Thursday, January 26, 2006

Pondering Heritable Behaviours on my GT Snow-Racer...Immaculate Conception Through Teaching?

So this past weekend at the Super-Fun Snow Jam of the Century, sitting on a GT snow-racer at the top of a cliff, working up the courage (ie insanity) to plummet down onto the ramp projecting over the ravine below, my thoughts inevitably turn to evolutionary biology. At first, I mostly ignored the whimpering and frantic looks from Mannie the German Shepherd, who was directly blocking my path, and tried to kick her out of the way. However, as I now know, German Shepherds are BIG and HEAVY and this one was determined I was not going down that hill. Then it dawned on me - this dog was herding me. I guess from a shepherd's point of view, her behaviour made sense. I was big and stupid enough to choose to rocket down to my own demise, but no idiot would want their sheep sent over a cliff, off a snow jump and into a ravine filled with running water.

Now here's what gets me. This dog has never seen a sheep in its life. Since it was probably cruelly ripped from its mother's bosom in infancy, neither did it ever have the chance to learn herding behaviours from its parents. Yet it does a great job trying to shepherd everything in site. A born shepherd. No doubt her offspring (if she still had reproductive capacity) would be the same. Heritable behaviour. Just like Rob's pointer hunting dogs.

That seems interesting to me, but maybe its not news to anyone else. At any rate, what seems even more intriguing to me is that not only are behaviours/skills heritable from one generation to the next, but they can be taught and learned between individuals (even unrelated individuals). As V.S. Ramachandran points out in the doco Rob posted, this ability is an obvious evolutionary advantage in terms of speeding up adaptation to environmental challenges. He suggests the capacity to learn is unique to humans and could be a function of mirror neurons. I tend to disagree; although humans might be the most prolific learners/teachers, you can clearly teach a dog tricks.

At any rate all this seems to suggest to me that behaviours learned by an individual after birth could be programmed into the genetic makeup of germ line cells and thus passed on to offspring. Thus, a university professor or celibate priest, by teaching or preaching ideas could reproduce their genes without ever gettin' it on so to speak. This doesn't seem to fit with current biological theory as I understand it, so can someone please explain to me why I'm wrong?


rob said...

I think what is most interesting about the dog thing is that it was totally introduced by selective breeding. Only pointers point, and herders herd. So not only are these behaviors heritable they have been introduced into the genetic makeup of these breeds in relatively short evolutionary time. I wonder if there are any dog breeders out there who know how these behaviors were origonally selected for. Were they trained and quicker learners were selected for until the breed was almost born with the behavior? Or was it selecting for a more sutle prexisting innate behavior and exaggerating it?