Wednesday, 23 April 2014

Cultural opportunistic infections

Until recently I had considered the obesity epidemic to be primarily a cultural epidemic - an epidemic of memes. Fast food companies spread their obesity-promoting memes throughout the population using advertising - and so manipulate people into eating more food, thus making them richer and financing the production of more obesity-promoting memes.

Obesity isn't just down to memes. Genes in foods are also involved - and humans are breeding fatter, tastier and sweeter produce to better cater to the human palate.

However, it is becoming clear that another source of genes is also involved - genes inside microbes in our intestinal flora. A variety of microbes have been fingered as obesity-promoting strains. One famous one is Candida albicans.

This suggests the disturbing picture of obese individuals as folks whose bodies have been hijacked by malevolvent microbes and turned into production factories that leave a trail of infection behind them. The microbes eating their food for them and pump hunger-promoting substances into their bloodstream.

This more complex picture of a swarm of obesity-promoting memes and genes makes it harder to blame the obesity epidemic on memes. However, it creates an interesting and unusual situation - where humans are being manipulated both by a swarm of memes and by a swarm of genes inside microorganisms. Can scientists learn anything from this simultaneous attempt to manipulate the same trait by both memes and microbial genes?

It may provide an interesting opportunity to compare organic and cultural evolution. For example, consider the question of whether genes or memes adapt faster. Most previous attempts to study this question have compared memes with human genes. However human genes reproduce at a very slow rate - and this is obviously an unfair comparison and a walk-over for the memes. Comparing memes and gut bacteria seems like a fairer comparison between the organic and the cultural.

Another related topic is cultural opportunistic infections when a host is infected by one parasite, that sometimes opens the door to other parasites. A classic example is Hepatitis D - which only attacks those already infected with Hepatitis B. In general, it is common for an overworked immune system to divert resources from one area to concentrate on an existing attacking force - leaving some areas less well protected. In the case of obesity, it is easy to imagine fast food memes promoting Candida infections. Probably hungry Candida sufferers are also more susceptible to fast food memes. Cross-domain opportunistic infections seem likely to be a real thing - but memeticists need to study this topic to better understand it.

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