The Cannibalistic Worm Controversy

What can these guys tell us about memory? Source Paul via Flickr

Memories. They are such complex and individual experiences. That even with all the scientific advances we have today, scientists don’t really know how they are stored in the brain. Though it’s currently hypothesised that memories are stored in neurons.

In the sixties, however, James V. McConnell, an assistant professor at the University of Michigan, proposed a very different theory. He suggested that memories were stored as RNA proteins, in a code like DNA, distributed throughout our bodies.

To test his idea, McConnell devised one of the most insane experiments I have ever heard. Which produced some of the greatest controversy in the neuroscientific field to date.

McConnell bred a bunch of flatworms, more specifically a breed known as dugesia dorotocephla. Then using shock treatment he trained the worms to curl their body in response to light.

Why worms?


  1. They are quick to breed,
  2. They can also regrow substantial amounts of their body if removed, and
  3. Like humans, they have a brain containing neurons and their brain is separate from the rest of their body

Then things got weird…

He then cut off the heads of the previously trained worms. Waited a month for them to regrow. Then tested how long it took them to relearn to scrunch in response to light.

To even McConnell’s surprise, the worms immediately appeared to remember the task. Learning in a matter of minutes to associate the light with scrunching. Far faster than the original worms did when they were trained.

McConnell went further. He cut the worms into thirds, quarters and they would still appear to retain their memory of the task.

Suggesting that somehow the memory of the task had been stored not only in the worm’s brain but in the rest of its body.

When decapitated dugesia flatworms can sometimes regrow an additional head, like the two-headed flatworms in this picture. Photo by Jonathan Marchant via Wikimedia Commons.

Even weirder…

McConnell then went one step further.

He bred another set of worms. Trained them to do a task, and then…. killed them.

This where things really get crazy.

He ground up the dead worms and fed their dead bodies to ANOTHER SET OF WORMS!

The new worms hadn’t been trained in the task before. But again when they were presented with the task, they learnt to do it far faster than the original worms did. Appearing as if by somehow consuming the previous worms they had managed to consume their memories as well.

Now if you are at all like me when I first heard this story, my brain immediately began to think about the possibilities of eating my university professors to gain the answers to my exams. Desperate times call for desperate measures, am I right?

Here comes the controversy…

Just like me, other scientists were amazed at these findings. McConnell was awarded several grants and honours for his groundbreaking research and other researchers began looking into what had become known as the ‘memory transfer’ phenomenon.

However, the other researchers found varying results. Many managed to successfully repeat the experiment, but others found that the cannibalistic worms didn’t show a significantly great memory of the training. Many more found the task of training the worms near impossible to begin with. Ultimately, the work was dismissed for its extreme ideas and McConnell’s whimsical reputation.

McConnell infamously created The Worm Runners Digest, considered by some to be the equivalent of a “scientific Playboy”. A journal publishing research in worms alongside comics and scientific satire.

Is memory transfer unique to worms?

The other issue with McConnell’s work was that it had only explored transfer in worms. So, other researchers then began experimenting with other animals, such as mice and rats.

However, one other unique trait of worms is that the chemicals they use to break down food are less harsh. Which McConnell believes prevented the cannibalistic worms from destroying the RNA contained in the trained worms when they were ingested. So, it’s unlikely other animals, such as ourselves, could obtain the memories of others by eating them.

Personally, I’d rather eat one of these guys… Photo by Bill Craighead on Unsplash

Though the jury is still not out as to whether memory could exist outside of neurons, in our RNA. In May this year, a team from UCLA successfully extracted and transferred RNA in snails. Finding the snails with the inserted RNA showed evidence of memory transfer from the trained snails. Though once again scientists are doubtful about the findings.

8 Responses to “The Cannibalistic Worm Controversy”

  1. Sally Jenkins says:

    Thanks for the feedback Cynthia!I really appreciate it 🙂 I am about to do a quick edit on it.

  2. Cynthia says:

    Great title

    The sentence starting “That memories are …” is very long – I would understand the ideas better if it was broken down into two smaller sentences.

    Should “devised one of the insane” be instead “devised one of the most insane experiments I have heard of”? Its a little hard for me to understand.

    The story about the worms getting memories from eating the trained worms will stay with me for a long time – very effective writing.

  3. Sally Jenkins says:

    Thank you Lewis! I first heard it mentioned in a neuroscience class earlier this year. Though the lecturer was pretty dismissive about the whole phenomenon.

  4. Sally Jenkins says:

    Haha! Great idea Tess. Thanks for having a read.

  5. Sally Jenkins says:

    Thanks Sam! Yes, two researchers, Michael Levin and Tal Shomrat recently revisited McConnel’s experiment. They used a more rigorous and automated method. Training flatworms to associate rough surfaces with food. They then decapitated the worms, waited for the heads to grow back and found that worms with new heads still moved towards rough surfaces more than untrained worms. You can read more about it here.

  6. lsingleton says:

    This is an amazing experiment that you’ve summarised here! I can’t imagine how you first heard about this.

    Also a really well written blog post.

  7. Sam Widodo says:

    This is really interesting! You explained McConnel’s experiment very clearly. Didn’t know that memory could be stored as RNA. Is there any recent finding regarding this?

  8. Tess Devine-Hercus says:

    I love the weird stories of science, and this one does not disappoint! Really enjoyed the way you structured the piece!

    Also, I feel like the Buzzfeed clickbait title for this post could be: “Can cannibalism fix your WAM?”