Life’s Adaptations Among the Stars

by Paul Gilster on May 14, 2010

Gliese 581 d seems to be emerging as the exoplanet to talk about in terms of possible life, at least for now. You’ll recall that the initial furor was all about Gl 581 c, but that world now looks to be more Venus-like than anything else, while Gl 581 d may just skirt the outer region of the habitable zone in this interesting system. Thus Dirk Schulze-Makuch’s contention at the recent astrobiology conference in Houston that this ‘super Earth,’ if it holds life, may have creatures on it that have adapted to the gravity of a planet at least seven times as massive as the Earth.

That would probably produce a population that tends to crawl rather than fly, said the Washington State researcher, and we can let our imaginations go to work on the possibilities. As to Gl 581 d itself, its orbit around this red dwarf may place it in the same relative position that Mars is to our Sun, but throw in volcanoes, a magnetic shield and a thick atmosphere with water oceans below and you could have the right astrobiological circumstances. I’m hoping readers will point me to science fictional treatments of higher-gravity settings a bit less extreme than Hal Clement’s Mesklin in the classic Mission of Gravity, where the local life-forms are 50-centimeter long intelligent beings in the shape of centipedes.

Image: Part of a John Schoenherr rendering of Mesklin from Hal Clement’s Mission of Gravity, from the cover of a 1960’s paperback. Could anyone capture the essence of a story better than the remarkable Schoenherr?

Meanwhile, the detection of a true Earth analog is probably not that far away, and when we do find it, what should we expect by way of living beings there? We won’t know for a long time, of course, but it’s worth noting that Simon Conway-Morris has long contended that certain body forms like eyes and wings keep showing up because they are ideal solutions for interacting with an environment like ours. It’s an argument that Charles Lineweaver (Australian National University) doesn’t buy into, as noted in this summary of the Houston conference from Astrobiology Magazine, where Lineweaver is cited on life’s unique evolutionary paths:

This theory of convergence, says Lineweaver, is flawed because it ignores the fact that life on Earth shares certain genes, and those genes are the foundation for what bodily forms can eventually develop. For instance, people often point to dolphin brain size as an instance of convergence with humans. Lineweaver says such a claim is ridiculous because it ignores the fact that 60 million years ago, humans and dolphins diverged from a common ancestor.

And will the life we eventually find be intelligent? Again, it will be a long time before we know, but I liked this ‘tweet’ from the same conference: “The word ‘intelligence’ is now so loaded it’s almost not useful. Better to say ‘species signaling apparatus.’ -C. Lineweaver”. Twitter skeptics should bear in mind how much a tiny message like that — sent by an attendee at a Lineweaver session at the conference — can turn a day’s writing in new directions.

You’ll find pocket summaries of some of the conference’s most interesting sessions in the Astrobiology Magazine feature, along with the predictions of Chris Impey (University of Arizona), who points to the future participation (if not driving influence) of private companies in the exploration of the outer Solar System. I’m not sure whether it was Impey or author Leslie Mullen who threw in the parting exhortation: ‘By 2060 – Voyage to Alpha Centauri!’ but I’m all for the idea, even if the realist in me thinks that voyage is about 250 years off. The beauty of the future, of course, is that our predictions are so often wrong, as I hope mine is.

tzf_img_post

Eniac May 14, 2010 at 9:40

This theory of convergence, says Lineweaver, is flawed because it ignores the fact that life on Earth shares certain genes, and those genes are the foundation for what bodily forms can eventually develop.

I think that this argument of Lineweaver’s is flawed. There are plenty of examples of convergent evolution where the underlying genes are not related at all. Photosynthesis has evolved independently, for example, once using retinal and proton transfer, and once using metal center chromophores such as chlorophyll and electron transfer. As far as I know, the genetic origins of the two are as independent as the physical principles they are based on. The retinal, though, lives on in our eyes, another example of how tenuous the relation between function and implementation really is in biology.

Many biological characteristics are clearly based on physical circumstances rather than biological ones. Wings have been mentioned, fins, limbs, eyes, etc. are all shaped by their function, biology just complies with requirements. Often in very different ways, as the comparison between mammals and insects shows. Is the range of features of extraterrestrial life going to be vastly grater than that spanned by mammals, fish, insects, and all the other lineages of life on Earth? I do not think so, but it could certainly be argued.

