I complain a fair amount about the failure of journalism to accurately report on science news. Maybe it’s not surprising, as reports of scientific literacy in the United States are generally pretty dismal–this one reporting that only 28% of adults are literate in the ways of science! If you want a short survey of how kids in schools are performing, check out TIMSS. With these kinds of numbers, we shouldn’t expect our entire journalistic workforce to have the necessary scientific literacy to accurately report findings with clarity and logic.
But even more importantly, being able to do it concisely.
Pop culture is more than just a genre–it’s a way of communication. Many forms of news media have suckered down into sentence-long paragraphs and embarrassing summaries. Certainly they understand their readers aren’t completely able to digest the relavent data. They also understand that when people read science news, they essentially want a summary of the way the news contributes to a bigger picture:
- Scientists close in on cure for cancer
- DNA evidence finds [this] meaning [bad pun]
- NEW PLANET LOOKS LIKE EARTH ZOMGZ
When I read science news, I’m nitpicky because I can be and because I should be. Misinformation is awful for the public, and it already runs rampant in a nation that obviously values blind faith over skepticism not only in religion but in everything. I’m excited to be a biology teacher to try and increase scientific literacy, and share the passion I have for science to the masses.
So when I read this article on Asian carp, I became a little upset. It discusses the use of “DNA testing” to look for Asian carp without actually finding the carp. They don’t bother explaining how they do this, except saying they did “DNA sampling of water columns”. They also happen to mention “eDNA” a few times without actually explaining what that is. It’s confusing. Period. Explaining how the results affect humans is important, but unless you understand what produced the results you can’t have an important opinion.
So I did some research a la Google. My first hit was a bit from the Army Corps of Engineers on how eDNA sampling is often used to test for the presence of Asian carp. A jump into the literature found this short biology letter. It looks like it was the result of a summer research project. There’s plenty to pick apart in the article enough, but it’s perfect to mention because it’s easy and quick to read. And it’s easy to understand. If you want to understand eDNA sampling, read the Methods section.
Essentially, scientists take a few samples of water from a pond, they extract the DNA using either a kit or phenol and cholorform, and then run a PCR reaction using a primer for a common gene. A PCR reaction is a reaction where you use a short strand of DNA called an oligonucleotide, or a primer. Your solution will heat, separating your sample DNA into 2 separate strands. The primer will bind to its complement in the sample. An enzyme will then come along and copy your sample. So if you start with one strand of DNA, add your primer and enzyme, you’ll end with two. PCR means polymerase chain reaction, so you can do it multiple times to end up with a huge amount of your sample. It’s about amplification, and you can run your result out on a gel to check it’s size and learn important things about your subject.
In this case, they use a particularly long primer for the cytochrome b gene from the bullfrog, a gene in the mitochondrium involved in the electron transport chain (a process which helps produce ATP, the cell’s energy source).
You’d expect something like this to turn up a lot of false positives (because something like all animals have this gene), but the primer is long enough that they are able to specialize it for only the type of animal they’re testing for (the bullfrog). However, the study does not say how they confirmed that the results were a copied bullfrog cytochrome b gene! This is important, because PCR reactions are particularly sensitive to false positive results from contamination. They may have had DNA in their sample, and the primer may have bound to an incorrect DNA sample, and the PCR reaction may have ran regardless. But they don’t explain how they confirmed the samples identity definitively, instead only reporting a result. This is mostly not relevant to the topic at hand, but again: it’s important to understand the background.
So, now, we get to answer the implicit question: Why is scientific literacy important? If you don’t understand how PCR works and its limitations, you can’t understand the news article to the full extent. The PCR reaction is not particularly complex to understand. However, it is often excluded from the type of biology class that doesn’t discuss evolution extensively. Because if you understand PCR, you probably also understand the molecular evidence for evolution! (and how awful that would be!)
And understanding the eDNA sampling in this case is important for the local ecology of the river and for the local economy of recreational fishers and industrial cargo ships! It can easily turn up false positives or false negatives.
Science journalism needs to be able to hand out not just the relevant results of scientific news, but also be able to quickly describe the concepts behind it. A fairly large portion of the population has passed out of high school, yet they are still falling behind in scientific literacy. High school biology teachers and college professors cannot effectively reach that demographic. We need to count on our science journalists to take up the case to raise literacy for everyone, to the point that every adult can pick up the NYT Science Tuesday section and read it with ease.
(images are not mine unless i claim otherwise)
