Are aliens little green men of unpredictable motives? Horrible insect-like face-hugging, chest-exploding monsters? Are they super-smart, super-slimy, super-fishy, body-cavity-probing, disc-flying creatures, searching for planets to colonize and people to destroy as Stephen Hawking warned, or are they something much more mundane? Could there be alien life already on earth, too microscopic, too different to notice? Could life on earth have been seeded from an alien land, with secret messages encoded in our DNA? We've been scanning the sky for extraterrestrial radio signals for years, should we have been scanning the earth for chemical traces of alien life instead? As Stephen Hawking said, "the numbers alone make thinking about aliens perfectly rational," so let's think a little about aliens and the search for alien organisms on earth.
A recent New York Times article asks if there are aliens already living on earth and we just haven't been looking hard enough to find it. In this case, alien doesn't necessarily mean this other life is from another planet, but the existence of a different form of life on earth would point to a higher possibility of a different kind of life starting up somewhere else. All life found on earth uses DNA and other common metabolic currencies, rooting the tree of life to a single common ancestor. If life arose multiple times, only our DNA-life won--unless there is a second biosphere that we just haven't found yet:
The denizens of the hidden "alien" biosphere -- let's call them Life 2.0 -- might employ radically different biochemical processes than the life we know and love. Microbiologists could easily have overlooked their existence, because their methods are focused on the biochemistry of standard life. Obviously, if you go looking for A, you will find A and not B.
There is a small group of scientists called astrobiologists now searching extreme environments on earth for clues about alien life. They search hot springs, undersea volcanic vents, and other inhospitable (except to some extreme but otherwise "normal" organisms) environments in search of organisms with different metabolisms, microbes that use arsenic instead of phosphorous or microbes that use mirror-image versions of common metabolites. If different kinds of life can coexist on one planet, each adapted to their own extreme niche or even sharing a single ecosystem, the prospects for life on other planets becomes magnified.
Others have suggested that not only could there be other alien forms of life on earth, but that all life on earth was seeded by an alien race, our nearest common ancestor landing on earth on a meteorite or dropped off by a spaceship. This concept, called panspermia, is not a new idea, but has been more recently advocated by the renowned biologist Francis Crick, who wrote a paper in 1973 hypothesizing about the kind of spaceship that would have brought life to earth, piloted by an alien race seeking out planets to terraform and replace their own dying planetary ecosystem (PDF).
Later that same decade, as molecular biology and sequencing technology improved, others investigated whether DNA sequences of earth organisms held encoded messages from aliens (ok, you would think that Francis Crick writing about spaceships would be the craziest part of this post but this is where the "rational" part of "thinking about aliens" really breaks down). Nick pointed me to an interesting article written in 1979 asking "Is bacteriophage ÏX174 DNA a message from an extraterrestrial intelligence?" The authors hypothesized that super-smart aliens could have sent messages to us in the form of a virus that infects one of the bacterial species common in our gut (E. coli). They noticed that one of the few proteins encoded by the phage genome had 121 amino acids, and as this is the square of 11--a prime number--they tried to decode the protein sequence into a binary color system looking for recognizable shapes in the 2D grid (the figure on the right shows a few attempts).
As they conclude in the article: "Unfortunately, no significant pattern was observed on the arrays so far examined. However further speculation is irresistible." Could our DNA really be a message from space? Could we someday encode messages to aliens in DNA that we leave behind somewhere else? Perhaps the most interesting and prescient aspect of this wacky study is the idea that sometime soon after it was written it would be possible for humans to synthesize large swaths of DNA and encode whatever messages we want in it. Already scientists have synthesized the genomes of viruses and bacteria, with the synthesizers' "signature" encoded as part of the sequence. Others are taking this idea even further--experimental poet Christian Bök (who first tweeted the link to the alien phage article) is working on a poem encoded into a synthetic strand of DNA. Perhaps someday in the future super-smart aliens will find these sequences and learn a little bit about us.
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"Could our DNA really be a message from space?"
While one obviously can't rule it out that seems like a pretty silly way to send a message. Though perhaps there's a knowledge gateway built in - once our understanding of bio-chemistry/protein reaches a certain level the message will leap off the page.
Once our understanding reaches that level presumably we'll also be able to figure out how the message was able to remain uncorrupted through millions of DNA replications.
Aliens are slimy biofilms making wet space rocks scuzzy. They don't achieve metazoan-like organization or if they do, they destroy their biosphere & go extinct.
@noastronomer
Code it into DNA helicase or one of the ribosomal rna subunits or something along those lines for the best chance of long term fidelity :p
This is ridiculously silly. The mutation rate of phages means that any message would disappear long before anyone became smart enough to notice it. That alone completely precludes any sort of "message" from being "sent".
I rest my case: the default mode of the human brain is magical thinking.
I think we have a kind of myopic lens in this arena. I have heard many of these speculations, (not so well documented as here). Can intelligence be active on a so large a scale it does not fall within our scope of consideration. Looking at the Gaia hypothesis, it sounds like a big plant or microbe maybe. Some speculate that the internet may become conscious at some point. But have we ruled out the possibility that the internet is an emerging organ in a larger and intelligent entity? How would one recognize larger scale embodiments of intelligence? Would it manifest in ways we could recognize? What if its "thinking" and speaking took place over time scales we don't recognize?
Most of this area is extremely silly, besides the "stable DNA" coding idea. But first a potential nitpick: the more modern term "transpermia" seems to have taken over.
