Domestication a dog’s breakfast, according to articles in Nature News, ScienceNOW and Nature doi:10.1038/nature11837, 23 January, 2013.
A group of scientists led by Kerstin Lindblad-Toh, a geneticist at Uppsala University, Sweden have compared the genes of wolves and domestic dogs to see if they could find out what genetic changes occurred during domestication. According to Nature News: “Canine-domestication researchers agree that all dogs, from beagles to border collies, are the smaller, more sociable and less aggressive descendants of wolves”.
The researchers studied the genomes of 12 wolves and 60 dogs from 14 different breeds. One of the significant differences they found was in genes that control the digestion of starch. Dogs have many copies of a gene named AMY2B which codes for an enzyme named amylase, which starts the breakdown of starch in the intestine. They also had some difference in the gene named MGAM, which codes for maltase, another enzyme involved in digesting starch. The variation found in dogs is a little longer than the wolf version and results in the enzyme being more efficient. This version of the gene is also found in herbivores, e.g. cattle, rabbits, and omnivores, such rodents and lemurs. These enzymes break down starch into glucose which is then absorbed from the intestine via transporter proteins. The researchers also found some differences in a gene named SGLT1 which codes for a transporter protein.
In their report in Nature the scientists wrote: “In conclusion, we have presented evidence that dog domestication was accompanied by selection at three genes with key roles in starch digestion: AMY2B, MGAM and SGLT1. Our results show that adaptations that allowed the early ancestors of modern dogs to thrive on a diet rich in starch, relative to the carnivorous diet of wolves, constituted a crucial step in early dog domestication”.
Evolutionary geneticist Erik Axelsson from Uppsala University in Sweden suggested that dog domestication occurred as wolves began to associate with humans who were beginning to settle down and farm, and these animals would have scavenged from waste dumps, which would have contained plant-based food, e.g. potatoes, grains.
The researchers claim their findings “demonstrate a striking case of parallel evolution whereby the benefits of coping with an increasingly starch-rich diet during the agricultural revolution caused similar adaptive responses in dog and human”. Robert Wayne, an evolutionary biologist who studies dogs at the University of California, Los Angeles, but was not involved with this research, commented that he is often asked by dog owners if they should feed their dog a wolf-like diet of lots of meat. He said that this new study suggests dogs don’t need a wolf-like diet. He went on to say “They have coevolved with humans and their diet”.
Editorial Comment: What the scientists actually found is that domestic dogs have more copies of a gene that aids plant product digestion, plus variations in other genes for starch digestion and absorption than undomesticated wolves. These differences explain why dogs can digest and absorb plant foods better than wolves. What the evolutionary scientists hypothesised, is that dogs are descended from wolves and somehow gained genes and made others more efficient for digesting plant food.
So what’s a Biblical view? The Genesis record tells us all animals were originally created to eat plants and to be subject to man’s dominion. They were created each belonging to separate kinds, and the world has degenerated since Adam sinned, and especially after Noah’s Flood. Therefore, all animals, including the dog kind, would have had the appropriate plant digesting enzymes, a man friendly attitude, distinct genetics from other kinds, and have been subject to devolution or degeneration.
Genetic studies confirm that wolves and dogs are part of the same canine kind, and unrelated to other mammals, such as cats, etc. Furthermore, any observant dog owner will tell you their dog can eat watermelon, cheese, bread, grass and grains. Robert Wayne’s comments about dog diets not needing to be wolf like, remind us that many commercial dog foods include cereal which is coloured red to look like meat purely for the sake of the dog owners who believe dogs evolved from wolves.
All these facts are consistent with the Biblical account. However, present day observation of genes show that as time goes on, genes are either lost or they degenerate. This phenomenon would have been especially true after Noah’s flood when environmental alteration was at its greatest, and many animals suffered mutations which caused loss and/or degeneration of genes. Therefore, a Biblical position is most likely that some of the original dog kind would have lost genes for digesting plants, and found it easier to digest a high meat diet. It is therefore more likely that both the wolf and the domestic dog are descended from a common ancestor that gave rise to the feral ancestors of wolves, who could no longer live on plant food, and those dogs that retained the ability to digest plants, who stayed with humans and became the ancestors of today’s dogs.
Evidence News 6 February 2013
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