVER Vol. 27 No. 03 | March 2006 | Medicine

http://www.discover.com/issues/mar-06/cover/

nannoh

It would be possible to compile an approximation by way of extrapolation with regard to the probablility or possibility of there being a form of life that resembles the human form (and function)

The method would be to compile all of the conditions that have contributed to the emergence of life and thus the evolution of humans on this planet.
This would entail making note of
- the distance of earth from the sun
- the type/size/composition of sun in this solar system
- the size and orbit of the moon compared to the earth
- the earths orbit including its presession or "wobble"
- the neighboring planets and their integral influence on this planet (protection from bombardment, gravitational influence or what have you)
- the mechanisms that produced water on earth
- the possiblity of viro-genesis on earth from extraterrestrially free floating viruses.
- the fact that some space debris has managed to hit earth in the past
- and ?

If we take these kinds of conditions to be the factors that have shaped the evolution of the human-form, with all our implications as an intelligent being, and apply them as probability factors, I wonder if we'd generate a statistic of how many planets are enjoying the same conditions as this one?

I mean if you take the probablility of the same conditions occuring in one or two locations throughout, say, 20 gallaxies (billions of suns in each) doesn't that begin to suggest that we may not be "unique" in terms of form and function?

berkeman

You're referring to the Drake equation, which DH mentioned in post #3. Check out his wikipedia link.

nannoh

Quote by berkeman

You're referring to the Drake equation, which DH mentioned in post #3. Check out his wikipedia link.

Thank you berkeman. What are the possibilities that I missed that? (100%)

The galactic habitable zone
Rare Earth suggests that much of the known universe, including large parts of our galaxy, cannot support complex life; Ward and Brownlee refer to such regions as "dead zones." Those parts of a galaxy where complex life is possible make up the galactic habitable zone. This zone is primarily a function of distance from the galactic center. As that distance increases:
The metal content of stars declines, and metals are considered necessary to the formation of terrestrial planets.
The X-ray and gamma ray radiation from the black hole at the galactic center, and from nearby neutron stars and quasars, becomes less intense. Radiation of this nature is considered dangerous to complex life. Hence the Rare Earth hypothesis deems unfit for life the early universe, and regions where the stellar density is high and supernovae not rare.
Gravitational perturbation of planets and planetesimals by nearby stars becomes less likely as the density of stars decreases. Hence the further a planet lies from the galactic center, the less likely it is to be struck by a large bolide. A sufficiently large impact may extinguish all complex life on a planet.
(1) rules out the outer reaches of a galaxy; (2) and (3) rule out galactic inner regions, globular clusters, and the spiral arms of spiral galaxies. These arms are not physical objects, but regions of a galaxy characterized by a higher rate of star formation, moving very slowly through the galaxy in a wave-like manner. As one moves from the center of a galaxy to its furthest extremity, the ability to support life rises then falls. Hence the galactic habitable zone may be ring-shaped, sandwiched between its uninhabitable center and outer reaches.

With so many galaxies to choose from (billions and billions) and many of them sporting a ring shaped habitable zone it seems as though life, complex or otherwise, can take place pretty well anywhere out there.

Vorticella

There are a 100 billion or so galaxies up there? No one could possibly even imagine what type of other life forms could exist beyond our planet. Who's to say it has to be carbon based? That is all we know. A far as we know, other life might not even contain anything close to a base pair type DNA... I would take a guess though that if intelligent life is out there, it evolved in a similar fashion to us. Some form of a brain evolved from a lesser species most likely. No one knows for sure...

vanesch

Quote by Chris Hillman

Exactly! This is perhaps the single most important point which could be made in discussions of this kind: we are talking about informed speculations, and not, strictly speaking, about science. History suggests in the most compelling fashion that when you haven't yet looked at what actually happens in Nature, preconceived notions are generally wrong. In this case, we have not yet examined very many biospheres, so it seems perilous indeed to attach much weight to alleged generalizations about biospheres in general.

I would like to add to that. We have a statistical sample of 1 element, and worse, we couldn't even have a statistical sample with 0 elements - antropic as this argument might be, it is valid to show the essential bias in our very limited sample set, which, after removing the bias, is empty! Probabilistic arguments based upon this *trivial* observation are hence entirely speculative with no ground at all, and stuff such as the Drake equation are just a factorisation of a single speculative quantity in several speculative quantities.

The observation that life *did* devellop on our planet, and moreover into an advanced and intelligent form is a non-observation, because every intelligent observer has to make that observation, even in a universe where the probability for this to happen is so low that it is even improbable to have happened in his universe. We cannot conclude from that fact that the devellopment of life into intelligent forms must somehow be "easy" and rather probable if the right conditions are present. Maybe it is, maybe it isn't, but the (biased) observation that it did on our planet (it had to, for us to be here to observe it) brings strictly no information in the debate.

The Moon landing was a great romantic adventure, there's no denying that, but the most important thing it accomplished, politically speaking, was producing an undeniably striking picture http://en.wikipedia.org/wiki/Blue_marble which could however have been taken just as easily, and a great deal more cheaply, by a robotic spacecraft.

I object to that: the most important devellopment from the apollo missions was the devellopment of easy cooking pans, no ?

NoTime

Quote by vanesch

we couldn't even have a statistical sample with 0 elements

Actually I think we do have a null set.
The definition of intelligence in this case seems to be transmission of a signal.

We don't transmit anything (barring the one minute Arecibo transmission back in the 70's)

That wouldn't qualify as a valid hit, based on what I know of current search algorithm, even if something was lucky enough to intercept it.

If there is another technological civilization why do we expect them to be more forthcoming than we are?
Seems to me you need to add another parameter to the Drake equation.

nannoh

Quote by NoTime

Actually I think we do have a null set.
The definition of intelligence in this case seems to be transmission of a signal.

We don't transmit anything (barring the one minute Arecibo transmission back in the 70's)

That wouldn't qualify as a valid hit, based on what I know of current search algorithm, even if something was lucky enough to intercept it.

If there is another technological civilization why do we expect them to be more forthcoming than we are?
Seems to me you need to add another parameter to the Drake equation.

Does life naturally evolve into a complexity that produces intelligence? It only appears to based on one example of what has emerged on earth.

It was a bolide that wiped out over 90 percent of life on earth that actually made it possible for mammals to become the dominant form of life on the planet. Without that catastrophy, mammals would probably still consist of a variety of small rodents.

Is it manditory that mammals be the intelligent form of life? Can viruses evolve an intelligent nervous system? Or reptiles? Are there signals that we're missing all together because they're generated by anerobic or nonaquatic life forms?

Thinking "out of the box" might help SETI with its mission.

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D H Mentor	Many factors may preclude the development of intelligent life. The Drake equation implies a large number of intelligent civilizations could be present in our galaxy. The Fermi paradox asks "why haven't we seen or heard them?" The Rare Earth hypothesis (see http://en.wikipedia.org/wiki/Rare_Earth_hypothesis) answers the Fermi paradox by saying that we are more-or-less unique.

berkeman Mentor	You're referring to the Drake equation, which DH mentioned in post #3. Check out his wikipedia link.