AAs a child I used to wander the countryside collecting moths and butterflies on the edge of the Great Lakes in Canada. It was as idyllic as it sounds: during the day I scoured the fields and forests for butterflies. At night, I left a white sheet and UV light in my backyard and got up at 5 a.m. to inspect the harvest of moths.
By the time I was an adult, I could identify about 700 butterfly and moth species by sight, deciphering the stripes, spots and colors on their wings and bodies.
In 1972 I moved to Australia and continued to collect. But I began to struggle: I wanted to understand as much as possible about the group of organisms I loved, but identifying them quickly became an impossible task. The species on the other side of the world were so different from those at home, and there was no room in my mind to recognize them all.
My crisis soon worsened. Throughout the 1970s I led expeditions to Papua New Guinea to collect moths in the mountains for weeks at a time. One night we turned on our lights and ended up collecting over 2,000 different species from a single location, more than twice as many as I had memorized over the course of my childhood. The process of identifying each of them felt overwhelming. I gave up.
I traded the tropics for the Canadian Arctic and stopped working on moths, focusing instead on microscales, a far less diverse group. But my instinct to identify them never went away.
Two decades later, I was in a supermarket and an idea began to develop in my mind as I walked through the aisles: what if a segment of DNA could be used to distinguish between species? Just 13 lines on the supermarket barcodes were used to identify everything around me. What if we could identify plants, animals and fungi in the same way?
In the years since my mission in New Guinea, new techniques have changed the understanding of the building blocks of life on Earth, leading me to refocus my research. The Human Genome Project began the task of decoding our DNA. Researchers have already begun to apply the techniques to animals, and other scientists have begun to suggest portions of the genetic code that can be used to distinguish between species. I began to develop my own theory.
To test the idea, I returned to the equipment of my youth. It was the summer of 2001. Then, in my mid-50s, I set up a powerful UV light and a white sheet in my backyard in Guelph, Ontario, and began collecting the moths of my youth. This time each sample had to donate a bone to science to test my idea. I believed that a single segment of a rapidly evolving gene was present in almost all animals – cytochrome c oxidase 1, also known as COI for short – can be used to tell the difference between species.
By the end of the summer I had collected about 200 species of moths: rose maple moths, hog finch and tiger moths. All were old friends. With their bones we used the PCR (polymerase chain reaction) method developed by Cary Mullis to focus on their section of COI so that it can be sequenced, taking each genetic code and dropping it one at a time into an Excel spreadsheet. One by one, it became clear: every single moth could be sorted using a small piece of their genome. DNA barcoding was 100% successful on its first test.
In early 2003, the study was published. In it we claimed to have discovered a reliable, cheap and accessible solution to identify the millions of animal species out there waiting to be discovered. At first, critics were harsh and believed it could not work reliably for other animals, but other scientists have since adopted it and shown it works for the vast majority of animal life.
Today, I believe DNA barcoding is humanity’s first chance to finally discover all life on Earth. The most common estimate is that we share this planet with 8.7m species, but I believe there are many more – somewhere between 20m and 40m. Since its debut in my backyard, this technique has helped conservationists to combat wildlife crime and monitor the impact of mining on biodiversity. One day I am confident that it will form part of a system to monitor the biosphere in the same way we monitor the weather.
