The recent discovery that dogs have evolved some adaptations to assist in the digest starches has set off a whole wave of speculation about what this means for the domestication of the species.
Some are thundering about the old Raymond Coppinger theory on dog domestication, which posits that the dog evolved from the wolf during the early days of agriculture. According to this theory, the dog is a self-domesticating animal that evolved solely from wolves losing their fear of humans in order to scavenge from our trash heaps.
The logic here is that starches were only a big part of the human diet only when we began to farm, and if dogs have these adaptations, then it must mean that they were domesticated in agrarian societies.
The problem with this logic is twofold.
The first is that dog remains– which no one argues actually are of dogs–have been dated thousands of years before agriculture. I am thinking of the dog discovered at the Bonn-Oberkassel site and another that was found in the Kesserloch Cave in Switzerland. Both of those remains are 14,000 years old, and they clearly predate agriculture by thousands of years. In addition to these two dogs, two dogs that were contemporaries of these Central European canines were discovered in Bryansk region of Russia. These two Russian dogs looked a lot like what we’d call mastiffs or mountain dogs.
And never mind that we have several possible dog remains that are even older than these. The Goyet Cave dog of Belgium and the Razboinichya Cave dog of the Altai Mountains are two canid remains that show signs of domestica tion that both date to over 30,000 years ago.
But most amazing of all has been the discovery of 31,500-year-old skulls of what appear to have been dogs in the Czech Republic. These skulls, which were found at the Předmostí, clearly had something to do with people. for one was buried with a bone in its mouth.
All of these discoveries put dog domestication well into the very distant past– long before we had massive trash heaps and long before we ate lots of bread. The dog is the product of wolves tamed during the time of the hunter-gatherers, not of the earliest farmers.
The other problem with claiming that dogs were derived from self-domesticated scavengers is that lots of animals scavenge off of people, including many populations of wolves.
Yet none of these animals– including the wolves– has become more like a dog simply through scavenging. If scavenging was all that it took, then the black-backed jackal would have been the ancestor of the domestic dog. These jackals have been scavenging off of our species long before wolves did, but even though they readily live in villages and often act as guard dogs to warn of the approach of leopards, they show no signs of domestication. There are no spotted or drop-eared black-backed jackals.
And there are no genetically tame raccoons, European badgers, spotted hyenas, or bears.
But all of these animals readily scavenge off our waste.
The only way the Coppinger domestication theory works is to ignore large chunks of science, but that is precisely what so many science journalists do.
The Coppinger theory is a very neat little package that attempts to make simple what was an inordinately complex move.
Almost everything we know about dog domestication is contradictory. We have competing archaeological and genetic evidence, and all that anyone can actually agree on is that the wolf is that the primary ancestor of the dog, the domestication happened before agriculture, and the domestication happened in the Old World.
Mark Derr takes to task some of the speculation that was generated from that study:
By every genetic and archaeological measure, wolves became dogs in the company of hunting and gathering people at least thousands of years before the advent of agriculture. There simply is no way around that.
Derr thinks that humans would have fed wolves cooked grains from wild grasses, which could have accounted for the selection pressures that would have caused dogs to develop the adaptations for consuming starches.
I am a bit skeptical that humans would have been collecting that much grain to feed dogs, but there are cases of hunter-gatherers doing just that. In How the Dog Became the Dog, Derr discusses a study of a site in China. Using isotopic analysis of human and “dog” remains from that site, the researchers found that the humans were growing broomcorn millet to feed both themselves and their dogs.
My bone of contention with this study is that it didn’t include large enough sample of dogs from a variety of breeds. There were no “primitive” breeds included in the study, and there were no dingoes. Even among the dogs studied, there was variance of how many copies of the amylase-production gene the dog had, which suggests that some dogs are better adapted to a diet rich in grains and starches than others. It would be interesting to see if dogs like dingoes, which lived for thousands of years on a continent with no agriculture, have more copies of the gene than wolves do.
The really interesting part of this study was the discovery that dogs have evolved a tolerance to eating grains and starches.
The unfortunate part of the study is that it caused so much speculation about a theory of dog domestication that is largely contradicted by virtually all the other evidence we have.
In discovering that dogs can eat bread, the researchers threw Raymond Coppinger a bone.
Coppinger is a figure like Lorenz, but unlike Lorenz, who eventually gave up on his hypothesis that most dogs were derived from golden jackals, Coppinger continues to adhere to his self-domestication through neotenic scavenger hypothesis.
Never mind that there are really big holes in the logic behind it.
It is an easy theory to explain between the margins of news copy.
It’s much harder to say that things are much more complex than that.