Fluoride and Fluorite: First Change since 1962: Decreased Levels of Recommended Fluoride in Drinking Water by the United States

          On Monday, April 27, 2015, the U. S. Department of Health and Human Services decreased the recommended amount of added fluorite in drinking water to about half the original recommendation. It is the first change in the recommended amount since 1962.

       
          The main documented side effect to over-fluoridation is fluorosis, a condition marked by white marks on the teeth. There are proven great benefits to low fluoride amounts to decreasing dental caries. Most people in the U. S are already getting fluoride directly on their teeth in the form of toothpaste and dental rinses. The NPR link above notes some believe fluoridation at higher levels is linked to other problems including thyroid issues, skeletal fluorosis, and ADHD.

           Much of the western world has already eliminated or decreased fluoride amounts in water supplies. There are some areas of the world that have naturally occurring fluoride which is over 1.5 mg/l (See world map here.) The high fluoride levels are linked to types of granite with the naturally occurring fluorite mineral (the purplish mineral in the pinkish granite below):

           The mineral fluorite, CaF2, is a member of the halide sequence.

          And, of course, fluorite is the namesake poster child for fluorescence under ultraviolet light:

          I am curious to hear about your views on the fluoride controversy. What is yours? Surely, the decreasing of the acceptable level by half is significant. 

Going with the fluo,

Steph

Capitanian: A Sixth Major Extinction 262 Million Years Ago?

      One of the first things geologists learn about is the major extinction at the end of the Permian Period (and Paleozoic Era) 250 million years ago. 96 percent of all species died during that mass extinction.

       Now geologists have discovered new evidence that may point to another extinction during the mid-Permian, 262 million years ago, just 12 million years before the major Permian-ending event. An April, 2015, Geologic Society of America (GSA) paper (Lead author David Bond) notes that the "Capitanian" saw the extinction of 87% of all brachiopod species.

        The Capitanian was named 20 years ago based on research in tropical to sub-tropical areas in China and elsewhere and believed originally to be more localized. Newest research in northern Norway suggests that this extinction may actually be more global (though several dissenters have commented on the publication in the well-respected GSA paper).

      
          Dr, Bond et al  write that the Capitanian extinction was likely triggered by the eruption of the Emeishan Traps, located in the southwestern Chinese province of Sichuan. Volcanic eruptions release large amounts of carbon dioxide, causing ocean acidification. Seafloor oxygen depletion may also have played a role.

             The major shift after the acidification and oxygen depletion was from domination of brachiopods to domination by bivalves after the Capitanian extinction:

      Brachiopods and bivalves differ in the number of adducting muscles, the way they eat, in their very classification, and in the symmetry of their shells. The two shells of bivalves are mirror images of each other; they are not in brachiopods.

          So, why were bivalves better suited than brachiopods for life after the Capitanian? Any guesses?

Shellfishly (and sleepily),

Steph

Exquisite Dating Tool: Zircons as Indicators of Earlier Closing of the Land Bridge Between North and South America

          New research indicates that the connection between North and South America was created 13-15 million years ago rather than 3-5 million years as previously thought. The age of zircons was the main indicator of the much older closing age. Here's an image of a  zircon (greenish elongate diamond) in crossed nichols polarization:

           Zircons are crystals that form when magma cools. Newly-formed zircons contain some uranium, but no lead.  Therefore, any lead found in an old zircon must have originated in the radioactive decay of uranium. Thus, zircons are a favorite tool for dating in geology. (as well as dinner and a movie ;-)).

          Zircons found in streams in Colombia and Panama have dated the closing of the gap and formation of the "land bridge" at 13-15 million years.

           The biggest mystery is why animals, especially mammals like this racoon ancestor, 

Chapalmalania, 

did not make the mass movement across the land bridge until 3-5 million years ago (as seen in the fossil record). Perhaps the "land bridge" was more like a series of volcanos with shallow waters in between so it took ten million years for a solid, continuous land bridge to form. 

            This research was performed by Camilo Montes et al. This article also contains a link to terror birds (if you dare). [And a new terror bird species has just been discovered as reported on April 13, 2015.]

             Any ideas as to what was going on in the 10 million years between the possible closing of the North and South American continents and the mass mammal migration (say that 5 times fast!)?

Zirconly,

Steph

Yawn, Yawn, Yawn: Emotional Closeness in Wolves and Other Species

     Here's hoping this post will make you yawn. 

       Researchers at the University of Tokyo collected data to show that yawns among wolves are related to emotional connection between individuals. The stronger the bond-- the more likely the yawn. The research is discussed here.

        There's evidence of interspecies transfer when it comes to yawns as well.

      

       Savor the etymology of yawn:

c.1300, yenen, yonen, from Old English ginian, gionian "open the mouth wide, yawn, gape," from Proto-Germanic *gin- (cognates: Old Norse gina "to yawn," Dutch geeuwen, Old High German ginen, German gähnen "to yawn"), from PIE *ghai- "to yawn, gape" (cognates: Old Church Slavonic zijajo "to gape," Lithuanian žioju, Czech zivati "to yawn," Greek khainein, Latin hiare "to yawn, gape," Sanskrit vijihite "to gape, be ajar"). Modern spelling is from 16c.

       May your day have lots of  yawns with whatever species you encounter today.

Here's to many more yawns,

Steph

And, seen at the Smith President's House yesterday (not far from the river otters):