"People inherit two genes for blood type; or, more accurately, two alleles, one from each parent. These alleles are represented as IA for type A, IB for type B, and i for type O.
So what light does this shed on human origins? Is it possible for the two people of the Creation
account (Adam and Eve) or the eight people on Noah’s Ark to give rise to all of the ABO blood types present in humans today?
If Adam and Eve were heterozygous for blood types A and B, respectively (one allele for type O and one allele for either type A or B), they could have produced children that had any of the ABO blood types. The Punnett square simply predicts what the possible phenotypes would be for a given couple’s children. From the number of children that Adam and Eve likely produced, it is not difficult to envision all of the ABO blood types being passed down to their offspring.
If Adam and Eve were heterozygous for the ABO blood type gene locus, then the allele frequency for the type O allele is 50 percent (2 of 4 alleles), the allele frequency for type A is 25 percent (1 of 4
alleles), and the allele frequency for type B is 25 percent. If there are no selective pressures or genetic drift for these alleles, then the allele frequency will remain constant through all of their descendants. The overall allele frequency in the Punnett square is actually the same for the children as it might have been for Adam and Eve. This scenario would also be true for Noah’s family and their descendants.
Do human populations today reflect these allele frequencies? The answer is yes.
There is a general increase in the frequency of the type O allele, and in many populations a drop in the type B allele. But as expected, the frequencies for each allele are close to what they could have been at the start of human history or with Noah’s family. The shift in frequency (the increase in type O and decrease in type B) can be caused by migration of people groups that had a higher or lower frequency for one of the alleles at the time of migration. It could also result from random genetic drift, or from a mutation that renders glycosyltransferase inactive—which would result in blood type O from type A and is likely one cause for the increase in the frequency of the O allele.
The deletion responsible for converting an A allele to an O allele is not present in chimpanzees, and sequence comparisons between humans and chimps indicate this allele is unique to the human lineage, further complicating an evolutionary scenario for the origin of blood type O. This scenario would fit better if the O allele was rare in the population today and appeared in a specific people group. However, the O allele is by far the most common allele globally, indicating that if it did originate via a mutational event, it had to occur when the human
population was extremely small and before humans divided into ethnic groups and spread across the globe.
It is possible to achieve the current O allele frequency via a mutation if it occurred at the time of Noah’s flood and was passed on by one of Noah’s family members. Noah or Mrs. Noah could have had the O allele and passed it on to each one of their sons, or the alleles could have mutated in one son’s offspring. The population of the human race at the time of the flood and immediately afterward certainly qualifies as a population size that would enable a mutated allele to become common as the population grew. With a starting population of only eight people, the O allele could easily have increased in frequency through random genetic drift in the post-flood population, reflecting the present levels that are observed today and consistent with computer simulations modeling fixation.
CMIAnd God said, Let us make man.... Genesis 1:26
So what light does this shed on human origins? Is it possible for the two people of the Creation
If Adam and Eve were heterozygous for blood types A and B, respectively (one allele for type O and one allele for either type A or B), they could have produced children that had any of the ABO blood types. The Punnett square simply predicts what the possible phenotypes would be for a given couple’s children. From the number of children that Adam and Eve likely produced, it is not difficult to envision all of the ABO blood types being passed down to their offspring.
If Adam and Eve were heterozygous for the ABO blood type gene locus, then the allele frequency for the type O allele is 50 percent (2 of 4 alleles), the allele frequency for type A is 25 percent (1 of 4
Do human populations today reflect these allele frequencies? The answer is yes.
There is a general increase in the frequency of the type O allele, and in many populations a drop in the type B allele. But as expected, the frequencies for each allele are close to what they could have been at the start of human history or with Noah’s family. The shift in frequency (the increase in type O and decrease in type B) can be caused by migration of people groups that had a higher or lower frequency for one of the alleles at the time of migration. It could also result from random genetic drift, or from a mutation that renders glycosyltransferase inactive—which would result in blood type O from type A and is likely one cause for the increase in the frequency of the O allele.
The deletion responsible for converting an A allele to an O allele is not present in chimpanzees, and sequence comparisons between humans and chimps indicate this allele is unique to the human lineage, further complicating an evolutionary scenario for the origin of blood type O. This scenario would fit better if the O allele was rare in the population today and appeared in a specific people group. However, the O allele is by far the most common allele globally, indicating that if it did originate via a mutational event, it had to occur when the human
It is possible to achieve the current O allele frequency via a mutation if it occurred at the time of Noah’s flood and was passed on by one of Noah’s family members. Noah or Mrs. Noah could have had the O allele and passed it on to each one of their sons, or the alleles could have mutated in one son’s offspring. The population of the human race at the time of the flood and immediately afterward certainly qualifies as a population size that would enable a mutated allele to become common as the population grew. With a starting population of only eight people, the O allele could easily have increased in frequency through random genetic drift in the post-flood population, reflecting the present levels that are observed today and consistent with computer simulations modeling fixation.
Conclusion
If Adam and Eve did not have all three blood type alleles, then there must have been a mutation creating the O allele while the human race was still very small and before humans dispersed across the globe. Whether the origin of blood type O was in Adam and Eve at creation or whether it arose as a mutational event that took place shortly before or after the flood, it strongly supports that all humans today are descendants of two individuals or a small group of people that eventually populated the globe. Both scenarios are consistent with the biblical model of human origins."CMIAnd God said, Let us make man.... Genesis 1:26
