To: All Dec0893 11:11AM Subject: Something for Creationists to chew on. Well, it's been pr

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From: Usenet To: All Dec-08-93 11:11AM Subject: Something for Creationists to chew on... Organization: The University of North Carolina at Chapel Hill From: KG Anderson Message-ID: <19931208111148KGA@uncmvs.oit.unc.edu> Newsgroups: talk.origins Well, it's been pretty clearly documented on this newsgroup that most Creationists aren't going to be swayed by the evidence. Nevertheless, I though the following factoid might be interesting; perhaps it could even go into a FAQ somewhere. Creationists assert that that humanity began as two individuals around six thousand years ago. It's been pointed out on t.o. before that this cannot account for the current genetic diversity we see in humans, since two people can carry four alleles (at most) between them for any given locus. Furthermore, Creationists assert that humanity was again narrowed down to a handful of people (Noah, his wife, their sons and their sons' wives) after the Great Flood .tm.. Again, this runs counter to everything we see in the current genetic diversity of human beings. (Never mind every other organism on the planet.) I've always liked this counter-argument to Creationism; it's succinct and easy to remember. (Let's face it, most of us don't leave home with the entire t.o. FAQs in our briefcase.) But I've also wanted a good reference to back it up, so that when the inevitable reply, "Oh yeah? *Prove* that humans have that much genetic diversity" comes along, I'll have something to show 'em. Well, I just found what I was looking for: "MHC Polymorphism and Human Origins," by Jay Klein, Naoyuki Takahata and Francisco J. Ayala, in the December 1993 issue of Scientific American (pp. 78-83). Yes, I know SciAm doesn't count as a hard-core scientific reference, but that's all the better: it's available to people who don't have access to research libraries, and it's written in plain English (unlike most papers in genetics journals), so pretty much any C'ist should be able to look it up if they won't take your word for it. In a nutshell, the major histocompatibility complex (MHC) is a bunch of loci located on chromosome 6. They are the genes responsible for labeling your own cells as your own, so that the immune system can recognize foreign cells (including those from transplanted organs) as "invaders," ripe for attack. (That's a gross simplification, but gets the point across.) One gene in particular is of interest to us: HLA-DRB1. Remember how the Creationist "Theory" "predicts" that there should be, at most, just a handful of alleles for any particular gene. On page 78 of that article, they list FIFTY-NINE alleles for HLA-DRB1. (Those are identified as "known alleles," so I guess there could be more out there, as yet unsequenced.) At this point, your shrewd creationist who's had a decent high school biology course (which rules most of them out) may point out that a single point mutation can create a new allele, as in the case of normal hemoglobin converted to the sickled form. I'll quote from p. 79 to answer that point: "The high number of alleles is, however, only one of two extraordinary features of the MHC polymorphism. The other is the large nucleotide diversity among the MHC alleles. In other genetic systems, alleles at a given locus usually differ by a few nucleotide substitutions at most. In the MHC, some alleles differ by 100 or more substitutions." The unescapable conclusion, of course, is that the major histocompatibility complex is far older than creationists would allow. (Another possible explanation is that humans were recently created, but did not begin with just two individuals. Instead, over fifty were created, and they were created with a large degree of genetic diversity. But I don't think anyone is advocating this view--it certainly runs counter to what Genesis says.) If any Creationists out there can think of any flaws in the above logic, I'd love to hear them. If not, we can just add this one to the FAQs-- I think it makes a pretty good "60 second" disproof of Biblical Creationism. KG Anderson kga@uncmvs.oit.unc.edu

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