A world without dogs sounds like no fun at all.
But many of the hundreds of dog breeds we know today are only a few centuries old.
And, according to current research, if you go back in time at most 34,000 years -- dogs,
as we know them, didn’t even exist!
Even though we know that modern dogs and modern wolves share a wolf ancestor, no one’s sure
exactly how dogs were first domesticated… or even when.
But we do know that at some point, dogs evolved from mostly ignoring humans to wanting to
be best friends with us.
That process of domestication came with consequences.
Some of them you’d expect, like dogs becoming tamer over time.
And others are just… strange.
For instance, there’s a trait that dogs share with other domesticated animals, that
even Darwin thought was weird: lots of dog breeds have floppy ears.
Evolutionarily, this doesn’t make much sense.
It’s a result of deformed ear cartilage, and it can actually make it harder for a dog
to hear.
So why would we breed dogs to have deformed ears?
Well, we didn’t, at first.
At least, not on purpose.
Instead, floppy ears seem to have a lot to do with other traits that domesticated animals
have -- like patches of white fur, and adorable little faces that retain their juvenile features
into adulthood.
According to a new hypothesis, it turns out that in the process of domesticating dogs,
we might have actually been affecting some of their stem cells.
In a dog embryo, there’s a group of stem cells called the neural crest.
And these cells are responsible for forming a specific set of physical features -- like
the dog’s coat, and the structure of its face, and its adrenal glands.
And according to this new research, a lot of the features that we associate with tameness
may actually come from changes that have been made to this neural crest.
The earliest dogs may have been less aggressive because they had smaller adrenal glands.
So when early humans bred for tameness, the dogs probably also ended up with changes to
other traits that are controlled by the neural crest -- like floppy ears, and the faces with
more juvenile features, such as smaller jaws.
So basically, by domesticating dogs, we may have ended up selecting for mutations in their
stem cells that made them less like wolves and more like the animal that’s probably
sleeping in your living room right now.
But domesticating dogs has had other useful side effects, too.
For example, dogs are a whole lot better than their wild cousins at digesting starch.
A study published in 2013 analyzed the genomes of 12 wolves, and 60 dogs of different breeds.
The researchers were looking for genetic differences that showed up in all of the dogs, but none
of the wolves.
They found changes in 36 regions of all of the dogs’ DNA.
Some of the results were somewhat predictable, like changes to genes that are involved in
brain development, which account for how friendly and tame dogs can be.
But they also found something that they didn’t expect: the dogs had three genetic variations
that helped them digest starch.
This fits with the theory that dogs first started to be domesticated as many humans
settled down to an agrarian life.
At some point, hungry wolves might have started venturing into human settlements and eating
their leftover starchy food… something that a lot of modern dogs seem to be into as well.
The wolves that were best able to digest the starch were better fed, so they survived to
reproduce.
And speaking of things that dogs are really into, you know how dogs really like chewing
on bones ... but it seems to take them forever to actually finish eating one?
Well, that has a lot to do with their ancestry, too.
Wolves eat meat.
And they’re really into the stuff -- it doesn’t matter how delicious you think your
pie is, a wolf is going to pick the steak any day.
So they’ve got really sharp teeth that are perfect for tearing apart flesh, and powerful
jaws that polish off a bone pretty quickly, especially if they’re looking to get to
the marrow inside.
But even though dogs inherited wolves’ desire to gnaw on bones, they have smaller jaws and
a less powerful bite.
Which means that it takes them a whole lot longer to finish a bone, if they can even
make a dent in it at all.
But if you’ve ever seen a dog chewing on a bone… it doesn’t seem like they mind
how long it takes to finish it.
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