Mr.Kitchen

How did blood tpyes develop? It seems to me that a creationist should have a hard time explaining why they exist. Since there is definately harm in there being more than one type and not much benefit to it.

MrDarwin

The Fall
(gee, that was easy, wasn't it?)

Mr.Kitchen

I love those graemlins but really that expalins nothing as you no doubt know

If you have the time could you produce the real explaination(the evolutionary one) a link would do.

[ August 09, 2002: Message edited by: Mr.Kitchen ]</p>

MrDarwin

Okay, slightly longer answer, starting with a question: what's the problem with blood types? Blood transfusions were not a part of the evolutionary process. Perhaps blood types arose by completely random and evolutionary neutral mutations, and only became significant when we started doing blood transfusions and organ transplants.

Or it's possible that different blood types give differential immunity to various diseases that are typical for different parts of the world (much like sickle cell anemia confers some resistance to malaria in Africa, although at the expense of children who are homozygous for the allele). It's also possible that this occurred several thousands of years ago, and modern blood types are an artifact of ancient selection events that don't really affect us anymore (perhaps the disease became less virulent, or humans became more resistant in other ways). Sheer speculation on my part, but now you've got me wondering so maybe I'll do a little websearching.

Now, if you're looking for the creationist explanation, I do indeed believe they would resort to "the fall", or perhaps mumble something about mutations always being harmful and/or leading to the loss of information.

theyeti

Blood types are just surface antigens (made from oligosaccharides) on RBCs. Blood type O is the absence of such antigens, which is why O is the universal donor, but people with O blood cannot accept transfusions from either A, B, or AB. Type O is the most common blood type. What the exact function of the ABO blood group is I'm not sure. But in general, surface antigens exist to help your immune system tell apart your proteins from that of an invader. In other words, they're used for cell recognition. I don't think it matters so much what types of blood groups you have, just that you have enough variety to recognize your cells as "you". Antibodies probably evolved to recognize polysaccharides, since this is what bacterial cell walls are made of.

There are actually 14 different blood group systems (ABO is just one) with over 100 different blood group antigens. Blood types are indeed strongly correlated to geographic location, though this is most likely due to the recent shared ancestry of people in a certain locale rather than selection.

theyeti

MortalWombat

<a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Display&dopt=pubmed_pubme d&from_uid=8420836" target="_blank">Here</a> are links to publications dealing with primate ABO blood type evolution, and related articles.

[ August 09, 2002: Message edited by: MortalWombat ]

[ August 09, 2002: Message edited by: MortalWombat ]</p>

tgamble

This is gonna sound stupid but...

On the Simpsons episode, Mr. Burns (and Bart, but neither of his parents apparently) has "00 negative blood" Is there such a type?

gallo

Blood types are, of course, genetic - each individual carries two alleles

AA = A
AO = A
BB = B
BO = B
AB = AB
OO = O

Negative refers to the Rh factor, which is either positive or negative. Rh positive is dominant. Thus it is possible that Bart's parents are either AO or BO and heterozygous for Rh. So Bart could be OO Rh-. I am O Rh-. We are about 6% of the population - not the rarest. We are the universal donar but can only be transfused with O Rh-.

It seems that I read a paper not too long ago that talked about blood types offering some resistance to certain common diseases.

Coragyps

And a factoid that we could perhaps put on a "What the Creationists Don't Want You to Find Out" list is that "Rh Factor" takes its name from having been originally found in Rhesus monkeys, not humans.

tgamble

ah, that's just the evil evilutionists making up the term to fit with their faith in the evolution religion. It doesn't prove monkeys gave birth to humans.