Dr. Donald Fredrickson 
May 3, 1976 
Page 2 
in the past and had such organisms had an evolutionary advantage they would 
he with us today. I really cannot accept this argument which - it seems to me - 
amounts to saying that everything that could have happened, in an evolutionary 
sense - has happened. I don't believe it. I do not believe there has been 
enough time nor opportunity to sample more than a small fraction of evolutionary 
possibility. 
The fact is we have no predictive theory of evolution . We have only the 
beginning rudiments of a quantitative retrospective theory of evolution. As 
Dr. Davis knows well there are major scientific controversies over the relative 
importance of "neutral” vs. "advantageous" mutations, over the relative signifi- 
cance of mutations affecting structural genes as compared to mutations affecting 
regulatory genes, over the possible role of viruses as vectors for gene transfer, 
etc. etc. Current theories of evolution can hardly begin to cope with questions 
as to the importance of non-linearities, of coincident mutational events, of 
"critical mass" effects, etc. (e.g. One E. coli bearing a gene for botulinus 
toxin might in fact be at a disadvantage and perish. 10^ E. coli bearing the 
gene for botulinus toxin might so change the ecology of an intestine as to be 
at an advantage). 
We know that homo sapiens evolved during the last 10^ years. I do not believe 
anyone could tell you why homo sapiens did not appear 10® years earlier - or why 
his appearance was not delayed another 10® years. There is no reason to believe 
that everything that could have happened in evolution has happened. (indeed 
many of the proposed benefits of genetic engineering are based specifically on 
that presumption) . 
I dislike taking an obscurantist role . But I believe that on a matter of 
considerable public concern such as this it is as important to make clear our 
ignorance as to make clear our brilliance. There is a lot we do not know and 
we should acknowledge such. Having done so, an administrative decision can - 
and of course must - still be made. 
With best wishes , 
Robert L. Sinsheimer 
Chairman 
cc : 
Dr . Davis 
Dr. Stetten 
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