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Dirty Science

Suppose you wanted to catalog the flora and fauna of your backyard. The way you would proceed would be to observe the plants and animals, recording their appearance and disappearance with the passage of time. This would establish the biodiversity record of your yard and is generally the method used by field biologists for large ecosystems.

Observation of nature is a pleasant task—field work is surely one motivation for choosing to become a scientist—but such work can also be tedious and time consuming. Is there a faster alternative? The answer is dirt, specifically the DNA fragments left behind in dirt by living creatures.

A Danish and Australian collaborative team extracted mitochondrial DNA from soil samples found in zoological gardens where there was an accurate record of the existing species diversity. They found a good match between the species identified by unique DNA sequences extracted from dirt and the known taxonomy gleaned from actual observation. Thus, vertebrate diversity can be determined without actually seeing any animals!

You might be wondering why all this DNA can be so readily found in dirt. The answer is that living creatures leave traces of hair, skin, secretions, excrement, and other gifts from our bodies wherever we go. It is now virtually routine to do chemical analysis on even minute samples, aiding the kind of ecological study discussed here, but also revealing how utterly impossible it is to hide out, undetected in the modern world.

Tom Tritton is President and CEO of CHF.

Posted In: Education

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