Tuesday, July 31, 2007


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Day 5 of the great Toothache. The swelling is down substantially, the pain has not subsided despite the inclusion of Tylenol w/Codeine as a new dietary staple. My taste is way off: I've developed an unquenchable thirst for Pineapple Juice. That got me wondering. Was I onto something? Then it hit me. I was accidentally locked out of the house, stranded on the back porch in nothing but a pair of swimming trunks. Minutes became hours, until I finally was rescued. "What are you doing out there?" I drank an entire can of Dole Pineapple Juice "Maybe I'm turning Hawaiian," I thought, recalling the old Vapors song "Turning Japanese I think I'm Turning Japanese... etc." After washing the Dole down with codeinated Tylenol, it took several hours before I gathered up enough of a head of steam to fire up the computer and do a little research.

Dr. Spiller has Mr. Tooth Decay's number. But I wanted to know WHY we are cursed by caries!

Dental caries: an infectious and transmissible infection

Here's an interesting tale of tooth decay and the part it has played in helping researchers to confirm the spread of our Homo sapiens ancestors from Africa into the world at large.

The team, led by Page Caufield, a professor of cariology and comprehensive care at NYUCD, discovered that Streptoccocus mutans, a bacterium associated with dental caries, has evolved along with its human hosts in a clear line that can be traced back to a single common ancestor who lived in Africa between 100,000 and 200,000 years ago.

S. mutans is transmitted from mothers to infants, and first appears in an infant’s mouth at about two years of age.

What possible evolutionary benefit could be conferred on a species by the inclusion of an element which causes a valuable ‘tool’ like teeth to weaken, decay and ultimately disintegrate, which often require extraction - not to mention the sheer pain and and dangerous infections that can often result in the interim.

“As humans migrated around the world and evolved into the different races and ethnicities we know today,” Caufield said, “this oral bacterium evolved with them in a simultaneous process called coevolution.”

It would be interesting to know how this bacterium managed to appear in the first place - did it, for example, coincide with a change in the dietary habits of early modern humans - was it caused by consuming starch or sugars that had not previously been on the palaeolithic menu, or did it jump from another species entirely. It would be good to have an idea of which other animals, presumably mammals, that have been in close contact with humans, and which also suffer from cavities caused by similar bacteria, and whether we can also trace their movements over the past few hundred thousands of years.

“By tracing the DNA lineages of these strains,” Caufield said, “We have constructed an evolutionary family tree with its roots in Africa and its main branch extending to Asia. A second branch, extending from Asia back to Europe, traces the migration of a small group of Asians who founded at least one group of modern-day Caucasians.”

Additional branches, tracing the coevolution of humans and bacteria from Asia into North and South America, will be drawn in the next phase of Caufield’s analysis. Hmmm. I ownder if there any "hidden benefits" of carrying this S.mutans thing around in our mouths?

Caufield’s coauthors were Deepak Saxena, adjunct associate professor of basic science and craniofacial biology; Yihong Li, associate professor of basic science and craniofacial biology, both at NYU College of Dentistry; and David Fitch, an associate professor in NYU’s Department of Biology.

Caufield’s findings are reported in an article in the February issue of the Journal of Bacteriology.

Wouldn't it be fascinating to uncover more about population expansion throughout Ancient America, as well as to discover whether the bacterium, and others like it, confer benefits that we have so far not yet detected - after all, natural selection would surely by now have rooted out a bacterial threat that only caused harm and pain at such a superficial level across so many members of the population, and the fact that Streptoccocus mutans is now available in 60 varieties, indicates that there is a very strong selective element at play.

And if our own natural selection processes are unable to get rid of S.mutans, it can only be a matter of time, and of course a huge leap in orthodontic and genetic technology, before we back-engineer ourselves to a state of pre-decay..

It is noticeable that even extremely old fossil teeth, and particularly those which belonged to Neanderthals, often look for all the world as if they had just won an entire series of ‘Tooth of The Year‘ competitions, such is their pristine and wholesome appearance.

Note: Information used in preparing this post includes material adapted from a news release issued by New York University and several individual articles identically titled "Tooth Decay Analysis Supports 'Out Of Africa' Theory Of Human Evolution"
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