From newshub.ccs.yorku.ca!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!rpi!think.com!spool.mu.edu!munnari.oz.au!uunet!mcsun!uknet!edcastle!aifh!bhw Thu Dec 26 23:57:32 EST 1991
Article 2312 of comp.ai.philosophy:
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>From: bhw@aifh.ed.ac.uk (Barbara H. Webb)
Newsgroups: comp.ai.philosophy
Subject: Re: Scaled up slug brains
Message-ID: <1991Dec20.164840.4658@aifh.ed.ac.uk>
Date: 20 Dec 91 16:48:40 GMT
Article-I.D.: aifh.1991Dec20.164840.4658
References: <12708@pitt.UUCP> <44970@mimsy.umd.edu> <1991Dec18.071959.4921@daisy.ee.und.ac.za> <45103@mimsy.umd.edu>
Reply-To: bhw@aifh.ed.ac.uk (Barbara H. Webb)
Organization: Dept AI, Edinburgh University, Scotland
Lines: 21

In article <45103@mimsy.umd.edu> harwood@umiacs.umd.edu (David Harwood) writes:

>In article <1991Dec18.071959.4921@daisy.ee.und.ac.za> mclarke@daisy.ee.und.ac.za (Matthew Clarke) writes:
>>(*) By "no problem" I mean no philosophical problem, there is of course the
>>empirical problem that brain complexity of various animals does NOT form a
>>continuum, but a discrete series with some (rather large) holes.

>	Eg - some animals have color vision. There is no evolutionary
>"scaling-up" of nervous systems with eyes having 1 pair of cones, 2 pair,
>3 pair, ..., N pair. No- they have genetically coded "color vision"
>cells and "circuitry", or they don't.

This doesn't seem like a good example: something like 1% of human males
have only two cones (not the usual three) due to a genetic difference
(have you ever heard of colour blindness?).
There are people who have only one cone (I have seen experimental reports on
such a subject). Turtles (and possibly some other animals) have four
cones. Colour vision is certainly not "all or nothing" in the natural
world.

B.W.


