Study: Starch Digestion Adaptation in Dogs

Shai

& the Muttly Crew
Joined
Dec 14, 2009
Messages
6,215
Likes
0
Points
36
#1
Thought a lot of folks here would find this interesting.

http://news.sciencemag.org/sciencenow/2013/01/dog-domestication-tied-to-starch.html?ref=hp

Diet Shaped Dog Domestication
by Elizabeth Pennisi on 23 January 2013

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.

They sequenced DNA from 12 wolves from around the world and from 60 dogs belonging to 14 breeds. They first looked for individual letters in DNA, called bases, that varied from one genome to the next, identifying about 4 million of these so-called single-nucleotide polymorphisms (SNPs). They ignored regions with the most SNPs and instead focused on places where there were very few or no SNPs. That lack of variation signals DNA that was so important for survival during domestication that any variation there was lost, so most dogs have the same SNPs. Those regions were the ones the researchers were most interested in following up on.

The analysis turned up 36 regions, with 122 genes in all, that may have contributed to dog evolution, the team reports online today in Nature. Nineteen of these regions contain genes important for the brain, eight of which are involved with nervous system development, which makes sense given the importance of behavioral changes in the transition to becoming man's best friend, Axelsson notes.

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.

Dogs and wolves have the same number of copies of another gene, MGAM, which codes for maltase, another enzyme important in starch digestion. But there are four key differences between the sequence in dogs and wolves. One difference causes dogs to produce longer versions of maltase. That longer protein is also seen in herbivores, such as cows and rabbits, and omnivores, such as mouse lemurs and rats, but not in other mammals, suggesting length is important to plant-eaters. These differences make the dog maltase more efficient, the researchers report.

Axelsson thinks these results support the idea that wolves began to associate with humans who were beginning to settle down and farm. Waste dumps provided a ready source of food, albeit not meat, the usual diet. Thus early dogs that evolved more efficient starch digestion had an advantage, he notes.

The finding of these diet-related genes is "very surprising and very exciting," says Elaine Ostrander, a geneticist at the National Human Genome Research Institute in Bethesda, Maryland, who was not connected to the study. "It hints that there are a lot more [genes] to be found" involved in domestication, she adds. As more researchers compare wolf and dog DNA, Ostrander expects more genetic differences between dogs and wolves to emerge. "We are really going to figure [dog evolution] out."

Robert Wayne, an evolutionary biologist who studies dogs at the University of California, Los Angeles, but was not involved with the work, is also pleased with the study. He says he gets contacted often by pet owners wondering if dogs, like wolves, should eat primarily meat. "This [study] suggests no, dogs are different from wolves and don't need a wolflike diet," he says. "They have coevolved with humans and their diet."
 

JacksonsMom

Active Member
Joined
Nov 1, 2009
Messages
8,694
Likes
0
Points
36
Location
Maryland
#6
Very very interesting. :)

I've been saying for a while that the whole 'dogs should eat exactly like a wolf' was a bit far fetched. We've changed dogs sooo much through the course of time, and while obviously vastly similar, I'd expect to see some dietary needs change throughout the course of humans breeding them.
 
Joined
Feb 26, 2011
Messages
6,405
Likes
0
Points
36
Location
Minnesota
#8
Very very interesting. :)

I've been saying for a while that the whole 'dogs should eat exactly like a wolf' was a bit far fetched. We've changed dogs sooo much through the course of time, and while obviously vastly similar, I'd expect to see some dietary needs change throughout the course of humans breeding them.
Yes, I've always felt that with all the other things we've changed about dogs, there must have been some physiologic changes as well.

What is exciting to me is not so much the evidence that a particular food can be digested, but that it appears that real genetic differences exist in the ability to digest certain things. So rather than saying "oh ALL dogs can eat this way or that way" it seems to open a door to feeding the dog in front of you based on what THAT dog tells you rather than based on some theory of what foods Dogs with a capital D "SHOULD" do well on - without excluding any food or group of foods just because. I've seen this is my own dogs for sure - Squash does best heavy on protein/meat, Pip does best with grain inclusive, and Maisy seems to do well on anything.
 

Aleron

New Member
Joined
Feb 19, 2011
Messages
2,269
Likes
0
Points
0
Location
NE Ohio
#9
Interesting!

Very very interesting. :)

I've been saying for a while that the whole 'dogs should eat exactly like a wolf' was a bit far fetched. We've changed dogs sooo much through the course of time, and while obviously vastly similar, I'd expect to see some dietary needs change throughout the course of humans breeding them.
I think since dogs are opportunistic scavengers/hunters by nature there is a wide range of diets they can thrive on in general. Some breeds or individuals seem to have issues with some ingredients but overall, I think dogs are pretty adaptable in what diets will work for them.
 

Shai

& the Muttly Crew
Joined
Dec 14, 2009
Messages
6,215
Likes
0
Points
36
#10
What is exciting to me is not so much the evidence that a particular food can be digested, but that it appears that real genetic differences exist in the ability to digest certain things. So rather than saying "oh ALL dogs can eat this way or that way" it seems to open a door to feeding the dog in front of you based on what THAT dog tells you rather than based on some theory of what foods Dogs with a capital D "SHOULD" do well on - without excluding any food or group of foods just because. I've seen this is my own dogs for sure - Squash does best heavy on protein/meat, Pip does best with grain inclusive, and Maisy seems to do well on anything.
Exactly -- I completely agree! I realize it probably comes as little surprise to many that some dogs do best with grains added in their diet, but it's exciting (to me at least!) to have quantifiable proof that not only have dogs as a group evolved to better digest starch but that within domestic dogs there is a huge variation in that ability -- it's the entirely of that "Dogs had four to 30 copies of the gene for amylase...[w]olves have only two copies..." that opens some interesting doors... :).
 

