jim stone wrote:The essential claim is that evolutionary theory (and associated mechanistic explanations) cannot account for two things--the emergence of new species and the emergence of life itself.
There's nothing particularly mysterious about th emergence of new species. (Unless you deny that mutations occur, in which case you have to explain why there are so many breeds of dogs.)
In the first place, there's nothing mysterious about species membership. Virtually every biologist now uses Ernst Mayer's definition of a species as a group of individuals who can (and do) interbreed and produce viable, fertile offspring. All that's needed at the molecular level to produce an individual that doesn't interbreed with its blood relatives is a mutation that affects sexual behavior.
However, the first thing to know is that speciation always involves some kind of reproductive isolation of a portion of an original population. This is most often geographical isolation, but
can also be situational. For example, if something happened that caused all dogs to die off except for the Mexican Hairless and the St. Bernard, there's a good chance that size differences alone would lead to reproductive isolation between the two breeds. Then, any mutation leading to a change in germ line genes in either of the two would finalize that isolation, so that even if further mutations led to larger Mexican Hairlesses and to smaller St. Bernards, those two kinds of dogs would no longer be able to produce fertile offspring, so they would then be considered to be new species.
Naturally, geographical isolation is a much more common factor. Plate tectonics has led to some notable examples of the effects of such isolation, such as the differences between Old World monkeys and New World monkeys. If most South American marsupials, except for a few species of possums, hadn't been wiped out by invading placental mammals when North and South America collided, we might see some interesting differences between them and the Australian species.
Anyone who thinks that the question of speciation is just armchair philosophy, unsupported by research, needs to try reading all of the articles cited on
this Molecular Ecology site. Note yet another speciation factor subject to mutational changes--sexual selection.
By the way, although I'm not aware of any experiments leading to speciation, there
have been experiments involving natural selection. One of the most interesting is the one involving John Endler's guppies, described in Johnathan Weiner's
The Beak of the Finch. (And, of course, Weiner's book is one of the premier descriptions of the observation of natural selection over relatively short time periods.)
Also they are doing a good deal of work involving probabilty theory and statistics. They argue that random mutation alone, even given the time frame evolution supposes, couldn't produce new species--the probabilities are too low.
Any links to examples of such statistical studies? It's impossible to argue against them without knowing their content. Meanwhile, I am, as usual, skeptical. I
will say that statistics are only predictions based on models. They are not laws. Evelyn Adams won the New Jersey state lottery two years in a row (1985 and 1986). What are the chances against that? (Be careful how you answer.)
The intelligent design folks demand a lot of explicit, detailed proof from the evolutionists. My question is, where is
their explicit proof of intelligent design? The best they can do is to show that they don't know enough to be convinced of evolution. As for the explanatory power of evolution by natural selection, it shows up in the details. Every biology-related book I read, from genetics to neuroscience, places its facts in an overall evolutionary framework that is then used to elucidate the relationships among those facts and others. What will "intelligent design" elucidate? What explanatory power does it have? "God made 700,000 kinds of beetles, each unrelated to any of the others. End of story. Move along, nothing to see here."
Also, science demands at least some experimentation and some specific testable predictions. Where are the intelligent design experiments detailed? What specific predictions does it make that can be tested?
If anyone believes that evolutionary theory is not well-supported both by data and by experiment, then they probably just don't read enough of the actual literature. It's easy to confuse "I don't know" with "nobody knows".
(Regarding anti-evolutionists in general, we often see demands to show every single intermediate form in an evolutionary line, but those who claim to be descended directly from Adam and Eve don't seem to be able to show many of their intermediate ancestors at all, and that should surely be a much easier task, given the relatively short time period many of them claim. In fact, the line only has to go back to the Noachian bottleneck, so it's even easier.)
