Wed Jan 23, 2013, 04:32 PM
pokerfan (27,009 posts)
Diet Shaped Dog Domestication
Fido may prefer steak, but his digestive system is also geared up for rice and potatoes. That's the conclusion of a new study, which finds that dogs have evolved to eat a more varied diet than their wolf ancestors. The shift parallels genetic changes seen in people and bolsters the idea that dogs and humans share similar evolutionary stories.
Dogs evolved from wolves more than 11,000 years ago, somewhere in Eurasia, though exactly when and how is under debate. The shift from wolf pack member to family pet involved more than just the ability to get along with people, says evolutionary geneticist Erik Axelsson from Uppsala University in Sweden. He and his colleagues compared dog and wolf DNA to learn which genes were important for domestication.
More surprising were genes for digesting starch. Dogs had four to 30 copies of the gene for amylase, a protein that starts the breakdown of starch in the intestine. Wolves have only two copies, one on each chromosome. As a result, that gene was 28-fold more active in dogs, the researchers found. More copies means more protein, and test-tube studies indicate that dogs should be fivefold better than wolves at digesting starch, the chief nutrient in agricultural grains such as wheat and rice. The number of copies of this gene also varies in people: Those eating high carbohydrate diets -- such as the Japanese and European Americans -- have more copies than people with starch-poor diets, such as the Mbuti in Africa. "We have adapted in a very similar way to the dramatic changes that happened when agriculture was developed," Axelsson says.
4 replies, 877 views
Diet Shaped Dog Domestication (Original post)
Response to pokerfan (Original post)
Wed Jan 23, 2013, 04:56 PM
Warpy (85,595 posts)
2. I honestly think cats were likely domesticated first
and mostly because we're messy eaters who dropped food that attracted their prey. In addition, cats tend to "club" at night, hanging out in groups. Hanging out with sleeping humans would come naturally to them.
I should say partially domesticated. We've never been able to train them out of their wild natures the way we have dogs and while they bring us gifts of dead rodents and birds, we've never been able to train them as hunting partners.
They seem to be the one species on the planet that simply likes us, adopting apes in zoos as well as humans in the burbs.
Response to pokerfan (Original post)
Wed Jan 23, 2013, 05:00 PM
hedgehog (35,702 posts)
3. Wait - some ethnic groups carry a gene that better enables them to digest grains?
So some of us are built for a Paleo diet and some of us aren't? Forget the dogs, we need to study people some more!
Response to hedgehog (Reply #3)
Wed Jan 23, 2013, 08:12 PM
Igel (22,858 posts)
4. I've run into a few genetic differences.
Yes, there's variation within groups. But there are only a few mutations for digesting lactose, and much of humanity can't handle fresh milk after age 4 or so.
Variation within groups is considerable, but that doesn't mean there can't be nifty cladistic analyses done showing how human groups split genetically (and sometimes later mixed or were submerged as another wave of humanity washed over them).
Studying that kind of "divisive" genetic variation isn't popular. It's deemed as supporting racism, esp. when some of the variation confirms those generalizations based on partial observation called "stereotypes." I think of it as "prototype theory"--there's the "ideal" phenotype for a group with a narrowly characterized genotype behind it, and that accounts for most of the population. Then there's the outliers that provide the variation. If you just focus on the amount of variation you miss the big picture.
The genetic variations I've run into were mostly accidental or incidental. I spend years interested in historical linguistics and things like homeland studies. You can look at language-internal stuff, words for "bronze" or "salmon" (for PIE) or similar kinds of words for Bantu languages or Austronesian languages. You can look at archeology and trade or migration patterns. Or you can look at cladistic analyses, many of which based on a completely different kind of data look startlingly like reconstructed language trees. Then you can look at the differences or compare them with the archeological record. (And, no, I think that most biologists/geneticists' clade-based analysis of language history are simply bone headed, based on facile comparisons or clumsily assembled data sets.)