If we ever meet aliens from another planet will we be surprised by what we see?

[Dinwar]

Originally Posted by Skeptic Ginger

I think you've gotten your quote sourcing confused. That or my brain is aging faster than I thought.

No, it was my stupid computer doing idiotic things again...I swear, I'm going to take a shotgun to it one of these days...I intended to be responding to THIS quote:

Quote:

Any reason 6 legs would not evolve away 2 of them as wasteful, like the way eyes devolve in critters who move into dark caves?

The reason is, we don't know that losing two would be in any way preferred. There are TWO vertebrate land animal skeletal structures on Earth: four legs and a tail, or no legs and a tail (one could argue that a third--two limbs and a tail--is intermittently trying to be developed in therapods, particularly avis, but it's not there yet). There's never been more than four legs on a vertebrate land animal. Unfortunately for our understanding of xenobiology, that's due to nothing more than a prehistorical fluke: our ancestors happened to have all of the necessary gear for migrating to the land, and had four limbs and a tail.

Without more examples of limb configurations, it's simply impossible to determine what configuration is best for land animals. It may be that there's NO best configuration, and on another planet multiple waves of invasions of the land could have resulted in numerous groups with different numbers of limbs. Or we could find a planet where all of the terrestrial vertebrates (and I'm assuming ad arguendum that we find vertebrates at all--certainly not a for-gone conclusion) have NO limbs, having evolved from a fish without fins (they existed for rather a long time, in fact). On that note, it's entirely plausible that a planet with something similar to chordata would have land animals with platty exoskeletons (that's how fish started, after all).

My point is, we have a single datapoint. Extrapolation from a dataset of one is impossible. Without more information, we simply can't guess as to how many limbs are preferred on land--all we can honestly say is "Our planet has terrestrial vertebrates with four or fewer limbs".

Quote:

Is there anything that 6 or 8 legs could provide a mammal that 4 legs does not? Just thinking this through, mind you, I'm not arguing the point. I wonder why we had to walk upright to evolve our hands and arms. I wonder why 4 legged critters haven't evolved arms and hands without walking upright?

It depends on what you call "upright". Therapods certainly developed arms and hands, yet their posture was far more horizontal than our own.

But you're falling into the trap of atomizing organisms into their constituent characters and trying to deduce survival advantages of individual characters, in isolation. Again, we have four limbs because of nothing more than a fluke. A different fluke could have caused us to have more or fewer limbs. Evolution is an emergent property of population genetics and epigenetics; therefore there's substantial latitude for random events to sway the evolutionary pathway. In other words, it could be that there's no real advantage for a land animal to have six legs, but there WAS an advantage for its fish ancestor to have six fins and it's a disadvantage to lose limbs at this point (channelization). Or it could be that a population of fish with six limbs due to a random mutation that offered no evolutionary advantage reaching fixation, then another mutation (timing really doesn't matter so long as it's the same population) allowing the organism to exist on land for a short time. Again, as long as six limbs is good enough the organism will retain that character.

[Skeptic Ginger]

Originally Posted by Dinwar

No, it was my stupid computer doing idiotic things again...I swear, I'm going to take a shotgun to it one of these days...I intended to be responding to

Ah yes, the infamous, "thought I hit the copy key but didn't so the last thing I copied got pasted instead, and I was asleep at the wheel and didn't notice." Yep, been there, done that. I blame keyboards designed for typewriters with keys that would stick if you typed some letter sequences too fast. I've often thought of using that software that will rearrange one's keyboard but I haven't had the guts to try it.

Originally Posted by Dinwar

THIS quote:

The reason is, we don't know that losing two would be in any way preferred. There are TWO vertebrate land animal skeletal structures on Earth: four legs and a tail, or no legs and a tail (one could argue that a third--two limbs and a tail--is intermittently trying to be developed in therapods, particularly avis, but it's not there yet). There's never been more than four legs on a vertebrate land animal. Unfortunately for our understanding of xenobiology, that's due to nothing more than a prehistorical fluke: our ancestors happened to have all of the necessary gear for migrating to the land, and had four limbs and a tail.