We could play a game: Name me an alien from science fiction, and I will name you an Earth creature that is remarkably similar. At least as long as it is adapted to an environment like that on Earth. Is the range of features of extraterrestrial life going to be vastly grater than that accessible to human imagination? I do not think so, but it could certainly be argued.

Here are some interesting questions: Why do macroscopic life forms not have wheels, treads, or propellers? All of these have proven useful to us. What about fire? Nuclear power? Has nature simply not discovered them? Are they inaccessible to evolution somehow? Operationally unsuitable for autonomous creatures? Impractical given the limitations of biological materials? Could this turn out different on other planets? I do not know the answers.

Zen Blade May 14, 2010 at 10:04

Regarding convergence vs. shared ancestry as the reason for two organisms (or proteins or anything) have similar functions or similar characteristics, Lineweaver is taking a relatively reasonable positions. However, I would need to know a lot more before deciding exactly where he falls on the divide.

HOWEVER, convergent evolution happens, plain and simple. You can look at very different organisms, the ability to fly for example, and see how flight was reached.
When was the last common ancestor between a flying insect and a bird or a bat or a flying fish? We’re looking at something like ~500 hundred million years, but I might be off by quite a bit.
So, yes, there are a lot of common genes, but flight develops fairly easily when a certain set of criteria are met; lighter, smaller creatures at first.

Also, if we look at creatures that live in the ocean, we see a convergence in the body shapes/plans that work for ocean living (the torpedo look), the changing of limbs into fins.

In both cases, these are the body plans that work best for the specific environment.

As for the need for specific genes… that’s more difficult to judge at this point in time. There may be multiple ways to reach intelligence/sentience through the construction of different “brains” (for lack of a better word). Not all grey matter is necessarily equal, although a lot of it appears to be relatively plastic/malleable in humans.

So, yes, we all share genes, BUT the environment an organism lives in selects for certain traits. Those traits commonly develop and can be seen repeated in many different organisms time and again.

Mark Meier May 14, 2010 at 10:19

Higher gravity would make a denser atmo possible. As a pilot, I know flying on cold days (denser air) gives better lift, so wouldn’t a high-grav planet with dense air allow a more sturdy creature to fly?

I may be wrong — I’m not a biologist — but that seems to make sense. Somewhat beside the point of the posting, but there it is.

ScottG May 14, 2010 at 10:24

It’s probably a very difficult but interesting exercise to develop an educated guess at the size of creatures living on a 7 Earth-mass planet… considering that here we have a huge range in size of animals that walk on land. E.g. according to a quick (unscientific) internet search, we have walking animals ranging in size from ants (mass of 0.0003 kg) to large herbivore dinosaurs (weighing up to 77,000 kg) — giving a mass range on the order of 100 million or so.

Nevertheless, I’m sure there are more scientific ways to put some constraints on the size of land animals on worlds of far different sizes than our own, by considering such things as the power required to move and energy required to build and maintain support structures (analogous to bones) in these animals.

One other interesting fact about this is that if it is harder for an animal to get around on a super-earth class planet, then it’s surely also harder for them to launch vehicles into space and harder for them to build massive communication devices large enough to send signals that can be detected light-years away (by us, for example).

Denver May 14, 2010 at 11:09

“That would probably produce a population that tends to crawl rather than fly, said the Washington State researcher,”

Swim? I would think that high-g would lend itself to life suspended in fluid. And the atmosphere of a planet 8x the mass of Terra will be nearly as dense as water to boot.

As far as high gravity worlds go,:

Jinx (Sirius)

Jinx is an oblong moon, pulled out of its round shape by its proximity to Primary, a gas giant orbiting the star Sirius. The equatorial region is shrouded in high-pressure gas, and no one goes there except to hunt Bandersnatch. The Ends stick out of the atmosphere entirely, providing centers for vacuum-based industry centers and spaceports. Between the Ends and the center are two bands of habitable living space.

Jinx has more mass than Earth. Over the years, the people of Jinx have evolved into a squat, stocky race, as wide as they are tall, and very strong compared to humans, though they tend to die younger. Jinxians are horrible punsters.

Notable Jinxians: Dr. Julian Forward, Emil Horne, “Captain Kidd” (real name unknown) For Further Reading: World of Ptavvs

Matt May 14, 2010 at 11:39

Perhaps something like a combination of a whale and jellyfish that rises to the surface to feast on photosynthesizing microrganisms but has to descend back to the bottom to “breath” iron from a volcano and refill its “gas-bag”?

