Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
4 online now:
Newest Member: popoi
Post Volume: Total: 915,806 Year: 3,063/9,624 Month: 908/1,588 Week: 91/223 Day: 2/17 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Question on how Evolution works to produce new characteristics
xongsmith
Member
Posts: 2578
From: massachusetts US
Joined: 01-01-2009
Member Rating: 6.8


Message 95 of 104 (565092)
06-14-2010 6:09 PM
Reply to: Message 94 by RAZD
06-13-2010 6:02 PM


Re: Cyanobacteria -- the ultimate "living fossil"?
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

This message is a reply to:
 Message 94 by RAZD, posted 06-13-2010 6:02 PM RAZD has seen this message but not replied

Replies to this message:
 Message 97 by Dr Jack, posted 06-15-2010 8:24 AM xongsmith has seen this message but not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024