[ExI] Complexity and Evolution (was extropy-chat Digest)

Tomaz Kristan protokol2020 at gmail.com
Thu Apr 30 14:54:00 UTC 2020

>  large mammals that colonize islands tend to undergo dwarfism

One counterexample:


On Thu, Apr 30, 2020 at 3:48 PM John Clark via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

> On Wed, Apr 29, 2020 at 10:13 PM Rafal Smigrodzki via extropy-chat <
> extropy-chat at lists.extropy.org> wrote:
>> *> 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.*
> True.
>> *> There is no general tendency for any given species to become more
>> complex. *
> Well there is Cope's rule, the general tendency of species to get larger
> over geological time, although I'm not sure larger size and more complexity
> is necessarily the same thing. And there are exceptions to Cope's rule,
> large mammals that colonize islands tend to undergo dwarfism, the fossils
> of Elephants the size of ponies have been found on the islands of the
> Mediterranean. But although the average may decline I do think the most
> complex species in one age is more complex than the most complex creature
> in a previous age, at least usually.
> *> On the other hand, the ecosystem as a whole tends to become more
>> complex*
> I think a good example of that would be the Carboniferous Age that started
> 359 million years ago and is where most of the oil, gas and coal we use
> today came from. Evolution had just figured out how to make Lignin, an
> organic polymer that gives wood its strength, and so it was the age of huge
> trees. There was probably more tonnage of living material during the
> Carboniferous than any other time in Earth's history, and as a result of
> all that photosynthesis the oxygen level in the air was about 35% versus
> 21% today; and so you could have 9 foot millipedes, dragonflies the size of
> falcons, and 18 inch long cockroaches.
> But Lignin is very tough stuff and nothing had yet figured out how to
> break it down, so when a tree died it didn't rot and, apart from some
> massive forest fires, the carbon in the dead trees didn't return to the
> atmosphere as CO2 and instead got buried and just piled up. Eventually
> after 60 million years a few species of fungi did find an enzyme that could
> break down Lignin, and so the Carboniferous Age ended 80 million years
> before the first dinosaur evolved. But by then there was a huge amount of
> inaccessible carbon in the ground, inaccessible until Homo sapiens came
> around.
>  John K Clark
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