A surface ecosystem based on walking on water through surface tension?

I’m sure plenty of biologists would volunteer to go see.

Athena Andreadis May 14, 2010 at 11:55

I prefer the depiction of Barlennan of Mesklin that I found by an unnamed artist, which I used in my article You Only Find What You’re Looking For (second image in the essay).

Many fictional planets have stronger-than-terrestrial gravity. Vulcan comes to mind right away and I believe that is also true of Wotan (home of the dragon-like yet vegetarian and Zen-Buddhist Adzel in Anderson’s Dominic Flandry stories within the Polesotechnic League cycle). And most rotating space habitats have a high-gravity zone invariably dedicated to extreme sports.

Both Conway Morris and Lineweaver are right — and wrong. Lifeforms will need senses that allow them to react to their environment — but they don’t have to be those of terrestrial lifeforms, which are indeed descended from a single initial program (though the Hox genes, to which Lineweaver undoubtedly refers, have diverged in dizzying fashion while retaining their basic patterning function).

kurt9 May 14, 2010 at 12:37

Does anyone know the density of this planet? If its low like an ice giant like Uranus or Neptune, the surface gravity could be the same or even lower than that of Earth. If its a dense terrestrial planet, then its surface gravity would be around 1.2-1.3 g’s. This is not too dissimilar to Earth.

If an ice giant like Uranua or Neptune is dragged in to the habitable orbit, would it turn into a giant water world? If so, this would make ice giants frozen waterworlds.

Tim May 14, 2010 at 12:59

Dirk Schulze-Makuch’s contends “… that this ’super Earth,’ if it holds life, may have creatures on it that have adapted to the gravity of a planet at least seven times as massive as the Earth.”
I was unable to find any information – perhaps because there isn’t any – about estimations of the diameter of this planet but note that IF it had a diameter of about 2.6 times that of earth, then its surface gravity would equal earths and no such adaptation would be necessary.

Tim May 14, 2010 at 13:12

Would flying organisms be more common on worlds with high atmospheric pressure?

andy May 14, 2010 at 13:28

Then again it may be that Gliese 581d is a water world with an ocean hundreds of kilometres deep, bounded below by a mantle of high-pressure ice. Such a composition is certainly reasonable under current planet-formation theories (as would be the possibility of it being a mini-Neptune similar to GJ 1214b), but as ever with exoplanets, we should expect to be surprised. Such a composition leads to the issue of how efficient delivery of material from the silicate core to the liquid ocean can be.

Another thing to consider is that if such high-gravity planets have thick atmospheres (which would presumably be required to sustain a greenhouse effect sufficient to melt the surface of the ocean), perhaps the development of flight would not be as difficult as might be thought.

Zarpaulus May 14, 2010 at 15:11

I think that high-gravity planets are so common in sci-fi so the writers can justify giving a character (heroic or villainous) super-human strength. Realistically larger planets are easier to spot so if we ever start colonizing other solar systems they’ll probably be some of our first targets.

James M. Essig May 14, 2010 at 15:13

Hi Paul;

The artistic rendering of the exoplanet scene is beautiful. Assuming that one out of ten stars has a habitable moon or planet, or at the very least, a Mars like planet, that translates into a total of about 10 EXP 22 individual lithospheres, biospheres, and/or atmospheres, just within our visible universe alone. This is plenty of eye candy for us space heads, especially those of us who enjoy outdoor photographs of city life, natural land features, clouds and the like. Now if we can just figure out how to prolong human life indefinitely, our descendents might have many exogeographical tourist attractions as possible vacation sites.

NS May 14, 2010 at 15:45

Lineweaver’s main argument is that although there are of course convergent features in evolution, human-like intelligence isn’t one of them:

http://www.mso.anu.edu.au/~charley/papers/ConvergenceIntelligence10.pdf

Athena Andreadis May 14, 2010 at 15:46

James, it’s the other way around: if we gain “indefinite life span” (however you define it) before we have access to resources beyond earth, it will be death by slow starvation and poisoning. Think of bacteria in a dish and you have a good picture of what human life on earth would look like.

