And it had generated a fair amount of good science fiction. Alan Moore used it to create the back story for the Swamp Thing: it was made of vegetal matter that had ingested a human, including its memories, knowledge and skills. Star Trek storylines featured a drip for memories. The great Larry Niven used it more than once as the protocol for the transmission of data between organisms.
At the time, the theory had a scientific basis: the work of the radical American biologist James V McConnell in the 1950s and 1960s, which suggested that long-term memories could be encoded in a type of ribonucleic acid which he named mRNA. If mRNA could be transmitted between organisms, memories and knowledge could travel between themand would be downloaded naturally to succeeding generations, roughly in support of Lamarck.
The theory was one of the outcomes of a search for the brains mechanism of storing knowledge. While experience is stored through an organisms lifetime and forms the basis of learning, there appears to be no obviously growing physical storage. Watson, Crick and Wilkins world-altering discovery of the structure of DNA stirred the scientific imagination. If DNA could store the information for building an organism and transmit its data to progeny, perhaps RNA could encode the sensory data of a lifetime, too
In 1955 at the University of Texas, McConnell and Robert Thompson conditioned planarian flatworms to associate a bright light with an electric shock, until they reacted negatively to the light alone. Planarians are primitive organisms which regenerate into two organisms when cut in half. They found that the regenerated planarians learned to associate the light with the shock much faster than the original. This behaviour was retained after several reconstitutions, when the final organism retained none of the structures of the original. This suggested that memory was transmitted chemically.
The next step was obviously to inject a conditioned flatworms tissue into an untrained worm and see if the learned behaviour was transmitted. However, the lab technology of the time, and the hypodermics, were too gross. Then, in 1962, McConnell learned of a cannibalistic flatworm, and the problem was solved: they were fed conditioned worms and reportedly learned the conditioned behaviour much faster than other worms. McConnell read this as evidence of the chemical basis of memory, but the experiment was discredited as an example of observer bias. No double-blind experiment has ever confirmed its findings.
McConnell appeared on TV and in magazine stories to drum up support for his claims. He had a sense of fun. He talked about futuristic memory injections and of learning to play the piano by taking a pill. It cant have made his peers very happy, since most of them had staked their lifes work on the notion that neurotransmission was mainly electrical, and he was soon being derided as McCannibal. A public figure whose work suggested that science might demystify and thereby desacralise life, and a best-selling textbook author, he was a natural target for the Unabomber, who studied maths on the campus at Ann Arbor where he taught. McConnell, a music lover, partially lost his hearing when his assistant opened a parcel and triggered a bomb, suffering shrapnel injuries.
After so much excitement, one might have expected that the flatworm route would be closed off by behavioural scientists. Not so, they are an intrepid lot. Last year, Tal Shomrat and Michael Levin of Tufts University published a paper in the Journal of Experimental Biology whose title says it all: An automated training paradigm reveals long-term memory in Planaria and its persistence through head regeneration. In short, if you train a flatworm to find its way through a simple maze, then cut off its head, it will still know its way around when the head regenerates.
This could have immediate implications for regenerative medicine. For instance, will regenerating the visual cortex of a person with an injury at the back of the skull restore visual memories And way ahead in the future, kids could be popping pills instead of going to school, learning algebra without even trying, as Nicholas Negroponte has recently suggested.