Technology & Medicine › Digital age
Genetic engineering (recombinant DNA)
1973 (Cohen & Boyer)· Invention or discovery· Germs, drugs & genetics
Well documentedSolid records, physical evidence or scientific consensus.
Cutting a gene from one organism and splicing it into another, so the host carries out the new instructions.
See it on the Technology & Medicine map →How it works
In 1972 Paul Berg at Stanford joined DNA from two viruses. In 1973 Stanley Cohen of Stanford and Herbert Boyer of UC San Francisco used restriction enzymes, which cut DNA at specific spots leaving 'sticky' ends, to paste a gene into a plasmid, a small ring of bacterial DNA. Placed in E. coli bacteria, the plasmid was copied each time the cells divided. Worried about safety, scientists paused some experiments and drafted rules at Asilomar, California, in 1975.
Why it mattered
It let genes move between species, launching the biotech industry and making possible engineered medicines, modified crops and, later, gene therapies.
Think of it like
Cut and paste for genes: enzymes are the scissors, another enzyme is the glue, and multiplying bacteria are the copying machine.
How we know
The 1973 paper by Cohen, Annie Chang, Boyer and Robert Helling in PNAS; Berg's 1972 paper; the Asilomar records; and the Cohen–Boyer patents, licensed to hundreds of companies.
Still unknown or debated
How to regulate it is still debated, from the 1975 Asilomar model of scientists policing themselves to today's arguments over genetically modified crops and gene editing.
Inside this (4)
Connections (6)
▸DNA double helix led to Genetic engineering (recombinant DNA)Well documented
The connection
The double helix showed that genes are written as a sequence of four chemical letters on two paired strands. Once DNA was understood as a code that can be read and copied, scientists found tools to cut it (restriction enzymes), join it (ligase) and copy it in bacteria. Combined in 1973, those tools became genetic engineering.
When and how
Watson and Crick at Cambridge, 1953; restriction enzymes found by Werner Arber, Hamilton Smith and Daniel Nathans, 1960s to 1970; Cohen and Boyer in California, 1973.
How we know
The 1973 paper and the 1978 Nobel Prize to Arber, Smith and Nathans trace the chain of discoveries from DNA's structure to gene splicing.
Debates and open questions
How much the helix guided the practical tools is debated: restriction enzymes were found by microbiologists studying viruses in bacteria, not by structural biologists.
▸Genetic engineering (recombinant DNA) led to Biotech drugs (human insulin)Well documented
The connection
Recombinant DNA let a human gene be inserted into bacteria, which then made the human protein in fermentation tanks. Herbert Boyer, co-inventor of the method, co-founded Genentech in 1976 with venture investor Robert Swanson to turn it into products; the company made the human hormone somatostatin in 1977 and human insulin in 1978.
When and how
South San Francisco, 1976–1982; Genentech's 1980 stock offering, whose share price more than doubled on the first day, launched a wave of biotech investment.
How we know
Boyer's role at Genentech, the Cohen–Boyer patents licensed to hundreds of companies, and FDA drug approvals document the direct path.
Debates and open questions
Whether universities should patent and profit from basic research, as Stanford and the University of California did with the Cohen–Boyer patents, is still debated.
▸Genetic engineering (recombinant DNA) was made precise by CRISPR gene editingWell documented
The connection
Since 1973, recombinant DNA let scientists cut and paste genes, but mostly into bacteria or at random spots in larger organisms. Earlier targeted editors, zinc fingers and TALENs, needed a new custom protein for each target. CRISPR uses a short RNA guide that can be made in days, so editing almost any gene became cheap and precise.
When and how
Cohen and Boyer in California, 1973; zinc-finger editing in the 1990s–2000s; TALENs, 2010; CRISPR at Berkeley and Umeå (2012), then the Broad Institute and Harvard (2013).
How we know
Lab practice changed visibly: CRISPR papers rose from a handful in 2012 to many thousands a year, displacing older methods.
Debates and open questions
CRISPR is precise but not perfect: unwanted 'off-target' edits and large DNA deletions are still being measured and reduced.
▸Genetic engineering (recombinant DNA) set the stage for gene therapies like the First approved CRISPR therapy (Casgevy)Mostly agreed
The connection
Recombinant DNA gave medicine the tools to put new or corrected genes into patients' cells, launching gene therapy trials in 1990. Early efforts used viruses to add genes and suffered setbacks, including a patient's death in 1999. Casgevy follows the same plan of modifying patients' cells outside the body, but uses CRISPR to edit them precisely.
When and how
First approved gene therapy trial at the US National Institutes of Health, 1990; Jesse Gelsinger's death in a Philadelphia trial, 1999; Casgevy approved in Britain and the US, 2023.
How sure are we?
The lineage is documented in medical literature: Casgevy uses the same remove, modify and return approach as earlier cell-based gene therapies.
Debates and open questions
Whether editing genes inside the body, rather than removing cells, will make such therapies cheaper and available worldwide is still being tested.
▸Genetic engineering (recombinant DNA) made possible the engineered T cells of Cancer immunotherapyWell documented
The connection
CAR-T therapy depends on recombinant DNA. Doctors collect a patient's T cells, then use an engineered virus to insert a gene for a 'chimeric antigen receptor', a designer sensor that latches onto cancer cells. The modified cells multiply and are infused back. Checkpoint drugs, too, are antibodies produced by genetically engineered cells.
When and how
Zelig Eshhar's first CAR designs in Israel, 1989; Carl June's team at the University of Pennsylvania treated leukemia patients from 2010; first approval, Kymriah, August 2017.
How we know
Published trial results, such as young Emily Whitehead's 2012 recovery, and FDA approval documents describe the genetic modification step.
Debates and open questions
Making CAR-T work against solid tumors, not just blood cancers, and lowering its cost of several hundred thousand dollars, remain open challenges.
▸Genetic engineering (recombinant DNA) supplied the lab methods of Karikó and Weissman's modified mRNAMostly agreed
The connection
To make mRNA in the lab, Karikó and Weissman used tools born of genetic engineering: a target gene inserted into a circle of bacterial DNA (a plasmid), then copied into mRNA in a test tube by a viral enzyme. This method, in vitro transcription, came out of 1980s recombinant DNA work.
When and how
Douglas Melton and colleagues at Harvard described making RNA from plasmids in 1984; Karikó and Weissman used such methods at the University of Pennsylvania, 1990s–2005.
How sure are we?
Their 2005 paper's methods section describes in vitro transcription from DNA templates, a standard recombinant DNA technique.
Debates and open questions
In vitro transcription also leaves by-products, such as double-stranded RNA, that trigger inflammation; Karikó's team showed in 2011 that removing them also matters, and how much each fix contributes is still studied.