Comment by TheSOB88 | Hacker News Reader

Comment by TheSOB88 | Hacker News Reader

Why people constantly stick to the idea that all possible organisms must have similar biochemistry to us is beyond me.

Think about it: Out of the humongous search space of chemicals, the ones we use happened to work for us. A combination of randomness and building on what worked before got us to where we are. Why should life not be able to use chemistry in completely different ways in order to replicate itself? Why are we so arrogant as to think that our design is the only design?

Edit: My point is that our ratio of "shit we know" to "shit we don't know we don't know" is infinitesimally small in the field of possible lifeforms' biochemistry. That is, we only know stuff very close to us on a cosmic scale; we effectively have blinders to all other possibilities. And there's already a lot of biochemical variation on Earth: To give some small examples, viruses don't even have DNA, and plants use less amino acids than animals.

The self-similarity of what we have so far can be explained, I think, by evolution. We all started out from the same point, so there's very little incentive to "reinvent the wheel" as it were. Only under extreme conditions like we have here, or the geothermal vents underwater, do we observe marked differences.

> Why are we so arrogant as to think that our design is the only design?

We're not. Nobody is. The reason scientists don't look for life on other planets that is made of other chemicals is that we may not be able to recognize that as life. It's much better - read, scientific - to look for something we can recognize.

Also, there are chemical properties of the elements that make up life on Earth that allow for fast reactions, bonding, etc. Most of the rest of the elements in the periodic table react more slowly in normal conditions, making the process for life less likely. Not impossible. Just less likely. We think.

So we focus on looking for what we know about. That's the best way to do it. Nobody worth their degree will ever claim that our "design" (bad word choice, by the way) is the only one.

I wasn't trying to address any bearing this has on finding alien life, just speaking theoretically - we shouldn't assume that everything should be like us. If it hasn't been your experience that most people think that way, then I must have misjudged.

I agree on the second paragraph, but especially the last sentence.

I know "design" is used by IDers, but what other word can adequately reference the incredibly complicated way our cells and bodies work?

Thanks for the response.

Use "structure", not "design". As in: "The human body's structure is...", not "The human body's design is...".

There is no need to use the word "design" to refer to the complexity of the human body. "Design" implies a creator; "structure" simply describes those aspects of the human body (or life in general) that makes it "work" and does not imply a creator.

So when Google uses A/B testing to improve their design, we should call it "web structure", not "web design"?

Human minds and evolution are both algorithms.

I agree with you that other life structures seem quite possible. I don't see the problem. But I'm not a professional biologists.

Still, it seems there are a number of biochemists who believe (or believed) that the structure of earth life could be unique. These people knew a lot more than me. So I wouldn't credit this to arrogance so much as a very complex question, one that doesn't necessarily get easier to solve the most data you get (at least on our scale of data).

I don't think it explictly comes down to such hubris. Certainly there are a lot of biases in this subject just like there are in any other ("rap isn't music," for instance), and human history is rife with analyzing the world in terms of the analyzer's perspective, the very definition of bias.

While replacing nitrogen in the air with, oh, sulfur, would likely have resulted in life forms (so the story goes) with an entirely different chain of evolutionary reactions and mutations, resulting in different body chemistry, yadda yadda yadda.

I do think it's news when we find out what one of these parallel evolutions might consist of. I mean, I'm not even sure sulfur-air would be a gas, so it's one thing to guess and speculate (fun), it's quite another to be able to say, in scientific fashion, "OK, what else is possible on this arsenic branch?" Said another way: there are a lot of grant proposals being written right now to finance exploration of this new territory. Hey, it beats paying for research into animals who produce petrochemicals as blood.

Who are people in this case? Most people don’t at all know what kind of life is plausible and not and they don’t care. I’m certain, however, that many biologists had an opinion on this prior to the discovery and I’m not really sure whether they thought that it was unlikely. For all we know most biologists expected this or a similar discovery, they just couldn’t yet assume it to be true because there wasn’t any evidence. Until now.

I think you might have confused unwillingness to talk about things we don't know with unwillingness to admit the possibility of things we don't know. Having some knowledge in common helps make conversations interesting. When two people talk about a possibility that's in the head of one of the participants, the conversation is unlikely to be on equal footing.

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