THE TELLTALE BLOOD
FROM RACES AND PEOPLE
BY WILLIAM C. BOYD PH.D. and ISAAC ASIMOV PH.D.
Copyright 1955 Abelard-Schumann, New
William Clouser Boyd, blood type anthropologist, science fiction writer with Isaac Asimov, and the discoverer of lectins (talk about a life!) used his work with blood types in Races and People to demolish the racist notions then commonly believed in this country during the
1950's. This section is on inheritance and constitutes one of the best
handlings of a complex subject for the layperson.
Fifty years later John H. Jenkins could still write of Races and Peoples:
"Asimov, as an unabashed liberal and champion of the essential value of any human being (partly because of his growing up as a Jew in an era when significant portions of the world found anti-Semitism innocuous or even virtuous), here attacks the notion of "race". He shows how it is hard to define and uses Boyd's research to demonstrate that the superficial characteristics, which so many of us use to define "race" and determine our value vis-à-vis other human beings, are utterly without value. In the end, again following Boyd, he resorts to blood typing as a method ”not to determine race” but to trace the different overall "types" of humanity and show how they have moved back-and-forth across the world.
This is truly a book which ought to be read much more today. (I speak as one who has unabashedly absorbed many of Asimov's liberal values.)
Boyd defined race as "not an individual, not a single genotype, but a group of individuals more or less from the same geographical area (a population), usually with a number of identical genes, but in which many different types may occur." For
Boyd you got your racial characteristics from where you live more than from your genes, and this explained why the variability made the notions of race untenable.
CHAPTER 8: THE
It is quite common
to hear people talk of blood as though it differed according to race
or nationality. You may have heard talk of "Negro blood" or
"French blood" or even "Jones blood' or "Smith
blood." During World War II some people wanted the American Red
Cross to keep the blood it received from white people separate from
that which it received from Negroes.
Supposedly this was to keep white soldiers from receiving transfusions
of "Negro blood."
Actually, this is
nonsense and superstition. If a scientist or a doctor were given a
sample of normal blood, there would be no way in the world be could
determine for sure whether it came from a man or a woman, a Frenchman
or a German, a Negro, an Aboriginal, a Chinese, or an American. Nor
could your body, if the blood were put into your veins.
Yet there are ways
in which your blood may be different from your neighbor's, or even
from the blood of your closest relatives. Let us see how.
Every once in a
while, during an operation or as a result of a serious wound, a man or
woman may suffer considerable loss of blood. To keep the patient
alive, it is sometimes necessary, then, to transfer blood into his
body from that of some healthy person (called a donor) who is willing
to give his or her blood for the purpose. (A person in normal health
can easily give up a pint of blood without pain or any harmful effect.
The body quickly manufactures new blood to replace that much.)
Such a transfer of
blood is called a transfusion.
When a patient
needs a quick transfusion of blood, it is not enough just to grab any
healthy person as the donor. The blood of one donor may save the
patient's life. The blood of another, equally strong and healthy, may
kill the patient. The use of a relative as a blood donor is no
insurance. The blood of the patient's own mother or sister may be
deadly, while the blood of a complete stranger, of a foreigner, or of
a member of a different race, may be life-saving.
Why is this so?
Let's consider blood a bit more closely.
The liquid portion
of blood is called plasma. Plasma is mostly water, but it contains
many dissolved substances of great importance to body chemistry.
Floating in the plasma are various kinds of cells. The most numerous
of these cells are the red cells, which are also called erythrocytes.
These are very small and simple cells. They are so simple that they do
not even contain nuclei. The erythrocytes are the only human cells
which do not contain nuclei.
do contain small quantities of certain chemicals known as blood-group
substances. Two important kinds of blood-group substances are referred
to simply as A and B. In any one person, all the erythrocytes are
alike in the kind of blood-group substances they contain. In one case,
perhaps, all the erythrocytes contain A, and none of them contain B. A
person with such erythrocytes is said to possess blood type A.