I don't disagree it could just be the luck of the prehistorical draw, I disagree that it is certainly the case.

Originally Posted by Dinwar

...On that note, it's entirely plausible that a planet with something similar to chordata would have land animals with platty exoskeletons (that's how fish started, after all).

I know what an exoskeleton is but my Google-fu isn't finding what a platty or platy exoskeleton is.

Originally Posted by Dinwar

.My point is, we have a single datapoint. Extrapolation from a dataset of one is impossible. Without more information, we simply can't guess as to how many limbs are preferred on land--all we can honestly say is "Our planet has terrestrial vertebrates with four or fewer limbs"....

... you're falling into the trap of atomizing organisms into their constituent characters and trying to deduce survival advantages of individual characters, in isolation. Again, we have four limbs because of nothing more than a fluke. A different fluke could have caused us to have more or fewer limbs. Evolution is an emergent property of population genetics and epigenetics; therefore there's substantial latitude for random events to sway the evolutionary pathway. In other words, it could be that there's no real advantage for a land animal to have six legs, but there WAS an advantage for its fish ancestor to have six fins and it's a disadvantage to lose limbs at this point (channelization). Or it could be that a population of fish with six limbs due to a random mutation that offered no evolutionary advantage reaching fixation, then another mutation (timing really doesn't matter so long as it's the same population) allowing the organism to exist on land for a short time. Again, as long as six limbs is good enough the organism will retain that character.

I get all that stuff, I'm not new to the genetics field. But you are still convinced selection didn't prefer 4 limbs while saying we don't have enough data. Seems like a contradiction.

[Dinwar]

Originally Posted by Skeptic Ginger

I know what an exoskeleton is but my Google-fu isn't finding what a platty or platy exoskeleton is.

Probably not.... Before Phylum Chordata got our spines, our ancestral fishes had exoskeletons. Many of them (the ones I'm most familiar with) consisted of plates of dentine extruded through the skin from cells that, in later vertebrate lines, would become the trapped cells in our bones. These early fishes had no internal bones; their entire skeleton consisted of their exoskeleton, which consisted of plates. In some lineages these plates overlapped, in others there were considerable gaps. In some they fused to form broad shields covering the head, though that's pretty late in the game. During most of this time locomotion in chordates consisted of twitching the tail side to side--fins hadn't evolved yet.

Quote:

But you are still convinced selection didn't prefer 4 limbs while saying we don't have enough data. Seems like a contradiction.

I'm not convinced; however, between the options "Evolution prefers 4 limbs" and "The number of limbs is due to chance", the latter seems infinitely more likely. It's analogous to the number of digits on each limb--early paleontologists thought that five was somehow perfect, and concocted numerous theories for why five was perfect, and obviously all our ancestors had to have five fingers (everything that didn't had fewer, and the loss of digits was obviously a derived trait). Except that once we found the digits of the first few critters that came onto land we found that the number was pretty random, and had any of the other amphibian lineages survived we'd be typing with a different number of fingers per hand--maybe even different fingers per hand on each individual! This is extremely similar to the arguments I've heard that four limbs are evolutionarily preferred, in that both arguments take a trait that's common in the present and attempt to discuss the evolutionary advantage of that trait back during a time when modern evolutionary pressures simply didn't exist. I mean, can you pick when four limbs became preferred? I can't--it could have been any time any one of our ancestors branched off any other chordate ancestor, up to the individual species of lobe-fined fish that crawled onto land and all the way back to the a split before we had actual bones.

And I've never argued that the four-limb configuration isn't evolutionarily preferred. I'm merely arguing AGAINST the idea that it IS, in two ways: first, by pointing out that these types of arguments are fraught with potential errors even if you avoid the more obvious ones (Just So Stories and the like), and second, by pointing out the lack of data upon which to base this discussion. I honestly don't have any clue as to what the best design for terrestrial organisms is; I also don't think anyone else does, either.

