When a study came out in 2012 associating gruesomely lumpy rats with genetically modified food, critics trashed it so thoroughly that a group of researchers and advocates called foul. This went beyond legitimate scientific critique, they wrote. It was evidence that “those with a vested interest attempt to sow unreasonable doubt around inconvenient results.”

More recently, a long-term GM feeding trial of pigs received a similar (though milder) treatment. Tom Laskawy here at Grist made the point that, though this study had flaws, the dismissals seemed knee-jerk — ideological rather than thoughtful.

So is there an echelon of corporate Pinkertons pouncing on any scientist who dares to dissent from the GM consensus? Are researchers who raise doubts about GMOs unfairly punished? It’s hard to assess while smoke billows and rhetorical bullets fly. It’s much easier to judge with the clarity of hindsight. The historical picture is sharper and simpler, and I think it really does show that scientists who step out of line on this issue are savaged in a manner that’s out of all proportion to their errors. These errors are real, but they should be exposed in the spirit of collaboration rather than castigation.

Back in 1998, Arpad Pusztai was just beginning his third year of research on the safety of transgenic potatoes when a TV program asked him to do an interview about his preliminary results.

Arpad Pusztai.

A Cold War defector to Britain from Hungary, Pusztai was a world expert on lectins — naturally occurring proteins that provide plants with a measure of pest resistance. Scientists had added genes for lectin production to potatoes, and Pusztai was feeding these potatoes to rats to test for adverse effects. He’d become more concerned when he saw that the rats he’d fed with transgenic potatoes were slightly smaller, and had less-reactive immune cells, than the others. (In the end, after statistical analysis, the only real difference was a slight change in gut cells.)

All these years later, we know what happened. The lectins themselves probably weren’t hurting the rats: Pusztai had cleverly designed his experiment with a control group of rats that ate non-transgenic potatoes plus a pure dose of lectin, so the problem (if there was a problem at all), was some unknown element of the transgenic potatoes. It seemed obvious to point to genetic engineering itself; that would be the only other difference, right?