For some reason or other we all share a UCA population. Not only because DNA and metabolic chains are shared, but because of phylogeny: very recently Douglas Theobald tested this by modern methods to the likelihood being 10 to the 2,860th power in favor based on proteins (IIRC). That is a _pretty impressive_ test!
This falsifies bacteriophage ÏX174 DNA as an outside originating "message". But it also by now comfortably falsifies non-UCA life, whether it was originated before the tested protein set (or our common codon set, for that matter), or not.
There are other problems with this of course.
- Evolution means competition between alleles, which is presumably why eternal biological entities aren't commonly observed. Nor would we expect "sharing a single ecosystem", since transpermia entities aren't adapted at all. They will be mercilessly out-competed.
On a related note, this bottleneck would make problematic the idea that observing, or not, "a different form of life on earth [that] would point to a higher possibility of a different kind of life starting up somewhere else".
If evolution is effective and robust, and our long lived UCA biosphere tells us so, we wouldn't know from observing a single UCA how large the original starting possibility was. Many potential UCA populations could have existed, in series or parallel. Conversely, if we would happen to observe a few non-UCA populations, we would mostly know that early evolution isn't as effective as presumed.
- "Extreme niches" or metabolisms aren't conducive for pro- or protobiotic processes and populations. So the likelihood for life originating here, instead of "transpermiated", is scant.
- Eukaryotes but also bacteria must handle "mirror-image versions of common metabolites" or likely die, since AFAIU once in a blue moon molecules mirror flip by quantum tunneling. Also, they have become quite adept to utilize the different biological reactions to mirror molecules, so we have several examples in our own body.
Apparently this has been an active area of medical research since the 2000, because you can find whole books about all the enzymes cells use to do this and their deep ancestry.
Transpermia is a testable hypothesis, but without observation it remains an unsound area. And it shows.
Which is why, I believe, enantiomer excess solutions go racemic over time. QED. :-)
I agree with Ellen. The idea that phage are some code written in DNA is absurd. Because, whatever the message was/is, it's long gone.
But - also - why is the leap made from panspermia to intelligent life contacting us?
Panspermia may just be seeding planets with things like amino acids that were formed in space. Like those amino acids recently found on a comet. This video discusses these new findings - http://bit.ly/9TjANi
On a side note - the guy who is writing a poem in DNA is clearly unreal!
Basically the nervous system works like this.
We have eyes that collect photons, which result in 2 little upside down images, uncolopred, with no depth, upside down, and less than 1/8th of an inch. Yes, this is what we actually get from the exterior world when it comes to vision, this petty, small, ridiculous information. From the Retina on out its action potentials coding everything, sorting wavelengths to color, creating depth, and putting it together.Numbers work similarly, there are probably nerve cells devoted to each number, as we already know this is the case for faces. (Numbers are a property of the brain completely, this is is a separate lecture)
We also know things like 'circles' 'ovals' etc. ie what we know as shapes ..are really us â the conscience human â just describing the properties of shape shells deep within our brain cell jelly â they are completely inherited and arbitrary. We should focus more on the parabola than the circle, it is more beautiful to me ( side note: Part of the illusion and mystery of the number pi â that old variable
Which has haunted humans from Aristotle to Russell.. the circumference to any diameter is 3.14.. is really just describing the properties of circle cell recognition we've inherited⦠if the shape cell was 3.24.. it would be this. Neat huh?)
The theme for idiots:
What I'm saying is in order for some 'intelligence' to exist which has created and tinkered with our dna, they must have a similar nervous system, perhaps see in similar wavelengths, have similar face/number recognition systems, have similar auditory cues, etc. Hell, the idiots who have posted before me donât even realize that what allows our whole nervous system is the gradients we lived in from the Cambrian sea! This is what even allows a nervous system to begin with! (Sodium Potassium) That's not going to happen. An âextraterrestial intelligenceâ is slang for idiocy clocked in authority due to some prolonged concentration in one field in science, which happens not to be the nervous system.
What's upsetting to me is my heroes, like Carl Sagan, getting it wrong when they search for extra terresetial intelligence. The 'great intellectual leap of our generation will be the realization that intelligence is all around us - that intelligence is just some made up word for the enigma as to how we compute and sense and perceive things, and that other organisms have this same system.
There is intelligent design in the microbes floating in one of the oceans of Saturns' moons. The E Coli in our Anus have their own heirarchies! This was the theme of Carl Zimmerâs E Coli books! For God's sakes, that to me is more intelligent than someone altering our own dna from another planet.
How more wonderful and interesting is the world, when we realize that as you and I read this blog, some hot shot in our anus is running around with a microbe rome, communicating and doling out responsibilities.
What a beautiful and amazing earth we live in.
I always thought it was interesting that Linus Pauling peddled the transpermia idea
I wouldn't be surprised if that is correct... I think Huygens -"so many suns, so many worlds" - had a similar idea.
I wouldn't be surprised if the 'life machinery' is embodied in some other molecule setup that isn't carbon..
Anyway, Chrsitina, take my post above further, there's debate now (Nature?) over nociceptors in fish, and whether or not they feel pain. There's no reason why (this a great thought idea) that pain sensory systems from another animal can't be hooked up to a human, this would allow humans to really feel finally what it's like for the dog to have to hold in her pee at 8am while the owner sleeps. I know "this seems a lot like fiction" - but the possibility is there.
you don't know the aliens are not like dinasour
I always thought it was interesting that Linus Pauling peddled the transpermia idea
I wouldn't be surprised if that is correct...