2 
3) More specifically, the danger from shotgun experiments with DNA from 
eukaryotes, including human DNA, is not significant. This conclusion is based 
on the following considerations, a) Even if the tissue should contain genes of 
a tumor virus, the amount of foreign DNA incorporated into any recombinant 
strain would lead it to have only around one chance in a million of picking up 
those genes, b) If the tumor virus genes are rare in man, the chance of their 
pickup is small; while if they are common, they are already widespread and 
the increment provided by recombinant bacteria would not add significant danger, 
c) Viruses themselves are known to be more infectious than their free DNA, 
by many decimal orders of magnitude. I would consider work with SV40 virus, or 
with any other tumor virus, considerably more hazardous than work with E^ coli 
containing the tumor virus DNA. 
On scientific grounds, then, the original guidelines are far too severe, 
and the proposed revisions are more than justified. I would hope that further 
revisions will follow as experience mounts without casualties and public anxiety 
recedes. The public cannot be blamed for having a high level of anxiety at present, 
in the light of the many alarming statements that have been made by some scientists 
but in time the public will surely catch up with the scientific realities. 
One may ask how I can justify such an apparently extreme view, since 
responsible scientists within the field felt deep concern at the start and even 
recommended a moratorium on certain kinds of work. I believe the scientists were 
victims of a serious misunderstanding of the problem, arising with the best of 
intentions. Among the reasons for this misunderstanding we may cite the following. 
1) The molecular biologists who initiated the problem exaggerated the 
role of genetic novelty in the evolutionary process, while ignoring the 
dominating role of natural selection in determining which novel genotypes 
spread and which are culled out. A novel artificial recombinant will not 
[Appendix A — 167] 
