Discussion about this post

User's avatar
Overcoming Bias Commenter's avatar

G, if you look at what organisms do, they take a wide variety of chemicals and find ways to convert them into a much narrower variety of chemicals first. Then they take these building blocks and build all the things they need. It kind of looks like a pair of funnels facing each other.

Simpler, earlier life presumably started with a much narrower set of precursors and built up a narrower set of products. We now have a system to build proteins out of amino acids -- tremendously flexible and efficient for enzymes etc. But strings of nucleic acids can make enzymes too. It would be simpler for life to start out as nucleic acids that didn't yet make proteins but only catalysed chemical reactions that let them reproduce themselves etc.

And we have had laboratory examples of RNA that reproduced itself in a particular environment, one that provides the precursors it needs. I argue that this is life.

Further, some vaguely similar environment is almost certainly where our kind of life started. A place that had lots of nucleic acids freely available and one where they spontaneously linked into chains, and some of those chains had random enzymatic activity, and then some started to reproduce themselves. This environment could have existed on earth -- but it's long gone now, everything that can be used has been re-used many many times since then. Or it could have been somewhere else. But it was probably nucleic acids that did it, and it happened in a place that had most of the building blocks handy and that needed almost no construction work beyond just a rather inefficient replication.

Expand full comment
Overcoming Bias Commenter's avatar

Douglas, g has a website and lists his e-mail address there.

Expand full comment
22 more comments...

No posts