Wander1963 wrote:
First, let's be clear that the development of most different breeds of dogs isn't a result of natural selection, but rather human selection. Bloodhounds were bred to enhance and maximize their sense of smell. Bull terriers were bred to kill rats and, later, each other in pit fighting. Greyhounds were bred for speed; dachshunds were bred to pursue burrowing rodents; huskies were bred to pull dogsleds across miles of snow, etc. The list goes on and on.
And even more recently, many breeds of dogs have been bred to meet some "ideal" conformation at dog shows. For a while these "ideals" tended to create problems, such as the hip dysplasia in narrow-hipped German Shepherds. Fortunately, these damaging breeding trends have been recognized and are being walked back.
My point in bringing up dogs was to highlight the human influence on a species' development. If all the humans disappeared tomorrow, dogs would go feral. Many would die, but the tougher ones would survive. Great Danes might breed with German Shepherds, but not chihuahuas. We have artificially diverged dogs from their wolf origins into many breeds, and this is right on the edge of speciation - the point at which two populations cannot successfully breed.
(Having said that, I'd like to point out that many zoologists are now regarding speciation as an artifact of our human drive to classify and name everything. Back to dogs - the Great Danes can't breed with chihuahuas, but they can with a Labrador Retriever, which can with a terrier, which can breed with a chihuahua. So it's a spectrum, a continuum, in which one end can't breed with another, but both can with the middle.)
Darwin, in his Chapter 6, wondered about the lack of intermediate species - because he accepted the strict Linnaean classification of animals as separate species, though mutable through natural selection. We now have a bigger picture of life than was available to him, and we know that there are, and have been, many examples of intermediate species - especially across time. We can track the development of tyrannosaurs, for instance, from Daspletosaurus to Albertosaurus to T. rex - mainly an increase in size over the span of a few million years.
So Darwin's "missing intermediate forms" in many cases have indeed been found. If my hypothetical future paleontologist named Great Danes and chihuahuas as separate species of the dog family, based on their wildly divergent skeletons, the "intermediate forms" would be abundant.
First, let's be clear that the development of most... (
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So, in your dog example, what new genetic code info have humans introduced? Dog sperm and dog eggs, whether combined in the lab or naturally still produces dog babies. Different dams and sires may be chosen to accentuate different characteristics in the dog DNA, but you still get dogs every time.
I’m pretty sure that Darwin would not be satisfied with your dinosaurs got bigger, hence were a different species argument. Humans in the last 500 years got bigger, but are still humans. Largely this was due to nutrition changes - like in your finch example.
In all your examples you are confusing variations in kind, bigger dino’s & finches, dogs with different canine characteristics, with evolution. You have not answered my original question and shown me an example of one kind transforming into another kind as evolution requires.