Yes, I know most atheists believe life came from vague primitive life forms. But my contention is that a large majority do not know that prevailing science states that all the millions of plant and animal species, including the dinosaurs as well as their family and friends came from the "same" "single" microscopic cell.
I guess that I'm just not getting the argument here.
We all know that it is a logical certainty that all the humans alive today had one common mother. It is a simple inductive argument: everyone has a mother (including all mothers), and so it must be that any given subset chosen from everyone who has ever lived is descended from a single "mitochondrial Eve" (
http://en.wikipedia.org/wiki/Mitochondrial_Eve). Also, everyone alive today had a single father (the Y-Chromosomal Adam) at some point in the past, for exactly the same reason. These two likely occurred at different times and places, and had no relationship except that one was descended from the other. And then, of course, everyone is also descended from his father, and his grandfather, and her mother, and so on. Interestingly, these two individuals are assumed to have lived about 130,000 years ago; There is another person, the MRCA (most recent common ancestor) of everyone alive today, who may have lived a late as about 3,000 years ago.
These arguments depend upon the fact that everyone has a father and a mother, that it takes both to cause a person. If we believe the Bible we may have had an anomaly in Jesus Christ, but he had no offspring (according to the Bible again) so that's ok.
Well, if you believe that (and you have to, given the definitions and the logic), then you have to accept, I think, that there is one common ancestoral entity for us all, and now we include all life on the planet. This seems to be a logical consequence of the theory of evolution. No matter that the offspring may be cloned buds or any of the other weird ways that life reproduces, there has to be just one. And it's not required that that one be the first live entity to exist (whatever that means) either, just that we all descend from one such animate entity; he may have been a member of a community, or he may have been the first to fulfill whatever definition of life you care to make.
This is a mathematical necessity. The only way you could avoid it is to hypothesize that life sprang up independently in different places at roughly the same time, and both (or several) of these were viable and were able to compete to have descendants today. This is unlikely, but not ruled out by archaeo-biology, as far as I know. Since it is well known that symbiosis did occur in early protobacterial beings, giving rise to the mitochondria within cells, it may be that the enveloping cells and the mitochondria have different parentages, but not likely, as their chemistry appears to be too equivalent to be accidental.
So, yes. To any thinking person who accepts logic and evolutionary biology, it must be apparent that all life, with a high confidence, descends from a single live entity somewhere in the past. All others which may have ever been alive are now, probably, extinct.
And what difference does that make? After I've accepted being descended from my parents, the rest follows.
His responses to me on a variety of subjects have the same tenor. Kinda': Your wrong because everybody else sees the facts that you can't see because your wrong.