The only way to answer once and for all whether the four-limbs-or-less body plan is best is to look back through time and determine when that lineage started, and what the ecological and evolutionary pressures on the taxa were. And as far as I know, we simply don't have the fossils.

[Skeptic Ginger]

We're still on the same page, Dinwar.

[Halfcentaur]

I would love to see giant tardigrade like beings. I can't decide if they are cute or look like hairless 6 legged moles. I love how they are so small but still look like an animal instead of some insect or cell.

I like to pretend we're all the descendants of interplanetary tardigrades.

[Dinwar]

Could be that they become a space-fairing organism--they go to space accidently via humans, then evolve to beat hell out in the black, since they can go into stasis.

Everyone always wonders how something could evolve space travel. What if it didn't? What if it simply was a cosmic accident, and the organism took evolutionary advantage of it? Wouldn't be the first time.

ETA: By "Wouldn't be the first time" I mean that it wouldn't be the first time either 1) an organism took advantage of a(n evolutionarily speaking) random event, and 2) an organism hitched a ride inadvertently with humans. Obviously it would be a first for a space-fairing organism that goes into stasis in hard vacuum and which evolved on Earth to obtain sentience in the manner I'm describing. Shut up, we just purchased some scotch and I had to have a taste-test! :P

[Reivax]

I just found this, and i'm not sure if anyone has seen it before but it was pretty interesting:

http://www.sivatherium.narod.ru/libr...on_3/03_en.htm

Basically it starts out with the history of human evolution and then projects it into the future. Tbh I have not read much of it because it's tl;dr but the pictures were really thought provoking.

-Reivax

[Reivax]

Personal favorite:

[xtifr]

Ok, the way I look at it is this: we can pretty much expect life from another planet to be noticably different from life on Earth. Where, why and how doesn't matter. We can reasonably expect it to be different, and we can reasonably expect it to be different in surprising ways. Therefore, if it's not surprisingly different in at least some way, then that will be a surprise.

So, to answer the question in the thread title: yes. Simple logic guarantees it. There is no way for us not to be surprised, because not being surprised would be a surprise.

(Of course, this may only apply to people who were smart enough to realize that they should have been surprised.)

[Cainkane1]

Originally Posted by xtifr

Ok, the way I look at it is this: we can pretty much expect life from another planet to be noticably different from life on Earth. Where, why and how doesn't matter. We can reasonably expect it to be different, and we can reasonably expect it to be different in surprising ways. Therefore, if it's not surprisingly different in at least some way, then that will be a surprise.

So, to answer the question in the thread title: yes. Simple logic guarantees it. There is no way for us not to be surprised, because not being surprised would be a surprise.

(Of course, this may only apply to people who were smart enough to realize that they should have been surprised.)

What if we were in prepared for anything mode? A spacecraft landing, an opening appears and we don't know what will be comming out?

[Marduk]

Originally Posted by Dinwar

There's never been more than four legs on a vertebrate land animal..

I think its unlikely that aliens will be vertebrate
how about super intelligent spiders
http://en.wikipedia.org/wiki/Planet_of_the_Spiders
could cause problems at the meet and greet ceremony when Michelle Obama goes spacko trying to kill the ambassador with her shoe

[GlennB]

Originally Posted by Marduk

I think its unlikely that aliens will be vertebrate
how about super intelligent spiders
http://en.wikipedia.org/wiki/Planet_of_the_Spiders
could cause problems at the meet and greet ceremony when Michelle Obama goes spacko trying to kill the ambassador with her shoe

Probly better than Michelle trying to turn an alien prawn ambassador into something you serve with mayonnaise and shredded lettuce.

[Soapy Sam]

As the aliens will probably hit us with a c- charged rock, the chances are we won't see anything but a brief flash.

[KingMerv00]

Originally Posted by MG1962

How long is a piece of string

Twice the distance from the center to either end.

