Out of the Earth, Out of the Blue

milhayser — Wed, 11 Feb 2015 16:28:02 +0000

Greg Laden reports on a hominid fossil "recovered from the seabed near Taiwan" which reveals new levels of dental diversity among proto-humans and may qualify as a new species. Greg says the specimen known as Penghu "is yet another indicator that multiple different hominids lived on the Earth at the same time after the rise of Homo erectus." But why was it located underwater? In another example of what lies beneath, Dr. Dolittle marvels at "an unexpected find and very exciting moment for researchers;" the discovery of small fish and invertebrates thriving below 740 meters of ice near the coast of Antarctica. Exactly how these animals survive in the stark ecosystem has yet to be determined. Meanwhile, on Uncertain Principles, Chad Orzel reflects on the history of surprising physics discoveries. He provides as an example the discovery of the muon in 1936, a subatomic particle that no one was even looking for. Chad writes, "The eminently quotable I.I. Rabi famously responded to the news by asking 'Who ordered that?'" No one, but we'll take it.

milhayser Wed, 02/11/2015 - 11:28

Categories

Life Sciences

Speaking of dental history, some of my best friends and golf buddies are dentists. I’ll have to ask them some time what theories they have, if any, on how teeth evolved.

I suppose first you’d have to evolve a mouth, though I’m not sure how the creature would have sustained itself directly before and after getting the mouth. Then how the creature dealt with hard food before getting the teeth. Maybe the teeth evolved in response to the creature wishing it could chomp on harder things. But first the jaw bones would have to evolve, and have the right kind of hinges so they’d go up and down in just the right way. Then the jaws would be ready for the teeth to evolve and implant their roots in the jawbone. Then the teeth would evolve into different shapes for different purposes and position themselves in the right spots with the molars in back and the canines towards the front and whatever the others are called in the very front. People probably wouldn’t guess this if asked, but teeth are the hardest substance in your body! And each tooth is comprised of different layers - enamel, dentin, cementum, and pulp. And let’s not forget the evolution of that peculiar flesh that wraps it all up - the gums. But the teeth and mouth are no good without the all-important multipurpose tongue, the esophagus, etc.

But given that teeth can get cavities and can go haywire positionally - and so require braces or other orthodontia – maybe even an atheist would say this is evidence that teeth are not designed or at least are poorly designed and thus your God isn’t much of a God because he’s obviously not an intelligent designer. Also, I think I’ve heard about people who made the same “poorly designed” argument about the esophagus, because you use the same pipe for breathing and eating and so could choke on your food and die. I guess they never heard of the epiglottis.

Anyway, the evolution of teeth provides a lot for one to chew on.

But first the jaw bones would have to evolve, and have the right kind of hinges so they’d go up and down in just the right way. Then the jaws would be ready for the teeth to evolve and implant their roots in the jawbone.

This is reasonable speculation, and it makes sense. But it's pretty much completely backwards. There's a nice outline of the evolution of teeth in Neil Shubin's Your Inner Fish.

GregH #2:
Neil gets into teeth at about 2:40.
http://thecolbertreport.cc.com/videos/xgsf42/neil-shubin

Now I’m a believer. And for about $10 grand, I’d consider buying his book and reading it.