I had a discussion today about flatworm learning (pretty rock and roll eh!). It was stated that flatworms that had been trained to run a maze could be ground up and fed to another flatworm who would then be able to run the maze, and that this must mean that learning could be inherited genetically. To be fair to the person (who shall remain nameless as the Internet has a long memory) this belief was based on work done by James McConnell in 1955, and I have seen it before, stated uncritically, more than once.
My view was that as a good skeptic, it sounded very unlikely because
a) I couldn’t believe a flatworm could run a maze at all – they aren’t that smart
b) I had never heard of even one case in the world ever of genetics being the basis for memory (to parahrase an excellent Tim Minchen song – embedded below for entertainment)
c) Even if genetics was used in the relevant nerve cells, almost every cell would have to be ‘reprogrammed’ for the digestion of the worm to pass that programming on, and that counters everything known about cellular lifecycles
d) If all the above was incorrect, the impact on many fields would be well known by now and I had never heard of them, which was unlikely
As such, my view was that whilst I didn’t have a better explanation, I would prefer to dig deeper than to assume anything … and in digging I would start by finding out if it had been replicated independently in a well controlled experiment. Put another way before you start searching for explanations for an observed effect, make sure that there IS an observed effect. A little digging on the trusty internet showed this one to be well debunked (e.g. see brief explanation on Wikipedia here, and the straight dope here). In short, observer bias – double blind tests are the way to go! (not sure whether you really need to keep a flatworm unaware of whether it is the test or control to be honest, but these were supposed to be pretty smart flatworms 🙂
And what about the link in the title to homoeopathic thinking? Well, that is the benchmark example of people searching for mechanisms for how it might work when there is no effect to search for – homoeopathic treatments work no better than placebos. The person I was having the discussion with, who passionately defended the case of the amazing flatworms, would be the first to debunk homoeopathy, and for the right reason. A good reminder that we need to be careful not to fall into traps, even when we know what traps look like.