It's come to my attention that a few folks have been insufficiently creeped, weirded, disturbed, freaked, frightened, terrified, or just plain disgusted by the idea and behavior of parasites, especially ones that demonstrate the nasty habit of affecting their host's behavior. Never one to disappoint, I'm here again -- lucky you -- with some further examples of how nature isn't just playful puppies and frolicking kittens.
Hardly.
This time we're going to be bouncing around a bit, so keep your trays in the upright position. Parasites, you see, aren't the only living things living in other living things. In fact there is a whole world of organisms that take up residence in us and other creatures that are all but guaranteed to make us rethink the idea of what it means to be "alone."
Before we get to the exotics let's visit the deep blue sea again and another parasite. This one didn't get mentioned the last time around because although Cymothoa exigua is a perfect example of a creature taking advantage of another creature it doesn't immediately make its host do anything it normally wouldn't do. But that doesn't make it any less ... well, you'll see.
Your hand is your hand, right? Your foot is your foot, correct? No one snuck in during the night and replaced them, lopped them off, and exchanged one or the other with something else. You're lucky, because if you were a fish then that might not be ... not your foot or your hand but rather your tongue.
Cymothoa is a crustacean that, while as a larvae, enters a fish's gills and makes its way to the mouth where is latches onto the tongue. No, it doesn't stop there. Yes, it gets worse.
Ready? Here we go: cymothoa then methodically eats the fish's tongue, chewing it up until there's nothing left but a little stub. But this crustacean isn't in it for the short term, just a snack of tongue and then onto the next unlucky fish. Instead, the crustacean hangs in there for the duration: Cymothoa becomes part of the fish, joining its host as a surrogate tongue. It spends the rest of its little crabby life feeding when the fish feeds, and the two of them go along swimmingly through life.
If you think that's bad, let's talk about sex.
Marlene Zuk, with the University of California, Riverside, has an interesting theory, and it's a whopper. First, let's talk evolution, let's chat survival of the fittest: the critter that breeds the most passes the secret of its success along to the next generation while the ones that don't have a leg-up die off. This is true of every critter on the earth, including us as well as bacteria.
Even bacteria like syphilis. For those who didn't see the film in high school, syphilis is what's commonly called a social disease. You catch it if you sleep with someone who has it. The good news is that it's treatable and really isn't a big deal anymore.
The bad news is that it's evolving with the rest of us, and according to Dr. Zuk, syphilis is working to make us better looking -- or at least not looking sick.
Think of it this way: dumb disease acts up, makes itself known. We spot it, we cure it, and it dies. A smart disease works to keep itself quiet, so we don't know we have it and so it doesn't get killed -- and so we pass it along. What I want to know is how long it'll take for the bacteria to take the next step: if it wants us to pass it along why shouldn't it work not just to make us less infected but rather more attractive? Give it time ... give it time ....
Let's go one step beyond parasites, when an organism doesn't merely look for a free ride but becomes such an integral part of the host that the two basically become one. The cell, the smallest part of any living thing -- excluding viruses, if they qualify as being alive -- began as individual protobacteria that figured out, over a very long time, that working together was better than swimming along through primordial soup. That happened before and it's still happening now.
Behavior can be affected by parasites, creatures can take over parts of other bodies, bacteria have developed to be more easily spread, but we are ourselves, right? We own our biological domain, correct?
Sorry but that's not true.There are approximately 100 trillion cells in the human body. They make up our feet, our hands, our faces, our minds: blood cells, skin cells, brain cells, etc. That's a lot of cells.
But there are more of them than there are of us. They live even between our cells, in our guts, our mouths, our blood, our skin, and even in our brains. Conservatively speaking, there are are ten times as many bacteria – more than 100,00 species -- in our bodies than there are human cells. Some of them are invaders, sure, but many of them are symbiotic: they can't live without us and we can't live without them. We live together in - mostly - biological harmony.
You are reading this. The words appear like a voice in your mind. But do they? Living in you, mixed with your human cells, are those tens of millions of bacteria. Are they listening in, wishing you would read something much more interesting or are they, somehow, adding their own tiny opinions? Where do you start and they stop?
I know: that's a lot to think about. Let's take a walk, let some of this heady stuff float around in a brain that may or not be only yours.
Oh, look; it's snowing. Isn't it nice? All those little flakes floating down from the sky: ice crystals supposedly unique. There's a whole world in each of those little things. Weather, chemistry, geometry, physics, and – I hate to tell you this -- biology.
They are all around us and, they outnumber us. And they are falling from the sky. Researchers recently discovered that snowflakes are snowflakes not just because of cold temperature and water vapor. According to these scientists a snowflake has needs. It has formed a kind of biological/chemical symbiosis with the very creatures that outnumber you in your own body: bacteria.
That's all for now, but that's not all there is. Go on with your day, your life, just remember one important little thing: you are never, ever, alone.
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