----- Original Message ----- From: "Robert J. Chassell" <[EMAIL PROTECTED]> To: <brin-l@mccmedia.com> Sent: Sunday, September 25, 2005 3:58 PM Subject: Re: Brave New Genetic Frontiers
> > Off hand, I cannot think of a shorter sentence that includes all those > > concepts. > > > > It would be great if someone else can. > > To which Dan Minette said > > I think the question can be expressed. > > Is the natural tendency for a population to disperse in gene space > through random mutations (in the absence of a natural selection > induced focus in gene space) sufficient to explain the existence > of blind cave fish. > > That is an interesting way to ask the question. It certainly focuses > attention on populations over time. But why talk about a case which > specifies the `absence of a natural selection induced focus in gene > space'? Because I think that's what is happening. From what I've read in this thread, the blindness is not the result of the eye structure totally disappearing, but the result of a key component disappearing. Thus, the advantage in efficiency afforded by this small change should not be a key factor in it's existance. If it were, wouldn't the advantage of eliminating the rest of they eye cause those parts to disappear too. Rather, I think one can look at the genetic tendencies to blindness that exists in humans now. They are rare for good reason: until very recently (compared to the time needed for genetic changes) blind people didn't get to pass their genes along. Blind lions, blind deer, etc. are at such a disadvantage, we do not expect them to be able to pass their genes along. But, in a cave, blind fish can pass their genes along. With the elimination of the pruning of the blind, blind cave fish developed. > It is like talking about one of Newton's laws > > "force is the product of mass and acceleration" > > while overtly leaving out the concept of mass. Actually, it's like talking about the path of a rock wirled around on a string after the string breaks while overtly leaving out centripital force. > The answer to your question has to be: to get blind fish without > selection is improbable. Why? Why can't genetic drift explain the process? Dan M. _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