In the plasma of a
person of blood type A there is dissolved a substance that has no
effect on A. However, if that substance in the plasma were to come in
contact with erythrocytes containing B, it would combine with those
erythrocytes and make them clump together in one large sticky mess.
The substance in the plasma is therefore called anti-B. Anti-B is said
to agglutinate erythrocytes containing B.
On the other hand,
a person of blood type B has a substance dissolved in his plasma,
which will agglutinate erythrocytes containing A. It is called anti-A.
We have now
described two types of people. One
kind has A in his erythrocytes and anti-B in
his plasma (the two always go together). The other kind has B in his
erythrocytes and anti-A in his plasma.
Suppose, now, a
patient who is of blood type A needs blood quickly. A healthy
volunteer offers his blood. He is also of blood type A. The donor's
blood mingles with the patient's without any bad effect, and the
patient's life may be saved.
But suppose the
healthy volunteer is of type B. As his blood entered the patient's
veins, the anti-B in the patient's Plasma would quickly agglutinate
the B containing erythrocytes of the donor. The patient would get no
good out of such a transfusion. In fact, the resulting clumped-up
erythrocytes in his blood vessels would probably kill him.
The same trouble
would result if one were to pump type A blood into a patient whose
blood was of type B.
There is a third
type of blood. Each erythrocyte of some persons may contain both A and
B. Such persons are said to have blood type AB. A person of blood type
AB has neither anti-A nor anti-B in his plasma. (If he did have anti-A
or anti-B, he would agglutinate his own blood and die.) Do you see
what this means? Without anti-A or anti-B, he can be given blood not
only from a donor of type AB, but also from a donor of type A or B.
(Of course, donors of type A and type B have anti-B and anti-A in
their plasma, which could agglutinate the patient's AB erythrocytes.
This is rarely serious, however. It is the donor's erythrocytes that
make trouble. If they are not agglutinated by the patient's plasma,
then all is well.)
Blood from a donor
of type AB can't be given to a
patient of type A, for the B in the donor's
erythrocytes causes them to be agglutinated by the anti-B in the
patient's plasma. The AB donor isn't good for a patient of type B,
either, for the A in the donor's erythrocytes causes them to be
agglutinated by the anti-A in the patient's plasma.
In other words, an
AB donor can give blood only to another AB, but an AB patient can take
blood from anyone.
There is still a
fourth type of blood. A person may have erythrocytes containing
neither A nor B. He is said to be of blood type O. Such a person has
plasma that contains both anti-A and anti-B. He can't accept blood
from anyone but another O. On the other hand, since his erythrocytes
contain neither A nor B and so can't make trouble, he can give his
blood to a person of any blood type. He is a universal donor.
Sometimes it is
only necessary to give the patient plasma, and that makes things
simpler. Plasma contains A and B, but only in solution; there are no
cells to be agglutinated. Furthermore, if the plasma of several donors
is mixed, the B in one counteracts the anti-B in another and the A in
one counteracts the anti-A in another. It is generally true, then,
that plasma can be transferred from any donor to any patient. It is
when whole blood (plasma plus cells) is needed that the rules of
transfusion must be observed.
GROUPS A, B, AND O
A single gene
series controls the production of the blood-group substances we have
mentioned. Whether a person is of blood type A, B, AB, or O depends on
the nature of the genes of that series which he
has inherited. Every person has two genes of that gene series, one on
each of a pair of chromosomes. He inherits one gene from his father
and one from his mother.
Three types of
homozygotes are possible among these blood groups. A person can be
homozygous with respect to blood group A; that is, he can carry an A
gene on both the chromosomes involved. Let's call him AA. A person can
have a B gene on both chromosomes or an O gene. He would then be BB or
The gene for A is
dominant over the gene for O. Suppose, for instance, that a man who is
homozygous for blood type A marries a woman who is homozygous for
blood type O. The man will produce sperm cells which will all carry
the A gene. The woman will produce egg cells that will all carry the O
gene. Any fertilized ovum will therefore possess one A gene and one O
gene. All the children of such a marriage will be heterozygous. We can
call them AO.
