Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site rti-sel.UUCP Path: utzoo!watmath!clyde!burl!ulysses!gamma!epsilon!zeta!sabre!bellcore!decvax!mcnc!rti-sel!wfi From: wfi@rti-sel.UUCP (William Ingogly) Newsgroups: net.sci Subject: Re: darwinism Message-ID: <268@rti-sel.UUCP> Date: Tue, 25-Jun-85 17:41:53 EDT Article-I.D.: rti-sel.268 Posted: Tue Jun 25 17:41:53 1985 Date-Received: Fri, 28-Jun-85 00:36:53 EDT References: <783@oddjob.UUCP> <34@escher.UUCP> Reply-To: wfi@rti-sel.UUCP (William Ingogly) Distribution: net Organization: Research Triangle Institute, NC Lines: 67 Summary: In article <34@escher.UUCP> doug@escher.UUCP (Douglas J Freyburger) writes: >1) Humans have very long lifespans compared to other >creatures (mammals) of similar mass. ... > Anyways, since >humans live very long, and since brain cells stop >replicating very early on in most (all?) mammal species, we >need the extras so our elders don't get feeble quickly. >Then, having experienced elders as knowledge stores, tribes >with the trait tended to survive better. ... This argument is based on the assumption that natural selection operates on the group level. Several people in the evolutionary science community were pushing group selection a few years back. As near as I can remember, group selection fell out of favor because there are some serious, fundamental problems with it except in certain very restricted cases. It seems that selection at the group level is simply a bad argument in many cases. Perhaps someone else who's been a little more active in the biological field can expand on this ... >2) There could be some sort of "critical mass" >required for a typically human task, like complete >language, or tool making, or something. I know there are >arguments of what a "typically human task" is, but you >still get the idea. I've used Z80 and Vaxen before, and >there are programs that simply can't be run on the smaller >machine's address space. It could be a similar situation >with humans versus orangutangs. I don't think the number >of neurons is linear with brain mass or volume, or that its >linear with processing power either. Still there might be >some sort of threshhold involved. And that we evolved big brains because we needed to pass this threshold for survival? The problem here (if I'm understanding your argument correctly) is that natural selection has no idea where it's going. You seem to be saying that human brains are big because we need them big to be human. This would seem to be a circular argument, or one that fails to understand how natural selection works. >3) The specialization of the human brain involves most >of its mass being in the cerebrum (the part on the top if I >got the name wrong). That part is a new invention in >evolution. Since it is so new, it is probably done >brute-force. Other creatures have had plenty of time for >their systems to be incrementally optimized by evolution, You're viewing Mother Nature as a rational designer, and she's not. Take The Easy Way Out and If It Ain't Broke Don't Fix It are her mottos. A complex system arises incrementally, through a lot of microchanges according to one view. The punctuationalists, on the other hand, believe that large changes can happen all at once via certain "controller" genes (that may be the wrong term). For example, some evolutionists have suggested that we humans look the way we do because we're neotenous primates. That is, we've lost the genetic equipment to make us 'grow up.' Take a look at a picture of an infant chimpanzee and compare it to an adult chimp. The infant chimp has a LOT of human-like characteristics that are lost in the adult. Consider, also, that young humans and young chimps learn at approximately the same rate until a certain point (I think around the age of two), then the chimp falls behind. The implication is that a controller gene has kicked on in the chimp, now on his way to becoming a dull adult. This hypothesis claims that we're human because we never grow up! -- Cheers, Bill Ingogly