I believe we have a consensus that 1) high-gravity planets are as common in SF fiction as, well, anthropomorphic aliens and 2) higher gravity with denser atmosphere will make flying easier (more lift), though take-off will be hard and flying in these circumstances may be more the gliding type.

Carl May 14, 2010 at 15:53

‘By 2060 – Voyage to Alpha Centauri!’ but I’m all for the idea, even if the realist in me thinks that voyage is about 250 years off. The beauty of the future, of course, is that our predictions are so often wrong, as I hope mine is.

I agree, Paul.

To Eniac: “We could play a game: Name me an alien from science fiction, and I will name you an Earth creature that is remarkably similar. ”

http://www.youtube.com/watch?v=d76fiWRobU4

NS May 14, 2010 at 16:18

Lineweaver has also co-authored a recent paper showing that life on Earth apparently does not inhabit every environment with liquid water, which will be relevant as we search for life on other worlds:

http://www.mso.anu.edu.au/~charley/papers/JonesLineweaver2010.pdf

amphiox May 14, 2010 at 16:43

When we think about convergence I think it is also imperative to consider those cases were convergence did not occur. For example, faced with similar environmental selection pressures, wolves and thylacines turned out morphologically very similar. But a different lineage, one that was actually pretty closely related, comparatively, and with only a slightly altered embryological process and genes, when encountering the same types of selective pressures, came up with velociraptors and terror birds.

Insect wings are very, very different from the wings of birds, bats, and pterosaurs.

Squid and fish both became torpedo shaped, but in quite different ways. And another lineage, the ammonites, faced with the same environmental challenges, went in a wholly different direction, developing armor and bouyancy instead of speed.

And as far as I know there are no convergent analogs to the octopus, even though many different lineages live in similar environments and make their living in a similar fashion.

Any developmental process is going to be constrained in the range of morphological types it is capable of producing, so similar developmental processes are going to have a limited number of options to choose from for adapting to specific environmental challenges. Lineages with similar embryonic processes will clearly be more likely to stumble onto the same or similar solutions and converge. The question is going to be how many different embryological processes are possible, and what are the ranges of constraints of each. If the processes themselves are constrained by the requirements of assembling a large multicellular organism into only a few viable options, then the likelihood of recognizable convergence between earth and alien life will be higher.

Basically, the question is whether or not the 35 or so distinct body plans found among animals on earth (deliberately plants and fungi for the moment for the sake of simplicity) represent a large or small subset of all the possible viable body plans that could exist for producing a multicellular organism.

Any earth analog is also going to be different from earth in a wide variety of small but telltale ways, and what impact such differences might have on the evolution and viability of potential body plans and embryologic processes might be hard to predict.

Dave Moore May 14, 2010 at 18:01

A good biomechanicist would be able to tell you how life would adapt to a higher gravity. From what I remember, land animals scale in some inverse proportion to the surface gravity, so everything would just be smaller. After all, some of the largest animals on Earth (T. Rex) went about on two legs.

Pulling equations out of the rusty recesses of my brain, assuming the planet has the same density as Earth, then I get a radius of 1.18 Earth’s and a surface gravity of 5 times Earth’s, but I may be wrong here.

andy May 14, 2010 at 18:11

Does anyone know the density of this planet? If its low like an ice giant like Uranus or Neptune, the surface gravity could be the same or even lower than that of Earth. If its a dense terrestrial planet, then its surface gravity would be around 1.2-1.3 g’s. This is not too dissimilar to Earth.

Unfortunately no transits of the Gliese 581 planets have been detected, and they have been ruled out for planets b and c, so no radius measurements as yet. On the other hand I am not sure if transits of Gliese 581d have been searched for, particularly in the light of the de-aliasing of the orbital period. Of course if the system is coplanar, the lack of transits of the inner planets implies planet d is also non-transiting, but there’s a recent paper out about Upsilon Andromedae that shows the coplanarity assumption is not true of all systems.

As for fictional treatments of high gravity environments, there’s always Robert Forward’s Dragon’s Egg, or Stephen Baxter’s Raft… oh wait, you said less extreme…

James M. Essig May 14, 2010 at 21:34

Hi Athena;

Thanks for the above response to my post.

In fact, I can just imagine the burden that un-checked life expectancy increases would pose for institutions that are against artificial contraception such as the Catholic Church.

Trying to contain a growing human population where each human lives essentially indefinately would pose a doctrinal pandomonium for those attempting to permit unrestricted family size.

