From: steinly@topaz.ucsc.edu (Steinn Sigurdsson)
Newsgroups: sci.environment
Subject: Re: A Technomaniac Position (was: Worse case scenario)
Date: 9 Apr 92 11:02:58 GMT
Article-I.D.: topaz.STEINLY.92Apr9120258
	<17823@oasys.dt.navy.mil> <1992Apr9.085854@IASTATE.EDU>
Organization: Lick Observatory/UCO
In-reply-to: danwell@IASTATE.EDU's message of 9 Apr 92 13:58:54 GMT

In article <1992Apr9.085854@IASTATE.EDU> danwell@IASTATE.EDU (Daniel A Ashlock) writes:


      I see the debate over synthetic biodiversity has sprung up again.  It
   strikes me that the people who claim the level of lost biodiversity in the
   tropics is approaching a critical level might be right, certianly there is
   cause for immediate concern and action.

      The combinatorial argument that we cannot find extinct spiecies by synthesis
   was correct in spirit; Assume a spiecies has 10^6 (an underestinmate in many
   cases) base pairs in a four letter alphabet.  This gives us 4^(1,000,000)
   possible combinations.  Even with efficent pruning of nonsense this is too
   much.

I bowed out of this debate when it flared a few months ago because I
was too lazy to do the combinatorics, but you have to be careful here.
Consider for example humans, there are a known 10**10 variations on
the human genome, all of which produce a recognisable human, further,
I claim you can mix and match any pair of 5*10**9 humans in one of
several million ways and produce a recognisable, distinct human!
You're now starting to divide by pretty big numbers! ie the genome
is relatively robust to variations. This also only explores a limited
fraction of the conceivable variations. You can perturb to some extent
particular genes, away from the human norm, thus human haemoglobin
is distinct from animal haemoglobin but I know of no proof that some
variation on some other species haemoglobin would not work in humans,
but be different enough not to be accessible by perturbing the human
norm, further, other proteins exist which can carry oxygen and co_2,
allowing potential qualitative changes while retaining the
functionality, although then you would most certainly need to start
restructuring the entire organism.
	Further, for ecological purposes, you need particular
functionality, not a phenotype or a genotype, and while the
functionality certainly arises in nature by coevolution, a designed
species might be squeezed into a particular niche, although this is
most likely to lead to "unforeseen side-effects" :-) 
	It should further be noted that you are not going to be
making a random patterning of the genome, but most likely perturbing
and splicing from known species, this is of course one argument for
the value of biodiversity, use the hard work nature has already done!
And again, you will have some structures known, for example you're not
going to include a O_2/CO_2 carrying protein by random search, you
slot in your favourite haemoglobin variation... also, if we start to 
understand how the damn thing works, we may be able to exclude a large
fraction of genome space a priori, knowing it will give garbage for
the purpose intended.
	This still leaves a very hard task, maybe impossible in
practise for any conceivable technology, but the combinatorics
presented so far do not (IMHO) _prove_ it. I still agree that it
is not prudent to rely on this being possible though, and that
biodiversity should be retained to the extent practicable and
neceesary.

      If one wanted to take a technomaniacal position one should ask about the
   practicallity of rebalancing a damaged ecology with available genetic
   information.  The idea is this; with genetic engineering you can mix and match
   traits accross spiecies boudries.  This means that ten spiecies with five
   useful traits could yield 2^50 (powerset of 50 traits) different potiential
   spiecies for repair building blocks.  Since there is an unbelievable
   investiment in sequencing and the _decoding_ the sequences of a spiecies the
   number of spiecies available for use in this this tinkertoy approach will be
   small.  Likewise, most of the combinations will be impossible leaving only, say
   2^20 spiecies ~1,000,000 from the ten spiecies I mention.

      The above, while still science-fictional, is still much more reasonable 
   than attempting to rebuild extinct spiecies with search heuristics :-).

Yup, still, speculation about the impossible can be fun ;-)
at least for those of us with a sense of humour...


|  Steinn Sigurdsson	|Strong and warm and wild and free  		|
|  Lick Observatory	|Your laws do not apply to me                  	|
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| "standard disclaimer"	|We can be what we want to be      - B.B. 1991	|