[Sjw]

1. The distances are too great. See robert park's book Superstition.

2. How could we possibly predict, since the mutations that lead to evolution are so random? We can look at an elephant or the HIV virus and see how it evolved, but couldn't have predicted either.

This is basically a sci-fi question, sort of like asking what humans will be doing in 10,000 years, but way harder.

[Beerina]

Well, there will be some statistical advantage to fewer limbs evolving over, say, 100. So four is probably marginally more likely than six, and less likely than two. Four is probably a happy medium for intelligent land animals as it allows locomotion with simultaneous carrying.

Of course carrying can evolve many ways not involving limbs, as can land locomotion.

Still, if limb-based and of large size, pre-intelligent, I can't imagine too many millipedal types.

[Ellen Travis]

I think it's perfectly possible that we see aliens from other dimensions all the time but fail to recognise them due to the limitations of out 4 dimensional perspective.

Slime mould (or slime mold to you in the US) for example always strikes me as something that only partially exists in our dimensions. In other dimensions it probably looks a lot like a flock of puffins diving into an ocean of crystals. or something.

Also intelligence is probably vastly different in other dimensions and observing slime moulds gives us a hint of a very different type of intelligence to our own.

xxx.youtube.com/watch?v=bkVhLJLG7ug

xxx.youtube.com/watch?NR=1&feature=endscreen&v=czk4xgdhdY4

eta

I am not a boffin and I have no idea if slime moulds really exist in different dimensions, it just seems more plausible to me that there are aliens existing here in different dimensions than the idea that they come to visit us in flying saucers. Plus slime moulds are amazing. Oh and squids too. Amazing and delicious aliens. (squids not slime moulds obviously)

[Dinwar]

Originally Posted by Beerina

Well, there will be some statistical advantage to fewer limbs evolving over, say, 100.

None that I can see. Remember, 6-legged critters dominate the land, and critters with far more leggs aren't uncommon. And fish don't just have four limbs either (remember, our limbs are modified fins).

Originally Posted by Ellen Travis

I think it's perfectly possible that we see aliens from other dimensions all the time but fail to recognise them due to the limitations of out 4 dimensional perspective.

Step 1 is proving that such dimensions exist. Step 2 is proving that such dimensions can have life of any sort, much less intelligent life. Then we can start working out what intelligent life is like.

[Ellen Travis]

I am sure that boffins have been able to demonstrate the existence of other dimensions. There was a huge boffin war over whether there are in fact 10 or 11. The current consensus is that there are 11. In fact some boffins claim that there are an infinite number of universes - something to do with brane theory that I struggle to understand THB but that sounds cool.

Who lives in the 11th dimension?
xxx.youtube.com/watch?v=xE7xRgfPjAI

De mens dem from da 11th dimension
obviously

you can see the whole documentary here
Parallel Universes - BBC Horizon - YouTube
xxx.youtube.com/watch?v=eFrcw62Sh-8

[Akhenaten]

Originally Posted by Ellen Travis

Also intelligence is probably vastly different in other dimensions and observing slime moulds gives us a hint of a very different type of intelligence to our own.

YouTube Video This video is not hosted by the JREF. The JREF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website.

I AGREE

YouTube Video This video is not hosted by the JREF. The JREF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website.

I AGREE

eta

I am not a boffin and I have no idea if slime moulds really exist in different dimensions, it just seems more plausible to me that there are aliens existing here in different dimensions than the idea that they come to visit us in flying saucers. Plus slime moulds are amazing. Oh and squids too. Amazing and delicious aliens. (squids not slime moulds obviously)

I made your Youtuby links a bit more user-friendly.

Trés cool.

[Dinwar]

Originally Posted by Ellen Travis

I am sure that boffins have been able to demonstrate the existence of other dimensions. There was a huge boffin war over whether there are in fact 10 or 11. The current consensus is that there are 11.

If I understand you correctly (I have no idea what boffinis are), I'd say that as far as my limited understanding of the physics goes you're right, it appears that there are 11 dimensions in our universe. That's Step 1.

Step 2 remains before we can get to Step 3.

