[ExI] extropy-chat Digest, Vol 199, Issue 71

[Re Rose]

Nice comment Rafal, your post clarified what I glossed over - thank you!
 :)

I posited that systems tend to increase in complexity, but as you correctly
point out a biological system is not defined solely at the orgainismal
level (such as, yes, poor little male barnacles, eyeless cave fish and
toads, and even at the organ level such as the appendix, or at the DNA
level such as in acumulation of some of the "junk" DNA, etc) but also at
the ecosystem level. Individual orgamisims can and do adapt by simplifying,
as often this is biologically "cheaper" and thus advantagous locally (to
the organisim itself).

One of my favorite examples of this loss-of-function happening at the
biomoleular level is the Biebricher et al series of papers on Q-beta
replicase, a viral RNA-replicating enzyme that, when put into an
undemanding (i.e., nutrient rich, with no need to infect other cells to
reproduce), loses much of its structure due to a rapid loss of sequence
information as it undergoes multiple cycles of replication, as the
structural function (for replication) is no longer needed. I thnk its
fascinating that this enzyme loses so much information so fast - such is
the power of evolutionary adaptation!

best,
Regina


-----------------------------

Message: 6
Date: Wed, 29 Apr 2020 22:09:12 -0400
From: Rafal Smigrodzki <rafal.smigrodzki at gmail.com>
To: ExI chat list <extropy-chat at lists.extropy.org>
Subject: Re: [ExI] extropy-chat Digest, Vol 199, Issue 71
Message-ID:
        <CAAc1gFinsaP3mn_PqO6yRkYFdxEp4pwj_dHLe9Xpn7sB+zE1XQ at mail.gmail.com>
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On Wed, Apr 22, 2020 at 2:31 PM Re Rose via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> Ben - Great question! People have attempted to answer this over decades
> and along the way discovered transposons and "jumping genes". For the
> details you could look up the work of prof Barbara McClintock, also profs
> Andrew Pohorille (of NASA Ames) and Stuart Kauffman.
>
> Basic idea is that sub-systems of highly complex, hierarchical systems can
> split off and transfer from one system to another. Viruses are usually
> considered non living because they are obligate parasites and co-opt other
> organisims' metabolisms to propagate.
>
> So they did not evolve to be a simpler system. They evolved from
 complex systems as a sub-system, not as separate self-sufficient
organisms. They are not even metabolically complete - ie, they can't live
on their own, or replicate on their own, and instead depend utterly on
hosts.


### Dunno. There are multiple cases of animals and plants undergoing
dramatic simplification of their function during both phylogeny and
ontogeny. There are parasites that started out with having a nervous system and
then devolved to just chunks of flesh. There are sessile marine animals that
start out as free-swimming, active larvae and then radically simplify their
body, while usually increasing in size. Animals that lose senses after
moving to caves.

There is no general tendency for any given species to become more complex.
Depending on the situation, a species can evolve for more complexity or devolve
- and the actual course of evolution depends on the availability of ecological
niches adjacent to the niche currently occupied by that species.
For many species, the mutational catastrophe imposes hard limits on
available configuration space - they can't just build more complexity
because the speed of information loss due to random mutations exceeds
their ability
to accumulate new and useful (i.e. fitness-enhancing) information.

On the other hand, the ecosystem as a whole tends to become more complex - the
existence of one level of complexity (i.e. improved intracellular signaling,
improved DNA repair, targeted DNA mutation) opens the space to explore next
levels of development (respectively for the above examples, multicellularity,
long chromosomes, adaptive immune systems), and with enough species
available these new levels are explored, eventually opening even more
opportunities for building complexity. Some species evolve, some devolve
but the whole ecosystem (ecosphere) gets bigger and more complicated, at
least until the next asteroid strike.

Rafal
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