This is strange. A person with a Ph.D. in
molecular genetics, Georgia Purdom, wrote a post in which
she claims to have shown that the development of antibiotic resistance
in bacteria is not an example of evolution.
Resistance of Bacteria: An Example of Evolution in Action?
by Georgia Purdom, Ph.D.
July 10, 2007
The extraordinary ability of certain
bacteria to develop resistance to antibiotics—which are
otherwise useful in speeding recovery from some illnesses—has
been a hot topic on the minds of doctors, hospital staff, reporters,
and the general public for several years. It is also heralded as a
textbook example of evolution in action.
These bacteria are being studied by evolutionary scientists with the
hope that they will reveal secrets as to how molecules-to-man evolution
could have happened.
But are bacteria really evolving?…
Dr. Purdom then makes several errors:
Although the mutant bacteria can survive
well in the hospital environment, the change has come at a cost. The
altered protein is less efficient in performing its normal function,
making the bacteria less fit in an environment without antibiotics.
Typically, the non-mutant bacteria are better able to compete for
resources and reproduce faster than the mutant form.
She waffles a bit on this point, so I can’t say she is 100% wrong.
Typically, the mutated bacteria are at a disadvantage in an
antibiotic-free environment. But not always. The
exceptions can be hugely important, though. It is not
appropriate to downplay them.
Bacteria can also become antibiotic
resistant by gaining mutated DNA from other bacteria. Unlike you and
me, bacteria can swap DNA. But this still is not an example of
evolution in action. No new DNA is generated (a requirement for
molecules-to-man evolution), it is just moved around.
This is just silly. Evolution does not
require that new DNA be created. Plus, when she acknowledges
that mutations can occur, she acknowledges that new DNA can
Mutation and natural selection, thought to
be the driving forces of evolution, only lead to a loss of functional
systems. Therefore, antibiotic resistance of bacteria is not an example
of evolution in action but rather variation within a bacterial kind.
Mutation and natural selection are two of the
mechanisms of evolution, but they are not the only ones. The
statement that they only lead to the loss of functional is simply
unsupportable. The statement, about antibiotic resistance not
being an example of evolution, does not follow at all from the
The strange thing about this is that she really ought to know better.
In fact, it is difficult to believe that she does not.
Yet, the statements indicate that she does not understand
evolution at all. She could state that the type of evolution
observed when bacteria evolve antibiotic resistance via DNA swapping
does not explain the origin of species. If she stopped there,
she would be fine. But when she tries to extend the argument,
the whole argument falls apart.