Evolution of human blood types?
As with anymutation that propagates through a population there is likely some sort of evolutionary advantage. After a brief online search I couldn't find any documents that state what advantage they could provide. I did however find a page that stated the blood types diverged over 13 million years ago, and similar blood types can be found in chimps and gorillas, so your question may be misleading. A and B antigens are glycoproteins that resemble bacterial antigens, and are thus highly immunogenic. Because we are immersed in bacteria every day, it may be an advantage or disadvantage to have self antigens that look like bacteria depending on the type of bacteria. Diet could definitely affect the spreading of a paticular antigen. For example, if all you can eat is cellulose, humans cannot digest cellulose, but some bacteria can. If your immune system kills the bacteria that digest cellulose, then you can't eat it. Now say someone comes along that has a self antigen that looks like the immunodominant antigen on this bacteria. That person will be less likely to develop an immune response to that bacteria...they can now eat cellulose and live happily and reproduce, passing on that blood antigen. My example is pretty far fetched...in a more likely scenario the bacteria would actually drop the antigen since they evolve much faster than we do.
What are the human blood types?
There are four major groups of blood that are determined by the presence or lack of the A & B antigens on the surface of the blood cells. These groups are A, B, AB, and O. A - only has A antigen on the blood cells and B antibody in the plasma. B - only has B antigen on the blood cells and A antibody in the plasma. AB - has both the A & B antigens on the blood cells, but contains neither A nor B antibodies in the plasma. O - has neither A nor B antigens on the blood cells, but contains both A & B antibodies in the plasma. In addition to the A & B antigens, there is a third antigen called the Rh factor, which can be either present (+) or absent ( – ). In general, Rh negative blood is given to Rh-negative patients, and Rh positive blood or Rh negative blood may be given to Rh positive patients. The universal red cell donor has Type O negative blood type. The universal plasma donor has Type AB positive blood type.
How did blood types evolve?
Blood types are primarily dictated by sugar decorations on proteins. Specifically, N-acetylgalactosamine for the A-type and galactose for the B-type. The O type is the complete absence of either sugar decoration. Could a new blood type arise, yes quite possibly it could. In other animals besides apes there are many different blood types. Pigs for example have a couple of incompatible blood types with humans. The primary incompatibility is alpha-Gal. This sugar decoration is a produce of a particular gene that is expressed in the porcine genome. In the primate lineage leading to humans, this gene has been rendered inactive and no longer expresses. Thus we as humans do not have the alpha-Gal blood group.It is quite possible that a new sugar decoration could exist in someone, conferred by the expression of a new gene. It would only take one such instance for the blood group to come into existence too. If that human procreated and their children inherited the gene that conferred the new blood group, then there is a chance this new blood group could grow and thrive. Evolution is driven by positive and negative pressure. if the new sugar imbues some benefit to survival or some advantage in procreation, then it would surely increase in likelihood. However Humans aren't really governed by evolution anymore, so in this period of human evolution, it is very unlikely that a new blood group would have a distinct advantage, at least one that would allow the new group to thrive in comparison to other groups.Take A/B vs O, in Malaria infested regions, O has a distinct advantage because they are more resistant to the malaria infection. Thus an O blood type is more likely to survive and procreate. It is unlikely a new blood group would have such an advantage over the current A/B mix. This dynamic of course would change if a disease that takes advantage of A or B to get a foothold for disease propagation. If your new blood group was resistant, then it would surely take off, as the A/B blood types died off to the new disease.Hope this helps
What do the ABO blood groups suggest about the evolution of the human species?
Two explanations are usually invoked to explain why some groups of humans have greater frequencies of particular blood types. The amount of actual data for either one is fairly small but both do fit into general models of human evolution. The first is that this is a product of genetic drift mechanisms. These include founder effects (small groups of individuals with different allele frequencies found a new population) and random drift (changes are in allele frequencies are just random chance). These type of explanations involve no selection for particular blood types and explain why different types are at higher frequency in different populations. The second explanation is that during outbreaks of particular diseases, one blood type does have an advantage over others. Since until recently, most disease outbreaks only infected one population of humans, each population could have enrichment for different blood types due to different disease histories. This explanation is used to propose that the Black Plague led to European populations becoming enriched in type O blood types.
Statistics question on blood types between chinese and americans? Distribution of blood types All human blood ?
Statistics question on blood types between chinese and americans? Distribution of blood types All human blood can be "ABO-typed" as one of O, A, B, or AB, but the distribution of the types varies a bit among groups of people. Here is the distribution of blood types for a randomly chosen person in the United States: A=0.4 B=0.11 AB=0.04 0=0.45 Blood types in China The distribution of blood types in China differs from the U.S. distribution given in the previous exercise: A=0.27 B= 0.26 AB=0.12 O=0.35 Choose an American and a Chinese at random, independently of each other. 4.22b What is the probability that both have the same blood type? Give your answer to two decimal places. Fill in the blank: The probability that both have the same blood type is: _______ .
Based on this information, what can you infer about the evolution of the human species?
This isn't evolution, it's just change of allele frequencies over time. Evolution requires an increase of information through mutations, that's not what is happening here. It is just change in allele frequencies of already present information. No new information coming about. Now to answer your question directly, This is an example of genetic drift and isolation so some alleles are not in the populations or are rarely in the populations.
What evolutionary reason is there for humans developing different blood types?
Good question. I have assumed that different blood types in mammals evolved to cope with different contagious diseases and that having a variety of blood types within a group maximizes the survival of the group and the variety of immune system responses available within the group not just the individual.One thing to bear in mind though that evolution never cared about blood transfusion because transfusion never happens in nature.This recent article from a respectable source Sort endorses the view.The Mystery of Human Blood Types