Trapping, Exploring, Hunting
The sales of furs, and the exploration of new routes to new lands, and finally the hunting of animals made a significant impact in the history of the modern world, and often the people living remote to civilization would have to take advantage of the ways of the native people and eat like them. In this way, they would be carnivores by need, as fishing, hunting, and eating trapped animals would be the best way to get a meal, and animals can be processed down into high fat pemmican to get the best bang for the buck when it comes to transporting fuel as weight.
Understanding the early development of anatomically modern humans through fossils.
Evidence where harm or nutritional deficiencies occur with diets restricted of animal products. A very general hypothesis that states that eating more plants, whether in famine, or addiction, cause more disease. Metabolic, hormonal, anti-nutrients.
The study of diseases suffered by the dead and discovered through looking at their remains, mostly bones. Nutritional deficiencies, chronic disease, and pathogens are visible on bones.
Facultative Carnivore describes the concept of animals that are technically omnivores but who thrive off of all meat diets. Humans may just be facultative carnivores - who need no plant products for long-term nutrition.
The carnivore diet involves eating only animal products such as meat, fish, dairy, eggs, marrow, meat broths, organs. There are little to no plants in the diet.