Since A is
dominant over O, only the A will appear when scientists test the
blood. An AO person will be classified as belonging to blood type A.
(Here is a case where a mother is of blood type O and all her children
are of blood type A. The children could not give blood to their own
mother, but any stranger of blood type O could.)
Suppose a person
is of blood type A. Is there any way of telling whether he is
homozygous (that is AA) or heterozygous (that is, AO)? The only way
one can sometimes tell is by considering the man's children. We have
already said that a marriage between an AA and an OO produces children
that are all of blood type A.
that an AO man marries an OO woman. Half of the man's sperm cells
contain an A gene and half contain an O gene. All the woman's egg
cells contain O genes. You can see that the fertilized eggs could be
either AO or OO. In the first case the child would be of blood type A;
in the second case he would be of blood type O.
So, you see, if a
person of blood type A marries a person of blood type O and has even
one child of blood type O, we have found out something. We have
discovered that the person of blood type A is AO and not AA. If he
were AA, children of blood type O would be impossible.
Of course, as we
have just said, an AO-OO marriage can produce either AO or OO
fertilized ova. Suppose, just by chance, that all the children
produced in the marriage happened to be AO. Here you would have a case
where all the children were of blood type A; yet you couldn't be sure
that the parent of blood type A was AA, In other words, you can be
guided by the type of children produced in a marriage sometimes, but
The gene for blood
type B is also dominant over the gene for blood type O. This means
that people who are BO are of blood type B. Blood tests cannot tell
the difference between BO and BB. The difference shows up (sometimes,
not always) in the blood types of the children of such people.
Neither the gene
for blood type A nor the gene for blood type B is dominant over the
other. Here is a case of incomplete dominance. If an AA person marries
a BB person, all the children are AB.
We can now
summarize the state of affairs in connection with these blood groups.
1. All people of
blood type O are homozygous. They have two O genes. You can see that
this must be true. If they had one A gene or one B gene, they would
no longer be of blood type O.
2. People of
blood type A fall into two groups. They can be homozygous, having
two A genes, or they can be heterozygous, having one A gene and one
O gene. For transfusion the difference doesn't matter. AA blood and
AO blood behave exactly alike in transfusion.
3. People of
blood type B fall into two groups. They can be homozygous, having
two B genes, or they can be heterozygous, having one B gene and one
O gene. In transfusion the two groups behave the same.
4. People of
blood type AB are all heterozygous. They carry one A gene and one B
By now you can see
one very practical use for blood groups. Suppose some mother had the
notion that the hospital had accidentally got her baby mixed up with
another baby. She might find out whether this was so by having her
blood and the baby's blood tested.
perhaps, that King Solomon, in the Bible, found it necessary once to
decide which of two women was the mother of a child. His decision in
that matter is the most famous example of the "wisdom of
Solomon." With modern blood-group tests the problem might have
been very easy.
instance, that one of the women facing Solomon was of blood type O.
She would then have two O genes. Suppose that the other woman was of
blood type A. She could be either AA or AO. Now what if the child were
of blood type AB? it would have one A gene inherited from one parent
and one B gene inherited from the other parent. But the woman of blood
type O possesses neither an A gene nor a B gene to pass on to the
child, and she could not possibly be the mother. The woman of blood
type A could be the mother. (Of course, if both mothers were of blood
type A, blood tests involving only this gene series would not help.)
In modern times, a
woman of blood type O, bringing home a child of blood type AB from the
hospital, would know that the hospital must have mixed up her baby
with another's. (Such mix-ups rarely happen.)
Blood tests may
also be helpful in deciding whether a certain man is the father of a
Suppose a man and
his wife are both of blood type O. Both must possess two O genes. Now
one of their children turns
out to be of blood type A. Immediately one can see that something is
the A gene could not have
come 'from the child's supposed parents. It doesn't I t matter whether
or AO. It must have at least one A gene, and neither its father nor
its mother could have supplied it.
