re: Switching to vegetarian diet

I'll get back to you, because I'm out of town. But to preface, the first article you posted link a study, that study's first cite was the carbon and nitrogen ratio study I posted. The study she first cited came to the conclusion that earlier chimp like ancestors ate plants, but homo erectus was the lowest...

as for the second study. Isotopic evidence for dietary variability in the early hominin Paranthropus robustus.

Paranthropus_robustus is not a dang human / homo erectus

Edit: drunk and meant homo sapien