http://www.sciencedaily.com/releases/2009/10/091029125532.htm
Basically, a shrew and a lizard, hardly cousins, evolved the same poison from a similar source—digestive enzymes, which evolved to a venom—a pretty nasty venom—that aids both species.
It’s often been asked whether life on other planets could be like us…in any remote degree. Now, imho, there are a couple of items that impinge on that. We are genetically about 1 percent or so removed from other critters, about 99.4 % identical to chimps, and probably not that far from mice. The planetary genome Acme Life Construction Kit is pretty general, until you get down to the nitty gritty that separates us from chimps. Or mice. Or shrews. That’s one. A planetary genome is going to be a pretty general thing, based on our sample of one, not necessarily close to us—but here’s where I have another thought. For instance—in dealing with the limitations of the silicon chip, there’s a lot of investigation of another element: carbon—a nice five-bonded little gem that gives you a lot of potential flexibility. It’s often been stated that if life hadn’t arisen based on carbon, silicon might have had a go at it. It has four bonds. BUT carbon is better at it. So carbon was elected.
One thing you can bet on, again imho, is that physics doesn’t change until you go somewhere really weird, like a black hole. Given an earthlike planet, it’s my bet that carbon is going to win just about every time, simply because it’s one jump better at ‘life’ than silicon. Given what carbon is and does, it’s my bet that some sort of reproductive process is inevitable, and that, again because of chemistry, certain chemicals are going to be better at it than not.
It’s my theory that, no matter where you invent an airplane, it’s going to look a lot like an airplane because of the job it has to do. Call it convergent evolution, but I think it applies much, much much lower in the chain of life, like the demands of physics, and the efficiency of certain elements at the jobs they do. And you start building a building with the same set of Lincoln Logs, and you may, just possibly, end up with straight walls, doors, and windows. Not that other designs aren’t possible, but they may be somewhat inconvenient and fragile, which adds up to “doesn’t work.” So carbon wins again, and, who knows, maybe we end up with dioxyribonucleic acid all over again…
Just some musings on the universe.
Interesting that you chose that topic, over on Charlie Stross’ blog he jsut tried to do a thought experiment using unthinking human he called meat probes, to see how uninhabitable our planet is even now, let alone a long time ago when life was evolving. His blog is alwasys interesting.
http://www.antipope.org/charlie/blog-static/2009/10/how_habitable_is_the_earth.html#more
I hear echoes of Bren Cameron and some of the discussions he’s had over the years with the Atevi when I read this. 🙂
As a matter of fact eyes and ears, and a lot of other stuff too, has evolved in similar ways in different species so a venom is no great leap. Or that’s the way I look at it.
I mean both humans and lizards have digestive tracts and I don’t feel very lizardlike. Most days, anyway 😉
On the lizard-days I do think it’s a wonder life has managed to cling to this space-traversing ball of dirt and water at all. On my human days I’m sure there’s life all over the universe, and beyond.
A few years back, I did some back-of-the envelope work with a little organic chemistry and decided that, based on their probable biochemistry, the knnn, t’ca, amd chi were most likely plants.
oooh, I like that! 😀
Look how many times flight has already developed (or nearly developed, in the cases of ‘flying’ fish and squirrels).
This reminds me of a discussion I was having with a friend, a relatively newly frocked neuropsychologist. We were talking about the “null hypothesis”, what Science say is so when nothing has been proven yet. We have a lousy record picking null hypotheses! Earth is the center of the universe–no, Sol–no, the Milky Way–no…. We are constantly “chauvinistic”.
Carbon chauvinism I tend to buy, though. Life gets *everywhere*. Silicon is readily available. If silicon was useful, life would have evolved to use it–probably. The old view was plants and animals; now we have fungi, archaea, protists, algae–and even more candidates, the field being in flux. They use all kinds of energy.
Photo chauvinism is still in the process of fading. While the old life zone is gone, it’s been renamed by some the habitability zone. It’s still the same flawed idea that a zone around a star determines where life can occur. All that really matters is energy, and liquid water for life as we know it. (Carbon is ubiquitous.) It’s a myth that Earth gets its energy from the sun: mines get warmer as you go down–Earth is still cooling, thermally and radioactively, from its formation. Io has too much energy from tidal warming–too much for liquid water. What kind of energy can life use? From the Wikipedia article on Fungus:
“Traditionally, the fungi are considered heterotrophs, organisms that rely solely on carbon fixed by other organisms for metabolism. Fungi have evolved a high degree of metabolic versatility that allows them to use a diverse range of organic substrates for growth, including simple compounds such as nitrate, ammonia, acetate, or ethanol.[61][62] For some species it has been shown that the pigment melanin may play a role in extracting energy from ionizing radiation, such as gamma radiation; however, this form of “radiotrophic” growth has only been described for a few species, the effects on growth rates are small, and the underlying biophysical and biochemical processes are not known.[28] The authors speculate that this process might bear similarity to CO2 fixation via visible light, but instead utilizing ionizing radiation as a source of energy.[63]”
Yet, even when Europa is considered by many to be the best hope for current life in the Solar System, we stick to yellow star (F class) chauvinism. The brightest yellow stars last about as long as our sun has already. But Europa is getting its energy tidally from Jupiter, cosmically so tiny it’s not even considered a brown sub-dwarf. And like there are few great mountains but billions of grains of sand, every spectral class has many more stars than the next hottest class: F, G, K, M, L, T, and they’re considering Y brown sub-dwarfs, and those aren’t as small as Jupiter, which is over-powering Io and powering Europa.
Then there’s “We got the only planets” chauvinism. Everything in the Solar system of appreciable mass, Sol and the four Jovian planets, have gobs of stuff orbiting them. But the null hypothesis is that no planets exist until proven.
