Re: [asa] three origin of life scenarios

From: Randy Isaac <>
Date: Wed Jun 10 2009 - 16:02:47 EDT

Excellent questions, Gordon. First, I think it should be clarified that,
despite Darwin's last paragraph in his book, the first life form would
probably not be a single or even a few organisms. Sustainability of life
needs a significant number of elements. If I get time, I hope to summarize
another good lecture from Hazen about that.
You are quite right about the tradeoffs between easy and hard for the
development of life. If it's easy it would happen a lot, if it's hard, maybe
never. We only know of one instance but would love to determine whether it
is one of many or the only one.
One option that must be considered is that a spectrum of primitive life
forms may have existed but then became either unstable and/or food for later
life forms. In other words, other life forms might have originated but be
lost without a trace. Just like species can become extinct without a
descendent species, life forms could have done the same. Much information is
likely to be lost forever but we still learn a lot by searching.

----- Original Message -----
From: "gordon brown" <Gordon.Brown@Colorado.EDU>
To: <>
Sent: Sunday, June 07, 2009 11:37 PM
Subject: Re: [asa] three origin of life scenarios

> This is not a response to any particular posting, but it is related to the
> origin-of-life question. This is far from my field, and so I welcome
> experts' corrections of my misunderstandings.
> The search for extraterrestrial life involves looking for earthlike
> planets. Apparently it is assumed that with similar chemistry and size and
> orbital characterisitics about its star and maybe a few other properties,
> life would have evolved there. Even though we can't yet show how that
> first one-celled organism arose on earth, it is assumed that since it
> happened and happened early in earth's history, it must have been easy.
> Now, as I understand it, evolutionary theory involves common descent of
> all life from that first organism. Correct me if I am wrong about that.
> Does the existence of one organism that arose in this way prevent other
> organisms arising independently in a similar way, rather than all having
> to be descendants of the original one? If not, then if it happened only
> once, that would make it seem that the origin of life is very hard and not
> so easy as the searchers for extraterrestrial life hope.
> Gordon Brown (ASA member)
> To unsubscribe, send a message to with
> "unsubscribe asa" (no quotes) as the body of the message.

To unsubscribe, send a message to with
"unsubscribe asa" (no quotes) as the body of the message.
Received on Wed Jun 10 16:03:19 2009

This archive was generated by hypermail 2.1.8 : Wed Jun 10 2009 - 16:03:19 EDT