Friday, April 5, 2013

What Darwin Didn't Know- Ch 1 -The Scope of Challenges - Part 5: The Problem of Intermediates - Pt 1


Book Cover: What Darwin Didn't Know
I (just realized I've been copy/pasting a grammatical error here for awhile - awesome) dove into Geoffrey Simmons' "What Darwin Didn't Know" (2004), to evaluate an anti-evolution book.

I'm maintaining an index of my responses here.

Today's Chapter - 1: The Scope of Challenges - Part 5:  The Problem of Intermediates - Pt 1
I started reading into this section, and didn't get far before I was face-to-face with an onslaught of false or unsupported claims.

For today, I'd like to address the topic of "transitional forms" or "transitional fossils", to help set the context.

Simmons did not provide a definition of "intermediate species." I think that's important, because there's a lot of obfuscation/confusion about the topic, and to some degree, I suspect he may be trying to define away the actual examples... like he was with beneficial mutations

As I've pointed out before, we have plenty of well established transitional forms. Here's another list. Note the citations. Keep in mind that fossil gathering and categorizing is only 150-200, or so, years old. Hardly a year goes by that we don't find more transitional fossils that further positively demonstrate, outside of the entire fields of study of phylogeny, genetics, etc, that evolution happens.

So, his first sentence of this section is simply unambiguously false - "A fourth problem with Darwin's theories is the lack of intermediate species." (I'm still not sure what other "theories" Darwin had, outside of Natural Selection).

Pointing at a creature, that we don't have any transitional fossils for, yet, is not a disproof. It doesn't work that way.

Misunderstanding the transitional fossil

Simmons says something fairly early on that makes me wonder what is his definition for transitional forms.

Darwin said whales came from bears, but there are no part-bear, part-whale fossilized bones.
Uh, of course there wouldn't be. The intermediate would be its own thing... not a mosaic combination of parts from each. Nor would it be literally half-bear and half-whale in the sense that a minotaur would be half-bull and half-human. 

That's not how it works. I don't know if this is what he means, because he clarifies and supports none of what he says. Maybe he just assumes that we all just are synchronized with his understanding of the words, but this is one spot he sorely needs some definitions.

It's not Half-One and Half-Two 


This is a common misconception. See The Atheist Experience clip to the right for an example.

Most of the time, the question of transitional fossils dies in a person's mind due to an inability to understand how it'd work.

Let's say there are two towns (Town A and Town B in the diagram below), and I'm claiming that there's a road that connects the two.

The creationist in this example would object.

Diagram depicting two towns with a pond between them. Two possible paths are drawn - one that goes around the pond, and the other that goes directly through the pond. Evolution is pointed out as being the path that would go around the pond, not through it.
[Creationist in my head says] If there was a road that went from Town A to town B, there would have to be a midpoint along the way. Looking at this map, the midpoint would clearly be in middle of the pond, which would make no sense. Also, we found no evidence of a road there, so clearly this road you speak of is completely fictional.
This objection stems from a definition of "mid point" (analogous to transitional fossil) that would be clearly dumb. They'll point out that there's never been "half an eye" or "half a leg", though it's not always clear what they mean by that.

In reality, the evolutionary path (or the road above) could be something that takes a detour, through  a series of whole complete forms, that is somewhat unlike the starting or end points. Also, Punctuated Equilibrium is the idea that that transition between "stable" forms would be relatively quick - like a ball rolling from the top of a hill to the bottom, which would reduce the quantity of transitional fossils that we find.

The creationist in my head is already complaining, saying that I'm making up an excuse as to why alternative stages, which are nothing like points A and B, would qualify as a transitional form. That's not the case. Clearly, a transitional fossil between a bear-like creature and a whale-like creature wouldn't appear to be a tree-like creature.

The key to understanding this is to understand, like the diagram above, that the path isn't always a bee-line from A to B, but rather, as we discover more data points, a much more meandering path.

Diagram depecting line segments, with lines connecting the dots - there are four stages, with each successive stage having more dots, and thus, more refined and sophisticated path.

As with photography, the more pixels (data points) we have, the clearer and more accurate the image. We may not be able to picture in our minds what the "halfway" point between a bear-like creature and a whale-like creature would look like, but we could probably picture, if we actually knew what that midpoint would be, what the "halfway" point between the bear-like creature and the "halfway" point would look like.

For instance, if in the town/pond diagram before, there was a Town C at the evolutionary path midpoint, on the shore, it would be easier for us to comprehend what the midpoint would be between Town B and Town C, than Town A versus Town B... and even easier if we pondered the midpoint between that new point between B and C, and B.

Our pre-evidence conceptualizations would be more accurate.

Keep in mind that there's more than simply looking at whether a new fossil appears to be a blend between two species, to determine that it actually is. Several different angles are taken when fitting the model with the new data. For instance, the location where the fossil was found, as well as it's dated age, are also considered when determining where it fits.

Is this what they think the transitional form would be between bear-like ancestors and whales of today?

Picture of Half-bear and half-whale
Actually, it wouldn't be that far from the truth, though slightly different. They'd probably look more like these:

Photo of a Walrus
Walruses
Photo of a manatee
Manatees

One could argue that polar bears, seals, penguins, walruses, etc, are all in various stages of evolving to take better advantage of the aquatic niche.  Polar bears are in the early stages, where they're basically full land-walkers that spend a significant amount of time in the water, and are good at it. Walruses, while awkward on land, still do find advantages to being able to rest on the shore, while still being able to dive into the sea for food.

That's the point, though. Transitional forms are bound to be fully-operational fully-developed species... not bizarre half-eyed half-legged monstrosities. Evolution wouldn't produce results like that.

Clearing up some Misconceptions

I'll close out with clarifying a few things, just so we're clearly clear. Clear.

Predestined Evolutionary Paths

There's no pre-destined path for any evolutionary lineage. A population of modern-day walruses may migrate somewhere where they survive better by being land dwellers, and they'll adapt back in the other direction again. It all comes down to history, basically - the events and environments that direct the evolutionary path like water streaming down a hillside, being deflected by every bulge, split by rocks, channeled by impressions. Instead of a hill, it's events in time - something we are very bad at predicting. For all we know, walruses are currently evolving back from whale-like ancestors back to full-fledged land-walkers

Bear-like Ancestors

I was careful to state "bear-like ancestors", instead of saying that whales evolved from bears. One of the problems with how we understand the evolutionary tree is the limitations of the categorical system (taxonomy) that we've overlaid onto it. To say that whales evolved from bears would be like saying that my distant cousin on my mother's side was born from my distant cousin on my father's side - which clearly wouldn't work.

When we say "bear-like", we're talking about a basic form that would look like a bear... but not actually be a modern day bear species. It's not dissimilar from the distinguishing between saying that humans evolved from "ape-like ancestors" versus a current modern day ape species (though, according to taxonomy, we are currently apes - so it'd be like saying we evolved from mammals, which is technically true as well).



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