Deciding whether an animal is endangered is important work. One of the ways we figure this out is by seeing how many individuals of a certain species are left.
But how do you do that? Usually by counting the animals you can see. You can trap and tag them. Or if they're fish, force them through a counting station. Or just watch with your eyes or a camera and see how many animals you see.
Not a very precise science! What do you do with shy ones? Or smaller ones? Or nocturnal ones? How many are killed in a trap? Which ones do you trap? Just the stupid ones? Or light colored ones? Or
Believe it or not, a lot of these problems can be solved by looking at an animal's poop. You may never see a panda but it will leave poop where it has been. And if the poop is fresh enough, the DNA can be looked at.
As anyone who watches CSI knows, every person's DNA is unique (except identical twins). If you do enough testing, you can figure out the difference between two people's DNA. Same thing goes for pandas.
What some Chinese scientists did was to collect a lot of fresh panda poop. They got the DNA and made genetic profiles of each of the pandas in a reserve.
Using conventional counting, scientists had estimated that around 32 pandas were living in the reserve. By studying DNA, the researchers concluded that somewhere between 66 and 72 pandas were actually there. More than twice as many as was previously thought.
This is great news if it can be extrapolated to all of the estimated 1600 pandas thought to be alive in the wild. Notice the if. We don't know yet if the same thing will be true in other places.
And while this is great news and good science, it is not cheap. It would be very difficult to do this for every endangered species. Imagine the outrage at scientists paying millions of dollars to collect and study an endangered lizard's poop. No, this will probably only be acceptable for cute, cuddly, high profile beasts like the panda.
But still this is a great use for poop DNA. And may prove useful for other endangered animals as well.