Evolution?

[topdog98]

Good luck on your exam today, Leebo!

[Leebo]

I'm guessing I've managed to piss off everyone except sanantone basically, so I'm not sure if you're being sarcastic, but if not, thanks.

Just waiting for my start time right now and posting with my cell.

[sanantone]

All I know is that something has to explain those humanoid skeletons.

[topdog98]

I'm guessing I've managed to piss off everyone except sanantone basically, so I'm not sure if you're being sarcastic, but if not, thanks.

Just waiting for my start time right now and posting with my cell.

Definitely not being sarcastic. Encouragement on testing is the one thing we all agree on.

[Leebo]

Passed, CLEP American Government. Chuckled at a question about people expessing lower approval for atheist groups than religious groups when using public venues for speech.

[topdog98]

Passed, CLEP American Government. Chuckled at a question about people expessing lower approval for atheist groups than religious groups when using public venues for speech.

Congratulations on the pass. Looking at your signature, your progress is really impressive.

[Jack1798]

Leebo,
First of all, you haven't ticked me off at all; I honestly enjoy a good rousing debate. Secondly, just so were clear, we are defining evolution as the theory in which all life developed, from a single cell amoeba to the human via natural selection. Before I continue on, I just want to make sure I am correct in my understanding. If I'm not, I would appreciate it if you would clarify. Thanks,

Jack

[Leebo]

Yeah, clarifying is always the way to start.

The theory of evolution describes the mechanisms capable of producing all the diversity that we see, and the evidence for common descent is overwhelming, but it doesn't cover any living things prior to the common ancestor. We can't say anything about earlier life, including the first life.

[Jack1798]

Leebo,
Just a few more clarifying questions before I move on.
1. How do we know that the mechanisms evolution describes are, in fact, capable of producing all the diversity that we see?
2. Can you list say, 2 or 3 examples of the "overwhelming" evidence for common descent?
3. If we can't say or know anything about this common ancestor, as you say, then how does the rest of the theory of evolution hold water? You most certainly would not let a Christian even begin to talk about creationism if they didn't already know something about God. This seems to be the same thing.

Skeptically,
Jack

[Leebo]

Quickly on this question, it's not the common ancestor we don't know about, it's what came before the common ancestor.

Imagine life begins, and it begins to diversify and speciation occurs (I know I'm asking you to accept this before answering the rest of your questions for the sake of an example). But a large number of those species go extict, and all living organisms are descended from one specific branch of that original family tree. We can't know anything from before that branch of the tree. That's all I mean.

The answer to your first two questions can kind of be handled by the same explanation.

I'm sure you're familiar with genetic testing to determine how closely two humans are related. You can kind of do a similar thing with different species.

First, it's important to understand how DNA works. DNA is essentially a long set of instructions for making different proteins at different times. That's really all it can do.

Proteins are made by taking the information from different segments of DNA. Let's say that a particular DNA segment looks like this "ACTGGGTACG" and it makes "Protein X". It's important to keep in mind that I'm keeping the DNA segment short just for ease of explanation. The way DNA works, sometimes mutations occur. Sometimes these mutations result in the protein being made incorrectly or not at all. That would probably be a fatal defect. Sometimes they are changed in beneficial ways. Most often, they are changed in neutral ways. It's possible for two slightly different segments to make a protein with the same physical structure.

These changes can accumulate because they don't impact the actual usefulness of the protein. If my parents had a mutation that didn't change the protein shape, I will pass it to my children because the protein didn't cause any problems with my health. My kids and their kids will have the same different segment.

This is how the science of evolution can make predictions. In a world where all organisms are related, we should see some structure of relatedness emerge from an analysis for any particular protein.

And it does. For any protein you can pick.

If someone had created all organisms from scratch, what reason would they have to give them slightly different DNA segments for the same proteins that resemble exactly what you'd expect if they had all been related to each other. One answer I can think of is that the creator is a jerk who wants to punish us for using our brain. I don't think that's how most people imagine God.

To summarize, let's imagine 3 the DNA segment for "Protein X" for 3 different organisms. When there's a difference I'll bold it.

1) ACTGGGTACG
2) ACTGGGTACC
3) ACTGGGTAAC

Notice in organism 2, only the last letter is different from organism 1. But in organism 3, the last 2 are different from organism 1, but only 1 is different from organism 2. We can infer that organism 3 is more closely related to organism 2 than organism 1.

This is highly simplified, but you can see how these patterns would emerge from the commonly understood elements of heredity.