Re: Web Page Nonlinear dynamics

Glenn Morton (
Wed, 19 Feb 1997 20:39:37 -0600

At 06:11 AM 2/19/97 GMT, Robert L. Miller wrote:
>>At 07:24 AM 2/18/97, wrote:
>>This is exactly what selection for resistance to antibiotics has done for
>>bacteria. In the 30's when penicillin was discovered, bacteria could not
>>handle it. The random mutations in the bacteria eventually gave rise to a
>>resistant form. Resistance began to be noticed in th 50s but it wasn't
>>until the 80s that it began to become a real problem. While selection didn'
>>t'look ahead' to that sequence o fdna which conveys resistance, the fact
>>that bacteria which were closer to that sequence had an increased ability to
>>survive forced the population in that direction. Today we hardly have any
>>antibiotics which do what penicillin used to do.
>Did the resistant form of the bacteria show up as a result of random
>mutations, or were they already in the population and became dominant when
>the non-resistant individuals were knocked off by the presence of
>penicillin? Is there evidence that will decide this question?

I saw David Campbell's response and would like to get his reaction to this.
I went back to some old books. I think there is some evidence from years
ago that the ability to tolerate antibiotics was a new mutation. In 1955
Dobzhansky wrote:

"Why, then, are most colon bacteria found outside of the
laboratories still susceptible to bacteriophage attacks and
sensitive to streptomycin? Why have the resistant mutants not
crowded out the sensitive genotypes? [Bacteriophages and
streptomycin have been used to kill bacteria for quite a while-
GRM] The theory leads us to infer that the resistant mutants
must in some respects be at a disadvantage compared to sensitive
bacteria in the absence of phages and antibiotics.
"This theoretical inference is strikingly verified in some
experiments. Close to 60 per cent of the streptomycin-resistant
mutants in colon bacteria are also streptomycin dependant; these
mutants are unable to grow on a cultural media free of
streptomycin. A substance which is poisonous to normal sensitive
bacteria is essential for life of the resistant mutants! e. H.
Anderson has shown that some bacteriophage-resistant strains of
colony bacteria require for growth certain food substances which
are not needed for the growth of sensitive bacteria. The
resistant mutants will be wiped out in environments in which the
required foods are not available."~Theodosius Dobzhansky,
Evolution, Genetics and Man, (New York: John Wiley and Sons,
Inc., 1955), p. 98.

Since the environment didn't have the drug, and the initial drug resistant
varieties could live without it, is would appear that this was a new
mutation, not something that was already existing in nature.

Creationists have used this need for antibiotics as a means of arguing
against evolution.(John Klotz, Genes, Genesis and Evolution, p. 225) If the
bacteria need the drug, it is a harmful mutation. But I do think that new
strains are out there that no longer need the drug. Maybe David Campbell can
shed light on this?


Foundation, Fall and Flood