Biologists and conservationists manage and protect the world’s biodiversity. Now they have a new tool: eDNA. That’s the DNA left behind by animals in water or soil. Locating eDNA can be easier than finding a live specimen of a creature that’s endangered or thought to be extinct.
Mark Stoeckle is a biologist at New York’s Rockefeller University. He collects water from the East River in a bucket. Then over the next few hours, he analyzes that water. He is looking for the genetic trail of the river’s diverse life.
The East River was once so polluted that many fish species could not survive. “We’ve cleaned up the East River significantly,” says Stoeckle. “This will give us a better idea of whether fish are recovering.”
In the past, scientists would have to catch live fish, assess their health, and estimate their numbers. But Stoeckle doesn’t need the slippery creatures for his work. He just needs to look for the tiny bits of DNA they leave behind to track them.
Animals lose hair, skin cells, scales, feathers, and waste as they move through their environments. All contain traces of genetic material. Each species’ genetic formula is unique to that animal’s kind. (See Genesis 1:21-24.) The trace materials can be detected hours, weeks, or under some conditions, even millennia later. This material that is shed into the animals’ environment is called eDNA.
Tracking eDNA has become increasingly popular in the last few years. It has provided clues about ancient mammoths in Siberia. It’s given scientists early warning about frog die-offs in California. And it has encouraged biologists that the elusive sawfish of Mexico may not be extinct—though only one has been found in the last decade.
The technique was pioneered about 15 years ago by a Danish geneticist. Eske Willerslev traveled to Siberia. There, he sampled the permafrost. Willerslev wondered if the deeply frozen soil might have preserved ancient genetic material intact within it. In 2002, Willerslev analyzed a permafrost sample the size of a sugar cube. In that one tiny sampling, he identified the eDNA of bison, horses, and many ancient plants. He also found the preserved DNA of mammoths.
Like a naturally occurring time capsule, frozen eDNA “helps us reach the inaccessible,” says Willerslev. And like a naturally occurring signpost, it can also show scientists where endangered species still remain. If they can find them, then they can help protect them—before they become a part of the past.
