From Mendel to recombinant DNA
Agent: Gregor Mendel; Avery, MacLeod and McCarty; Franklin, Watson and Crick; Boyer and Cohen
Source / date: 1866–1975
Reference: Recombinant DNA
The century in which the mechanism was found, ignored, rediscovered, identified as DNA, structurally solved, and then deliberately cut and pasted between species. Gene splicing stopped being a hypothesis in 1973.
Class: Directed modification actually performed by people, on the record, with names and dates.
The thirty-four years nobody looked
Mendel published Versuche über Pflanzen-Hybriden in 1866, in the proceedings of a provincial natural history society in Brünn. The laws of inheritance sat in print, in the open, in a monastery garden’s worth of pea data, and were effectively unread until 1900, when de Vries, Correns and Tschermak arrived at the same result independently and found he had got there first.
This is the cleanest example in the whole section of something operating “in the background from human perception” with no concealment whatsoever. It was published. It was available. Nobody had the frame to see it.
Then the machinery
1944 — Avery, MacLeod and McCarty show the hereditary material is DNA, not protein. 1953 — the double helix, from Rosalind Franklin’s diffraction data, published by Watson and Crick. 1973 — Stanley Cohen and Herbert Boyer construct the first recombinant organism, moving a gene from one species into another and having it work.
1975 — and this part is unusual enough to record: the scientists called a halt on themselves. Paul Berg’s 1974 letter proposed a voluntary moratorium, and the Asilomar conference of February 1975 set the containment rules before regulators existed. A field paused itself at the moment it acquired the capability.