Gemmell specializes in ecological genetics. He examines pieces of DNA—the molecule that carries hereditary information—that creatures leave behind in the environment. This material is called eDNA. All creatures have identical copies of their unique genetic instructions in every one of their cells. This eDNA gets scattered into their surroundings as they shed fur, hair, skin, scales, and feathers, as well as when they leave behind pee, droppings, and saliva.

Scientists like Gemmell can detect traces of this DNA in samples of air, soil, ice, and water. That’s what he planned to do at Loch Ness. He hypothesized that if there was a monster in the water, then its DNA would be there too.

When Gemmell’s team reached the lake, they boarded a small research boat named Deepscan. Over the course of two weeks, they sailed the entire length of the loch, collecting water samples at different depths. They even scooped up water from an area where Nessie had supposedly last been spotted. The researchers also sampled water from nearby lakes (not believed to have resident monsters) to use as controls, or standards to compare their results against.

Gemmell studies ecological genetics. DNA is the molecule that carries hereditary information. Gemmell looks at pieces of DNA that creatures leave behind in the environment. This material is called eDNA. All creatures have their own genetic instructions. And identical copies of these instructions are in every one of their cells. When they shed fur, hair, skin, scales, and feathers, this eDNA gets scattered around them. The same happens when they leave behind pee, droppings, and saliva.

Scientists like Gemmell look for traces of this DNA. They find it in samples of air, soil, ice, and water. Gemmell planned to do that at Loch Ness. He had a hypothesis. If a monster was in the water, its DNA would be there too.

Gemmell’s team reached the lake and boarded a small research boat named Deepscan. For two weeks, they sailed the entire length of the loch. They collected water samples at different depths. They even took water from the last spot where Nessie had supposedly been seen. The researchers also collected water from nearby lakes not believed to have monsters. These samples were used as controls, or standards to compare their results against. 

Once the eDNA was extracted from the water samples, it was sent to several universities around the globe. Researchers got to work identifying what species the DNA belonged to. “By sorting out the DNA in a water sample, we get a snapshot of all the creatures, from bacteria [single-celled microbes] to vertebrates [animals with a backbone], in the area at a moment in time,” says Gemmell. If any mysterious DNA turned up that didn’t match a known species, then it could possibly belong to Nessie.

Gemmell wanted to make sure the DNA analysis was as accurate as possible. So he had the teams conduct their tests independently of one another. Gemmell’s group had collected multiple samples from each site they visited on the loch, so each team received similar ones to study. The results of the labs would be compared to make sure they all identified similar species.

The teams were also blind to, or didn’t know, where the samples they were studying had been collected. “We wanted to avoid experimenter bias,” says Gemmell. That’s a process where scientists performing research unconsciously influence the results toward a certain outcome. “We didn’t want the fact that the DNA came from Loch Ness to motivate them to look for something unusual.”

The eDNA was removed from the water samples. Then it was sent to several universities around the world. Researchers got to work. They figured out what species the DNA belonged to. “By sorting out the DNA in a water sample, we get a snapshot of all the creatures, from bacteria [single-celled microbes] to vertebrates [animals with a backbone], in the area at a moment in time,” says Gemmell. What if mysterious DNA turned up that didn’t match a known species? Then it might belong to Nessie.

Gemmell wanted the DNA study to be as accurate as possible. So he had the teams work separately from one another. Gemmell’s group had visited different sites on the loch. They’d collected several samples from each site. So each team received similar ones to study. The results of the labs would be compared to make sure they all found similar species.

The teams studied the samples, but they didn’t know where the water had been collected. The teams were blind to that information. “We wanted to avoid experimenter bias,” says Gemmell. That’s when scientists doing research unknowingly influence the results toward a certain outcome. “We didn’t want the fact that the DNA came from Loch Ness to motivate them to look for something unusual.” 

The analysis of eDNA from Loch Ness revealed that the lake is home to some 3,000 species. Most are microscopic, and some, like certain fish species, aren’t native to the lake. “Invasive species are the real monsters of Loch Ness,” says Gemmell. “They don’t belong in the loch and could damage its ecosystem.”

“Of course, the question everyone wants us to answer is: Did you find anything that explains what the legendary monster or creature is?” says Gemmell. Maybe. His team didn’t find evidence to support the popular notion that a Jurassic-age reptile lives in Loch Ness. “Our analysis found zero reptile DNA,” says Gemmell. “The plesiosaur idea doesn’t hold up based on the data that we have.”

The DNA evidence also didn’t support that the fabled monster might be a giant catfish, sturgeon, or shark. “There’s no shark DNA in Loch Ness,” says Gemmell. “No evidence of catfish or sturgeon either.” But scientists did find something unusual: an extraordinary amount of DNA belonging to eels—snake-like fish. “We can’t discount the possibility that there may be giant eels in Loch Ness,” says Gemmell.

The study of eDNA from Loch Ness revealed that about 3,000 species live in the lake. Most are microscopic. Some, like certain fish species, aren’t native to the lake. “Invasive species are the real monsters of Loch Ness,” says Gemmell. “They don’t belong in the loch and could damage its ecosystem.”

 “Of course, the question everyone wants us to answer is: Did you find anything that explains what the legendary monster or creature is?” says Gemmell. Maybe. One popular idea is that a Jurassic-age reptile lives in Loch Ness. His team didn’t find evidence of that. “Our analysis found zero reptile DNA,” says Gemmell. “The plesiosaur idea doesn’t hold up based on the data that we have.”

Some thought that the famous monster might be a giant catfish, sturgeon, or shark. The DNA evidence didn’t support those ideas. “There’s no shark DNA in Loch Ness,” says Gemmell. “No evidence of catfish or sturgeon either.” But scientists did find something unusual. A large amount of DNA belonged to eels, a snake-like fish. “We can’t discount the possibility that there may be giant eels in Loch Ness,” says Gemmell. 

So, could Nessie actually be an unusually big eel? “People say they’ve seen very large ones in Loch Ness,” says Gemmell. “But further investigation is needed to confirm or refute that theory.”

Although Gemmell’s experiment may not have found concrete proof of Nessie, he’s still pleased with the results. “We went to Loch Ness to discover the species that live there,” he says. “Our analysis did just that. We now have an excellent database that will enable us to identify trends and changes in the loch’s environment.”

As for the Loch Ness Monster, even if science could prove or disprove its existence, it probably wouldn’t matter, says Gemmell. “There will always be people who believe in Nessie. People love a mystery, and we’ve used science to add another chapter to Loch Ness’s mystique.”

So, could Nessie really be a huge eel? “People say they’ve seen very large ones in Loch Ness,” says Gemmell. “But further investigation is needed to confirm or refute that theory.”

Gemmell’s study may not have found hard proof of Nessie. But he’s still pleased with the results. “We went to Loch Ness to discover the species that live there,” he says. “Our analysis did just that. We now have an excellent database that will enable us to identify trends and changes in the loch’s environment.”

What about the Loch Ness Monster? Even if science could prove or disprove its existence, it probably wouldn’t matter, says Gemmell. “There will always be people who believe in Nessie. People love a mystery, and we’ve used science to add another chapter to Loch Ness’s mystique.”