And day/night chauvinism. How easy would life have it in a tidally locked world like Europa! No temperature changes. Plants have to use sunlight by day and sugars–like animals–by night. Tidal forces, sure, but constant ones. No tidal zone where life has to adapt to drowned then dry. No seasons, so no hibernation needed.
Maybe we don’t get alien visitors because they’re used to a nice stable tidally locked planet, living off tidal warming instead of solar *radiation*, and they consider Sol such a long shot as a home for life, why look? Billions of more likely candidates exist!
In case anyone is interested, there appears to be a new ocean forming in Africa. Of course, it may take a million years or so to actually get to the “ocean” stage. Here’s a link to the news:
http://www.physorg.com/news176395329.html
And a picture of the new rift:
http://www.bgs.ac.uk/research/highlights/images/afarRift1Large.jpg
This is apparently 35 miles long, and appears to have happened in a matter of days.
I love geology! One of the things I enjoyed doing in Forge of Heaven was (literally) worldbuilding…in the timescale of a guy who’s capable of enjoying it. 😉
It always annoys me when I hear scientists say that life on other planets will be nothing like life here. To me, it’s just human arrogance that makes us think we are the only “humanoid” species in the universe. I say we’re not unique at all and that most sentient species we meet, especially from planets similar to ours, will be humanoid…but with different colours and bumpy foreheads. 😀
Diane Duane’s High Wizardry includes a silicon planet that is a giant super-computer, with layers of silica being distributed as volcanoes erupt and silicate comes sifting slowly down. I’m not sure why the tidal forces that make the volcanoes don’t also crack the layers and screw up the motherboard… but hey, it’s a pretty sweet idea! 🙂
Many,many years ago I learned that the oils of wintergreen and black birch are chemically the same. I assumed in my totally non-scientific reasoning that it was due to the path of least resistance.
James White’s Sector General books dealt with a huge variety of life forms of diverse chemistries. Enjoyable books if one could get past the gender chauvanism.
Speaking (writing?) of Forge of Heaven, is there any possibility of another? I love the idea of immortals as your principle characters.
If I could make a living from e-books, it would be a go—I really enjoy the characters. In today’s NYC, if a publisher has faded on a particular series no other publisher will pick it up, no matter how popular it’s been or could be. I got a window on what happens when I took some books to Ballentine: somebody (probably a Warner guy) started a buzz among the salesmen (who talk to each other) that these were books Warner had rejected: completely untrue, but that did it. It hurt them, and they didn’t get the distribution they should have. This is a small sample of what goes on in the book biz. Far from noble behavior. I write pretty fast, and one publisher can’t handle all the books—so I’ve played the field, so to speak, though I’ve often been told if I’d write fewer books and make them scarcer I’d make more money—but I write because I love writing, and enjoy writing different things, and that’s the situation.
So, you are one of those people, like Isaac Asimov, who can’t not-write?
Yep. I’m compulsive. If I weren’t a fiction writer I’d be one of those people writing volumes of letters to the editor of this and that newsservice. Or keeping a journal, or, or…
Oops! I did it again! *Principal* not principle!
The really tricky thing about convergent evolution is protein chirality- it’s a fifty-fifty toss-up which way your proteins spiral, so you could easily find a planet where everything looks perfectly Earth-like but you can’t digest a single thing. It’s rather convenient how rarely people run into this problem, but I suppose the book where Tully is captured by the kif and immediately starves to death would be short and boring.
Of course, if their DNA happens to spiral the opposite way you couldn’t get any viruses either, so I suppose there’s a trade-off.
We had a discussion a couple of months ago in my meteorite listserv about why life on earth is predominantly based on levulo-rotary rather than dextro-rotary amino acids. It was sparked by an article someone posted about aminos that hitched rides on incoming meteorites and comets during the first Heavy Bombardment period that gave us a lot of our liquid water; apparently for some physics reason they were biased in the direction of levulo- rather than dextro. As a result, we were skewed that way from the start 🙂
Personally I’m pretty amazed at all these alien species breathing an oxygen mix we humans can live with. Again, good – even necessary – for the story, but…
Downbelow/downers and the Mri planet of origin feels like outstanding exceptions in the genre. Because most often the sentient species of choice breathes just what we do, do they look like slugs or crabs or…
Now, I don’t demand provable science in my science fiction (I once had a rather hot discussion with a person who didn’t think SF books featuring FTL was SF but fantasy, as FTL is not possible even theoretically today) so it’s not a big problem. But it’s often the first thing I note – “oh wow, the humans can breathe without extra gear, AGAIN, how convenient” 😉
Hi CJ I have been along time fan and I’ve been lurking here for a while.
I am a chemist so I just had to comment on this.The point about other elements as a base for the biochemistry of alien life depends on the ability to form complex molecules which are also stable under the enviromental conditions experienced and have an evolutionary pathway to generate them in the first place. As an example, silicon has a group of compounds known as silanes which are less varied and less stable than the carbon equivalent alkanes. So carbon does seem to be the most likely bet, unless your speaking of designed artifical life forms.
To Spearmints point about Tully starving to death because his gut could not absorb any nutrient from alien food because of the non-terrestrial biochemistry. The first thing you do is feed him food pills which deals with I am allergic to alien peanuts/shellfish problem. This doesn’t solve the chirality problem, however when starving to death it is usually lack of carbohydrate that gets you. A human diet gets carbohydrate principly from sugars, which are chiral, and fats which aren’t although they are quite complicated so you couldn’t depend on being able to metabolise those.
This brings me to the point of this post. Idealy you would want to stick to a nice simple molecule. I propose ethanol (ethyl alcohol) although I not sure what the crew of the Pride would make of a male alien who is either drunk or hungover.