101 YEARS OLD AND STILL REMEMBERS WORMS...

CATCHING up on some recent scientific research I reacted with astonishment and delight when I saw a paper about snails published in a neuroscience journal in July. My astonishment was caused by its resuscitation of a theory I had last seen over half a century ago; my delight was caused by the memories it brought back from that era.

The earlier research was published in the mid 1960s and concerned memory in flatworms. This was only a decade after Crick and Watson had discovered the double-helix model of the DNA molecule and work on both DNA and its close relative RNA had been gathering pace. Two scientists at the University of Michigan, James McConnell and Al Jacobson, were investigating a theory that RNA held the key to memory. Was it possible, they wondered, that new memories resulted in the creation of new RNA molecules? If this was the case, it might be possible to transfer a memory from one organism to another by extracting RNA from the first and injecting it into the second. If the theory was right, they conjectured, the simplest creatures it might work on would be flatworms, so they proceeded with a series of bizarre experiments.

The first involved teaching a worm something then cutting it in half, waiting for both halves to regenerate, then seeing if either of the new worms still remembered what it had learnt.

The results suggested that both halves did. They even tried cutting the first worm in half, letting the back half regenerate, then cutting it in half again but this time letting the front half regenerate. Result: a worm none of which was present at the original training. Yet it still seemed to remember. They even tried mincing a worm and feeding it to another worm to show that knowledge was edible.

Then, for a variety of other reasons, the RNA theory of memory was ditched and different reasons were sought to explain the worm results. The edible knowledge flatworm cannibalism results were then, like the worms themselves, quietly buried.

The new paper however resuscitates the theory with the results of some experiments not on worms but snails. The Los Angeles neurologist David Glanzman designed an experiment giving mild electric shocks to a marine snail, then extracting RNA from its nervous system and injecting it into another snail to see if its behaviour was influenced.

The shock treatment had taught the snails to defensively withdraw their delicate gills and syphons for long periods after they were gently touched. Other un-shocked snails were found to do the same when they received injections of shocked snails’ RNA. However injections of RNA from un-shocked snails had no effect. We are assured, incidentally, that no snails were hurt in these experiments.

Had the shocking memories really been transferred? “I expect a lot of astonishment and skepticism,” Glanzman says, which was much the same as McConnell received all those years ago. Yesterday it was worms, today it’s snails. This is the inexorable progress of science, I suppose.