September 07, 2006

Slime Mould - Genetically Programmed Fascists

Carl Zimmer has a look into the social dynamic of slime mould, studies have shown that certain species of slime mould have kin-affinity when it comes to creating spores. Slime mould create a spore when localised resources become scarce, its a form of transport. However, when forming a spore, only abouot 20% of the individual amoeba actual get transported, the remaining population sacrifices itself to allow these guys to propogate to areas unknown.

Self sacrifice is often touted as an anti-natural instinct, so the sacrifice of 80% of this little population for that successful 20% might be used as evidence that people should stick together no matter what. However, due to kin selection, Dictyostelium purpureum, is a total fascist - it typically sticks together with its own kind with a xenophobic to creating spores with colonies it doesn't regard as one of its own kind. The advantage in this strategy is twofold - by sticking to your own kind, you ensure that your genes to propogate (especially as an asexual organism); and by mistrusting other organisms, you avoid "cheaters" who might have the genetic advantage over yourself. If there was any microbiological psychology, you might even be able to pin it down to paranoia.

Luckily, not all Dictyostelium spp. are doomed to unprogressive conservative dogma, other species, like D. discoideum do embrace multiculturalism and create slugs and spores with cells outside their own direct lineage. There are obvious advantages in this strategy too, and not just if you are a cheater - "cousin" (not-clone) amoeba might have slightly different diets, have better genes (and transfer them), be weaker or suck at the "stalk forming lottery", or have other beneficial attributes for the slug.

So what did we learn from this?

Not much.

Despite some intriguing similarities, I really don't think it's wise to try and gain any sort of social lesson from the behaviour of single celled organisms. Some amoeba are fascists, some aren't, and they both seem to still be kicking around. I wonder how well they get along with each other?

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