That's pretty strong evidence that the first known life were responsible for the formation of stromatolites.
...so far.
I think we have to consider probability theory and things like Maximum Likelyhood...and I think Mr. Jack was arguing that this evidence of stromatolites - while supporting the notion of cyanobacteria being the earliest known life forms - was not necessarily evidence that it was the oldest life form. He says:
... and the fact that it is more parsimonious with the known evidence to think that the divergence of Archaea and Bacteria predates the emergence of cyanobacteria and, indeed, that the major Bacterial lineages diverged before cyanobacteria emerged.
Now when he's saying "more parsimonious", I take it to mean "more likely". His evidence is at the molecular level, where I have no expertise. Are we talking 12% versus 11%? 52% versus 31%?
x% versus y% where all we may suspect so far is that x is greater than y, because it's more likely?
let's look at this:
O
\
\'
\
/\ ?
/ \' \
/ \ \
A B C
O = common ancestor
A = a-type descendant
B = b-type descendant
C = c-type descendant
The question might be: where does C attach to the tree? There are 2 little possible marks shown here. C attaching to the A leg is not diagrammed out for clarity. We do know that C does attach somewhere. Above or below the branch. Correct me if I'm wrong, but I think Mr. Jack is only arguing that, on a molecular basis, it looks like "below" is more probable?
Genetic "clocks" are relative dating mechanisms that can tell you that P happened before Q which happened before R, but not when they actually happened.
That IS what we seek here, isn't it? - the order. How much in common is A to C compared to how much in common is B to C?
Trying to understand the argument.
- xongsmith, 5.7d