The origins of Old Yeller

Since the last few days (hell, the last few years) of news has been filled with one horrible thing after another, today I'm retreating into my happy place, namely: the cool scientific discovery of the week.

And puppies.  Lots o' puppies.

I don't know if it's ever occurred to the dog lovers in the studio audience how unusual dog coat coloration is.  I can't think of another animal species that has such striking variability -- from the jet black of black labs to the solid bronze of golden retrievers to the spots of Dalmatians to the particolored patches of collies, there is huge variation in fur color across the species.

One additional one that is especially curious is called agouti coloration -- when the base of the hair is yellow and the tip is black.  This is frequently seen in German shepherds, and was also the coat pattern in my beloved rescue dog Grendel:

If you're wondering, Grendel was not spoiled.  At all.

As you can see, Grendel also looked a bit like someone created a Frankendog by stitching together parts of about six different breeds.  He didn't have any other German-shepherd-like characteristics, but he definitely seemed to have pilfered his fur from one while it wasn't looking.

Well, a new piece of research that appeared in Nature Ecology and Evolution this week indicates that five very common coat color patterns in dogs come from the activity of a single gene.  Where and when this gene activates (and creates a gene product called the agouti signaling protein) determines the deposition of two pigments -- eumelanin (which is black) and pheomelanin (which is yellow).  The amount and placement of these two pigments creates five different color patterns, as shown below:

[Image from Bannasch et al.}

One of these alleles, dominant yellow, is apparently of ancient origins; the researchers determined that it was present in an extinct canid species that branched off from wolves over two million years ago.

I'm a little curious about another dog coat feature, the white blaze, something my current non-spoiled dog Guinness has:

He also has white toes, which may or may not be related:

As you can see from the image from Bannasch et al., some of the dogs expressing each pattern have white blazes and some don't, so whatever genetic mechanism controls it must be independent of the agouti gene.

But if you have a dog with some yellow or agouti coloration, you now know that your pooch descends from a branch of the canine family tree that is two million years old.  As far as Guinness goes, I flatly refuse to believe he descends from wolves.  His level of fierceness is somewhere between "cream puff" and "cupcake."  He is basically a seventy-pound lap dog. 

In any case, that's the latest from the field of canine genetics and evolution.  Me, I wonder where another important dog feature comes from, and that's the cute head tilt.  There's no doubt that it's a significant selective advantage:

Guinness:  Play ball? 

Me:  Dude.  It's raining outside. 

Guinness:  Please play ball? 

Me:  Don't you want to wait?  I really don't want to go stand out in the... 

Guinness: *adorable head tilt* 

Me:  Dammit.

Speaking of which, I need to go get my dogs their breakfast because they're staring at me.  You'd think if they really are descended from wolves, they could go hunt down a squirrel or something, but I guess the decision to take advantage of sofas was made at the same time as they figured out it was easier to wait for someone to place a bowl full of dog food in front of them than to wear themselves out chasing some scrawny squirrel.

You gotta wonder who has trained whom, here.

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I was an undergraduate when the original Cosmos, with Carl Sagan, was launched, and being a physics major and an astronomy buff, I was absolutely transfixed.  Me and my co-nerd buddies looked forward to the new episode each week and eagerly discussed it the following day between classes.  And one of the most famous lines from the show -- ask any Sagan devotee -- is, "If you want to make an apple pie from scratch, first you must invent the universe."

Sagan used this quip as a launching point into discussing the makeup of the universe on the atomic level, and where those atoms had come from -- some primordial, all the way to the Big Bang (hydrogen and helium), and the rest formed in the interiors of stars.  (Giving rise to two of his other famous quotes: "We are made of star-stuff," and "We are a way for the universe to know itself.")

Since Sagan's tragic death in 1996 at the age of 62 from a rare blood cancer, astrophysics has continued to extend what we know about where everything comes from.  And now, experimental physicist Harry Cliff has put together that knowledge in a package accessible to the non-scientist, and titled it How to Make an Apple Pie from Scratch: In Search of the Recipe for our Universe, From the Origin of Atoms to the Big Bang.  It's a brilliant exposition of our latest understanding of the stuff that makes up apple pies, you, me, the planet, and the stars.  If you want to know where the atoms that form the universe originated, or just want to have your mind blown, this is the book for you.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]