Finnyhaha
Member
I recently started reading a book of this title written by Richard Dawkins, and I am starting this thread with the intent of posting specific questions that I have about the work (with the hopes that someone will be able to help me with them), as well as just interesting tidbits of information that I find worth sharing.
To begin with, in his discussion of the most recent common ancestor (MRCA) of (for example) modern humans, Dawkins distinguishes two historical points. Firstly, he terms the time at which the MRCA lived as "Chang One" (after the reasearcher who constructed the formula for making an estimate as to what point in history that would be). He then goes back further to a point (called "Chang Two") at which all alive at that time are either the ancestor of all modern human beings, or of none of them. He then makes a statement (without giving a mathematical basis for the claim, presumably because it is either too obvious to be bothered to include, or too complicated for the average reader to understand) that 80% of the population at Chang Two will be ancestors, while only 20% will not be. Is there anyone here who can explain those figures? Is it just a statistical fact that 20% of individuals have lineages that dead-end after a certain period of time while 80% survive that time-frame? Is there an obvious explanation that I'm missing here?
Well, that's the question I have so far. I'm hoping to open up discussion on the work as a whole and will be posting more on this topic shortly. I'd also be interested in using this post to more general evolutionary genetic discussion.
Mu
Finny
To begin with, in his discussion of the most recent common ancestor (MRCA) of (for example) modern humans, Dawkins distinguishes two historical points. Firstly, he terms the time at which the MRCA lived as "Chang One" (after the reasearcher who constructed the formula for making an estimate as to what point in history that would be). He then goes back further to a point (called "Chang Two") at which all alive at that time are either the ancestor of all modern human beings, or of none of them. He then makes a statement (without giving a mathematical basis for the claim, presumably because it is either too obvious to be bothered to include, or too complicated for the average reader to understand) that 80% of the population at Chang Two will be ancestors, while only 20% will not be. Is there anyone here who can explain those figures? Is it just a statistical fact that 20% of individuals have lineages that dead-end after a certain period of time while 80% survive that time-frame? Is there an obvious explanation that I'm missing here?
Well, that's the question I have so far. I'm hoping to open up discussion on the work as a whole and will be posting more on this topic shortly. I'd also be interested in using this post to more general evolutionary genetic discussion.
Mu
Finny