You Are Not a Fruit Fly: Why You Should Side-Eye Science Headlines
Catchy headline, right? When you write about science on the Internet, that’s really the key. Last week, dozens of media outlets took this “shocking” tactic in blurbing a new study on fruit fly reproduction, the research written up with headlines about lovers and accompanied by photographs of bouncing human babies. I even received an email from a pregnant friend that read, “Shit. Does this mean my kid is going to look like my ex?”
I wrote back to her, “Not unless you’re a fruit fly.”
How did we get from Telostylinus angusticollis to the human infant? Start with a scientific study that can be generalized to something people identify with or fear. Then lead with an eminently clickable headline about motherhood and promiscuity, striking fear in the hearts of the sexually active, raising concerns that the skeevy dude they picked up in a bar last year is actually going to haunt them forever through the face of their future offspring. Make a subtle but technically correct change in the wording of a study by anthropomorphizing female flies and their offspring as mothers and babies. Spend a few sentences referencing the science and then speculate on what this means for readers. Hit publish.
One of the first rules you learn as a researcher is to read the source material. So let’s talk about the actual findings published in Ecology Letters. The study’s authors (Crean, Kopps, and Bonduriansky) hypothesized that characteristics of previous mates could influence female flies’ future offspring, specifically their size.
To test this, the researchers first grew male flies of variable body size by placing larva on either a nutrient-rich or nutrient-poor media. Female flies with immature ovules were mated with either the large-bodied or small-bodied male flies. They were then paired with a fresh set of mates and the offspring were studied by researchers.
To understand the process, you need to know a bit about the reproductive development of female fruit flies. (I know, exciting! You can see why this study was so widely publicized internationally.) The immature eggs of newly hatched fruit flies ultimately develop a hard shell. The thought is that the development of the immature eggs can be influenced by non-genetic factors in semen but, once they have matured, the eggs are no longer susceptible to these changes.
The results were consistent with researchers’ hypothesis: the body size of the offspring matched the size of the female fly’s first mate rather than the genetic father of the offspring. It seems fly semen of a prior partner has the ability to influence egg development and have non-genetic paternal effects: in this case, determining body size. If you’re interested in either fruit flies or insect genetics, this is a fascinating discovery.
But of course, the study never mentions humans. Why would it mention humans? The research is about flies, a species with a vastly different reproductive anatomy and cycle than mammals. That taxonomical leap was made entirely on the part of the media.