http://www.theoblogian.org/Quality theological discussion.60 http://ww.theoblogian.org/Post.aspx?s=rc&idpPost=11#Comment_19I am really enjoying that book though I am wondering about assumptions that have been made about time spans. Being a Bible-carrying member of the YEC club, I am uncomfortable with more than 4 digits preceding the words "years ago." Gonzalez and Richards are unconcerned about ice-core samples taken from Antarctica providing data dating back 400,000 years and Greenland providing data for 12,000 years. You refer to their fudge factor ambiguity, but I am wondering about the assumptions underlying all their zeroes.<BR>A point of comparison is&nbsp;a few years ago when some woman christened “Eve” got a little attention thanks to mitochondrial DNA (mtDNA). She is the matriarchal ancestor of all of us, and she was estimated to have come from north Africa about 200,000 years ago. That is 6 digits before the words “years ago” so I dug into how scientists had arrived at that number. One explanation I found said that it was based on percentage of differences between mtDNA samples. The difference translated into years based on the fact that human and chimp DNA differ by ~5% and the theory that we climbed down out of the family tree 5 million years ago! <A class="" title="Mitochondrial DNA and Human Evolution" href="http://www.artsci.wustl.edu/~landc/html/cann/" target=_blank>A similar explanation</A> bases its “Tentative time scale” on the arrival of humans in New Guinea (30,000 years ago), Australia (40,000 years ago), and the New World (a mere 12,000 years ago).<BR>There is a theoretical basis, but no scientific basis for 200,000 years. David Plaisted discusses the effect of these assumptions in his article, <A class="" title="Mitochondrial DNA Mutation Rates" href="http://www.cs.unc.edu/~plaisted/ce/mitochondria.html" target=_blank>Mitochondrial DNA Mutation Rates</A><BR>So how scientific are the times that Gonzalez and Richards use? They mention that the 11 year cycles of sunspot activity can be detected through isotopes in core samples taken from Greenland (p.25). Does this mean that scientists have actually found over 1000 cycles or did they skip surface layers and begin analyzing deeper core samples?Brian7/7/2005 8:49:00 PM