Hi Jim, 
Thank you for the fascinating post!

This description of stable isotope analysis raises several questions in my
mind:  
1. Since sea levels are much higher now, since the last major glacier
retreat, I would expect only to find human remains that were well inland
based on prior sea levels. Tha6t would induce a bias. We would be much more
likely to find only the bones of those who were eating inland terrestrial
prey. But many bones have been found from earlier than the last major
glacial retreat. Has any attention been paid to this issue with respect to
the isotope analysis?

2. If so, have these results been reported in a form that is accessible to
the average neophyte like me? 

3. What sorts of errors are predictable when using a mass spectrometer? 

4. Have any remains from near the Great Rift Valley? And do they suggest a
preponderance of fish consumption? (I'm thinking of the Aquatic Ape theory.)

5. Are there any other known factors that would alter stable isotope ratios?


6. Would carbon isotopes be able to differentiate between a diet of shore
dwelling mammals (that feed off fish and other aquatic life) compared to
diets either dominated by inland animals or by aquatic life?   

That explanation of stable isotope measurement was excellent! It was new
material for me but I intend to learn more about it. Thanks again for
sharing this information. 
Best Wishes, 
Ron