In that case
either the supposed mother is not the real mother or the supposed
father is not the real father. (Or perhaps neither parent is the real
that the child turns out to be of blood group O, like both its
parents. Does that prove the child is really theirs? It doesn't. It
shows the child might be theirs, but it doesn't prove it is. The
hospital might have mixed it up with another O-type baby. Or the real
father might also be of blood group O.
We can make a
general rule. A blood test can prove a supposed parent is not the real
parent. It cannot prove a supposed parent is the real parent.
a blood test proves that a supposed parent is not the real parent, it
is inconclusive. A decision must then be reached by other types of
You know enough
already to take other cases and see for yourself which blood types are
possible among the children of a marriage and which are not. If the
father is of blood type O and the mother is of blood type AB, then all
the sperm cells carry the O gene, while half of the egg cells carry
the A gene and half the B gene. The fertilized ova can only be either
AO or BO. It follows that the children of such a marriage must be
either of blood type A or of blood type B. Children of blood type O or
blood type AB are impossible. This is an interesting case because it
is one in which it is impossible for children to be exactly like
either their mother or their father in this physical characteristic.
Here is another
interesting case. Suppose the father is of blood type A and the mother
of blood type B. The father might be AA or AO; it would be impossible
to tell which. The mother might be BB or BO; again impossible to tell
which. Suppose they were AO and BO. In that case half of the sperm
cells would carry the A gene and half the O gene. Half of the egg
cells would carry the B gene and half the O gene. The fertilized ova
could possess any of these combinations of genes:
OO (blood type O),
AO (blood type A), BO (blood type B), and AB (blood type AB)
So you see that,
if one parent is of blood type A and the other of blood type B, the
children could belong to any of the four types. It would be impossible
to prove that any child at all did not belong to this couple if only
this gene series were considered.
It is not
necessary to give up in despair over this A-B marriage we have just
discussed. The scientist who tests blood is not at the end of his
rope. There are two varieties of A, called A1, and A2, and these can
be told apart by careful testing. This may help in making the
decision. (As far as transfusions are concerned, it doesn't matter
which variety is present in either donor or patient.)
Then, too, there
are other blood-group substances in the erythrocytes which are
controlled by different gene series altogether. They are inherited
completely independently of the A, B, and O genes.
There is, for
instance, a gene series controlling the so-called M and N blood-group
substances. One gene of that series causes the formation of M, the
other of N. Neither is dominant over the other. If you have two of the
M genes, you are of blood type M. If you have two of the N genes, you
are of blood type N. If you have one of each, you are of blood type
MN. (The M and N blood groups are of no importance in transfusion, by
Now the M and N
blood groups have no connection with the A, B, and O blood groups. A
person can be of blood type M, N, or MN, regardless of whether he is
also of blood type A, B, O, or AB.
that both parents are of blood type O and so are all their children.
Only O genes are involved. But suppose that both parents are also of
blood type M and so are all their children except one. That one is of
blood type MN. He must have got the N gene somewhere. One or both of
the supposed parents can't be the real one.
Still another gene
series controls the formation of a number of blood-group substances of
the Rh series. (The "Rh" refers to the fact that they were
first discovered in experiments with the Rhesus monkey.) There are a
large number of genes in this series, and as many as a dozen different
Rh types (including some heterozygous ones) can be tested for. These,
too, can be used to help decide parentage problems. The more types of
blood groups we use, the greater the chance of settling such questions
difficulties, too, of course. The methods used to test for the
different blood groups can be quite complicated, especially in the
case of Rh. It is necessary to understand the exact way in which all
the various Rh genes can be inherited. It is also necessary to be
certain that you have the proper chemicals to work with. (The most
important chemicals are in the liquid portion of clotted blood, called
serum, obtained from certain people or animals. It is sometimes a very
delicate matter to determine whether the serum being used is just
right for the purpose.) To run blood tests properly, an experienced
laboratory man is required, and there are not very many of those.
Blood tests, by
the way, can also be used in murder cases. It is possible to tell
whether a blood stain is human or not. If it is human blood, one can
sometimes tell whether it is of the same blood type as that of the
murdered man. Even ancient Egyptian mummies have been successfully
tested for blood type.