The origin of motor symphonies is an interesting problem because it is not possible to exactly determine whether one is learned or contained in the genetic material. Some motor symphonies are more likely to be inborn than others. In this category are those that allow a newborn animal to survive in the first moments of its life. For example a tadpole needs to know how to break out of the egg and then imidiately swim away which involves a series of complex motor symphonies. A bird is in a similar situation when its trying to fight its way out of the egg. These animals do not have time or opportunity when to learn these symphonies, thus these are more likely to be genetic in origin. Some of these behaviors become more sophisticated(swiming) when the organisms is exposed to inputs because they allow it to learn and incorporate the new knowledge into the old symphony.

Functions that are not essential for survival are less likely to be storred in the genetic material. The ability of some people to write does not offer enough selective advantage, over the people who cannot write, so the evolution mechanisms did not have enough incentive, or time, to store this pattern into our genome. However, writing and other human behaviors, such as lifting a coffee cup, are in a way peculiar. Every person has a characteristic way of performing these tasks. We all engage same muscles to do it but the sequence in which we use them and extent to which we use some of them and not the others varies from person to person. This is why experts on handwriting are able to distinguish one persons writing sample from that of another person. This also shows that there is a pattern, or score, for the motor symphony storred somewhere in the nervous system. This is the only way we can explain why a letter "A" always looks the same or very similar when the same person writes it or why we are able to recognize a person's walk by the beat of their footsteps. If everyone of these behaviors had to be reinvented every time according to the outside inputs these characteristics would not be possible. A genetic element in all of the "learned" behaviors must exist in order to explain how we are able to learn and produce any movement, in case of writing it would be ability to hold a pen and move our fingers.

It would be reasonable to say that in general motor symphonies are generated as a combination of the genetic and learned material. This statment is true for all behaviors until we are able to prove otherwise(that the behavior is purely inborn or learned).

Very interesting. Yes, good bet, in lieu of other information, is combination of genetic and learned (is, in fact, what usually turns out to be the case). Certainly some early needed behaviors are heavily dependent on genetic information. But some later appearing ones may be as well (bird flight, despite appearances). What really intrigues me, though, is your thoughts about the variabilities even in stereotyped behaviors and the meaning of that. Yes, they do tend to be variable (and not only in humans). And they show constant general characteristics despite the variation (try signing your name with your opposite hand, or with your foot). That raises some quite interesting questions about exactly what one means (at a more sophisticated level) about CPG. Stop by if you're interested in talking more about it. PG