Even if we learn how to live for “only” thousands of years, we had better develope some extreme gamma factor travel methods so that one tick of the human reproducive clock on space bound missions for cosmically distant locations is greatly dilated so as not to produce more children then a near C human colonization wave front could possibly support.

I still hold out hope for superluminal warp drive, wormhole travel, and multiple space time connectivities and the like, but such would only stave of the human population growth problem for so long.

As for extreme velocity increases, out right science fantasy relativistic gamma factors equal to infinity or infinity EXP n, where n can be made arbitrarilly great and/or time dilation-less superluminal travel at speeds of (infinity) C and (infinity EXP n)C would be a solution to a reproductive free for all, but I honestly do not see such extremes being accomplished on this side of eternity, at least not any time soon.

Unless we have innumerable parallel universes to access, or other human life friendly universes, my guess is that when we determine how to augment human life expectancies, and I think we will make progress in this regards if only by small incremental steps, I do not see how unchecked human reproduction can be sustained over the long run.

jeff May 14, 2010 at 22:11

High gravity means proportionally higher friction between paws and ground. In any gravity, creatures have the ability to accelerate horizontally at about the same value as the gravity. Assuming Darwinian competition among predators, the creatures should be much faster than on earth and would need proportionally better reflexes to compete. Imagine a predator that can accelerate at 7G, or more if it digs in, and has reflexes adapted to an environment where everything moves that fast.

Tom May 14, 2010 at 22:53

Yes, I’ve read Dragon’s egg, excellent.
But in more moderate cases I would expect that higher gravity will simply produce large looking animals at a smaller scale.
e.g. elephants/rhinos are built to withstand a large mass, but would be smaller.
So I agree with Dave Moore, Basically, earth but with animals half as large (if 8 times the gravity)

Adam May 14, 2010 at 23:29

Hi All

Basica equations – planetary radii, R, are functions of their mass, M, relative to some reference body (Mo) of radius Ro.

R = Ro*(M/Mo)^b

…in the case of an Earth-like silicate/iron mix, for masses of 1-10 Earths, b is ~0.27, and Ro is 1 Earth radius. For 50/50 ice/rock-iron objects, Super-Ganymedes, in the same mass range the reference radius is ~1.26 Earths, similar index. Thus a 7 Earth mass silicate/iron body is 1.69 Earth radii and has a surface gravity of ~2.45 g. A Super-Ganymede of the same mass is 2.13 Earth radii and gravity = 1.54 g. This assumes it doesn’t spin extremely rapidly and reduce its surface gravity via a centrifugal counter-force.

Since the centrifugal force increases with angular velocity squared, a planet with Earth’s primordial rotational period of ~6 hours would reduce the surface gravity by ~0.55 m/s^2 from that alone. However its equatorial radius would increase too, thus increasing the decrease… this effect means that a planet rotating at ~1/3 of its spherical equatorial orbital velocity flattens so much that it begins to lose mass from its new equatorial radius. In Earth’s case it would need to spin once every ~4 hours. Extreme!

Mesklin was ‘stable’ because its mass was mostly centrally condensed so the rotational flattening instability was reached at a higher speed. Hal wrote in some revised notes on his Mesklin series that fans had calculated the planet would’ve been a rather different shape at equilibrium, but he kept it as it was.

Denver May 15, 2010 at 9:42

To Eniac: “We could play a game: Name me an alien from science fiction, and I will name you an Earth creature that is remarkably similar. ”

Can I play, too? :)

Tribbles
Gort
The ID monster from Forbidden Planet
Flatcats – The Rolling Stones
Roundballs – Red Planet
Ptavvs – World of Ptavvs
We are Borg resistance is futile.

Zen Blade May 15, 2010 at 9:45

amphiox,

I am not sure that you dinosaur vs wolves analogy is a good example. One difference is the 4 legs vs 2 legs, 2 arms common in many (all??) of the carnivorous dinosaurs. However, there were (to my knowledge) also herbivores with 2 legs, 2 arms. I am not an expert, so I don’t know what the thinking is behind this format… or why certain dinosaurs stuck to 4 legs while others changed to 2+2.

However, that being said, if one considers speed and the ability to hunt, it could be that given their body plans, two legs was better for hunting down prey than four legs. But really, we would need an expert to understand what the current thinking is regarding that evolutionary trajectory.
Many carnivorous mammals with four legs still use their front two as “hand-like” appendages for holding and grasping at things.

