Alex_Sanders said:
A creationist raised dog as an example, saying what we call dogs, are actually sub-species of grey wolf, thus they are also wolves, thus micro evolution is possible, but from a more macro angle, dog didn't evolve at all, how to counter this argument?
He admits current taxonomy, so I would like to point out for him that grey wolf belongs to a even larger category which has coyote and other canis. Can coyote and dog cross-breed? Do you folks have any better idea than mine?
Hey Alex,
The problem that most creationists have with evolution is the one you are dealing with "micro vs macro". What they mostly fail to understand, is that biologists don't mechanistically (for the most part) distinguish the two. "Macroevolution" is the accumulation of microevolutionary processes over some subjective definition of time.
Most creationists I've known, like to inject the "interbreeding" boundary of species. And then point out that dogs and wolfs can form a contiguous breeding population, which they then propose follows the "Creator creating the 'dog kind'"-line of logic they try and use.
I'd point out that dogs are a sort of ring species, much like gulls or salamanders. Those distinct populations of dogs we call "breeds" could allow something like a chihuahua to breed with a great dane. Of course they can't directly breed because of obvious mechanical problems. But in theory, you should be able to breed chihuahuas with progressively larger dogs, until such a point their genes enter the gene pools of great danes'. And visa versa. However, suppose tomorrow some terrible K9 disease fell upon the world, wiping out all those in between breeds. Such that chihuahua and great dane gene pools would now be isolated from each other. Then, you would have two distinct species of dog. The chihuahua species and the great dane species.
Now suppose some terrible disease arose which wiped out all people on earth. Such that the great dane and chihuahua species were once again "wild". Because of their morphological variation, they would have to occupy different ecological niches. Which means each would be subject to different environmental pressures and would "evolve away from each other". How divergent they become from each other (and their wolf ancestors) would be a function of the intensity of selective pressures and time since they diverged.
If your friend doesn't believe you, you can point out that this same thing happens in nature as well. Probably my favorite example is with the salamanders in the genus Ensatina
http://www.kqed.org/quest/files/ensatina.gif
What you can see in this illustration is salamanders live in the mountainous regions surrounding the San Joaquin Valley, which is inhospitable to their livelihood.
On the southern side of the circle, you find two species of salamander which look very different and don't interbreed. However, they are connected by populations extending north around the San Joaquin Valley and back down the sides, where interbreeding between subspecies occurs.
If some unfortunate chain of events led to the extinction of those "in between" subspecies, you'd be left with two distinct species incapable of gene flow and who are thus, reproductively isolated. Because each occupies a slight variation of ecological niche and each occupies a slight variation of environment, then each gene pool would accumulate changes which diverge the two populations farther and farther apart over time.
Interestingly ring species are a geographical representation of what happens temporally in evolution.
Stress to your friend this point. Its one that even most "advocates" of evolution don't understand.
"Macroevolution" is only visible and possible because of the extinction of intermediary populations.
If all the populations since the divergence of chimps and humans were still alive (like the ring salamanders) creationists would probably claim "God created one 'kind' of ape" and microevolutionary processes took it from there.
We only look at chimps and humans as "distinct" isolated gene pools (populations) because the intermediary populations are now extinct.
Of course that hellacious line of logic that creationist use to explain ring species (creating a "specific" kind) would fall apart if every intermediary population never went extinct. Creationists then would be forced to conclude that god created a "universal kind" from which "microevolutionary processes gave rise to all kinds", in essence macroevolution.
Edit to add; Alex,
Of course you must also consider that creationists are notoriously immune to reasoned and evidenced based arguments. You might consider that the time spent arguing with your friend, could be well spent on something else. I'm of the opinion if we teach evolution in our schools correctly, and only actively "attack" creationism when it rears its head and tries to gain entry into science classes; then in a generation or two's time, creationism (like those who currently hold the belief) will go the way of the dodo. I don't think its feasible to try and educate all current creationists, their http://www.talkorigins.org/origins/postmonth/feb02.html" keep their beliefs unscathed besides for anything not tied to the front end of a Mac truck (and sometimes that's not enough!).
