Computational behavior theory and cultural evolution
Our latest paper on the cultural evolution of preferences for dog breeds came out yesterday in PLOS ONE. The message is simple: dog breeds that are featured in successful movies (Lassie come home, 101 Dalmatians, and many others) tend to increase in popularity, sometimes for many years after movie release. This influence was quite strong until, approximately, the 1970s, but has declined since—probably because cinema no longer dominates the media as it used to. You find a nice writeup with more details on co-authors Hal Herzog’s Psychology Today column and Alberto Acerbi’s blog. Some press coverage is here:
Some time ago I wrote about fashions in dog breeds, pointing out the wild fluctuations in popularity in many breeds. Why do these occur? Owning a dog is a serious commitment in terms of time and money, and it would seem natural to try to acquire a dog that is healthy and with a good temperament. I set to find out whether this is actually the case with my colleagues Alberto Acerbi, Hal Herzog, and James Serpell.
In our new paper Fashion vs. Function in Cultural Evolution: The Case of Dog Breed Popularity, we show that, surprisingly, people do not prefer breeds that are better behaved or healthier. On the contrary, the most popular breeds are the most unhealthy, with a host of genetic defects that are at least partly related to intense selection to adhere to quirky breed standards, and possibly with more behavioral problems such as fear of other dogs, aggressiveness, or separation anxiety. We obtained these results crossing data from the C-BARQ database of dog behavior created by James (the actual data used in our analysis are here), data about dog registrations provided by the American Kennel Club to Hal Herzog (available here), and previously published health data (references 14-17 in the paper).
Thus many people (at least those interested in breed dogs) prefer to acquire a dog that is socially recognized to meet a certain “standard” than a healthy and well behaved dog. If you are unfamiliar with breed standards, I can tell you that they are quite exacting, and to many may appear just pointless. Here is, for example, what the nose of a bulldog is supposed to look like:
The nose should be large, broad and black, its tip set back deeply between the eyes. The distance from bottom of stop, between the eyes, to the tip of nose should be as short as possible and not exceed the length from the tip of nose to the edge of underlip. The nostrils should be wide, large and black, with a well-defined line between them. Any nose other than black is objectionable and a brown or liver-colored nose shall disqualify.
(From the AKC web site)
Note: “disqualify” means that the dog should not be considered a “true bulldog.”
As announced a few weeks ago, our paper “The Logic of Fashion Cycles” has been published, and is freely available on the PLoS ONE website. You can find a good summary at The National Post.
I have recently attended a one-day course on data visualization with Edward Tufte and I have tried to put his advice on virtual paper in this supergraphic on the popularity of dog breeds, using AKC data (courtesy of Hal Herzog). The graph shows the popularity of 100 breeds over time (most popular breeds first), indicating the maximum in popularity and other peaks (if any). I have produced this graph as an inspiration for my ongoing work on cultural dynamics (some features are idiosyncratic to the data analyses I am making). Here are a few things I see in the graph:
What else can you see? And how to explain it? In am working, with Alberto Acerbi and Magnus Enquist on an explanation of fashion cycles based on the cultural dynamics of preferences, as foreshadowed in our previous work on how social learning influences openness to new information. The paper is now under review at Plos ONE.
drghirlanda 