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On 30/04/2020 06:04, Rafal wrote:<br>
<blockquote type="cite"
cite="mid:mailman.5.1588223053.2039.extropy-chat@lists.extropy.org">
<div dir="ltr" class="gmail_attr">On Wed, Apr 22, 2020 at 2:31 PM
Re Rose via extropy-chat <<a
href="mailto:extropy-chat@lists.extropy.org"
moz-do-not-send="true">extropy-chat@lists.extropy.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="auto">
<div dir="auto"><span
style="font-family:sans-serif;font-size:12.8px">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. </span></div>
<div dir="auto"><span
style="font-family:sans-serif;font-size:12.8px"><br>
</span></div>
<div dir="auto"><span
style="font-family:sans-serif;font-size:12.8px">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.</span></div>
<div dir="auto"><span
style="font-family:sans-serif;font-size:12.8px"><br>
</span></div>
<div dir="auto"><span
style="font-family:sans-serif;font-size:12.8px">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.</span></div>
</div>
</blockquote>
<div><br>
</div>
<div>### 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.</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
<div>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.</div>
<div><br>
</div>
</blockquote>
<br>
The virus example may be arguable, they are rather bizarre things
after all, but as Rafal points out, there are plenty of examples of
metabolically complete organisms evolving less complexity.<br>
<br>
But ecosystems, or at least the ecosphere as a whole, tending toward
more complexity is an interesting idea. If true (which it seems, at
first glance, to be), then evolution <i>does</i> produce more
complexity. That's something I've never considered before, and I'm
wondering what the implications of it might be.<br>
<br>
<pre class="moz-signature" cols="72">--
Ben Zaiboc</pre>
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