An interesting paper appeared in a recent issue of Behavioural Processes (2009, vol. 82, pp. 355). The author, William Helton from New Zealand, examined results from three published studies in which breed and head shape were reported, to answer the question of whether morphology (head shape, in this case) reflected intelligence in dogs. Now, a little background because there a lot of caveats associated with this work.
First, what do we mean by head shape? The classic measure of head shape, used here, is the cranial index. This is the ratio of the width of the skull to the overall length of the skull, and can be easily measured with calipers. But of course, this is only one possible way to measure a skull shape. It turns out that dogs are interesting for this kind of question because, through our breeding, we have produced a wide range of head shapes, on a continuum of cranial indices. So extremes in the cranial index values reveal dolichocephalic dogs (with a long cranium, the running dogs and sight hounds; think greyhound) and brachycephalic dogs (with a very wide cranium, bred for fighting and holding, grasping; think Staffordshire Bull Terriers) and in between, mesocephalic breeds, whose heads are less extreme in length or width. So we can divide breeds into three parts of this continuum, or ask as the author did, whether dogs of extreme shapes, the breeds that are more specialized in their breeding, might have a lower or higher intelligence. One hypothesis might be that medium-head-shape dogs, of less specialized duty (historically), might be less intelligent.
Another issue is, “what do we mean by intelligence, and how was it measured?” A very good, and very difficult, question. We really have VERY little data on the cognitive capabilities of breeds of dogs (or of course, of most species of animals). But some work HAS been done on what might be one aspect of intelligence: trainability. Now, while we have a few studies on this topic, among breeds, we still have very little. But one way that has been used to “get at this question” has been to survey experienced dog owners, especially those with a broad exposure to breeds, to rank the PERCEIVED trainability of various breeds. One good source of such information is obedience judges, and Coren has published these very consistent and repeatable results in a number of places. So now we are no longer talking about intelligence, or even trainability, but perceived trainability… but it’s the best we’ve got, until we do more research!
So now, to the results of this work: what is the relationship between head shape, especially extremes of head shape, and ranking of perceived trainability (our stand-in for intelligence)? Well, to a degree not accountable by simple chance, medium-head-shape dogs are perceived to be more trainable, and dogs with more extreme head shapes, whether long or wide, are perceived to be less trainable.
There are some other interesting findings to go with this main point. For instance, what else does head shape tell us? It turns out that the shape of the head also tells us a lot about the visual abilities of dog. Breeds with long heads, associated with coursing or hunting by long-distance running, like greyhounds, have a retina designed with a wide area of receptivity: their vision is most acute in the horizontal and at the horizon. Breeds with wide heads have their greatest receptivity in the center, like primates including us, and thus have their best vision in the center and close up. So there are differences in the nervous system associated with head shape and there certainly could be differences in other facets of their brains and learning abilities. Perhaps it is true that highly specialized breeds, so specialized that they LOOK different, might not have needed a broad intelligence to do their job, while your basic, unspecialized, medium-head-shape dog needed more wits to get the job(s) done!
Or perhaps this study tells us more about human perception. Perhaps there is something in us that tells us that things that look different are (have to be?) different in other ways. The answer lies in learning more about the actual intelligence, or at least the actual trainability, of dog breeds, a project that we at Companion Animal Solutions have begun, and that other ethologists around the world are undertaking. The questions never end, and I hope that if you have questions, you will contact us here at Companion Animal Solutions.
Dr Jim Ha 