"come again? news to me. i think you might be thinking of the constant rates of intake. but the different rates of c14 production in the past do affect c14 dating, do need to be accounted for, and are."
No, thrre can be no constant rate of intake. that would require a stable level of C14 evenly distributed in every breath and in every bite of food. Without the ratio to C12, there would be no way to calibrate a C14 reading. Yes, you could say that C14 has decayed at a certain rate, and that a specimen has "X" amount of C14 left. But, without comparison to C12, then the decayed level of C14 is meaningless. But because organisms, like human bodies, maintain a fairly constant ratio of C14 to C12, then one can now make sens eof the residual levels of C14 in comparison to C12 which does not decay. That is how the dating of death is determined. With "X" amount of C14 as a ratio of C12 one can know how long ago the organism was still alive.
I did a few long posts on this on JWD and H20. They contain the supporting references. If you wish, I will go back and bring them to this post.
what i meant, and i hope im explaining it right, was that given a particular atmospheric ratio of c14/c12 at a given temperature, a given type of creature will take in a steady ratio of c14/c12, closely matching that found in the environment (not exactly, but thats another story belonging to a discussion on paleoceanography) and since it is continually processed while alive, it remains the same during the creature's lifetime.
your comment seemed to be saying (perhaps i misunderstood) that despite differences in c14/c12 ratio in the atmoshpere in different eras or due to nuclear testing, creatures had some kind of equilibrium that was independant of environmental variations. that was what i was commenting on. as near as i understand, the ratios are entirely dependant on the environmental ratio and temperature and this ratio does fluctuate, and does cause radiocarbon dates to be wrong, that is, until they are calibrated.
