ET Should Look Familiar

[Ramo]

Was reading through the arXiv blog, and came across an interesting paper.

20 amino acids make up proteins on Earth. Experiments intended to approximate the conditions of early Earth replicated many of them (i.e. 10 of them in a classic Miller-Urey experiment). There are also ideas about interstellar synthesis, and a lot of the same amino acids are measured in meteorites.

A couple guys decided to rank the biological amino acids observed in these systems (principally the meteorites). This ranking was compared with the energy associated with formation (a thermodynamic potential called the Gibbs free energy) of these amino acids, under conditions resembling the Earth surface.

Sure enough, they agreed. Very well (see the attachment - the ranking is R and the potential is delta G). The order associated with the first 10 actually matches up almost exactly.

Quoting the paper:

Our results also indicate that a certain degree of universality would be expected in the types of organic molecules seen on other earth-like planets. Should life exist elsewhere, it would not be surprising if it used at least some of the same amino acids we do. Simple sugars, lipids and nucleobases might also be shared. Our analysis suggests that the first genetic code was a stripped down version of our present code, one whose simpler structure reflected the limited set of available amino acids in the prebiotic environment. Although there are countless ways that the code could have developed from those origins, the combined actions of thermodynamics and subsequent natural selection suggest that the genetic code we observe on the Earth today may have significant features in common with life throughout the cosmos.

http://arxiv.org/ftp/arxiv/papers/0904/0904.0402.pdf

[self biased]

there's also the theory of parallel evolution, that certain niches in the ecology demand certain shapes.

[DinoDoc]

[SlowwHand]

Ramo, you're getting as boring as Krazy Horse. That's bad, if you don't know it.

[Ramo]

[Krill]

Ramo, you do know that graph uses delta G when in sea water? So It is basically bollocks to use it in reference to ET.

[self biased]

that's okay ramo. next time i'm in austin, we'll hit sixth street and go hopping.

[Ramo]

I stated that (conditions resembling the Earth's surface). The point is it matches up to the meteorite distributions pretty well.

[Ramo]

that's okay ramo. next time i'm in austin, we'll hit sixth street and go hopping.

Definitely

[KrazyHorse]

Ramo: the thread title is completely misleading. Should read:

"ET Should Taste Familiar"

[Ramo]

Yep. Superman tastes like chicken.

[Berzerker]

I'd expect life to be very similar, but look at how varied life is right here. Certain conditions are required for at least advanced forms of life to evolve. I dont know that creatures like in the movie the Abyss could evolve in the seas of another planet or here), seas are much more stable and walking upright with opposable thumbs aint gonna help. It would appear to me life needs to be tough for critters to evolve to our levels. But evolution here has been jumpstarted several times, an asteroid wiping out dominant species like the dinos made room for primates to become relevant. That may have taken much longer or may have never happened without celestial intervention. We will find critters out there that look like rocks but we wont find silicon based rock life forms as in Star Trek

[Krill]

ET came from a comet?

[Ramo]

As Kitty alluded to, by "looking familiar" I mean a very small length scale.