But, like we both said, certain traits, certain convergence does happen dependent on what is required to survive in an environment.

Interesting point on the cephalopods… the ammonites are extinct though.
Genetics definitely plays a role in how an organism evolves and changes to adapt to its environment, but even then certain traits are common, as we both pointed out.

NS May 15, 2010 at 14:14

Re two-legged dinosaurs, I don’t know if the large heavy tail preceded the transition to two legs or not. If it did it would have made the transition easier since it allowed a dinosaur to balance on its hind legs while still keeping the body more or less horizontal. OTOH in hominids the pelvic bone had to be completely reshaped, the way the internal organs were anchored had to change, etc. Supposedly our back problems are in part a result of this as well.

Adam May 15, 2010 at 17:56

Hi NS

Bipedalism was a mark of all the early dinosaurs, with some of the larger herbivores later returning to four-legged stances though still able to rear-up when they needed to. The early bipedal dinosaurs were all small, but the tail still acted as a balance. Early birds retained the bony tails but soon lost the bone tails as feathers took over.

Eniac May 15, 2010 at 20:29

Tribbles
Gort
The ID monster from Forbidden Planet
Flatcats – The Rolling Stones
Roundballs – Red Planet
Ptavvs – World of Ptavvs
We are Borg resistance is futile.

I guess we should restrict it to creatures that make sense, biologically. So telepathic fur balls probably don’t apply, although they could well be a cross of sea urchin and rabbit.

The Borg, as I understand them, are many different species, so you would have to name a specific one. I do not know the others, but maybe I’ll google them :-)

Eniac May 15, 2010 at 20:48

Basically, earth but with animals half as large (if 8 times the gravity)

This is not correct. If an animal was half the size, it would indeed weigh the same as the one on Earth, but its legs would be thinner and would break. The correct formula has animal size inversely proportional to gravity. Weight goes with the third power of scale, bone and muscle strength with the second (cross-section). The balance between the two goes linear.

If you take a dinosaur to be the largest practical land animal on Earth, at 50 meters long, the largest Mesklinite able to go to the ~600 g pole would be about 8 cm long. That makes Hal Clement’s Mesklinites (at 50 cm) too large for comfort, but they are built sturdier, so it might be ok. I am sure he had it all figured correctly.

On the other hand, those spherical rocks in the picture seem like they would almost certainly be crushed under 600 g. Perhaps this scene is from near the equator?

Eniac May 15, 2010 at 21:35

Jinx (Sirius)

Jinx is an oblong moon, pulled out of its round shape by its proximity to Primary, a gas giant orbiting the star Sirius. The equatorial region is shrouded in high-pressure gas, and no one goes there except to hunt Bandersnatch. The Ends stick out of the atmosphere entirely, providing centers for vacuum-based industry centers and spaceports. Between the Ends and the center are two bands of habitable living space.

This one is also ill-conceived, physics-wise, as the Wikipedia article explains:

(In reality, though a prolate spheroid might be a reasonable shape for a planetary-mass object in a strong gravitational gradient, the atmosphere would be in the same kind of hydrostatic equilibrium as the solid object. The force of gravity would have to be normal to the surface at every point, and so the average atmospheric pressure at the surface would have to be the same everywhere.)

Eniac May 15, 2010 at 21:57

According to my rather shoddy research, Gort and Ptavvs are humanoid. Gort is disqualified, being a robot. The ID monster to me looks like a bipedal lion, Flatcats are like Tribbles and I could not find anything about Roundballs…. :-)

mike shupp May 16, 2010 at 2:50

The most memorable heavy gravity “earth-like” world I can recall described in classical SF is
Ragnorak, “the Hell Planet” in Tom Godwin’s THE SURVIVORS. It had a surface gravity of 1.8G.
Memory says Doc Smith had ax-weilding Space Marines from a 2G world in his Lensmen series,
but the world itself was not described. And I seem to recall 8 ft humans from some 1.5G world
somewhere in James Schmitz’s works, but that only merited a paragraph of description.

NS May 16, 2010 at 4:15

Thanks Adam. I wasn’t aware (should have been) that all early dinosaurs were bipedal, although their ancestors would have been quadrupeds so I guess some of the same considerations apply.

