>You must define all the terms you use. Newton already knew that things evolve. The question is how much they actually did. We can tinker with existing things and nature may do the same, but how much change is possible or allowable? We can get gold out of lead, but can we get cats out of dogs?<
Why try to ruin a perfectly good dog?
Seriously, both cats and dogs are relatively specialized for particular approaches to carnivory. Thus, there is little opportunity for an aspiring dog to become more catlike in the face of existing competition. However, some of the foxes take a more cat-like approach to hunting than do wolves. Conversely, the cheetah has some unfeline aspects. If you eliminated all cats and catlike predators from an island that previously had them, introduced dogs (if they were not already there), and waited a few million years, you would probably get some catlike dogs.
Part of the problem is exactly what do you want in order to qualify as a cat for the final product. South American and Australian marsupials independently produced cat-like forms, such as the marsupial lion of Australia and the sabertoothed marsupial cats of South America. However, these are not true cats, and the last of the South American forms seem to have been outcompeted by true cats upon their arrival after formation of the Panamanian isthmus. However, none of these produced anything that might be mistaken for a domestic cat by any competent observer.
The fossil record and molecular systematics indicate that cats and dogs are on two separate branches of the carnivore tree. Thus, neither gave rise to the other. Instead, both have a common ancestor in the form of a primitive carnivore. A textbook on vertebrate paleontology (mine are all boxed up and at home) will provide more information about primitive carnivores and transitions from them towards cats and their relatives, on the one hand, and dogs, bears, and kin on the other hand.
Dr. David Campbell
46860 Hilton Dr #1113
Lexington Park MD 20653 USA
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 Droigate Spa
Sent via the WebMail system at mail.davidson.alumlink.com
This archive was generated by hypermail 2b29 : Fri Oct 12 2001 - 14:17:50 EDT