On Aug 14, 1:06 am, John Harshman <jharshman.diespam...@pacbell.net>
wrote:

Friar Broccoli wrote:

On Aug 13, 8:38 pm, John Harshman <jharshman.diespam...@pacbell.net>
wrote:

K_h wrote:

Fermi's paradox suggests that there are little or no other intelligent
civilizations within the Milky Way galaxy.  On the other hand, intelligent
life should exist on a substantial fraction of planets with life because
natural selection broadly increases intelligence with time.

 .

Does it? News to me. What evidence do you have that this is the case?

 .

There has been an increase in the intelligence of a broad range of
species on earth with time.

Has there? What broad range, exactly? And if natural selection
broadly increased intelligence with time, we would expect all
species to be undergoing this push, wouldn't we?

 I don't see how this follows at all.  I would expect different
 species to adopt widely differing strategies depending on
 circumstances.  In plants, intelligence would be a complete
 waste of resources.  Others like Starfish and Jellyfish have
 used other strategies to ensure they can navigate and persist in
 their environments without needing intelligence.

 Brains are one method for allowing adaptive behaviour which in
 turn allows creatures to harvest an often wide range of
 resources, while avoiding a wider range of dangers in an
 increasingly complex environment. (Not all species need or use
 this strategy, just as not all use hard parts, or get really
 big or whatever.)

Yet we see that brains exist only in a small subset of species
within one restricted clade (Metazoa), and that, depending on
how you define the word, complex brains exist only in a small
subset of those (which I will choose to interpret here as
Cephalopoda and Gnathostomata), and that particular complex
ones exist only in a small subset of those (Aves and
Mammalia), and that only one species has human-level
intelligence, and from observing usenet, that only rarely.

It's hard to consider this a general trend. Similar results
could be achieved by random diffusion starting at a barrier,
with a great deal of variance in the intelligence of the
extreme tail.

 But you don't appear to be arguing a diffusion model.  When we
 had this same discussion (with respect to the broader measure
 complexity - of which intelligence is a subset) and I pointed
 out that trees had added complexity; you asserted that that
 increase had ended in the Permian.

 (that discussion was here:
 http://groups.google.com/group/talk.origins/msg/dd0e90c2d77de083)

 So you appear to be arguing that such characteristics pop (rather
 slowly) into existence and then remain static for the rest of
 time.  Your entire model bears an eerie similarity to an Old
 Earth Creationist model.  Are Pagano, Martinez, and Pitman
 starting to wear you down?

 And even if you are arguing a diffusion model it plainly
 doesn't fit some obvious facts:

 Assuming that brain size as shown in the fossil record is an
 adequate surrogate for intelligence (admittedly it is far from
 perfect):

 If we consider the starting gate for the dinosaurs was the
 beginning of the Triassic and the gate for modern mammals the
 beginning of the Paleocene then mammals today are
 proportionately at the Middle Jurassic, but the brain to body
 ratio of the average large mammal vastly exceeds anything the
 dinosaurs produced then or at any other time in their history.
 And with the exception of the Ratites we don't (as far as I
 know) see any large small-brained reptile-like land animals
 competing with us.

 Furthermore, our own recent evolutionary history in no way
 matches a diffusion model.  Something caused a spike in primate
 brain size about 15 million years ago, and then we saw an even
 more dramatic spike during the last 3 million years.  I know a
 few theories about what drove the latter spike, and while I
 don't have the slightest idea, which, if any of them are "true"
 it is clear from the abrupt change in slope of the curve that
 something was DRIVING that increase.

 Now returning to the specifics of which groups have done well
 in the brain game, it appears to me that we have enough data
 points to show an increase in brain size with time:

1- Metazoa/multicellars - begin with no nervous system
    Obviously intelligence depends on the development of
    multicellularity but that seems to be an inevitable outcome
    of evolution given enough time.  You said further down that
    it occurred at least five times.

 Brain development began in three separate lines of multicellular
 animal:

2a - Cephalopoda (squids, octopuses)
2b - Gnathostomata (jawed vertebrates)
2c - Arthropod (crabs and insects)

 Your paragraph above mentions aves (together with mammalia) as
 achieving exceptional levels of intelligence, but I know of no
 work suggesting that birds are smarter than crocodiles, or
 sharks (which have a brain/body ratio similar to mammals), or
 octopus.

 So in my book we see significant advances in intelligence in
 at least five group lines:

3a - Cephalopoda(squids, octopuses)

 And within Gnathostomata:
3b - Sauropsida/reptiles (Crocodiles)
3c - Chondrichthyes (Sharks)
3d - Aves (birds)
3e - Mammals (John Harshman)

 Since Sauropsida began evolving about 300 million years ago and
 Aves about 150 million years ago and modern mammals began
 seriously diversifying 65 million years ago, we know that the
 enhancement of intelligence (or its surrogate - brain size) has
 been more or less continuous since the Cambrian although
 probably not in all the reference groups over the entire
 period.

 So it seems to me that we have passable physical and
 inferential evidence for a steady increase in brain size and
 intelligence over time, as well as a plausible model
 (adaptation to an increasingly complex and competitive
 environment) to explain why it occurred.

 Once again, I will ask you for evidence that the self-evident
 and expected pattern is not (more or less) the one I am
 describing.  Can you do any better than:

   "I'm wary of claims that anything is self-evident, and
    attempts to push the burden of proof onto the negative."


 Cordially;

 Friar Broccoli
 Robert Keith Elias, Quebec, Canada  Email: EliasRK (of) gmail * com
 Best programmer's & all purpose text editor: http://www.semware.com

 --------- I consider ALL arguments in support of my views ---------