In 1984, British geneticist Alec Jeffries John developed a genetic fingerprinting technique that uses differences in the genetic code to identify individuals, DNA technology, which later became one of the most powerful tools used by security agencies to identify people from the remnants of DNA they leave behind, whether from saliva, semen, blood or hair.

Although DNA fingerprinting technology is used in important and sensitive areas such as forensic medicine or to identify disaster victims, modern applications have gone beyond that to what is known as "environmental DNA fingerprinting" of DNA samples, which are traces collected from a variety of environmental samples such as soil, seawater, ice or even air.

With the ever-evolving development of environmental DNA extraction techniques, scientists have noticed that human DNA is prevalent everywhere humans are; on the beach, in the ocean, along riverbeds, and even in the air, we cough, spit and scatter our DNA in all these places and much more, so signs of human life can be found almost everywhere, according to a recent study published in the journal Nature Ecology and Evolution).

Scientists have found high-quality DNA from footprints left by a researcher on an uninhabited island (Shutterstock).

Our traces are scattered in the environment around us

The researchers report that the field of environmental DNA (eDNA) is advancing rapidly, yet its applications are still underutilized, and the adoption of large-scale environmental DNA analysis will lead to many benefits in pathogen surveillance, biodiversity monitoring, endangered species discovery, and population genetics.

In the press release published by Eurek Alert, David Duffy, a professor of wildlife disease genomics at the University of Florida who led the project, said, "We were surprised by the amount of human DNA we found and the quality of it; in most cases, the quality is roughly equivalent to whether you took a sample from someone."

The team found high-quality human DNA in the oceans and rivers surrounding the laboratory where the research was conducted, near the city and away from human settlements, as well as in the sands of distant beaches, and the researchers even traveled to a remote island that no one had visited before, and was free of human DNA, as expected, but they were able to recover DNA from the footprints of volunteer participants in the sand and were able to sequence parts of their genome.

The team also successfully used environmental DNA to study endangered sea turtles and vulnerable viral cancers, and were able to extract DNA from turtle pathways in the sand, Duffy also tested this technique in his native Ireland along a river running through the city, and found human DNA everywhere except the mountain stream away from the city, and scientists collected room air samples from a veterinary hospital, and recovered the DNA of staff, animals and common animal viruses.

Environmental DNA samples can be useful in the fields of medicine, environmental science, archaeology and forensic medicine (Shutterstock)

Ethical caveats

Given the ease of obtaining samples and accurately identifying individuals, the researchers point out that strict ethical controls should be established for this type of research, and that this level of personal information should be treated with extreme sensitivity.

"When we make scientific progress, there are always useful things that technology has to offer," says Duffy. It's no different here, these are issues that we're trying to raise early so that policymakers have time to develop regulations."

Environmental DNA samples can be useful in the fields of medicine, environmental science, archaeology and forensics; for example, researchers can track cancer mutations from sewage or identify undiscovered archaeological sites by checking hidden human DNA, and they can identify suspects from DNA swimming in the air of a crime scene.