We can use DNA similarities to establish parent → child relationships. Two people who were both orphaned at birth and raised in different families can use DNA analysis to determine if they had the same birth parents. DNA can also be used to determine if someone is a (relatively) recent ancestor as was done for the descendants of Thomas Jefferson and Sally Hemings. The same concept holds true for species. We can use DNA analysis to determine if the species shared a common ancestor, and roughly how long ago the common ancestor lived.
Art, I agree that self splicing introns is an interesting subject but I am trying to point out to Tim that symbiosis does not begin to explain prokaryotic to eukaryotic transition.
A separate origin is not a hypothesis that can be dismissed out of hand.
Then what’s the problem? You agree DNA can be used to establish evolutionary relationships, right? If it works for individuals it also works for species.
As an argument that does not fly. It works for an individual human, therefore it works for species. I am trying to understand the logic of the argument. So “the problem” would be that I do not understand the logic of the argument.
Let me see if I can re-phrase.
Let’s say you want to convince someone that paternity tests are reliable. How would you do that. Now, let’s say someone accepts your argument that paternity tests are reliable. And so then you say, therefore you should accept common descent of all species from a common ancestor.
But that simply doesn’t follow. So I am looking for the unstated premises in that argument that would lead one to that conclusion.
Paternity testing cannot even tell us that humans share a common ancestor , so how can it establish that all species share a common ancestor?
It flies just fine for all those not predisposed to reject scientific findings due to religious biases. Or because they just like being contrary.
I’ll ask you the same question I asked Bill: Do you dispute the scientific finding some humans have an admixture of Neanderthal and Denisovan DNA? Why or why not?
So in the Lenski experiments I believe those are all the same species. I don’t think we have the original “parents” but only colonies descended from them. I could be wrong.
I wonder if phylogenetic analysis could successfully resolve how the various colonies are related. That is an interesting question. So it is hypothetically possible to set up an evolutionary experiment where we track the different “offspring” populations and then see how well our phylogenetic tools can recover the true phylogeny.
Rozen, D. E., D. Schneider, and R. E. Lenski. 2005. Long-term experimental evolution in Escherichia coli . XIII. Phylogenetic history of a balanced polymorphism. Journal of Molecular Evolution61 :171-180.
Researchers examined blood samples collected this year from known descendants of the family of America’s third president and from those who trace their ancestry to Hemings. In a paper published in the Nov. 5 issue of the journal Nature, they report that DNA comparisons all but conclusively prove that Hemings’s youngest son, Eston, was fathered by Jefferson.
So can we agree that the DNA of the known descendants of Thomas Jefferson was DNA from Thomas Jefferson? So in that sense we could say we have Thomas Jefferson’s DNA.
