Somewhere between Darwin and Baldwin lies... Lamark?

My understanding of Lamarkian evolution is that changes that occur to one animal's morphology are passed on to it's offspring. An example: A short necked giraffe stretchs for the tree tops. It's children can stretch further, and the next generation further still.The experiment which disproves Larmark: Start breeding mice and cut off all their tails. You'd expect to, in short order, be raising new generations of mice which lack tails. Doesn't happen.It sounds like, from the other posts, that Baldwin is talking more about "instinctual behavior". And here we get into tricky ground. Different species of birds make different shape and size nests. A bird raised away from it's parents will make the nest just the same (so it's not a learned behavior). Does this mean that the "program" for the nest resides in the genes of the bird?Possibly, but I recall an interesting study about pregnant rats.Pregnant rats build nests. If you raise a rat with it's mother in a nest, it will later go one to build a nest when it gets pregnant. Likewise, if you take the rat from it's mother and raise it without a nest, when it gets pregnant, it also builds a nest.Now, here's the kicker. If you take either rat (nest raised and nestless) and keep them in a container with a warm bottom, when they get pregnant they don't build a nest.Why? Well, when the female rat gets pregnant, her nipples swell and touch the ground. They get cold / irritated and the rat responses by building a nest to solve that problem. Illiminate the irritation, you illiminate the impulse and therefore no nest.Now is nipple swelling programmed in the genes? Ya. Was it selected for because having a nest better ensures the survivability of the young? No idea.

Well, from my observation, I do believe that all mammals experience nipple swelling during pregnancy. So, I gotta think that pre-dates the rat nest building by quite a bit

Well, not all mammals have nipples that drag on the ground. Honestly, I couldn't tell you where and when rats started building nests. I'd be surprised if anyone could.My larger point was that a change in a gene can have a physical effect which in turn causes a particular behavior. That doesn't mean that the behavior is in and of itself genetically programmed.

Maybe in the rice scenario, but not in the mouse one. The odds of a given mouse being born tailless should be universal. The odds of that mouse being part of the study in which we cut off mice tails, pretty astronomical. But, even if the mouse was born into that study, it wouldn't have been because of the abuse visited on the previous generations.

Sure, but the first crab which had this feature didn't "strive to have a face on his back". It just happened. Then, as a result, he lived and had kids that had similiar markings.It's even possible that multiple crabs independantly developed face-like features on their backs, since, I'm assuming here, all these crabs have some feature and it's really subjective on the part of the fishermen what is face-like.In the mouse study, according to Larmarkian evolution, a tailless mouse would be born in short order as a result of cutting off the tails of the parents. It's important to the study that every mouse survive to reproduce (since cutting the tail off is what is causing the change in the future generation).What I'm saying is that if you have two groups of mice. One group as a control. The other gets it's tail cut off. And every mouse is raised to reproduce. Eventually (maybe a thousand years of this, but eventually) you'll get a mouse born with no tail. However, that mouse is as likely to be born to the control group as the tailless group. The mutation that causes taillessness is not caused by tail amputationThis message has been edited by Nuggin, 09-29-2005 11:26 AM