Mailbag: Diet and isotopes

Re: "Tartar control and Neandertal plant use".

In your review of the study on Neadertals and grain in dental calculi, you wrote the following:

"The remains of starch grains and phytoliths tell us about diet breadth but not the proportions of different foods. They do note that nitrogen stable isotopes are most informative about protein-rich food sources, so that a substantial consumption of starchy plants such as grains and USOs might be hidden by isotope analysis."

I also read this study, and I was curious about this comment in the discussion, as this is way outside my field of expertise. I was wondering if you could write a blog post commenting in more detail about what isotope data can and cannot tell us about the proportion of foods or food groups eaten by pre-historic populations, or if you have already done so, if you could direct me there.

Many thanks for writing! You've been doing some nice work there.

I have a long essay on the stable isotopes and diet:

http://johnhawks.net/weblog/reviews/early_hominids/diet/stable_isotopes_2005.html

And two that deal more extensively with Neandertals and nitrogen isotopes:

http://johnhawks.net/weblog/fossils/neandertal/neandertal_mammoth_diet_2005.html

http://johnhawks.net/weblog/fossils/neandertal/neandertal_fish_drucker_2004.html

And here's one about cave bears:

http://johnhawks.net/weblog/reviews/behavior/non-primate/ursus/cave_bear_meat_consumption_2008.html

But all these are out of date in some respects. I've since had several conversations about the nitrogen isotopes. One thing that elevates 15N is breastfeeding, so the time of enamel formation relative to weaning makes a big difference. In more recent populations, the isotopes are often employed to give a picture of the place of birth relative to where the bones were found. A more comprehensive review is in order, but I'm not sure what the next find will be in hominins.

Anyway, I hope that helps, and thanks again for the kind words!