One of the most notable aspects of scientists is their caution. Obviously this is not true of all scientists, but it is a common trait. They’re trained to be sceptical, including of their own results. Consequently, there is a tendency to qualify, to admit to doubts even when the evidence is pretty strong.
I had a doozy of a case of this recently. I was interviewing Professor John McGrath of the Queensland Brain Institute. For quite a while McGrath has been chasing the hypothesis that Vitamin D deficiency at birth is a major risk factor for schizophrenia. Over the years he has built up a lot of pieces of evidence for this (as have others). None of these have been conclusive on their own, but as a layperson the combination of them was pretty much enough for me. Now Mcgrath has come up with the single most convincing piece of evidence yet. It makes what was already a strong case look unassailable. My article on this won’t be up for a while, but here’s the media release.
McGrath was clearly very pleased with this work, although he said he’d like another data set to back it up. Yet he wouldn’t say the issue was settled. No, despite dozens of papers with data from around the world, both human and animal studies, all showing that lack of sunlight and/or vitamin D deficiency in the latter part of pregnancy (and possibly early months of life) is a major risk factor he continued to maintain he could have this wrong. It was quite sweet really.
Generally of course this is a healthy attitude to take. But it does run into problems when the enemies of science take advantage. As the tobacco companies used to say “doubt is our product”. If the scientist doesn’t sound too sure, other interests get a chance to muddy the waters. McGrath probably doesn’t have to worry about this. I’m not aware of any lobby group advocating that pregnant women don’t spend time in the sun every day. Moreover, as McGrath points out, the case for Vitamin D’s role in preventing bone problems is so clear that we don’t need other mental issues to justify public health campaigns on the topic.
Nevertheless, it was a reminder to me of just how wrong those who accuse scientists of jumping to conclusions usually are.