[Ellen Travis]

thanks Akhenaten

[Ellen Travis]

Originally Posted by Dinwar

If I understand you correctly (I have no idea what boffinis are), I'd say that as far as my limited understanding of the physics goes you're right, it appears that there are 11 dimensions in our universe. That's Step 1.

Step 2 remains before we can get to Step 3.

My understanding - as a non-boffin - is that brane theory, which is now fairly widely accepted demonstrates that there are 11 dimensions, most of which probably don't have life as they are very small. However some boffins posit that there are an infinitesimal number of universes. Please don't ask me to explain it, watch the bloomin video from the BBC with all the boffins in it.

[Craig B]

Originally Posted by Ellen Travis

My understanding - as a non-boffin - is that brane theory, which is now fairly widely accepted demonstrates that there are 11 dimensions, most of which probably don't have life as they are very small. However some boffins posit that there are an infinitesimal number of universes. Please don't ask me to explain it, watch the bloomin video from the BBC with all the boffins in it.

Brane theory does my brain in! But not as much as the idea that there are "an infinitesimal number of universes". That totally does my brain in!!

[Mark6]

Originally Posted by Dinwar

Step 2 is proving that such dimensions can have life of any sort, much less intelligent life. Then we can start working out what intelligent life is like.

I read once that in any space with more than 3 dimensions stable orbits are impossible. In our 3-D space omnidirectional influences such as light and gravity decrease as square of distance, as they (crudely speaking) spread as a 2-D surface of expanding sphere. In 4-D such influences would spread as a 3-D volume of expanding hypersphere, so they would drop off as a cube of distance. The result is that no stable orbit around a gravitational point source is possible. Any slightest perturbation would either send an orbiting object out into space, or down into its primary.

The article included differential equations which demonstrated how inverse-square law leads to stable orbits, and inverse-cube does not, but I had long forgotten the details.

I don't think a universe without stable orbits is conducive to life.

[Ellen Travis]

Originally Posted by Mark6

I read once that in any space with more than 3 dimensions stable orbits are impossible. In our 3-D space omnidirectional influences such as light and gravity decrease as square of distance, as they (crudely speaking) spread as a 2-D surface of expanding sphere. In 4-D such influences would spread as a 3-D volume of expanding hypersphere, so they would drop off as a cube of distance. The result is that no stable orbit around a gravitational point source is possible. Any slightest perturbation would either send an orbiting object out into space, or down into its primary.

The article included differential equations which demonstrated how inverse-square law leads to stable orbits, and inverse-cube does not, but I had long forgotten the details.

I don't think a universe without stable orbits is conducive to life.

mmm

I thought that we exist in and experience 4 dimensions, the 4th being time

That's the really challenging thing about trying to understand other dimensions, if we don't consciously experience them ourselves then we don't have a frame of reference for how to begin to understand them.

The boffins only started to understand their existence by working out the reasons why some phenomena - e.g. gravity - do not work in a way that they should work if the laws of physics as we understand them operate correctly. So rather then having proved the existence of other dimensions they have hypothesised them into existence in order to demonstrate why some things work the way they do. or something

My brain hurts

[Mark6]

I should have added "discounting the time dimension", as gravity propagates in 3-D.

[CapelDodger]

Originally Posted by Reivax

IBasically it starts out with the history of human evolution and then projects it into the future.

The problem there is a fundamental lack of data on the future. More data comes in every day but we're barely keeping up with it at present, let alone getting ahead of the game. By the time we process it it's already history.

[Cainkane1]

Carl Sagan once put forward this situation. If intelligence and civilization developed on a planet that lacked trees they might not share our desire to fly. Their philosophies would be very different from ours

What if we ran into a civilization that had no interest in us whatsoever. Their attitude being who needs you?

[dasmiller]

Originally Posted by Cainkane1

What if we ran into a civilization that had no interest in us whatsoever. Their attitude being who needs you?

So . . . like . . . if all the women I've asked out had their own civilization?