Of course, we are then faced with the challenge of defining species, which is harder that it would seem. However, we can again, arguendo, agree (even though it has problems) to accept the common working definition: if two populations cannot successfully breed, then they are distinct species.
I'll say from the onset there is no point is actually arguing with someone who affirms micro but not macro evolution. No amount of evidence will persuade them. Been there, done that, and didn't get as much as a T-shirt. I have never (and I have witnessed literally hundreds of such arguments) encountered someone who changed their position on macroevolution. This is not a debate that is approached with open minds.
But for the sake of completeness: the evidence is overwhelming. There is the fossil record with millions of snapshots of macroevolution occurring as an aggregation of microevolutionary steps. For a “living” example, there are ring species. 2 There are also candidates for witnessing speciation in complex organisms in much smaller time scales than previously imagined. Birds that suddenly (from microevolution) split into populations with two very distinct migratory paths appear to be on the cusp of speciation.
The purpose of this post is to present an analogy, which will convince nobody because, as already mentioned, nobody who says “micro-yes, macro-no” is actually willing to evaluate the evidence. So this is mostly for fun.
Micro and macro physics evolution
An astronomer with a telescope is a cosmic paleontologist. When an astronomer gazes at something a billion light years away, they are, given the finite speed of light, looking back in time approximately a billion years. 3 What they are seeing, in every sense of the word, is a fossil. The farther we look is just like the deeper we dig.
Looking farther away we are seeing (a bit counterintuitively) younger things, in the sense they are as they were at a time closer to the creation event, the big bang.
And what we see as we gaze from the farthest reaches to our local area is physics (cosmic) evolution. Far away we see nascent galaxies and stars made from the products of the big bang but with low metallicity (because metals, which to astronomers includes anything beyond helium, didn't exist when the star formed. Why not? Because it takes stars to manufacture metals and then die and obligingly seed space with these heavier elements that can then be incorporated in the next generation of stars.) 4 As we gaze closer to home we see more complex structures (such as mature galaxies) that formed later.
So we see fossils with a clear evolutionary process, from clouds of hydrogen and helium to the interstellar medium condensing to early stars and galaxies all the way to more recent (but older in terms of time from the big bang) complex galaxies and structures such as our Milky Way. We see fossils including transitional forms.
So imagine this point of view:
Ken: I believe in micro physics evolution, but not macro physics evolution. If I drop my phone, the laws of physics cause it to fall and hit the earth. The screen might crack, but it’s still a phone. The earth might change ever so slightly, but it’s still the earth.
Charles: But the very same process (gravitation) is what caused stars and galaxies to form from the primordial hydrogen and helium produced by the big bang, from a long drawn-out series of gravitational micro-steps. We see this evolution very clearly in our telescopes.
Ken: How do you know there was a process? Has anyone seen it in real time? Maybe the distant galaxies look “young” not because we are looking back in time, but that’s how they will always look, even to their nearby observers, if there are any. They were just created that way. No, unless I see hydrogen and helium clouds form a spiral galaxy, I’m not going to believe it.It’s the same argument, is it not?
1 I’m a theistic evolutionist. Which means that I accept the theory of evolution but add to it the supernatural presupposition that the process was/is never outside the domain of God’s sovereignty. Just like I accept the physics laws governing gravity, even though I don’t accept that they operate outside of God’s sovereignty. There is no scientific consequence of this presupposition. A practicing theistic evolutionary scientist would perform the same experiments and analyses as their atheistic colleagues. Science doesn’t give a rat’s derriere about your philosophical leanings. It only demands that you follow the rules of the scientific method.
2 In a nutshell a ring species is like this: species A is thriving in California. Part of the population, for whatever reason, moves east to Iowa. After a while this B population is visibly distinct. But A and B can still breed. Same species. Now part of B migrates farther east, to Virginia. After awhile this group, call it C, is visibly distinct from both B and A. However, there is a lack of breeding transitivity. While A can breed with B, and B with C, A cannot breed with C. A and C are distinct species, arrived at by a series of microevolutionary steps, even though A (where it all began) is not extinct.
3 This is only approximate because of the expansion of space (which is really, in some sense, the continuous creation of space which leads to the appearance of expansion). The range of our vision (a physics limit, not a technology limit) is about 43 billion light years, at which point we see objects as they were very shortly after the big bang, a bit shy of 14 billion years ago.
4 Astronomers designate the generations of stars by Population 1, 2 or 3. But astronomers are crazy people who do everything bass-ackwards. The first stars created are Population 3.
Really great post! Thanks!
ReplyDelete"I accept the theory of evolution but add to it the supernatural presupposition that the process was/is never outside the domain of God’s sovereignty."
ReplyDeleteAt least the numbers for populations in stars are in some kind of order, even if it's backwards. That's pretty good for astronomy.
ReplyDelete"This is not a debate that is approached with open minds." Having also witnessed literally hundreds of such arguments, may I observe that the "open minds" issue is not limited to one side of the argument.
ReplyDelete"nobody who says 'micro-yes, macro-no' is actually willing to evaluate the evidence." Poisoning the well, much? Typically, only the most close-minded will insist that their opposition is entirely close-minded ;-)
Doug,
DeleteFair enough.
David
Before reading this I would have said "micro yes, macro no" but now I am not so sure. So 1 person willing to change their mind?
ReplyDeleteJH,
DeleteIf so I'll have to post an update! Thanks for reading.
David