Re: Scientific theory

In "Darwin's Dangerous Idea" Dennett repeatedly makes the point that you wont recognize a speciation even when it ocurrs in front of you.

Saint Bernard's and Chihuahuas could be the ancestors of the future line of the Chihuahua sp. and Saint Bernard sp. but that will not be evident for millions of years.
  ----- Original Message -----
  From: Don Winterstein
  To: asa ; bivalve ; Don Winterstein
  Sent: Wednesday, December 15, 2004 3:52 AM
  Subject: Re: Scientific theory

  For understanding evolution perhaps it makes little difference where one crosses the species boundary. It's more important to trace lineage than to pinpoint when an animal was no longer genetically able to breed with a descendant. Paleontologists still assign species names; but do they have adequate basis? And if they had good fossils of Chihuahuas and St. Bernards but none of mid-sized dogs, what would they conclude if they knew nothing about dogs other than what they learned from those fossils?

  Don

    ----- Original Message -----
    From: Don Winterstein
    To: ASA ; bivalve
    Sent: Tuesday, December 14, 2004 1:38 AM
    Subject: Re: Scientific theory

    Question: I understand you to imply that the definition of species involves any kind of "reproductive isolation." In your example, the isolation would be mechanical, not genetic. Presumably the definition would not include simple geographic isolation, even though geographic isolation is known to lead to new species. Correct?

    Don

      ----- Original Message -----
      From: bivalve
      To: ASA
      Sent: Monday, December 13, 2004 3:39 PM
      Subject: Re: Scientific theory

> And that kind of change is the sort of thing that these people have been told about and are interested in: "man from ape." Can you make dog variations seem relevant to someone who doesn't accept evolution? <

      It would probably help to have skeletons of various breeds to help visualize the magnitude of differences that have been created, since we are already familiar with and thus ignore the external variations. One aspect of particular relevance is the role of neoteny in both creation of certain dog breeds and of humans. Short-faced dog breeds resemble puppies of other breeds in their cranial proportions. Similarly, the relatively large brain to body ratio of humans is more similar to that of very young apes than adult apes.

      Another way in which dog variation may be brought to relevance is to point out that if we were to eliminate all the middle-sized dogs, there would be reproductive isolation between, e.g. chihuahuas and St. Bernards. This would create of separate species, something which is denied by some antievolutionists despite the many known examples.

          Dr. David Campbell
          Old Seashells
          University of Alabama
          Biodiversity & Systematics
          Dept. Biological Sciences
          Box 870345
          Tuscaloosa, AL 35487-0345 USA
          bivalve@mail.davidson.alumlink.com

      That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa
Received on Wed Dec 15 06:26:46 2004