SEPTEMBER 11, 2017 11:13 IST
On September 10, 1984, Alec Jeffreys, while studying how inherited illnesses pass through families, made an accidental discovery. And that has advanced our understanding of genetics. A.S.Ganesh revisits Jeffreys’ Eureka moment...
Are you aware that DNA, like fingerprints, can be used to uniquely identify individuals? If your answer is no, then it’s worth knowing that this technology was discovered only in 1984. If you answered yes, then it might interest you to find out more about DNA or genetic fingerprinting.
Working in a genetics lab at Leicester University, Alec Jeffreys was studying how inherited illnesses pass through families. As part of this work, Jeffreys had to look for patterns in the repeated DNA segments carried by all humans.
In the summer of 1984, Jeffreys set up an experiment to help his research. As part of this experiment, cells were broken open, their DNA extracted and this DNA was attached to photographic films. Radioactive probes were added to identify the repeated sections of DNA and the entire set-up was placed in a photographic developing tank.
Blessing in disguise
Left over the weekend of September 8-9, 1984, Jeffreys hoped to find something that would be useful for his research on that Monday morning. But instead, his first reaction on September 10 as he removed an X-ray film from the developing tank was that it was a complete mess.
Moments later, Jeffreys had a flash of brilliance. He realised that the results at hand were completely futile with respect to their current research, but he did not fail to recognise their value. The sequence of bars in each film represented different number of DNA repeats among the individuals and animals involved in the experiment.
Jeffreys realised that he was onto something and that the different bar codes, when mapped the other way, could uniquely identify individuals. Like fingerprints, DNA could be used to precisely zero down on individuals, except in the case of identical twins or likewise. Furthermore, it was also evident that half of an individual’s DNA came from their mother, and the other half from their father.
Jeffreys got his staff together and they brainstormed to find potential uses of this serendipitous discovery. By the end of the day, they had a growing list which included establishing biological kinship in paternity cases and aiding detective work to figure out criminals.
Put to use
While the initial years saw a flood of immigration cases settled by determining lineage, it was soon used in forensics as well. With the lab kept extremely busy owing to a deluge of requests from around the world, the technique was commercialised and came into effect in labs everywhere in 1987.
There is a growing concern that this technology intrudes on an individual’s right to privacy like never before, but there are plenty of other positives stemming out of the work as well. Biologists use it to study genetics not only in humans, but also in other species.
Anthropologists use DNA fingerprinting to study evolution in humans and their current global variation through millions of years.
A discovery that took Jeffreys just an instant is helping us trace back through our own history.
