April 05, 2016

Dear Christians: Answers to Questions for Atheists, Part XIII

Today, in the thirteenth part of this series, I'm looking at the Fossil Record and Information. This is an incomplete discussion of the Cambrian period, but I've done my best with what resources I have.

I'd love to see how readers (atheist and theist alike) would answer some of these...


FOSSIL RECORD
1.    How do you account for the Cambrian Explosion?  What is your evidence?


It's kind of hard to address this question, because it's so vague. What exactly is wrong with the Cambrian Explosion that needs to be accounted for...?

Short of the author clarifying this, I'm going to address the arguments against evolution that utilize the Cambrian period that I'm familiar with.

What's the Cambrian Explosion?

About 542 million years ago (give or take a few million years), there was a seemingly rapid expansion of animal life with little ancestral evidence.

What's the big deal?

In the 1840s, we came across the first evidence of the Cambrian explosion, and even Darwin wrote in 1859 that it was trying for his theory of evolution via natural selection.

The Cambrian Explosion was too fast.

At the least, the "Explosion" lasted 5 million years. At the most, it was up to 30 million years. That's a considerable period of time for evolution to occur in.

There's no evidence of significant evolution before the Cambrian.

Actually, there's a lot of evolutionary gains observable in the Precambrian. Here's a handful:


  • 3800 Million Years Ago: Organic signatures indicates abundant life
  • 3500 Million Years Ago: stromatoliths
  • 2700 Million Years Ago: Nucleate cells
  • 2100 Million Years Ago: Many-celled organisms
  • 1200 Million Years Ago: sexual reproduction

So there's a significant amount of change occurring well before the Cambrian.

All animal phyla developed during the Cambrian.

No. 3 phyla existed before the Cambrian, 15 during, and 1 after. More than half of the 35 animal phyla taxonomists have identified don't have a substantial fossil record due to them being soft-bodied.

And, those phyla that did develop would likely be unrecognizable to us today:

And that just considers phyla. Almost none of the animal groups that people think of as groups, such as mammals, reptiles, birds, insects, and spiders, appeared in the Cambrian. The fish that appeared in the Cambrian was unlike any fish alive today. 

Diversification is too sudden to be due to natural selection.

I think TalkOrigins says this way better than I could:

There are some plausible explanations for why diversification may have been relatively sudden:  
The evolution of active predators in the late Precambrian likely spurred the coevolution of hard parts on other animals. These hard parts fossilize much more easily than the previous soft-bodied animals, leading to many more fossils but not necessarily more animals.  
Early complex animals may have been nearly microscopic. Apparent fossil animals smaller than 0.2 mm have been found in the Doushantuo Formation, China, forty to fifty-five million years before the Cambrian (Chen et al. 2004). Much of the early evolution could have simply been too small to see.  
The earth was just coming out of a global ice age at the beginning of the Cambrian (Hoffman 1998; Kerr 2000). A "snowball earth" before the Cambrian explosion may have hindered development of complexity or kept populations down so that fossils would be too rare to expect to find today. The more favorable environment after the snowball earth would have opened new niches for life to evolve into.  
Hox genes, which control much of an animal's basic body plan, were likely first evolving around that time. Development of these genes might have just then allowed the raw materials for body plans to diversify (Carroll 1997).  
Atmospheric oxygen may have increased at the start of the Cambrian (Canfield and Teske 1996; Logan et al. 1995; Thomas 1997).  
Planktonic grazers began producing fecal pellets that fell to the bottom of the ocean rapidly, profoundly changing the ocean state, especially its oxygenation (Logan et al. 1995).  
Unusual amounts of phosphate were deposited in shallow seas at the start of the Cambrian (Cook and Shergold 1986; Lipps and Signor 1992).

There's no transitional fossils in the Cambrian.

TalkOrigins again:

There are transitional fossils within the Cambrian explosion fossils. For example, there are lobopods (basically worms with legs) which are intermediate between arthropods and worms (Conway Morris 1998). 

Major animal groups appear together and fully formed.


TalkOrigins once more:

1. The Cambrian explosion does not show all groups appearing together fully formed. some animal groups (and no plant, fungus, or microbe groups) appearing over many millions of years in forms very different, for the most part, from the forms that are seen today.  
2. During the Cambrian, there was the first appearance of hard parts, such as shells and teeth, in animals. The lack of readily fossilizable parts before then ensures that the fossil record would be very incomplete in the Precambrian. The old age of the Precambrian era contributes to a scarcity of fossils.  
3. The Precambrian fossils that have been found are consistent with a branching pattern and inconsistent with a sudden Cambrian origin. For example, bacteria appear well before multicellular organisms, and there are fossils giving evidence of transitionals leading to halkierids and arthropods.  
4. Genetic evidence also shows a branching pattern in the Precambrian, indicating, for example, that plants diverged from a common ancestor before fungi diverged from animals.

2.    Can you provide specific evidence for species-to-species transitional forms in the fossil record?

Why do I feel like any answer I provide would be unacceptable to the author of these questions?

Anyway, for anyone who is really interested in a list of transitional fossils, try TransitionalFossils.Com. There's too many for me to list comfortably here...


 INFORMATION
1.    Regarding the information encoded in DNA, if a supernatural transcendent Almighty God did not author it, what did?  How do you know?

I don't know. I'm not a geneticist, nor do I have to be. I understand enough of the process to know that it works with no supernatural intervention required, and that the way the process works explains the diversity of life as we know it.

If you're truly interested in the full workings of DNA, might I suggest taking a peek at this post. It's informative.


2.    Do you object to the notion of Intelligent Design because of your lack of religious values?

Wait...what? How is that even reasonable?

I'd like to refer this question back to last week's refutation question: Evolution is NOT a refutation of religious belief. There are plenty of religious people who also understand and accept evolution. The two aren't mutually exclusive...

I don't object to the notion of Intelligent Design because of my secular values. I object because it's an unnecessary addition to an explanation that doesn't need any supernatural help.


*****

TalkOrigins is an excellent resource if you, like me, are a recovering creationist still figuring these things out. Their searchable archive breaks down creationist arguments against evolution and really handles them in depth, point by point. I can't recommend it enough.

Once again, a bit of bias has leaked into the questioner's points, and I find myself wanting to reiterate, once again, that evolution is NOT a refutation. It's an explanation for observations seen in the natural world. Full stop.

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