When you think about aliens, you probably imagine a benevolent, ET style friend, or a gruesome, abdomen ripping monster. Or maybe you just imagine a small green man, or a blob of a space tyrant like Jabba the Hutt. But according to a new essay and podcast in PLoS Biology, we should care less about what these potential aliens look like, and more about what they're made of.
Gerald F. Joyce, a researcher at the Scripps Research Institute in La Jolla, California, has his own ideas about what we should be looking for when we search for life beyond our own.
In his essay, Joyce asks the question: "Why are we so confused (or so lonely) that we have such trouble distinguishing life from non-life and distinguishing our biology from another?" He's referring to the many times we've "discovered" new forms of life. Like when bacteria was supposed to be using arsenic to build life, or when researchers built a synthetic cell. None of these are new life, or different from the biology we know.
His answer is that it's hard to discover something we don't know how to look for. We only know our own biology. Which makes looking for things that are not like us very difficult. Even if we were to have something in our hands that was alien, how would we know it?
"A genetic system that contains more bits than the number that were required to initiate its operation might reasonably be considered a new form of life." If you're scratching you're head, it's okay, me too. Here's the breakdown.
Let's use life we know it as an example. Humans have a genetic system made up of four bits: the four base pairs, A, T (or U), G and C. Using those four base pairs there can be all sorts of combinations, and that's how evolution works. New life would have different bits, bits totally removed from our base pairs.
Joyce proposes two ways of new life forming. The first way is through chemistry. For that new life to form with its new bits, it would require what he calls a "bit generating system." So, for us, that was the primordial soup of chemicals around when the Earth was young. From there we got self-replicating molecules, and from that we could get evolution.
But the second way is through biology. What if a few chunks of Earthly life found their way to a distant planet? At what point does that life become alien? That's where the "more bits than the number that were required to initiate it" comes in. If the life on these distant planets still has four bits, let's say A, T (or U), G and C, it's not alien. If it has more, then it's biology is fundamentally different, and it is.
Okay, but Joyce isn't the first person to have an idea for what alien life is or isn't. Smart Planet's own John Rennie has a great, extended discussion of how we might find aliens. The SETI institute has been searching for over 25 years, and NASA has flip flopped on findings from several missions.
Other people argue that we're looking in the wrong place for extraterrestrials, or at least evidence of them. Rather than pointing our instruments towards the sky, Paul Davies at Arizona State University thinks we should be looking for footprints of those aliens here on earth, according to Space.com. What he's looking for is far from Joyce's bit-based system of evolution, but rather messages from those aliens or evidence of a Dyson sphere they might be using to trap the energy of stars.
And all this talk of aliens is also, apparently, quite telling about ourselves. Anthropologist Kathryn Denning studies how we look up, and down, and around, for aliens, and what that really means. She told Wired,
" I think one good example is the variable of L, the lifetime of civilizations, which dominates the Drake equation. [An estimate of the number of intelligent extraterrestrials that could exist in our galaxy.]
The speculation on this has been frankly goofy sometimes. I mean you can make up basically any value of L that you like and justify it in some way. So people say we should try to use Earth’s data to look at it. We should ask what really does cause civilizations to collapse or revert to a lower order of complexity or technological regime."
But Joyce, for one, recognizes that often the search for alien life is odd and troubled, and hopes humans can do it better. "I think humans are lonely and long for another form of life in the universe," he said in the press release, "preferably one that is intelligent and benevolent. But wishing upon a star does not make it so. We must either discover alternative life or construct it in the laboratory. Someday it may be discovered by a Columbus who travels to a distant world or, more likely in my opinion, invented by a Geppetto who toils at the workbench."
Image: C G-K, Flickr