Quote Originally Posted by cheeseburger View Post
The only source I accept is an article from an accredited scientific journal. Sorry. Books fall under many genres, one of which is fiction.
That is too bad because I was about to recommend a book that raises some of the issues I think are pertinant to this discussion. It is The Language of God by Francis Collins. Dr Collins has a PhD in Medical Genetics, is an MD, and was head of the human genome project. His book is as unbiased a book as I have ever read, and raises some serious questions about the current levle of understanding of genetics and evolution. He also raises questions about theistic evolution, which is the model he seems to prefer.

Ok. Everyone knows that the Y chromosome is passed down along the male lineage, since boys are XY and only the father can contribute the Y.

Mitochondrial DNA is passed along the female lineage, because a fertilized egg cell, or zygote, already has a mitochondrion. When it divides, just like any other cell, the mitochondrion divides first, and then the cell divides. Sperm has no play in this, and so mitochondrial DNA is passed down from mother to child.

The reason I'm saying this is to give you a better understanding of why people even want to 'trace' mitochondrial DNA. However, tracing it 'all the way back' is pointless. Humans are not the only species with mitochondria, so if you want to find out where the organelle originates, you turn to the secondary endosymbiotic theory, which is a fancy way of saying "what you engulf and can't digest you make friends with."
Humans are genetically unique because we are the only species on Earth that has mitochondrial DNA? Interesting, isn't it? But coming up with a theory to explain that with no way of actually testing it seems pointless to me. I have tried to read up on this, but molecular biology is not my fielad and i will need some time to study the subject before I can reply in a manner that would make any sense to me. I do enjoy learning about these things though, so I hope that you will continue to educate me. I especially enjoyed the definition you gave about making friends with something if you cannot digest it. This is essentially waht we do everytime our digestive tract gets upset, our 'friendly' bacteria battle with the invading bacteria, and we adapt or die.

This is an extremely simplistic definition that does not hold true in many cases. Mules are one common example.

The way things are done now, they sequence the genome of a species and compare it to that of another. Good match means either same species or pretty close - but keep in mind, the difference is in the .01% or there abouts. I'm no expert on this, but what you stated is clearly wrong.
I can see that now, and am able to admit that I am wrong. But I am now faced with the problem that I have no definition of species, nor does anyone else. How are we supposed to debate a topic with no objective definition?

Reorganized is a better word.

Wasn't me. And by the way, this means nothing. Another example of this is D. Melanogaster mating with D. Yakuba. Big deal; they're unlikely to create viable offspring due to post-zygotic mating barriers. Nothing is being 'diluted,' whatever you mean by that.

You are diluting it, but not entirely. Let me add some detail but still keep it really simplistic.

Basically, under the right conditions (reducing atmosphere, lightning, whatever) you form organic (organic simply means containing carbon) molecules that are polar on one side and non-polar on the other side. In an aqueous solution, the non-polar sides get pushed together and you get a very rudimentary membrane, allowing some separation. This means you can do things inside your membrane that couldn't go on outside. Once you have something that reproduces itself, like some self replicating RNA enzymes ('ribozymes') the cat's out of the bag and whatever replicates the fastest sticks around.

If you're at a loss, let me explain. Something that reproduces asexually can very quickly 'fill up' a niche that it is well suited to. Any change in that niche that makes it unfavorable for one of these creatures makes it unfavorable for all of the creatures since they're basically clones, and they all die.

And clearly environments change over time. Life is basically adapted to survive stressors. So, some mechanism that enhances variation among a species was highly selected for - since everything else died out once the environment changed.

Or, some creature multiplied so fast mutations became significant and added to the variation. Viruses and bacteria are like this; mutations add a lot of variation to a culture of bacteria because they reproduce something like once every couple hours.

Although bacteria can also reproduce sexually, at a greater cost. If you stress them, by say adding antibiotics, then the 'cost' of reproducing sexually outweighs the 'cost' of dying to the antibiotics, and they all suddenly start reproducing sexually and passinga round resistance genes.

I typed this a little rushed so I apologize for any spelling/nonsense errors.
I certainly will not complain aboiut spelling and nonsense errors as I make more than my share of those. I have a question for you though, are you saying that bacteria have been observed to reproduse sexually? I thought that the mutations that you spoke of where selected for when all the competing bacteria died out from the antibiotics.