I’ve been dipping my toes in the Stand To Reason apologetics website – mostly through its podcasts Stand To Reason (with Greg Koukl) and Thinking Out Loud (with Alan Shlemon). This post is a response to Shlemon’s assertion in this episode that macroevolution is a whole separate thing from microevolution.
This is a familiar trope among those of us who try to keep an eye on the creationist pushback against the science of biological origins. Many many people have countered it – in books, in articles, in encyclopedias and FAQs, in blog posts and videos, in debates and other personal interactions.
I have nothing new to add, really: the science is in, and creationism fails the test. There are ways to work God into your worldview without contradicting reality, but many people aren’t willing to adapt their beliefs to the evidence. Their loss.
Anyway, as I was listening to Shlemon smugly dismiss the scientific objection that macroevolution is simply the accumulated effects of microevolution over large enough time spans, I was thinking how I might respond. If an acquaintance were to offer that argument, how could I respond in a way that might get them past the cognitive block they have?
Here’s what I came up with:
Imagine that each species can be described by a (potentially very long) line of letters. Let’s say we only use letters corresponding to the four basic elements: A (aqua, for water), C (combustia, for air), G (gasea, for air), and T (terra, for earth).
Now, imagine there are ways of changing the sequence of letters, so that a child doesn’t have exactly the letters of its parent or parents. Let’s call a single letter change “microevolution”. That could be, for example, a “C” changing to an “A”. Or a “T” being inserted between a “G” and another “T”. Or an “A” being lost altogether.
And let’s say that “macroevolution” means a wholesale change of the sequence: no letter is the same as it was before.
Can you imagine a way to do microevolution over and over again and eventually get macroevolution?
I sure can.
And that’s it.
Oh, there are some constraints. Biological evolution requires that each stage – each mutated offspring – is viable and is not at a substantial selective disadvantage relative to the other variants present in its population. So, in the real world, it is not the case that any species could evolve into any other species by any textually-sufficient chain of genetic mutations. But that’s not the claim of modern evolutionary science. The strongest claim it makes is that there has been at least one such path leading from life’s early progenitor(s) to each species that has ever existed on Earth.
Anyway, what do you think of my illustration? Does it replicate what someone else has produced? If so, please point to them in the comments. Does it seem clever? Useful? Scientifically accurate?