Tuesday, April 27, 2010

From Madgascar's tapeworms to 'link economy'

Carl Zimmer has another nice article Why Madagascar’s Tapeworms Matter–To You. Excerpts:
"But, like it or not, tapeworms–or at least the pork tapeworm Taenia solium–has an intimate relationship with us. After all, it can only live in our guts as an adult, where it will dwell for years and grow over 20 feet long. Without us, these tapeworms would simply not exist. From the safety of our guts, they can shed six egg-loaded segments a day, each of which contains 50,000 eggs. If a pig swallows one of these eggs, it hatches in the animal’s instestines, drills its way into the abdominal cavity, and finds a muscle to infect. There it dwells in a barely visible cyst, for years if need be. In order to complete its life cycle, it must get into another human, which it does if a human eats a piece of infected, undercooked pork.
....
As hominins expanded their ranges both within Africa and beyond it, they carried their tapeworms along for the ride. As hominins scavenged new game, the tapeworms adapted to new intermediate hosts. Hominins gradually developed the skills and weapons to hunt game, offering still more opportunities for their tapeworms. Neanderthals and other hominins hunted wild boar as well, and it’s likely that we infected them with the ancestors of today’s pork tapeworms.

Starting about 11,000 years ago, humans domesticated pigs many times over, both in East Asia and in the Near East. Now the trip from host to host became riduclously easy for the tapeworms. Instead of waiting for its wild boar host getting speared by a hunter, it could make the journey on the dinner plate. Judging from the deep split in the evolution of pork tapeworms, the parasites must have made two separate shifts from wild boar to domesticated pigs, in both East Asia and the Near East.

The genealogy of the tapeworms also matches up nicely with the human history of Madagascar. People only arrived on the island 2000 years ago. They came from two directions. Bantu farmers sailed from the west from Africa across the Mozambique channel. Asians came from the east, traveling thousands of miles across the Indian Ocean from Indonesia. Malagasy culture emerged from the mingling of these two origins. That culture also includes the livestock that the Bantu and Indonesians brought to the island. And those animals brought parasites with them that had been separated for almost 700,000 years, reaching back to a time when our ancestors had yet to invent fire or spoken language."
The first bit reminded me of toxoplasma gondi, and the next bits of evidence for evolution, parallel evolution etc. I searched through mu blog and find some parallels and more links. It seems that what I started doing is a bit like what some were doing more intensively with something called 'common place book' long ago. From
Steven Johnson's The Glass Box And The Commonplace Book:
"Scholars, amateur scientists, aspiring men of letters—just about anyone with intellectual ambition in the seventeenth and eighteenth centuries was likely to keep a commonplace book. In its most customary form, “commonplacing,” as it was called, involved transcribing interesting or inspirational passages from one’s reading, assembling a personalized encyclopedia of quotations. It was a kind of solitary version of the original web logs: an archive of interesting tidbits that one encountered during one’s textual browsing. The great minds of the period—Milton, Bacon, Locke—were zealous believers in the memory-enhancing powers of the commonplace book. There is a distinct self-help quality to the early descriptions of commonplacing’s virtues: in the words of one advocate, maintaining the books enabled one to “lay up a fund of knowledge, from which we may at all times select what is useful in the several pursuits of life.”
..........
Each rereading of the commonplace book becomes a new kind of revelation. You see the evolutionary paths of all your past hunches: the ones that turned out to be red herrings; the ones that turned out to be too obvious to write; even the ones that turned into entire books. But each encounter holds the promise that some long-forgotten hunch will connect in a new way with some emerging obsession. The beauty of Locke’s scheme was that it provided just enough order to find snippets when you were looking for them, but at the same time it allowed the main body of the commonplace book to have its own unruly, unplanned meanderings.

But all of this magic was predicated on one thing: that the words could be copied, re-arranged, put to surprising new uses in surprising new contexts. By stitching together passages written by multiple authors, without their explicit permission or consultation, some new awareness could take shape."
And much more from Foursquare to 'link economy' in Steven Johnson's article and comments. He concludes:
"The reason the web works as wonderfully as it does is because the medium leads us, sometimes against our will, into common places, not glass boxes. It’s our job—as journalists, as educators, as publishers, as software developers, and maybe most importantly, as readers—to keep those connections alive."

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