Sunday, May 2, 2010
I was searching for something on Mother's Day, which made me think of roses which brought thoughts of bugs which dared me to ponder unusual facts about parasites which inject themselves into said creatures. Ready?
A grasshopper infected with the parasite hairworm (spinochondodes telinii) will seek out water and toss itself in, a clear suicidal behavior. This action insures the hairworm will reproduce. Spooky.
Rodents infected with toxiplasma gondi exhibit strange behaviors. They lose their instinctual aversion to cats. This is beneficial to the parasite because it sexually reproduces in cats that have eaten infected mice or rats. Then the cats spread toxi through their droppings. But wait:
People infected with toxiplasma gondi act a little nutty too. If you're infected with this parasite through cat droppings, you're likely to act neurotic and uncertain. They've even studied the correlation between countries with a high rate of toxi infections and mental illness. Holy moses, they need to study my relatives!
Some crustaceans, once infected by tremotodes, will shy away from light, another suicidal or evasive behavior, as it makes them crawl around in the open looking for shade, hence more likely to be eaten by birds - who in turn, are now infected with the trematode parasite. Pretty sneaky.
Ah - plasmodium! The cause of malaria, affecting both mosquitoes and animals. Once infected, a mosquito is more likely to bite more than once in a night, spending far more time drinking blood. In turn, if a human is infected with plasmodium he becomes more attractive to mosquitoes, thus continuing the life cycle of the parasite. Astonishingly brilliant.
Of course, all this makes fertile ground for science fiction, with parasites invading the brain and taking control of the human. Ewww!
The truth is, retroviral infection from parasites and microbes have had quite an effect on human evolution. Over millions of years, they have been incorporated into our genomes. It is estimated by biologists and other high-thinking persons that as much as a third of our genome consists of bits and pieces of old retroviruses - remnants of ancient virual infections.
So what the heck are you talking about, Cathy?
Fair enough. It basically means that these very old microbes, with us for quite awhile, may be part of the reason humans evolved their intellect quicker and on the scale we have. These living viruses cannot leave the host cell and infect other cells, so you'd think it would die when the host does. But by evolving mutations in their own genetic code, now get this - it can use the host cell - US - to make copies of itself including a protective protein which allows it to leave the cell and go infect other cells. To travel! Parasitic life forms have evolved with us, and made us...smarter?
It's something to dare think about.
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Note: I have not posted any pictures to help keep you from losing your lunch.
Posted by Cathy at 6:39 PM