Denver May 16, 2010 at 12:35

[q] Eniac May 15, 2010 at 20:29

Tribbles
Gort
The ID monster from Forbidden Planet
Flatcats – The Rolling Stones
Roundballs – Red Planet
Ptavvs – World of Ptavvs
We are Borg resistance is futile.

I guess we should restrict it to creatures that make sense, biologically. So telepathic fur balls probably don’t apply, although they could well be a cross of sea urchin and rabbit.

The Borg, as I understand them, are many different species, so you would have to name a specific one. I do not know the others, but maybe I’ll google them :-) [/q]

Thanks for the reply.

If you have children the Heinlein Juveniles (both “The Rolling Stones” and “Red Planet” are among them) are excellent readers for 10 year olds and up. Every library will have the entire collection, or should.

Administrator May 16, 2010 at 13:19

andy wrote:

As for fictional treatments of high gravity environments, there’s always Robert Forward’s Dragon’s Egg, or Stephen Baxter’s Raft… oh wait, you said less extreme…

I’ve read the Forward, but didn’t know about Raft. Thanks for the tip! Also thanks to Denver for this:

Notable Jinxians: Dr. Julian Forward, Emil Horne, “Captain Kidd” (real name unknown) For Further Reading: World of Ptavvs

I love early Larry Niven anyway. This would be a re-read to look forward to.

And Mike Shupp wrote:

The most memorable heavy gravity “earth-like” world I can recall described in classical SF is
Ragnorak, “the Hell Planet” in Tom Godwin’s THE SURVIVORS. It had a surface gravity of 1.8G.

Haven’t ever read the Godwin, but will look forward to it. I’ve got some James Schmitz around here some place but can’t recall the high-grav world — will have to do some checking.

Adam May 16, 2010 at 16:24

Hi Paul

“Raft” features a Universe in which big ‘G’ is 1 billion times stronger. Stars are only a mile across and burn for a year, producing iron cores that refugees from our Universe mine for metals – they live in an orbital ring around a dead star as well as in a “flying island” built around their wrecked starship. They’re in a high density nebula with a breathable atmosphere – but the atmosphere is becoming polluted by chemical evolution as the stars age.

The novel has some memorable depictions of some rather alien life in a world where people can orbit around each other and feel each other’s gravity, where mini black-holes can form molecules and truly alien life-forms.

TK_AK May 16, 2010 at 17:11

In Mass Effect (a very good game IMHO) the population from a high gravity planet is depicted as follow : http://masseffect.wikia.com/wiki/Elcor

( for what it’s worth :) )

James M. Essig May 17, 2010 at 0:22

Hi Folks;

I like the floating mountains in Avatar. A really cool biomechanical adaptation would entail ETI persons having bodies that are reduced in effective weight by the Miesner effect such as having bodies with superconducting features. On problem with this concept is that unless they had a good deal of muscular strength, they might become stuck in position.

One conjecturer gave an account in a popularization of science book I read about 2 decades ago, about how life forms made from compressed atomic matter located on the surface of a neutron star might dwell on its surface and evolve very rapidly commensurate with the rate of bodily change of state that could occur at the distance scales measured in nanomters to picometers, and given metabolic effects that might progress at relativistic velocites on these small scales.

I imagine I still have this book, but it is probably down in my basement packed away in a box.

The ironic thing is that these creatures could not naturally survive off their world surface since upon doing so, they would immeadiately decompress and effectively decompose into a gaseous, or plasma state. The notion is simmilar to we humans stepping out into space without a suit on, only the consequences would be far more immeadiate and extreme for neutron star surface dwellers who stepped out into the vacuum of free space unprotected.

Our cosmos seems to naturally evolve living organisms. As a result, life in general, seems to be a fundamental aspect of nature. We might consider that the developement of single organism based sentient or atleast affective animal life is a long phase change that our universe is going through.

I can’t wait to see the results of nuclear powered Mars Rovers that are scheduled to launch next year, if I am not mistaken.

By the way, this is an excellent thread. I have been looking back on the various Sci-Fi space novels, movies, and TV shows I have watched over the past 40 some years, and am looking foward to What Dreams May Come

Administrator May 17, 2010 at 7:44

TK_AK, thanks for the tip re Mass Effect, and the link!

