An earlier post reviewed recent work by Bocherens and colleaugues (2005) attributing high nitrogen-15 proportions in Neandertal bones to mammoth consumption. I wondered what had happened to the argument of Richards et al. (2001), which suggested that high nitrogen-15 in later Upper Paleolithic remains had come from consumption of fish or other aquatic resources.
Today I found another paper by Drucker and Bocherens (2004) that answers this question, in part. They performed chemical analysis of aquatic animals and otters, which predominantly consume riverine resources. The study found that the riverine fish and eels were had relatively low nitrogen-15 proportions, while lacustrine fish as well as salmon were higher. These freshwater resources do not provide a better explanation for high nitrogen-15 content than terrestrial animal consumption, so there is no reason to support one over the other.
Their bottom line:
Considering this updated estimate, obligate implication of freshwater resources in human diet is not so convincing. Although we do not exclude any fish consumption, we consider that contemporaneous terrestrial resources are sufficient to explain the isotopic signature of anatomically modern humans. This conclusion is also sound as far as Neanderthals are concerned (Drucker and Bocherens 2004:172).
OK, so the isotopes leave doubt about what Neandertals (and later Upper Paleolithic Europeans) ate. It could be mammoth, it could be salmon. Personally, I'm sure that both were consumed as much as possible. Possibly together. If it were me, I'd smoke them.
Drucker D, Bocherens H. 2004. Carbon and Nitrogen stable isotopes as tracers of change in diet breadth during Middle and Upper Palaeolithic in Europe. Int J Osteoarch 14:162-177.