...In 1991, researchers first revealed that the fossilized bones of Neanderthals had high ratios of nitrogen 15 compared with nitrogen 14 -- usually the signature of a high-meat diet... bigger meat eaters than even hypercarnivorous hyenas and lions. Butchered animal bones at archaeological sites reinforced the view that our close relatives relied heavily on meat from big game hunting....archaeologist John Speth of the University of Michigan... described accounts by missionaries and Arctic explorers of people who fell sick with "rabbit starvation" -- an illness that afflicts those who eat mainly lean, high-protein game meat and too little fat...Speth's paper offered...