Valentine Pontifex

It took me a few days to notice but Wesley Elsberry put up the latest feedback for the Talk.Origins Archive.

The big draw this week is not the usual nuts, but some nice detailed responses.

Some good stuff on Pb-Pb isochrons (which work a bit differently from the Rb-Sr isochrons people usually mention in these types of forums), quantized redshifts, etc.

http://www.talkorigins.org/origins/feedback/may03.html

(And if you want to link to a specific part of it, you can do so. Look in the source code for something like name="f13" or name="r13" and add a #f13 or #r13 right after the html in the URL.)

Secular Pinoy

Thanks for the reminder. In a certain response, Bob Patterson says By one measure, the range a variation within the human genome is about .030 percent. Can anyone elaborate on this measure of difference? How was it measured? This statement implies other ways of measuring differences, what other means of measurement are there, and what are their merits? Is the 0.030 % difference normal compared to other species, or are they higher or lower?

ps418

Rufus would be the one to give you a real answer, but I'll take a stab. You can measure variability of different types of genetic data. For instance, nucleotide variability of whole genes, nucleotide variability of exons or introns only, variability of noncoding regions like minisatellites, variability of Y chromosomes, or mitochondria. You'll get a different answer depending on the type of genetic data you're looking at. The most important measure I'd think would be autosomal genes, since this represents the bulk of genetic information in humans.

Presumably Patterson is referring to a measure of average nucleotide diversity, but nothing indicates which genes or genetic data are being referred to. One estimate of average nucleotide diversity that I've seen, based on a sample of 313 human autosomal genes, is 0.058% (Stephens et al, 2001). Stephens et al's paper is available as a free PDF:

Stephens et al, 2001. Haplotype Variation and Linkage Disequilibrium in 313 Human Genes. Science 293, 489-493.

Patrick

ps418

Also, I wonder what is the variability within human genes of nonsynonymous nucleotide substitutions. The difference between humans and chimpanzees with respect to this measure of difference is only about 0.6%, according to that recent paper by Wildman et al.

Wildman et al, Implications of natural selection in shaping 99.4% nonsynonymous DNA identity between humans and chimpanzees: Enlarging genus Homo. PNAS Published online before print May 23, 2003.

Patrick