Is there such a thing as genetic memory?

Zenstar Asks:
what exactly is "genetic memory" and how does it work exactly? And if a person were to eat a tapeworm could they find the food?

Well, after a long hiatus I have decided to finally answer your question, just in time for publication in ClawMarks. It is rather complex question, so in time honoured SchpatDope tradition I'm going to write an answer that deals with your topic, but might not answer the question exactly. The spirit of the question is more important than the letter of the question, or something.

First of all let's address "genetic memory". The idea of inheritance for physical traits was first introduced by French naturalist Jean Baptiste de Lamarck. His theory was two fold:

1. If an organism made use of a particular organ it would grow and become more functional. If an organ was disused it would shrink and become less functional.

and

2. The functional changes in the organism would be passed on to it's offspring.

At one point this theory was widely held as the mechanism for evolution, even being adopted by Darwin himself. His assertions were eventually discredited by showing that organisms that had organs removed, and survived, did not pass this absence on to their offspring. Recently however work in the field of Epigenetic inheritance has shown that Lemark's theorys may have had something to them.

Now I realise that you don't really care about the ability of genes to remember previous generation’s physiology, but I thought I'd include it anyway. What you really want to know is can memories and knowledge be transferred from generation to generation.

The nature of memories and how they are stored has been a hot topic debated by humanity’s greatest minds since the middle ages. Inherited memories are often used as plot devices in fiction, as an example it’s a major part of Frank Herbert’s “Dune”, but no scientific evidence has been found to prove their existence in humans or any other organisms for that matter. Instinctual behaviour has been put forward as a proof for the inheritance of memory, but it is far more likely that instinct is merely reaction to stimulus. Some scientists have stated that observations of primates using tools that their ancestors used, without any contact between them, is proof of inherited memory. Again it’s just more likely that a clever chimp is simply going to find out for himself that he can use a rock to crack a nut.

On the more alternate side of things some whack jobs out there believe that inherited memories are a scientamarrific way to prove that memories of past lives actually exist. Of course their arsenal consists of circular reasoning, misinterpretation and blatantly ignoring opposing evidence. Does this behaviour remind you of a different group of idiots? Yes, even the sciento(m)logists believe in genetic memory. They believe that space operas like Star Trek are genetic memories of humanity’s past, before Xeenu obviously.

So to answer the first part of your question I’m going with: If they believe it, it just can’t be true.

Man, everything I investigate does lead back to Trek! Wow.

On to part the second.

Back in the Renaissance it was commonly held, by illuminated folk like Michelangelo and Leonardo DaVinci, that memories were stored in Cerebrospinal Fluid. It was thought that the fluid was somehow altered by the process of learning. Theory had it that memories could be passed from one individual to another by injecting or, even worse, ingesting the spinal fluid of the recently departed. This was even a major plot device in a movie starring Ray Liotta. Experiments however failed to prove these claims.

In the 50's the possibility that memories were stored biochemically raised its head again. However this time the theories were that memories were encoded into DNA, RNA or other related molecules. These speculations were brought about by apparently ground breaking experiments conducted by one J.V. McConnell.

McConnell got himself a bunch of flatworms and proceeded to train them to respond to certain stimuli. In one experiment he shone a bright light on the worms and then quickly proceeded to electrocute them. Now the natural reaction of a flatworm to light is to stretch out, their reaction to electricity is to curl up. He got his worms to recognise the light as a precursor to electricity and curl up the moment they were bathed in photons. Great, pavlovian conditioning, nothing new here.

Then he cut the worms up and fed them to another bunch of flatworms, these new worms were able to learn the conditioning more quickly than the original bunch and more quickly than a control group of worms fed on normal worm food. He continued his experiments by teaching his worms to run a maze in search of food. The maze in question was rather simple having only one decision, it was a basic T-Junction. Worms that turned right got snacks while worms that turned left got, yes you guessed it, electrocuted! They eventually learned that right was better than left. Again he embarked on his program of forced worm cannibalism and again the cannibal worms learned the route faster. Somehow his worms had learnt something by eating other worms, he claimed that memory was obviously biochemical in nature.

Others tried to replicate his experiments and met with varying success. The maze example in particular was one that either worked for you, and worked over and over no matter how many times you conducted the experiment, or just yielded no results at all. The scientific community was polarised, however his experiments were included in High School text books and millions of scholars performed them, even as late as the 80's. In the late 60's it was discovered why the experiment either worked or didn't, it all came down to cleaning. Labs that cleaned their mazes thoroughly with organic solvents invariably found that they could not replicate McConnell's results. Those that just cleaned them casually with inferior detergents, the kind used in most high school bio labs, had left scent trails which were being followed by cannibal worms, worms smelt like food!

McConnell defended his theories by pointing out that his experiments with light conditioning could not be explained by scent trails and were still perfectly valid. Three scientists: Frank, Rosen and Stein decided to prove him wrong.

They however chose to torture rats. They took three groups of the furry critters and submitted them to three different circumstances. One group was conditioned to associate the light side of a test box with electric shock, another group were put in the test box and allowed to go where every they wanted without fear. The last group had themselves sealed in a jar and rolled around for hours on end. Then they ground up their livers and brains and fed them to three new groups of rats. The group that ate the conditioned rats learnt to avoid the white side of the box more quickly when electrocuted than the group that were fed the unconditioned rats. However the group that ate the rats from the jars learnt quicker still. Their findings: rats that had been fed the livers and brains of rats that had been stressed learnt to avoid pain more quickly. This they found out was due to chemicals produced by the stressed rats, the higher the stress the higher the levels of these chemicals and the quicker the learning rate. McConnell's theories and findings had been discredited.

Even rational people like Theodore Kaczynski hated McConnell. 1985 Kaczynski, at this time known only as the Unabomber, sent dear old Prof McConnell a bomb disguised as a manuscript. Unfortunately McConnell’s assistant opened the package and McConnell got off lightly with only a little hearing loss. Indecently Kaczynski had a PhD in advanced mathematics, but was not held as a child.

What have we learnt? Well three things. Firstly, scientists love to torture poor defenceless critters, secondly that if you eat a tapeworm all you’re going to find is a parasite in your lower intestine, and thirdly that if you want to do well in you exams you should seal your classmates in a barrel and roll them down Jamie Steps a couple of thousand times, then eat them.

Schpat