Biological Future of Man 
JOSHUA LEDERBERG 
Today, with a new biology we mirror his future. Poetry 
may speak more bravely than Science. However, Policy 
must rely on Science for an accurate vision of the bounds of 
human evolution. 
[)m: theory set off the historic debate on man’s past. 
MOLECULAR BIOLOGY 
Molecular biology has lately unravelled the mechanism of 
heredity, and we can say that the main features of terrestrial 
life are within the perceptible grasp of experimental chemistry. 
Many of its puzzles have already worked out with astonishing 
simplicity. The basic strategy of life is that of molecular struc- 
ture. The linear, bi-helical structure of deoxyribonucleic acid 
(DNA) (and who would have thought that genes would be 
resolved before tendons?) tells us the mechanism of molecular 
reproduction—the selection of nuclein molecules that have a 
complementary fit to the available space on the existing DNA 
chain. We have also a fair picture of how the nuclein sequence in 
DNA is translated into the corresponding sequence of amino 
acids in proteins. And the coiling of the amino acid chain, 
determined by this sequence, generates the three-dimensional 
shape by which the protein works. The protein molecules, by a 
similar fit of shape, recognize one another to aggregate into 
structural fibres and membranes, or enfold smaller molecules to 
direct the metabolic flow chart of the cell. 
Now we can define man. Genotypically at least, he is six feet 
of a particular molecular sequence of carbon, hydrogen, oxygen, 
nitrogen and phosphorus atoms—the length of DNA tightly 
coiled in the nucleus of his provenient egg and in the nucleus of 
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