Hey, yo momma’s an amoeba! No, really. I’ve come to the conclusion that there is no essential difference between single- and multi-cellular organisms. I put together some ideas about cholera, biomats, slime molds, sex cells and somatic cells, and phosphorescent squid, and that’s what I got. Maybe not the conclusion that most people would logically reach, but that’s why you’re reading my blog, not theirs.
It all started with slime molds. Slime molds are some of the neatest organisms on the planet, with the possible exception of the platypus. They’re fungi that spend most of their lives as single cells in moist, rotting wood. When food is scarce and the weather is just right (cool and damp), they start migrating onto the surface and band together into clumps. The resulting aggregate creature looks vaguely like a slug, complete with a large slimey foot. When the slime mold senses that it has reached a critical mass (through quorum sensing), the individual cells start to differentiate into somatic cells and sex cells. (Somatic cells are the ones that sacrifice their lives for the larger organism, not passing on their genetic material, while sex cells get to have all the fun and continue the germ lines. Which would you rather be?) Differentiation is a hallmark of multicellular, complex organisms. Make note of that.
Don’t see it yet? Alright, let’s take cholera. Not orally, though. The Vibrio cholerae bacteria will give you diarrhea to end all diarrhea — diarrhea that can kill in as little as 8 hours if not properly treated. Nasty as a bout of cholera may be, the vibrio themselves are fairly apathetic towards you. Humans are simply one possible way of getting from place to place, and not even the preferred method. In fact, vibrios naturally live in aquatic environments like rivers, estuaries, and oceans, revolving through a decently complex lifecycle involving zooplankton, algae, biomats, and copepods.
Those biomats are something else again, I tell you. Not mere biofilms like the stuff that grows on your teeth, biomats have complex 3-dimensional structures that incorporate multiple species or genera, often working together to gather nutrients, extract energy, excrete waste, reproduce, and adjust to the environment. Those are criteria of life, mind you — and they apply to the entire biomat, not just the component cells. There is in fact a very intriguing theory that perhaps biomats are the adult form of bacteria, and that the loners wnadering about in the environment are nothing but seeds. Could it be? Have we had it backwards?
I was rather stunned by the implications of this complete reversal of the theory of bacterial life-cycles. What if we apply an inverse of that theory to ourselves? Perhaps we are nothing but complex carriers for sex cells, which use us as transport and selection devices to allow themselves to mate with sex cells in their own carriers? After all, the sex cells are the ones in charge. They are the ones that pass on genes. Any somatic cell is relying on the sex cells to perpetuate their own genetic line.
It’s really just a thought-experiment. I’m not seriously suggesting that we drop all distinctions between single- and multi-celled. But it is thought-provoking, at the very least.
And I take back what I said about your mom, alright? Chill out.