Re: Evolution and other planets

From: deowll (deowll_at_bellsouth.net)
Date: 12/29/04 

Date: Wed, 29 Dec 2004 06:09:01 +0000 (UTC)

"Malcolm" <malcolm@55bank.freeserve.co.uk> wrote in message
news:cqo24m$1pp2$1@darwin.ediacara.org...
>
> "Perkowski" <perkowski1@optonline.net> wrote
>>
>> If life can possibly exist on other planets that are similiar to Earth,
>> what are the chances of animal and plant life on those planets following
>> the animal and planet life here on Earth?
>>
>> For example, could a planet somewhere in our galaxy be the home
>> of past creatures like the dinosaurs that appeared here on Earth?
>>
>> All things being equal, would animals/plants on other world follow
>> the same evolutionary map that animals/plants on Earth do?
>>
> The problem is that we don't have another example of a life-bearing
> planet.
> So any answer must be highly speculative.
>
> Organisms on earth are dividied into prokaryotes (bacteria) and
> eukaryotes.
> Eukaryotic cells are much more complex, and seem to have formed from
> several
> cells living symbiotically.
>
> One of the features of eukaryotic cells is that they contain mitochondria,
> which produce ATP, which is used by all cells on Earth as their primary
> energy source.
>
> Now it is hard to believe that cells from other planets would also contain
> mitochondria. It is easier to believe that they would use ATP as energy
> currency, but even that is difficult to determine.
>
> All multicelular organisms on Earth are eukaryotes. It is not really
> understood why that should be, and some bacteria do appear to have a
> certain
> amount of social life, and be partway to multicellularity. Until we
> understand what it is about eukaryotes that leads to many of them becoming
> mutlicellular organisms, we cannot really give an answer concerning the
> possibility of mutlicellular life on othe planets. It may be common, it
> may
> be extremely rare, it may be that some other system that is analogous to
> neither multi-celled nor single-celled terrestrial organisms is in fact
> the
> norm.
>
> As for whether the animals would look anything like vertebrates, almost
> certainly not. Science fiction movies you see with aliens like lizards,
> clutching laser guns that look more or less like modern assualt rifles,
> are
> showing a serious lack of imagination.
>
>
So you think that the life forms of Earth have unlikely and nonfuctional
designs? That is abserd. Selections kills the poor designs. One reason new
broad catigories of life aren't showing up is that only so many designs work
well. An awful lot of what stands a chance of working can be found in the
fossil record.

It is also true that once a phlya shows up other options are preempted. We
could have had jaws that work from side to side but so what?

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