Date: March 2004
Give an example of A Helpful mutation. Explain why it is
Pretty much all the variation in existing creatures living on earth are the result of helpful
mutation, otherwise, the only living things on earth would be exactly the same as the ones
when life first came to be on earth.
Pick almost any species of animal, and you will find physical reasons that it is not exactly
like similar species, reasons that will help it survive in the location it lives.
Any mutation that creates a protein that wasn't there before, but can now be used by the body
for something is helpful. For example, hemoglobin is a protein in your blood that carries
oxygen. It is made of four protein chains, 2 called alpha and 2 called beta. There are
different versions of these proteins found on your chromosomes. They all appear to have
come from an original hemoglobin-like protein and all came about because of mutations. So
for example, the beta chain is similar to the gamma chain and is different by a few mutations.
However, the gamma chain allows the hemoglobin to bind oxygen even more tightly. The gamma
chain is used by the fetus during pregnancy when it has to share oxygen with the mother.
This is definitely an advantage to the fetus. So fetal hemoglobin is made of 2 alpha and 2
gamma chains.Just before birth, the gene for gamma turns off and the gene for beta turns on
and at birth and after the hemoglobin is made of alpha and beta and doesn't need to bind
oxygen quite as tightly.
There are many other examples.
Answer: The most famous example of a helpful mutation is the gene for sickle
cell disease, which has the ability to protect carriers from malaria.
Malaria is common in Africa, and this gene is common in people of African
ancestry. It appears that the malaria protection in heterozygotes, people
carrying one copy of the gene, was so useful that the gene was preserved in
the population because people carrying the trait survived to have more
children, on average. This benefit existed in spite of the fact that
children carrying two copies of the gene were afflicted with sickle cell
Many other gene differences exist between different people. Our faces, hands
and bodies, internally and externally, are all unique, and many of these
differences are caused by genes. Some characteristics may be caused by
single genes but most have multifactorial inheritance - many genes
interacting with each other and with environmental factors, adding their
effects together. Some of these changes are inherited from our parents and
some may occur as new gene mutations in every generation.
Of all the many genetic differences, those that cause disease get more
publicity, but other mutations may be very useful. Some may make a person
prettier, or stronger, or smarter, or more resistant to disease - even if we
cannot yet pinpoint these genes and say which they are. Perhaps with future
research this may become possible, especially after all the research that
has been done on the Human Genome Project.
Another thing to keep in mind is that some gene mutations may be harmful in
some situations and beneficial in others. Imagine a person with a blood
clotting gene who also has a bleeding disease such as hemophilia. Although
the blood clotting gene is not helpful to most people, since it increases
the risk of a dangerous blood clot, could it perhaps be helpful to the
person with hemophilia? This question may soon be answered by medical
Also, bear in mind that the situations that make a mutation beneficial or
harmful may have a cultural basis that depends on historical reasons rather
than medical reasons. For instance, suppose there is a war and someone who
wants to join the army is refused because of a genetic disease caused by a
harmful gene mutation. It might be that this person's life is saved by not
joining the army.
It sounds strange, but there are cases known, for instance in Tsarist
Russia, where people injured themselves on purpose to avoiding serving in
the army. They considered that living with a crippling injury for the rest
of their lives would be less harmful than 25 years of military service in
harsh and cruel conditions.
Besides this, there may of course be some deeper, philosophical meaning in
the lives of people with genetic diseases. They may be grateful or, at
least, content to live their lives with mutations that the rest of us
consider harmful. This may perhaps even be true for suffering caused by
social factors such as poverty or oppression.
We should all do our best to reduce the amount of suffering in the world.
Everyone's life is unique and meaningful in some way, and all of us have
some potential to improve the lives of those around us and somehow to
Sarina Kopinsky, MSc, H.Dip.Ed.
Click here to return to the Molecular Biology Archives
Update: June 2012