How many dogs does it take to change a light bulb?
The answers, which (with variations) are all over teh interwebz in the same way that pet hair congregates in great fibrous drifts beneath the furniture in the Salon Des Girrafes, are diverse, and, more pertinently for what follows, breed-specific. [ahem, clears throat].
Golden Retriever: Who cares about a silly old light bulb? Let’s go to the beach!!!
Border Collie: Just one. And then I’ll replace any wiring that’s not up to spec.
Dachshund: You know I can’t reach that high!
Rottweiler: Make me.
Boxer: Not bothered. I can still play with my squeaky toys in the dark.
Labrador: Oh, me, me!!!!! Pleeeeeeeeeze let me change the light bulb! Can I? Can I? Huh? Huh? Huh?
German Shepherd: I’ll change it as soon as I’ve led these people from the dark, checked to make sure I haven’t missed any, and made just one more perimeter patrol to see that no one has tried to take advantage of the situation.
Jack Russell Terrier: I’ll just pop it in while I’m bouncing off the walls and furniture.
Old English Sheep Dog: Light bulb? What light bulb?
Cocker Spaniel: Why change it? I can still pee on the carpet in the dark.
Greyhound: It isn’t moving. Who cares?
Poodle: I’ll just blow in the Border Collie’s ear and he’ll do it. By the time he finishes rewiring the house, my nails will be dry.
The joke (don’t you just hate it when people try to analyze humour?) … as I was saying, the joke takes the well-known and very definite temperamental characteristics of breeds, and exaggerates them. For dogs differ not only in their physical attributes, but in their behavioural traits – they are bred that way. On the downside, everyone knows that persistent inbreeding in dogs leads to a range of potential physical problems – and not only that, mental ones. For example, the sensitive, intelligent, conscientious border collie – the one who would not only change the light bulb but rewire your whole house while he was about it – can suffer from anxiety attacks brought on by loud noises. Dogs of various breeds suffer from a version of obsessive-compulsive disorder, and others are prone to outbreaks of sudden, uncharacteristic aggression.
Intriguingly, these episodes of barking insanity could be the latest contribution that Man’s Best Friend is making to human health, as my colleague Dr. D. C. of Tokyo reports in this intriguing article in this week’s number of your favourite professional science magazine beginning with N.
It’s like this. Clinicians suspect that many psychiatric disorders or personality traits in humans run in families – conditions such as manic depression, schizophrenia, autism spectrum disorders, the conviction that the world is made of spoons, and so on. So much is clear. What is much, much harder is tracing the genetic roots of such disorders more specifically. Part of the problem is that diagnosing some of these disorders can be difficult, and the possibility remains that what we think of as a single disorder could have many different, distinct causes. What, then, is to be done?
Some headway can be made by breeding mice to isolate genes of interest, and so create mouse ‘models’ of various disorders. Mouse models for psychiatric conditions, however, are hard to compare directly with the real thing in humans. After all, how does one know if a mouse is showing aberrant behaviour in a way that can be compared directly with human psychiatric disorders, let alone isolating a strain in which we can be sure that the mice are convinced they are Napoleon?
Dogs offer a halfway house, being more complex, cognitively, than mice, and much more similar to humans in terms of cognitive ability. They have the distinct advantage over humans, however, in that they are highly inbred. I am convinced, for example, that all golden retrievers are made in the same factory. Why, on the beach the other day, Canis croxorum and I met two other golden retrievers that matched her precisely in colour, even down to the collars. When we parted company, me and the other owners had to make doubly sure we were accompanied by the right dogs.
But I digress.
The highly inbred nature of dogs means that it is much simpler to isolate mutations of clinical interest than in us mongrel, outbred humans – fewer dogs are needed in any particular program, and fewer genetic screens are required. It is therefore (relatively) easy to link a particular disorder with a particular genetic mutation, and once that is done, one can compare the data with the cognate genetic region in humans to see if anything shows up. Of course, there need be no direct match between dog and human genes, but there tends to be one far more often than not. In this way, scientists hope to discover what genetic lesion makes some dogs (say) suffer from anxiety attacks, or chase their tails obsessively, and test whether the cognate genetic region in humans is associated with panic disorders or OCD.
Such is the progress of science. However, scientists will have to go much further before they can do the same things with cats. I deliberately omitted the punchline in the light-bulb joke above, which I can now reveal.
Cat: how ridiculous. Dogs don’t change light bulbs. Humans change light bulbs. So how long will it be before we get some light around here? And a meal? And my tummy tickled?
Moral: Whereas dogs have masters, cats have staff.
Note: my colleague Dr M.-T. H. of London came up with the title of this post, one so obvious that everyone else missed it.