Friday, December 28, 2007

Memes and fat

I've gotten side tracked.

In the Fiaf post I suggested that our gut microbiota might be controlling both our metabolism and possibly our behaviour. This led to some very interesting email conversation off blog. Stan broached the subject of the ability of protozoal parasites to influence the behaviour of their hosts. My wife immediately pulled a pathology textbook off of the shelves and pointed out an interesting bug, this time a slightly larger parasite.

Look at the complexity of the ant behaviour induced by the fluke to ensure completion of it's life cycle.The ant has a few cells in a ganglion for its brain. I'm not sure what the fluke has in terms of a nervous system... Yet the ant does as the fluke needs.

The protozoal parasite which Stan pointed me towards was actually toxoplasma gondii.

I have spent many years dutifully blood testing neurological patients for evidence of active toxo infection, occasionally with some success. I never had the slightest idea that toxoplasma gondii was neurotropic for a reason, other than some quirk of misfortune on the part of the patient. But here is the reason. When the toxoplasmosis organism is in its intermediate host, which should be a mouse or rat, it wants to go home to where it belongs, which is in the digestive system of a cat. It wants the rodent to get eaten. So it pops in to the mouse's brain, removes all fear of cats, makes the smell of cat highly attractive and then lets the meeting of these two mammals allow it to complete its life cycle. But it doesn't want the mouse to die in any other way, say at the hands of a human or a fox or under the wheel of a car. So normal fears are left strictly in tact to maximise survival chances, enhancing "cat-meeting" opportunities. Not bad for a single celled organism.

That's attributing an awful lot of "intelligence" to a single celled organism. But evolution has had a lot of time to play with and this is the sort of thing that is happening in your own back garden today. Perhaps it is less subtle than the microbiota and Faif, but you can see a common drive to improve the survival chances of a particular organism(s). Not even I am suggesting that either toxoplamsa, dicrocoelium or the gut microbiota have any specific "plan" in "mind". The "plan" harks back to chaos theory and the generation of complex structures or behaviours from very simple basic rules or equations. It is clearly possible to develop very complex structures (or patterns like fractals) from what can be very simple ground rules. And this can include very specific effects on complex mammalian behaviour in the result.

From here we wandered away from microbes to ideas or "memes", in particular to the parallels between the two. Humans carry ideas which form cultures that can change and evolve with time. As best I can understand it, a meme is a unit of cultural information, in much the same way as a gene is a unit of biological information. Both generate systems which can not only evolve, but also compete. There is an obvious comparison is between groups of memes forming cultures and groups of genes forming organisms. Memes are present in and are carried by the human brain, supported by the human body. Some are highly beneficial to that human body, others less so.

Some memes are just so unpleasant that they cannot occur without severely impacting their host. An ebola virus like meme came and went with the Rwandan genocide. Too violent and too destructive to persist, yet it probably seemed like a good idea at the time (to those carrying the meme of cultural superiority that is). On a bigger scale we have the Holocaust of the last world war doing exactly the same thing. Thankfully neither has become a cultural norm.

But not all destructive ideas are so transient. Some have a low enough level of virulence that they can shape human behaviours over generations and DO become the cultural norm. I've yet to read Garry Taubes' book Good Calories, Bad Calories, but it is very obvious that there is a "low fat" meme which has infected human culture for many generations. It has so far proven to be essentially indestructable. The low fat meme has nothing to do with science, it is an idea which has found fertile ground in the human mind and is doing very well thank you very much. As with other memes (or genes for that matter) its "plan" is self perpetuation. If it can influence the physical form of humans to improve its persistence I see no reason why it shouldn't do so.

If the low fat meme produces a human behavior (eating low fat junk food) which damages the human brain in such a way as to allow the meme to spread more effectively, the scene really is truly set for persistence.

But this is looking memes down at the virus level. Think back to chaos theory and the generation of fractals. Then think about big culture. Are there any major cultural icons of the low fat meme? Obviously the national diabetes associations of the developed nations are products of the low fat meme. I can see no other explanation for their bizarre advice to diabetics. Obviously the American Heart Association competes well too. Weight Watchers.

These are all organisations generated by the low fat meme which are essentially driven by their own need for self perpetuation. The health and well being of the patients they purport to help is unimportant. Converting healthy people in to diabetics strengthens the meme. This can be surreptitiously achieved by lowering the threshold for diabetes diagnosis and more concretely by strengthening the advice to currently healthy people to eat a low fat diet. On a fixed intake of calories this essentially means a high carbohydrate diet. The rollercoaster of high and low blood glucose levels and the corresponding swings in blood insulin levels do nothing for brain function. If anyone thinks that a high carbohydrate diet helps brain function they just need to think about the classification of Alzheimer's as type three diabetes. Or have a read at my post here.

Generating a body, and particularly a brain, damaged by the low fat meme is the perfect base for further propagation of the meme.

The meme is getting more aggressive as it gets backed in to a corner by the islands of hard facts and science based common sense. Time to look at a few examples from Regina Wilshire's blog that illustrates these points.



dave_lull said...

Seth Roberts' interview of Gary Taubes part one can be found here.

Peter said...

Thanks for that dave, enjoyed the interview. Seems like once people become fossilised they are no longer scientists...


Sonia said...

You may never read this but I was wondering if any studies had been done to see if the cats, given the option, would prefer the infected rats over non infected rats.

This creeped me out.

Peter said...

Hi Sonia, it creeps me out too. Especially when you realise quite how basic and stripped out the DNA of the toxo organism is...

I can see that the intestinal toxo bug in the cat would help its species by encouraging cats to prefer toxo infected rodents, but it wouldn't help the happy toxo DNA in the cat's gut to have more competing DNA from new toxo organisms arrive, so maybe this doesn't happen. No one's looked as fat as I know....


BTW the software tells me about comments, even on old posts. Helps me remove the spam.

LeenaS said...

Hi, peter.

I reread this blog post recently, with fascination equalling to the that encountered on the first read. Today I stumbled on this bit of science, on fungi's ability to control ants. Just for interest:

With regards,

Peter said...

Hi LeenaS,

The Voices tell me that this is fascinating. They are correct!

Best wishes


George Henderson said...

We may also see behaviour modification with RNA viruses.
Hepatitis C virus expresses a protein which inhibits mitochondrial oxidation and promotes insulin resistance. This creates hypoglycaemia and promotes a sweet tooth; resulting in increased expression of liver DGAT1, which is essential for HCV virion completion, and increased expression of virion in VLDL triglycerides.
In fact the HCV meme is parasitic on the low-fat meme. It's as if the virus spent the 1970s reading Readers Digest "I am Joe's Heart" articles and thought, "AHA! This is their weak spot; they don't understand cholesterol - I have a cunning plan. Nyahaha!"
It can also make its hosts feel so bad that they expand their indulgence in pain-relieving behaviour that results in the sharing of blood and more viral propagation. As viruses go HCV is particularly good at inducing dysphoria without actually killing its hosts. But this also requires the assistance of the low-fat meme.