Beanie

Clicker Cult Coordinator
Joined
May 17, 2006
Messages
14,012
Likes
0
Points
36
Age
39
Location
Illinois
#11
Wow. Usually studies of this kind have been done as scatology studies examining what things ARE eaten rather than looking at genetic studies of what CAN be eaten. The genetic side of it is oddly fascinating to me.
 

GoingNowhere

Active Member
Joined
Jul 13, 2008
Messages
1,793
Likes
0
Points
36
Location
USA
#12
fascinating! It took me awhile to scout out the full text article, but after going through my university, I managed to find it and it's an interesting read (PM if you'd like). It only became available online today.

Thanks for sharing - I went ahead and shared it with my genetics professor who I thought might get a kick out of it.
 

Pops2

Active Member
Joined
Sep 21, 2008
Messages
3,072
Likes
0
Points
36
Location
UT
#13
Just because they CAN digest a lot more starch doesn't mean they SHOULD. Just like you & I can digest high fructose corn syrup, but there are definite downsides to doing so.
It only confirms my conviction that dogs did not evolve from wolves.
 

Red.Apricot

Active Member
Joined
Aug 28, 2011
Messages
2,984
Likes
2
Points
38
Location
Southern California
#14
Just because they CAN digest a lot more starch doesn't mean they SHOULD. Just like you & I can digest high fructose corn syrup, but there are definite downsides to doing so.
It only confirms my conviction that dogs did not evolve from wolves.
What do you think they evolved from? Is there evidence for a different origin?
 

Pops2

Active Member
Joined
Sep 21, 2008
Messages
3,072
Likes
0
Points
36
Location
UT
#15
IF you believe in evolution, there is pretty good evidence they evolved from a common ancestor rather than directly from wolves.
 

Red.Apricot

Active Member
Joined
Aug 28, 2011
Messages
2,984
Likes
2
Points
38
Location
Southern California
#16
IF you believe in evolution, there is pretty good evidence they evolved from a common ancestor rather than directly from wolves.
Well it would obviously be impossible for them to have evolved from modern wolves (like, the ones alive on the planet now). I don't think anyone thinks otherwise?

But the common ancestor of wolves and dogs is very recent and would have been much much more like modern wolves than it would have been like modern dogs. ETA: so much like modern/on the planet today wolves that, were they transported here in a time machine, they would in all likelihood have been called wolves.

Are you saying that you don't think evolution happens, and so the whole comparison is a bunch of hogwash?
 
Joined
Feb 4, 2008
Messages
7,099
Likes
1
Points
38
Location
Illinois
#17
Very cool!

I've always been a vegetable inclusive raw feeder so it's nice to have a little bit of science back up what I've always kinda thought about them being true scavengers.

It always amazed me how when I would talk to a raw feeder and say I fed veggies I would get the look. Now I feel validated :rofl1:
 

PWCorgi

Priscilla Winifred Corgi
Joined
Apr 12, 2006
Messages
14,854
Likes
0
Points
36
Age
34
Location
Twin Citay!
#19
The only look I think of when feeding veggies in RAW is the look of the poop, it always changes color depending on the veggies :)
Can't say I've ever had that issue. My dog's diet is about 5% veggies and if they're broken down correctly they aren't going to show in the poop. If I feed him a whole carrot, yeah he craps orange, but the veggies that have been cut down through a processor seem to digest just fine.
 

Lyzelle

Active Member
Joined
Feb 28, 2012
Messages
2,826
Likes
0
Points
36
Location
Colorado
#20
In a way, I'm not surprised, but in another I'm not really sure what this is supposed to change anyway. Humans have no species-specific diet, but there are a lot of things we *can* digest that aren't necessarily good for us, such as grains and starches. In no way does this mean dogs should have a diet high in starch or carbs, but it's the same as it has always been. Feed your dog according to it's own personal needs. Some dogs, some breeds, are slightly different than others when it comes to nutrition. Siberian Huskies typically do better on fish, for example. That was their diet for a couple thousand years, so it's natural that their bodies would have optimized in order to get the most out of that diet. And some cons, too, such as being more sensitive to a diet lacking copper and zinc, since the diet they became acclimated to was so high in it. Really no different from some humans who can tolerate cow milk(unnatural to humans), but most can't. How some people handle carbs or grains better than others.

So, in the big picture, I really don't think it has changed anything at all. Amylase is still a protein that turns starch into sugar, and then maltase breaks it down into a more simple sugar. Sugar carries little to no nutritional benefit at all, and these proteins aren't extracting any nutritional benefit from it. No minerals, no vitamins. If anything, sugar is converted to fat, and the dog's body would simply then burn the usable stand-by body fat in lean times, while still starving on a molecular level from the lack of nutrients. Common enough for a scavenger.

In no way would I see "oh, they can digest this, so they must NEED IT". I mean, scavengers can also digest rotting, vile meat. Do you think there's any nutritional value or need to feed your dog rotting meat? Probably not. They can have it, but it's not like it's any better for them to have it over fresh meat.

So I guess I really don't see how anything has changed at all, except maybe proving it, I guess.
 

Members online

No members online now.
Top