Yesterday a molar screamed for attention too loudly for me to ignore any longer, so my dentist was kind enough to drill into it, at the same time drilling into my checking account. In less than an hour the molar’s nerve roots were no more, and, if money indeed is the root of all evil, I am significantly closer to virtue. I have been fortunate with my health in my life to date, except for my teeth which always have demanded care. All 32 of them are still there, but only thanks to copious reinforcement with gold, silver, and porcelain.
Paleolithic skeletons are remarkable for their good teeth. There are exceptions, but by and large their choppers are in excellent shape. This probably is a matter of diet. Eskimos with a traditional diet of virtually all meat also have superb teeth, as do most predominately carnivorous peoples. (That’s not a plug for the Atkins Diet; there are many advantages to a vegetarian diet in other respects.) The teeth of ancient farming Egyptians, on the other hand, commonly show severe wear, apparently from grit and sand mixed in with the grains. Modern peoples have all sorts of culinary temptations seemingly purpose-designed to rot the teeth, so there is no unemployment problem for skilled dental technicians.
It is possible, though, that there is a biological as well as dietary element to declining dental health. One author as long ago as 1933 thought so. In that year anthropology curator HL Shapiro in a Natural History Magazine article titled “Man—500,000 Years From Now” (http://www.naturalhistorymag.com/picks-from-the-past/151691/man-500000-years-from-now) noted worsening human teeth: “Since it is improbable that we shall return to the tough, resistant food on which our predecessors thrived, the chances are that our dentitions will continue to deteriorate. We perceive a progressive recession of the jaws, a decrease in the size of teeth, a loss in number, and an increase in maleruptions.” He projected the trend far into the future. Mr. Shapiro’s article, even allowing for the year of its publication, has problems, to put it kindly, and the 500,000 year timeframe is the least of them. Still, it probably is true that modern dentistry reduces the extent to which bad teeth affect reproductive success, which in turn might make bad teeth more common.
This week, articles about ongoing human evolution are in the news again, due to a study in the Proceedings of the National Academy of Sciences that examined 18th and 19th century birth and death records in four Finnish villages. In this period, half of the inhabitants died before age 15. The reproductive success of the adult inhabitants varied greatly, especially among males, ranging from 0 offspring to 17. The authors see in these numbers evolutionary pressures to adapt (to life in Finnish villages) that are fully the equal of those on most wild mammals in their environments. The conclusion is that evolution continues.
I don’t think anything in the Finnish study is a big surprise. Exactly how humans have changed since Paleolithic times, remains debatable, however. In the past 30,000 years we’ve certainly evolved resistance to some diseases and our brains actually seem to have gotten smaller (see http://richardbellush.blogspot.com/2012/01/incredible-shrinking-brain.html), but little else is clearly discernable. How humans will change in the future is, in truth, unknowable.
It is still fun to speculate though, just as it was for Mr. Shapiro. Bio-technology makes this even more of a guessing game than ever since genetic engineering opens an entirely different path from natural selection. So far, however, performance of bio-tech hasn’t matched the hype. In particular, for all the talk of telomeres and “aging genes” we’ve yet to alter the human lifespan by a single day. Statistics that seemingly show increases in longevity really simply show that people are less likely to die early from disease and injury; the maximum possible lifespan beyond which we just wear out (122 is the oldest age ever confirmed) hasn’t budged in thousands of years.
One change that is occurring – that is hard to miss – isn’t even biological. People are becoming cyborgs, more or less permanently attached to their electronic devices and their internet access. Perhaps as our machines become larger and larger components of ourselves, they will become the more important part. This won’t take 500,000 years either. Will the machines ever become the only part, as so many science fiction tales would have it? Maybe, but then we’re not talking about human evolution any more, are we? We’re talking mechanical design.
I have a suggestion for the designers of the upcoming borgs and robots. If they still have mouths, give them better teeth.