Tulse May 17, 2010 at 11:22

One conjecturer gave an account in a popularization of science book I read about 2 decades ago, about how life forms made from compressed atomic matter located on the surface of a neutron star might dwell on its surface and evolve very rapidly

That sounds like the previously-mentioned Dragon’s Egg, the novel by physicist Robert L. Forward.

mike shupp May 18, 2010 at 0:53

If memory serves, the high-G planet is in Schmitz’s AGENT OF VEGA, and doesn’t really feature in
the plot. As I recall, one Agent is a very very tall woman found as an infant — the single survivor
on a space life boat. Being 7’10” or so she never feels comfortable around smaller people; at the
end of that portion of the book, the real hero of the story has steered her towards a nice 8′ tall man,
who comes from said high-G planet.

I dunno that this is worth digging up for a couple of paragraphs. On the other hand, one can do
worse than kill a few hours with a Schmitz novel.

bruceleeeowe May 20, 2010 at 7:57

I think gravity doesn’t matters much if you are going to speculate alien life forms. Didn’t you aware of Forward’s CHEELA, a resident of neutron star? I don’t think now you would bother to talk about millions of time intense magnetic field and gravity, enough to squeeze anything in universe. Or you can remember peter watts’ Dyson single cell creatures.

Bernd Henschenmacher May 22, 2010 at 9:13

I think we need to learn more about the long-term behaviour of stochastic processes and complex systems to understand, whether complex life forms are rare or relativley common. I share the view that both Morris and Lineweaver are right in some sense, especially Lineweaver’s argument, that we cannot view human intelligence as a convergent feature of evolution, as it appeared only once so far. But to dismiss convergnce just because all organisms share some genes and have common anchestors is a little bit misleading. Convergence occurs (in some cases) in species , which are far apart in the tree of life. And as I recall , Morris uses the gene argument in favour of his theory, arguing for example that some genes presently active in human brains can also be found in yeast, therefore evolution does not use all possible gene combinations and their is no need to generate entirely new genes for new functions. On the other hand evolution has produced many. many species and a unparalled diversity, but only one species has developed radio telescopes. In general I would follow Lineweaver’s advice to conduct SETI, in order to collect more data. If we don’t find evidence of intelligent life, we know that we are unique and that intelligence is an evolutionary fluke, otherwise we know that high intelligence is a more or less likely outcome of evolution and that a trend towards complexity may exist.

Ronald May 23, 2010 at 2:49

There seems to be some misunderstanding about convergence. Convergence, by definition, means that similar environmental conditions (i.e. selective pressures) lead to similar forms and functions, where those similar forms and functions are not an expression of genetic relatedness. If the latter is the case, it is synapomorphy, a common derived trait.

It is no use talking about humanoid intelligence and self-awareness in terms of convergence, since it is unique (on earth). Unicity, by definition, is not convergence.

And it entirely remains to be seen whether similar planetary habitats will lead to similar intelligence. Simply and completely unknown.

Lila Sovietskaya February 11, 2011 at 3:17

The bone structure in a heavy planet might have an avian similarity to reduce weight and provide sturdy support. While here on earth bones have a calcium components. on a heavy planet, bones could be made of other minerals. I am not sure if life could imitate carbon fibers as structural material for the bones. An alternate or auxiliary support system would be biological buoyancy of bio-gas.

On a very heavy planet, the atmosphere would be very dense. hence the sky might be a dark blue and the surface could receive less illumination than if it had a thin atmosphere like the earth.

The light of the local sun would shape the vision system of the creatures of the heavy planet. Eyesight would be suited for the color of the star. Infrared sight might be more common than on earth to deal with less light on day and night. Same with Ultraviolet vision if the local sun is rich in UV and local life has adapted to heavier radiation than on earth

Hearing will also evolve to suit the environment. The sound quality depends both on atmospheric composition and density. Our earthly music with earthly instruments would not sound the same there. if intelligent being would have developed music, it would be adapted to their hearing. if performed on Earth it would not sound the same as on its native planet.

DNA is the foundation of all earthly life. is it the only way to have life? We do not know, We have only one sample of life.

The repugnance factor. Any animal who is very different from our shape is repugnant to us humans. Example, roaches. Any animal that is closer to us it is likely to be more admired. Example dogs (two eyes, nose, mouth with teeth, four limbs) Beings from such different planets may look very repugnant to us. Some might look very beautiful and weird

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