> Too much protein can definitely kill you, or at least make you ill, as discovered by the Europeans who explored the northern parts of America and who had initially tried to live from the meat of hunted animals, until they learned from the natives that they must eat enough fat besides the lean meat, in order to survive (most wild animals have little fat, except the bone marrow, which must be extracted).
That's an issue of too little fat, not too much protein. The question is whether, when your other nutritional needs are being met, an excess of protein is an issue.
No, it was too much protein, not too little fat, because they had to eat a lot of meat from hunting to provide enough calories, as they did not carry with them enough food containing starch and/or fat that could provide calories from other sources than protein.
It does not matter if most of the calories (i.e. more than two thirds) are provided by carbohydrates or by fat, as long as they are not provided by protein.
Fat was the solution for living far in the north because they did not have plant cultures that could provide carbohydrates.
Both the amount of fat and the amount of carbohydrates eaten in a day can vary in a very wide range without causing health problems, while the protein intake must be in a relatively narrow range to avoid problems. When eating fat with the right composition, i.e. from sources rich in essential fatty acids and in fat-soluble vitamins, something like at most 40 grams per day should be enough, so it is unlikely for someone to suffer from eating too little fat.
Do you have any sources for this? I have also heard of rabbit starvation many times over the years, and it has always been in the context of too taking in too little fat -- essential fatty acids -- as well, due to the extreme leanness of the meat.