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

[Rafal Smigrodzki]

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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